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General Category => General Discussion => Topic started by: rusty rotor on September 13, 2021, 12:50:10 PM

Title: PHM40 mysteries and magic
Post by: rusty rotor on September 13, 2021, 12:50:10 PM
Mysterious to me anyway.

Context: '78 LMI, big bore, big valves, ported, polished, Dyna, dual plugs, etc. A Hecht beast.

Everything fresh by a Gooz resto pro. New Dyna, coils, cables, wires, plugs, hoses, petcocks, you name it. Full carb rebuild, or so I'm told, this guy has some very weird ideas about how to refresh a bike.

Had issues with carburetion when the bike was first delivered. Oh and it was dumping fuel out of the carbs. Back it goes, the old-style floats got filed or dremeled or something, as they were 'swollen' and sticking.
Then another round of carb tuning.

Get the bike back and everything is 'pretty good', until I finally get it on the freeway and discover rough running on steady throttle at 70mph-ish, also and especially when you whack the throttle.

Now the bike seems to fairly quickly detuning itself. Starting to run rougher, and bogging pretty strongly when you smack open the slides. Smooth and gentle inputs all the time result in 99.9% smooth running. What fun is that!
Right pipe a little smoky, right tip a little sooty, left side clean.

Weirdly, this bogging on acceleration seems to be intermittent. I can't reproduce it every time.

And just to add a pinch of fun, as I do this I hear some knock from the left cylinder only. But this bike has always done this. Huh?

Start with the low end needle? Are these screws inclined to move by themselves? I twiddled em, carefully putting them back where they were, and I notice one moves very freely and the other has some resistance.
Title: Re: PHM40 mysteries and magic
Post by: guzzisteve on September 13, 2021, 01:09:09 PM
Have you re-torqued the heads & reset valves since getting it back? Might be time. If you have the chromemoly pushrods it is .002" in & ex. Screws don't move on their own. There is an accelerator pump jet, make sure it's a #38 and squirts across the room.
Title: Re: PHM40 mysteries and magic
Post by: rusty rotor on September 13, 2021, 01:16:14 PM
Have not, it's been under 500mi. I (ahem) expect that was all done, but am finding my mileage to vary if you know what I mean.

Sorry to bother, anyone have the sheet with the torques?
Title: Re: PHM40 mysteries and magic
Post by: Antietam Classic Cycle on September 13, 2021, 01:33:10 PM
Mysterious to me anyway.

Context: '78 LMI, big bore, big valves, ported, polished, Dyna, dual plugs, etc. A Hecht beast.

Everything fresh by a Gooz resto pro. New Dyna, coils, cables, wires, plugs, hoses, petcocks, you name it. Full carb rebuild, or so I'm told, this guy has some very weird ideas about how to refresh a bike.

Had issues with carburetion when the bike was first delivered. Oh and it was dumping fuel out of the carbs. Back it goes, the old-style floats got filed or dremeled or something, as they were 'swollen' and sticking.
Then another round of carb tuning.

Get the bike back and everything is 'pretty good', until I finally get it on the freeway and discover rough running on steady throttle at 70mph-ish, also and especially when you whack the throttle.

Now the bike seems to fairly quickly detuning itself. Starting to run rougher, and bogging pretty strongly when you smack open the slides. Smooth and gentle inputs all the time result in 99.9% smooth running. What fun is that!
Right pipe a little smoky, right tip a little sooty, left side clean.

Weirdly, this bogging on acceleration seems to be intermittent. I can't reproduce it every time.

And just to add a pinch of fun, as I do this I hear some knock from the left cylinder only. But this bike has always done this. Huh?

Start with the low end needle? Are these screws inclined to move by themselves? I twiddled em, carefully putting them back where they were, and I notice one moves very freely and the other has some resistance.

Why don't you just come right out and say who worked on it Jose/Jerry?

I'll "out myself": I worked on this Le Mans for him, the first time was in January and I had a one-day, 50 degree, window where I could test ride it, put 40 trouble-free miles on it. Delivered it to him, he rode it around his neigborhood, all seemed well. But as warmer weather arrived, he was complaining about the bogging issue, so he bought it back here. Floats (replacement white ones) had expanded and were dragging on the carb body. I trimmed them slightly so that they moved freely (since no better replacements are available), went down one size on the idle jets, test rode it 150 miles over the next several days, in every type of environment (backroads, town, interstate, etc.) and all was well. No "bogging".

Whenever a bike I've never worked on before comes into the shop, I do "everything": head retorque, valve adjustment (to Manfred's specs. in this case), check tightness of every fastener on the bike - all in addition to the repairs or modifications asked for by the customer. I corrected a lot of issues on this Le Mans.

