Ambo won't stay running - advice?

[neetones]

Hi all.

I just went through this very new to me 69 Ambassador with Gilardoni cylinders. Here's what I did:

- rebuilt carbs, set screws to factory recommended settings, set initial slide sync with drill bits, checked throttle play
- changed all fluids, cleaned sludge from oil pan
- new spark plugs
- set distributor up based on factory specs, cleaned points
- checked generator belt tension
- rebuilt petcocks
- set valve clearances

So now I can get it to start on full choke but it will soon die even if it stays on choke. Won't start at all without full choke.

Here is a video: https://photos.app.goo.gl/BZ7SCLVyzATkFFc3A

Any suggestions?

[Turin]

did you double up on intake manifold gaskets? intakes checked for leaks at the gaskets?

my 69 ambo ended up needing the throttle stop screws and air bleed screws being set differently from recommended specs.

[Tom]

Have you checked the cables and slides?  Set the cables.  After that check the 2 into 1 cable pull canister.  Forgot what it's called.  You'll have to synchronize the slides when they open & close.  Minor tinkering.  You'll have to take the tank off.

[Antietam Classic Cycle]

What size of drill bit did you use to set the baseline slide open with? A 9/32" seems to work best for me.

Did you set the float level to 24 mm +/- .5 mm?

I don't use the choke for starting in warm weather (and rarely even cooler temps), I just twist the throttle twice and start it.

Have you tested fuel flow (hoses disconnected from the carbs, into a container)?

Make sure the vent hole(s) in the gas cap are open.

[neetones]

Thanks all. No air leaks and yes, double gaskets on the intake. Fuel flow is good on both sides.

Set baseline with 9/32" bit and float levels are good.

I did play around with the bleed screws and got it to run for a bit without choke, but it's still sputtering out.

Going to continue to adjust cables and get some even fresher gas for tomorrow's testing. Looks like I might be making some progress.

[Antietam Classic Cycle]

"Bleed screws"? Idle mixture screws? I set those at 2 1/2 turns out to start and adjust for the best idle from there.

You didn't mention what jetting is in the carbs. Stock is 45 idle, 145 main, 268 atomizer, V5 needle with the clip in the middle slot, 60 slide, 80 "choke" jets.

[neetones]

I meant to say mixture screws. I'll try setting them out a bit further than recommended. Any suggestions on where to start with the idle screws?

All other jetting appears to be stock.

[Antietam Classic Cycle]

I meant to say mixture screws. I'll try setting them out a bit further than recommended. Any suggestions on where to start with the idle screws?

All other jetting appears to be stock.

The idle screws (knurled with exposed springs) are what you should have already used to set the slide height with drill bit. The mixture screws (small, recessed into the carb body) are what I set at 2-2.5 turns out. 

[neetones]

This is hugely helpful. Thank you

[neetones]

I was misreading things and trying to set the idle stops via the throttle freeplay. Dummy.

It runs now with no choke but the revs start to run away when I give it some throttle. Time to do a lot of tweaking.

This forum is priceless.

[Kiwi_Roy]

This forum is priceless.

Priceless but not free, we need 

[neetones]

Priceless but not free, we need 

[Turin]

I had to do the same thing last month with my ambo. Carbs were cruddy. I let it sit due to leaky petcocks and a hand injury that left me without a usable thumb for a year. after the rebuild I had the same symptoms. It's just a matter of messing with a screwdriver.




https://www.youtube.com/watch?v=1m9YuXPIXvM

[Tom H]

I see you have it running now I was going to mention that when you install the square slides, the large flat side goes towards the head.

"Runaway"... If you mean you give it a little throttle and then let off, close the throttle grip, the revs keep going for a few moments. I  have noticed that if the air mix screws are set a bit on the lean side, it will do something like this. But........

I would also make certain the cables are working freely (if in doubt, lube them) and do not have any very tight bends in them. Tight bends "can" cause a cable to bind. Also, if you have the cable splitter under the tank, they have been known to gum up and need to be cleaned and lubed. Sometimes just a good spaying where the cables enter the splitter (just pull the cable sheath out of the splitter a bit) with something like WD40 will help.

Just some thoughts,
Tom

[neetones]

Thank you! Runaway throttle solved. Running pretty well now, though I'm sure more tuning will help.

My issue now is that the engine struggles to stay running if I start letting the clutch out in first. I've tried adjusting the tension - ensuring that there's some freeplay. Can't figure it out yet.

Also I've got a pretty good leak coming from what looks like the clutch pushrod seal....I'm going to have to pull the transmission to fix this, aren't I?






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[Antietam Classic Cycle]

Thank you! Runaway throttle solved. Running pretty well now, though I'm sure more tuning will help.

My issue now is that the engine struggles to stay running if I start letting the clutch out in first. I've tried adjusting the tension - ensuring that there's some freeplay. Can't figure it out yet.

Also I've got a pretty good leak coming from what looks like the clutch pushrod seal....I'm going to have to pull the transmission to fix this, aren't I?






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Remember that the shift pattern for this bike is "backwards" - up for 1st and down for the other three.

It's not uncommon for the four-speed to leak from the throw-out bearing outer body area. The outer body is sealed with an o-ring and that could be old and hardened, or there could be a groove worn into the transmission rear cover where it slides in and out. The o-ring can be replacing with am "X-ring" which seals better. If there a groove worn, that's a lot more work - the transmission needs to be removed and partly disassembled, then the bore the outer body slides in sleeved (Patrick Hayes can do that for you).

Someone has substituted a bolt for the clutch arm pivot pin and used button-head screws instead of hex-heads. How "artsy". 

[Tom H]

So how did you solve the overrun?

With what Charlie said about the O ring issue........

I would pull the trans fill plug (or even the oil level plug) and with a screwdriver, stick, Q tip or the like gently slip it into the trans to see what color the gear oil is.

Your pic makes me think it "could" be grease on the bolt (why a bolt????? unless it's a shoulder bolt with a long shoulder) dripping when hot. I guess the gear oil in the trans could drip down that way? Clean the drips/runs off and run it to see where it may be coming from. I would also change out that bolt to the correct "clevis" pin, unless the bolt has a shoulder for the arm to pivot on. You can change the bolt out without removing much. Could be done all from under, but I would consider removing the battery tray and assorted bits for better access.

Just some thoughts,
Tom

[neetones]

I can't believe that my clutch problem was just me trying to pull away in 4th gear. 1 up and 3 down! Solved!

Took my first glorious ride around town at sunset. Transmission is clunky and I'm sure the carbs and timing could be dialed in more, but she runs beautifully.

Tom, it's definitely gear oil. I just changed it and the color is the same. I'll see about replacing that bolt with a pin and look into what it will take to pull the transmission and fix the leak. Thank you for the advice here everyone - especially you, Charlie - you saved me days of blind experimenting. Glad to be learning.


online foto maken

[pehayes]

The oil leak can be solved with the transmission in place.  Remove the swingarm and the throwout system will be fully exposed.  You can replace or improve the o-ring.  Good idea to check the quality of the throwout bearing.  Not a lifetime item.  If the bearing failed in a prior life then it may have torn up the inside of the rear cover bore hole.  That is much more complex to correct.

It was hard to see, but it looks like you do have vacuum ports on the intake manifolds. Can you post a picture?  If you do have vacuum ports then use those to manage the minute adjustment of carb settings.  Using vacuum comparison is much more accurate for balancing and synchronizing the carbs.

Patrick Hayes
Fremont CA

[John A]

Tight valves can cause