There was no "knock" at any time when the bike was here, and it not being present, I could have never said it had always done it.

Title: Re: PHM40 mysteries and magic
Post by: rusty rotor on September 13, 2021, 01:53:57 PM
Well, it's very simple. The forum rules are clear, and my exactingly factual observations about the results of your work could be construed to be in violation of those rules.

Plus this is your livelihood. To me this all seems to be an awfully small thing to mess with a guy's, an individual uniquely skilled craftsman's, livelihood. What you do, is you don't do business with that person again.
You, or at least I, don't flame that craftsman or as you say "out" him.

I will say this:

The electrics that you redid from stem to stern seem impeccable and they are in fact awesome. All the hoses cables controls etc, ditto.

After that, things become less rosy, (cough, braking, cough) and in point of fact, the bike is quickly losing tune, and was never tip top.

And yeah, this bike has always, as in before, long before Antietam, demonstrated some knock on the left side.

As I say, mysterious to me. Maybe Manfred had a twitch in his wrist.
Title: Re: PHM40 mysteries and magic
Post by: guzzisteve on September 13, 2021, 02:19:59 PM
I usually go 3-5 heat cycles, so quickest is around 50mi. 32ft lbs is torque. Check pushrods w/magnet to see if steel.
Title: Re: PHM40 mysteries and magic
Post by: Antietam Classic Cycle on September 13, 2021, 02:27:05 PM
I usually go 3-5 heat cycles, so quickest is around 50mi. 32ft lbs is torque. Check pushrods w/magnet to see if steel.

Steve,

This bike has already been well beyond "3-5 heat cycles" - as I wrote above, I retorqued the heads and adjusted the valves the first thing when I began working on it. I did it again when it was here the second time, to rule it out as a factor in the "bogging". The first time the head nuts were found to be tightened to spec., but the valves out a bit (right intake was at .004" and the left exhaust was the same). Pushrods are steel, so all adjusted to .002". Second time nothing had moved - not surprising given that it hadn't done many miles.   
Title: Re: PHM40 mysteries and magic
Post by: Antietam Classic Cycle on September 13, 2021, 02:44:58 PM

I will say this:

The electrics that you redid from stem to stern seem impeccable and they are in fact awesome. All the hoses cables controls etc, ditto.

After that, things become less rosy, (cough, braking, cough) and in point of fact, the bike is quickly losing tune, and was never tip top.

And yeah, this bike has always, as in before, long before Antietam, demonstrated some knock on the left side.

As I say, mysterious to me. Maybe Manfred had a twitch in his wrist.

The mystery to me is how a bike that runs perfectly well over the course of 150 miles of different conditions, can be "never tip top". Maybe I'm supposed to ride it 500 miles (all non-billed hours BTW). I am very exacting about how a bike runs and can feel when something isn't right, even when a customer may not be able to.

Braking? You mean that the bouncy ride home in a U-Haul trailer dislodged an air bubble somewhere in the brake system and you had to bleed it? Despite me bleeding the brakes extensively, pushing the caliper pistons in to remove any air there and tying the lever back overnight to allow any bubbles to escape, it still happened. Not sure what more I could have done. 
Title: Re: PHM40 mysteries and magic
Post by: guzzisteve on September 13, 2021, 03:37:40 PM
My LM3 would be changing sync on carbs every time I rode it, the quick change levers on the tops. In a few days it would run the same, nature of the beast. Using the normal carb top is a better set-up. I lived w/it and new cables made it worse.
Title: Re: PHM40 mysteries and magic
Post by: rusty rotor on September 13, 2021, 03:42:51 PM
Mr. Mullendore:

What you’re perpetrating here is a completely unsolicited and unhelpful hijacking of a request for assistance with carburetion.

If you really want to argue with me, you have my number.

Otherwise…
Title: Re: PHM40 mysteries and magic
Post by: Antietam Classic Cycle on September 13, 2021, 04:09:21 PM
Mr. Mullendore:

What you’re perpetrating here is a completely unsolicited and unhelpful hijacking of a request for assistance with carburetion.

If you really want to argue with me, you have my number.

Otherwise…

Not arguing. Putting the facts out there that others might need to help diagnose your issue. And to defend myself when you make comments like this: "this guy has some very weird ideas about how to refresh a bike".
Title: Re: PHM40 mysteries and magic
Post by: jwinwi on September 13, 2021, 04:19:52 PM
Mr rotor:
Did you disassemble the carburetors or any other part of this bike after you got it back from Charlie the last time?
Title: Re: PHM40 mysteries and magic
Post by: Tony F on September 13, 2021, 05:14:04 PM
Is the right hand coil the issue? Try another coil or swap the coils side to side and see if the pipe and plug symptoms follow. This does remind me of an issue (a long story but..) I had many years ago, a coil was breaking down when it got hot. Very difficult to track down what was going on and only proved when after two hours on a coil tester the coil stopped sparking.
Title: Re: PHM40 mysteries and magic
Post by: rusty rotor on September 13, 2021, 07:10:05 PM
I have studiously avoided futzing with the carbs. They constitute a known unknown to me.

And I really thought it was ok. Only after I got it up to highway speeds did I see the symptoms I’m describing.

Since then there’s been a noticeable slide in performance around town, similar to what I saw on the freeway.  Can’t think of a reason to expect it to be any better on the highway now.

I AM interested in jetting. But am working under the assumption that jetting is very much in the ballpark, or it would never have run well in the first instance.

My shocking observation is that something’s changed and may be continuing to change.

My ask is for help through that process.
Title: Re: PHM40 mysteries and magic
Post by: guzzisteve on September 13, 2021, 08:00:03 PM
I'd check the valves, .002" isn't much to tighten up when hot, round town driving.
Title: Re: PHM40 mysteries and magic
Post by: rschrum on September 13, 2021, 08:22:06 PM
Brake problem is obviously rusted rotors.
Title: Re: PHM40 mysteries and magic
Post by: Motorad64 on September 14, 2021, 01:37:43 PM
Rusty-

Intermittent, under-load carb problems in my past have frequently been traced to ignition system issues: coil, wires/caps, condensers.  I sourced a NOS coil for one of mine that was swollen/rattly on my LM1 and am careful not to leave the ignition 'on' when not running to avoid overheating.  Have heard the Dyna's can be sensitive to that, too. 

I also went to double fuel-banjos from single after some starvation issues on an experts suggestion that really helped a mid range stumble.  Just had an intermittent running issue on my BMW R69s turnout to be a failing condensor.  Might be worth checking. 

My setup has stock 850 cyls, stock PHF36s with some mild port work, a V7 Sport cam, Lafranconis with stock headpipe diam and lightened flywheel.  It's jetted richer than stock care of the prev owner w/ 152 mains, 62 idle 70 starter and K5 needles.   Stock ignition.  Carburetes great across the rev band.  Just pulls smoothly from idle to redline.   Whacks of throttle at midrange give a nice, solid surge.  Zero pinging and good looking spark plugs. 

Good luck getting to the bottom of it.

Title: Re: PHM40 mysteries and magic
Post by: Motorad64 on September 14, 2021, 01:43:48 PM
Meant to add...have recently had a partial-plugged main jet from random gas/tank schmutz throw my old BMW off it's game.  Made it feel like I was running on 1 1/2 cylinders.  And I guess it was. 

I usually drain/clean my carb bowls at the end and beginning of riding season, but can happen anytime.  So another +1 to dropping and cleaning carb bowls/jets and making sure some detritus didnt find it's way to one of your jets.  Luckily that's super easy on these bikes. 
Title: Re: PHM40 mysteries and magic
Post by: Stevex on September 14, 2021, 03:04:56 PM
I've never heard a good thing said about those white replacement carb floats.
Luckily my LM2 is still using the originals.
Title: Re: PHM40 mysteries and magic
Post by: lazlokovacs on September 14, 2021, 06:44:07 PM
just a thought, cable adjuster backing backing itself off?

Those widdly 8mm nuts can wander....

Title: Re: PHM40 mysteries and magic
Post by: Scout63 on September 14, 2021, 07:03:51 PM
I'd start with plugs and wires and work back to the coils.  Then check valves and timing.  Then carbs.  I don't know PHM's, but most carbs stay in pretty good tune if set up right and used regularly (Norton Concentrics excepted of course).  Good luck with the diagnosis.  If all else fails, ship the bike to 12 Shore View Drive in Orleans MA with the title signed in blank and I'll get it running right eventually.
Title: Re: PHM40 mysteries and magic
Post by: Antietam Classic Cycle on September 14, 2021, 09:58:05 PM
I'd start with plugs and wires and work back to the coils.  Then check valves and timing.  Then carbs.  I don't know PHM's, but most carbs stay in pretty good tune if set up right and used regularly (Norton Concentrics excepted of course).  Good luck with the diagnosis.  If all else fails, ship the bike to 12 Shore View Drive in Orleans MA with the title signed in blank and I'll get it running right eventually.

I replaced the plug wires (solid core Belden), caps (NGK) and outer plugs (NGK also) but not the inners (dual plugged). I don't know how many miles Jerry has put on it since it was here, but I set the valves and timing (new Dyna III ignition) then. 
Title: Re: PHM40 mysteries and magic
Post by: John A on September 14, 2021, 10:19:57 PM
On a modified 43 year old bike it can take some chasing.  So many variables to check. I’ve had float needles that were perfect but would intermittently stick closed. I found that by putting on clear float bowels and watching them as I was blasting down the hiway. Stuff like that makes you want to wander in the wilderness.
Title: Re: PHM40 mysteries and magic
Post by: Scout63 on September 14, 2021, 10:21:49 PM
How did the tank look?  Maybe something clogging a float needle?
Title: Re: PHM40 mysteries and magic
Post by: Antietam Classic Cycle on September 14, 2021, 10:25:38 PM
just a thought, cable adjuster backing backing itself off?

Those widdly 8mm nuts can wander....

The PHMs have bellcrank tops, no adjuster except the one in the cable, at the throttle (2C).

How did the tank look?  Maybe something clogging a float needle?

No rust inside when it was here. Has inline "Visu-filters". 
Title: Re: PHM40 mysteries and magic
Post by: huub on September 14, 2021, 11:54:48 PM
personally i would change coils plugs etc, and bring it to a carb specialist with a dyno.
a few runs on a dyno can pinpoint any issues with the carbs, to get the same info you will spend days swapping jets and needles and checking plugs.
it is just not worth the efford if you cant do it yourself and enjoy tinkering wit carbs.
Title: Re: PHM40 mysteries and magic
Post by: lucian on September 15, 2021, 06:46:28 AM
It sounds to me like your carbs are out of sync. You mentioned one pipe is sooty . Have you tried pulling off one plug cap while idling and and seeing if ,or how long it will run on the opposite side? Do the same on the other side, if one side is continuing to run longer/stronger than the other ,they are out of balance and need to be re synced.
Title: Re: PHM40 mysteries and magic
Post by: Scout63 on September 15, 2021, 10:16:53 AM
Maybe switch plug leads from one side to the other and see if the problem shifts?

I know that I am a boy among men in this discussion.
Title: Re: PHM40 mysteries and magic
Post by: moto on September 15, 2021, 11:45:28 AM
Has the owner tried operating the choke and/or the fuel petcock at 70 mph to determine if he is lean or rich there? From the Dellorto Guide:

Quote
3.6.5 Selection of the correct size of main jet
The correct main jet size should be selected by running on the road, preferably by first starting with an over-large size jet and gradually reducing it.
At full throttle, turn the starting device (choke) on, thus further enriching the mixture and, if this produces a worsening in engine running ie. it reduces engine rpm, it is advisable to reduce the main jet size until you finally get satisfactory operation.
Other signs revealing the main jet is too big are a very dark exhaust pipe, dark exhaust gases and damp spark plugs and an improvement in engine running when the fuel supply is temporarily shut off.
In a case where too small a main jet has been fitted at first, and the running with the choke on makes a noticeable improvement, you should increase the main jet size until the conditions mentioned above occur.

Contrary to implication of the section title and the recommendations for changing main jet sizes, the method really applies at any steady throttle opening. The Guide asserts earlier that the atomizer/needle combination determines the mixture from 1/4 to 3/4 throttle, which is where this bike would be operating at a steady 70 mph. So the results of the method applied at a steady 70 mph would implicate the atomizer/needle combo rather than the main jet.  (From the Guide, section 2.2: "In the "D" period of full throttle and, with all the circuits of the earlier periods operating correctly, the size of the main jet is now finally selected.") If the method shows a lean mixture, the correct response would be to raise the needles in the slides by one notch and try again. If rich, drop them one notch and try again. If moving the needle in the required direction is not possible, either a different needle or a different atomizer jet would be the next step.

The combination of rough running at a steady 70 mph and bogging when the throttle is whacked open at the same speed suggests leanness there to me. It is really important that the bike should not be running lean at 70 mph. The owner should take the responsibility of completing this very simple diagnostic procedure requiring no tools.

Since the owner said new "Dyna, coils, cables, wires, plugs" were included in Charlie's refresh, I wouldn't expect an electrical problem. Except maybe a loose connector or spark plug wire. Has the owner fiddled with any of those?

Moto
Title: Re: PHM40 mysteries and magic
Post by: rusty rotor on September 15, 2021, 07:57:55 PM
Thanks for that.

I have checked every spark plug cable, coil wire, fuel line.

Chokes not present on these carbs. Tickle 10x, crank the fast handle 10x, fires right up.

Oh and another symptom: sputtering and a little backfire from the right side which is the slightly smoky sooty side.
Title: Re: PHM40 mysteries and magic
Post by: rusty rotor on September 15, 2021, 08:17:02 PM
Oh and, can someone recommend a nice straightforward and last-forever carb sync tool?
Title: Re: PHM40 mysteries and magic
Post by: moto on September 15, 2021, 09:18:50 PM
Thanks for that.
...
Chokes not present on these carbs. Tickle 10x, crank the fast handle 10x, fires right up.
....

You don't need an actual choke. At 70 mph, hold down the tickler(s) That will raise the gas level in the float bowl(s) and richen the mixture. See if the motor runs stronger then, indicating you were too lean. (You can probably get away with doing one tickler if doing both at the same time, at 70 mph, makes you nervous. But doing both would be better. Practice your moves first in your garage.)

It's the same in reverse for the other test. No special tool is needed. Just close the petcock at 70 mph, which will make the mixture leaner as the gas level in the float bowl decreases. If the motor runs stronger when you do this, you were too rich.
Title: Re: PHM40 mysteries and magic
Post by: Scout63 on September 15, 2021, 09:35:22 PM
You don't need an actual choke. At 70 mph, hold down the tickler(s) That will raise the gas level in the float bowl(s) and richen the mixture. See if the motor runs stronger then, indicating you were too lean. (You can probably get away with doing one tickler if doing both at the same time, at 70 mph, makes you nervous. But doing both would be better. Practice your moves first in your garage.)

It's the same in reverse for the other test. No special tool is needed. Just close the petcock at 70 mph, which will make the mixture leaner as the gas level in the float bowl decreases. If the motor runs stronger when you do this, you were too rich.

Great advice and very interesting to remember Moto.
Title: Re: PHM40 mysteries and magic
Post by: moto on September 16, 2021, 04:54:20 PM
Thanks, Scout.

Another simple thing to try is replacing the inner spark plugs. Charlie said he did not replace them, though he didn't say why. Even if they looked very good, you can never tell about spark plugs and they are cheap enough to replace for diagnostic reasons.
Title: Re: PHM40 mysteries and magic
Post by: rusty rotor on September 16, 2021, 08:24:01 PM
I’m imagining myself fumbling for the ticklers at 70mph.

Sounds trickier than my first brassiere, with infinitely worse adverse consequences.

I like and appreciate the advice…how do i deconflict the fact that one side is smoky/sooty, one clean?

Because right now I can easily envision one side is lean and the other rich. Which would confound my result, no?
Title: Re: PHM40 mysteries and magic
Post by: nc43bsa on September 16, 2021, 08:32:05 PM
First thing I would recommend is to verify the fuel levels in both carbs are the same.  Clear float bowls are the easiest/best way to confirm this.
Title: Re: PHM40 mysteries and magic
Post by: moto on September 16, 2021, 08:57:49 PM
..
Because right now I can easily envision one side is lean and the other rich. Which would confound my result, no?

It's it's probably better to test each side separately, given the concern you mentioned. You should be able to perceive the result for each side.

Nc43bsa's suggestion is excellent.
Title: Re: PHM40 mysteries and magic
Post by: berniebee on September 16, 2021, 09:19:24 PM
Thanks for that.

I have checked every spark plug cable, coil wire, fuel line.



The best check for ignition parts is substitution or swapping sides. An incorrect resistance measurement definitely identifies a bad component but unfortunately a correct resistance is not a guarantee of a good part.  Swapping the coils, plugs, caps and wires left to right is easy to do. (Well maybe not the wires...) Sometimes new parts go bad quickly. 

A quick check: Take the carb float off the sooty side and check to see if it has leaked- Ie: shake it, does it have fuel inside?
Title: Re: PHM40 mysteries and magic
Post by: rusty rotor on September 19, 2021, 02:54:16 PM

Just got off the bike. Quick reminder, LMI Manfred, big everything. PHM40’s acting up. Or something.

Just as an aside, was behind another bike for miles. You know the type, rear tire that would look at home on a funny car. He was wearing all the gear, all the HD-branded gear.
And sandals. Hey at least they weren’t flip flops.

Speaking of ignorant, I went ahead and started to futz with the carbs today.

First I baselined and took notes.

Before I get into all that, a couple of observations:

The right side carb spews gas when you tickle it aggressively. Sometimes. I didn’t know this was happening as I tickle hunched over on the left side, it just happened today that my hand got spattered with fuel. Squirt squirt squirt from a tiny port above the tickler. What’s that mean? Left side dry.

The right side double banjo may not be seeing full flow. I looked down while stopped at a light and happened to be watching as a big glug of gas moved through the back hose.

The left side petcock may not be delivering fuel adequately as the left side filter is only sometimes full of fuel. The right side seems fine. Both brand new.

So, baselines:

Idle mix screw
RH out 2.25
LH out 2.20

Today I turned each one out one full turn. This upped idle speed to about 1100. Why? Why the hell not.

Rode the bike, and it seemed noticeably better, though a little rough and sputtery on steady throttle or just off throttle, mainly on the right side.

Pulled over, set the petcocks to reserve in case there’s a blockage that might help with. Didn’t see any difference in fuel flow.

Baselined the idle speed adjuster screw. 

RH was 5 turns out
LH was 5.5 turns out

Turned the left side out 1/2 turn. Why? Because it’s there.

That took the idle up to 1400 fully hot, but the bike ran better.

Still seeing intermittent less severe bogging when cracking the slides hard, but then it grabs and goes hard.

Oh and I seem to have made the detonation in the left side worse. It still takes a handful of throttle to produce it, but it seems louder and more aggressive. It’s pretty bad so I back off right away. Sigh. Better get the tool to do a leak-down test.

In case it's the floats, are there any NOS floats out there somewhere?

One of the vendors of transparent float bowls states to never install them permanently. That accurate? They only a diagnostic tool?

Where do I go from here?

Title: Re: PHM40 mysteries and magic
Post by: rusty rotor on September 19, 2021, 03:16:06 PM
Oh and, temperatures are a solid 15-20F lower than they have been. Just to make things more interesting.
Title: Re: PHM40 mysteries and magic
Post by: John A on September 19, 2021, 09:56:37 PM
Oh and, temperatures are a solid 15-20F lower than they have been. Just to make things more interesting.




Yep, an engine that’s stepped on is more sensitive to ambient conditions.  That’s what makes it interesting sometimes
Title: Re: PHM40 mysteries and magic
Post by: nc43bsa on September 19, 2021, 10:54:04 PM
Before I get into all that, a couple of observations:

The right side carb spews gas when you tickle it aggressively. Sometimes. I didn’t know this was happening as I tickle hunched over on the left side, it just happened today that my hand got spattered with fuel. Squirt squirt squirt from a tiny port above the tickler. What’s that mean? Left side dry.

Keep in mind what the tickler does;  it pushes the float down to allow more fuel into the bowl than the float would by itself.

So, if using the right tickler produces a gush of fuel out of the bleed hole and using the left tickler does not, what does that mean?  It means the fuel level in the right carb is higher than the level in the left carb, BEFORE the tickler is used.

Until you verify the correct fuel levels in both carbs, you'll be chasing your tail 'til the cows come home.

<edit>  I went back and read the original post: "Right pipe a little smoky, right tip a little sooty, left side clean."

Another indication the right fuel level is higher than the left.  Higher fuel level = richer mixture
Title: Re: PHM40 mysteries and magic
Post by: moto on September 19, 2021, 11:48:14 PM
Keep in mind what the tickler does;  it pushes the float down to allow more fuel into the bowl than the float would by itself.

So, if using the right tickler produces a gush of fuel out of the bleed hole and using the left tickler does not, what does that mean?  It means the fuel level in the right carb is higher than the level in the left carb, BEFORE the tickler is used.

Until you verify the correct fuel levels in both carbs, you'll be chasing your tail 'til the cows come home.

<edit>  I went back and read the original post: "Right pipe a little smoky, right tip a little sooty, left side clean."

Another indication the right fuel level is higher than the left.  Higher fuel level = richer mixture

As you pursue nc43bsa's excellent deduction, remember there are two ways the right bowl can have a higher fuel level: mis-adjustment  of the tab on the lever; or one of the floats in the right carburetor may be full or nearly full of gas, causing it to float lower in the gas pool and so allowing the gas level in the bowl to rise. My bet is the latter. You can check for this by shaking the floats, after removing them. You can also use sensitive scales to compare the total weight of the right carburetor floats with that of the left ones.

Of course if you have the transparent float bowls, you can compare the levels directly.

EDIT: Here is the document showing how to set the floats on your PHM carburetors: https://www.thisoldtractor.com/dellorto_setting_the_float_height_on__carburetors.html (https://www.thisoldtractor.com/dellorto_setting_the_float_height_on__carburetors.html)
Title: Re: PHM40 mysteries and magic
Post by: rusty rotor on September 20, 2021, 01:02:19 PM
You guys rock. Thank you for the help.

I'll be working on those floats.

I've found Dellorto brand black plastic floats for PHM40. It is the white ones that suck, yes? New black ones all good?

Also, have I said anything here that indicates the floats may not be the right weight (is it weight, flotation?)? I ask as the vendor lists four weights.

I never really appreciated how well-carbureted this bike was, till now.
Title: Re: PHM40 mysteries and magic
Post by: moto on September 20, 2021, 01:57:26 PM
It has been said for many years that Dellorto black floats are no longer being manufactured. Sometimes vendors show products on their websites that are not available. You might want to confirm availability before ordering. If you do find new Dellorto black floats please let us know where, after satisfying your need.

I don't know the proper float weight specification for your carburetors. You can read the weight in grams on your current floats, cast into the plastic. I'd go with that, but only after having confirmed there is a weight discrepancy in your current set of floats.

Since the float height specification is given as a physical measurement of the float as it sits in the empty carburetor body, there is no allowance for an incorrect float weight. Floats that are too light or too heavy will sit incorrectly on top of the pool of gasoline, too high or too low, causing leanness or richness, respectively.

EDIT: It is just conceivable that the manufactured weights of the floats in the two carburetors differ, with the right one heavier. Easy to check. Nearly unimaginable, though, given who worked on it.
Title: Re: PHM40 mysteries and magic
Post by: Antietam Classic Cycle on September 20, 2021, 04:13:53 PM
The white floats are all 8.5 grams.
Title: Re: PHM40 mysteries and magic
Post by: moto on September 20, 2021, 08:59:26 PM
The white floats are all 8.5 grams.

I believe it. It's all I've seen.

The original float weight specifications are a mystery to me. The T3 and other contemporary Tonti's had 10 gram floats, per the Haynes manual. The factory workshop manual agrees. Mine still has the originals, I guess, in a dark olive color.

The Haynes manual, using the T3 as its subject, gives separate height specifications, 1mm apart, for the 10g and 14g floats. As makes sense, the 14g floats are set to run deeper in the bowl (a greater measured height specification).

The Dellorto Guide says its floats:

"are usually available with two different weights:
   • a light float to obtain a low level (for two-stroke engines)
   • a heavy float to produce a higher level (for four stroke engines)"

EDIT: Note the implication here is that the light or heavy float would be used with the same height specifications, contrary to the practice illustrated in the Haynes manual, where two different-weight floats could be substituted for each other by changing the height.

I don't know if the 8.5g float now available in white would have been intended for two-stroke engines, since it is lighter than the 10g stock unit in the T3. (The V700 had a 14g float, per either the Chilton or the Haynes manual.)

I conclude that using a lighter-than-original 8.5g float would produce a somewhat lean mixture across a lot of the throttle range, maybe mostly toward the lower end. Probably this would be compensated for (if at all) by using larger pilot jets or raising the needle. Alternatively, the float height specification could be decreased, to let them run higher in the gas pool. Maybe by less than 1mm.

As for the original poster's problem, of course, the main thing he should work on now is to make sure both sides are the same.
Title: Re: PHM40 mysteries and magic
Post by: Antietam Classic Cycle on September 20, 2021, 10:13:06 PM
I believe it. It's all I've seen.

Seems they are available in 10 gram and heavier as well - just saw some on Stein-Dinse. Still crappy white floats though...
Title: Re: PHM40 mysteries and magic
Post by: rusty rotor on September 21, 2021, 09:25:24 AM
Acquired Dellorto manuals and sync tool.

Am likely to shotgun the floats, something’s up w them.

$200 for floats!? Ouch.
Title: Re: PHM40 mysteries and magic
Post by: moto on September 21, 2021, 11:37:34 AM
This is general information about the floats (same for the PHM and the VHB), from DellortoShop.com:

Quote
This is the double float for the Dellorto PHM carburetors.

Originally, these came only in the early style, black, style with metal linking arm but these have been phased out in favor of the, new, white version.

Please choose the replacement for your defective float according to the part-number on your original.

Available in the following versions:

7450.1 8.5 gram white - replaces 7450.1 10 gram black
7450.2 12.5 gram white - replaces 7450.2 14 gram black - Sold out at the moment
You can order this size but the delivery time is unknown at this moment
7450.3 6,5 gram white - replaces 7450.3 7.5 gram black
Required quantity per carburetor: 1
...
Dellorto Part Number: 7450

So there were originally weights of 7.5, 10, and 14 grams in the "black" model, each replaced by a lighter version -- 6.5, 8.5, and 12.5, respectively -- in the white version (according to the site, at least).

Why the change in weights? It couldn't have been to make all the carburetors run leaner. Instead, it must be that the center of mass of the original floats with their brass linking arms is closer to the pivot, so the effective weights of the original and newly-recommended replacements are approximately the same.

The OP should try to determine the original float weight for his PHMs and proceed accordingly.

Moto

P.S. Stein-Dinse lists the same white floats of 6.5, 8.5 and 12.5 grams as found at DellortoShop.com.
Title: Re: PHM40 mysteries and magic
Post by: rusty rotor on September 21, 2021, 02:51:43 PM
My Dellorto shop states unequivocally that the white float failure thing is not just overblown but vastly so.

He tells me failures exist but are very much the exception not the rule.

Title: Re: PHM40 mysteries and magic
Post by: jwinwi on September 21, 2021, 03:06:04 PM
My Dellorto shop states unequivocally that the white float failure thing is not just overblown but vastly so.

He tells me failures exist but are very much the exception not the rule.

 :popcorn:
Title: Re: PHM40 mysteries and magic
Post by: rusty rotor on September 21, 2021, 08:41:18 PM
Do go on
Title: Re: PHM40 mysteries and magic
Post by: Kiwi_Roy on September 21, 2021, 10:22:32 PM

Now the bike seems to fairly quickly detuning itself. Starting to run rougher, and bogging pretty strongly when you smack open the slides. Smooth and gentle inputs all the time result in 99.9% smooth running. What fun is that!
Right pipe a little smoky, right tip a little sooty, left side clean.

Weirdly, this bogging on acceleration seems to be intermittent. I can't reproduce it every time.
 
I have an electrical background so I always blame electrical first, weak spark can cause bogging as you open the throttle the denser air in the cylinder makes it harder for the spark to jump the gaps. here's a simple test you can do
Measure the resistance  from cap to cap each side, this will be the sum of caps, leads and coil. of the coils.
Compare one side against the other, since you have twin plugs it will be from one plug cap to the other plug cap. I'm guessing about 8,000 Ohms each side. Do you have resistor caps, you shouldn't have resistor leads. What plugs do you have, they shouldn't have an R in the part number if you have resistor caps
If you notice any difference side to side please post all the component part numbers.
Plug
Coil
Caps
I hope you didn't replace the condensers during the refresh process, the condenser is a critical part of producing a spark and modern condensers are CRAP, you are better off with a 40 year old one when they knew how to make them properly, yours should be engraved with a decent manufacturers name, not some generic M.I.C.
Title: Re: PHM40 mysteries and magic
Post by: Antietam Classic Cycle on September 22, 2021, 08:39:42 AM
I have an electrical background so I always blame electrical first, weak spark can cause bogging as you open the throttle the denser air in the cylinder makes it harder for the spark to jump the gaps. here's a simple test you can do
Measure the resistance  from cap to cap each side, this will be the sum of caps, leads and coil. of the coils.
Compare one side against the other, since you have twin plugs it will be from one plug cap to the other plug cap. I'm guessing about 8,000 Ohms each side. Do you have resistor caps, you shouldn't have resistor leads. What plugs do you have, they shouldn't have an R in the part number if you have resistor caps
If you notice any difference side to side please post all the component part numbers.
Plug
Coil
Caps
I hope you didn't replace the condensers during the refresh process, the condenser is a critical part of producing a spark and modern condensers are CRAP, you are better off with a 40 year old one when they knew how to make them properly, yours should be engraved with a decent manufacturers name, not some generic M.I.C.

It has solid-core Belden leads, NGK resistor caps and non-resistor plugs, (new) Dyna III ignition and green coils.
Title: Re: PHM40 mysteries and magic
Post by: pressureangle on September 22, 2021, 10:30:26 AM
So who has checked the charging voltage?

My LM1000 had all these precise symptoms- when the battery ran down a bit. Between a good headlight and the dyna ignition, the charging system was too weak to keep up. I put a Euromotoelectric system on it and everything became shiny.
Title: Re: PHM40 mysteries and magic
Post by: rusty rotor on September 22, 2021, 04:01:48 PM
That’s actually a fascinating idea. I dont understand how it would work, but interesting anyway.

Plus the battery is always nice and strong, however unscientific that is.
Title: Re: PHM40 mysteries and magic
Post by: Antietam Classic Cycle on September 22, 2021, 05:51:20 PM
So who has checked the charging voltage?

My LM1000 had all these precise symptoms- when the battery ran down a bit. Between a good headlight and the dyna ignition, the charging system was too weak to keep up. I put a Euromotoelectric system on it and everything became shiny.

Rusty's Le Mans has a new (ETX30L) battery, solid state voltage regulator and Grote LED headlight (and taillight, signals, gauge illumination bulbs and warning light). Charging output was checked and output was 14.2 max.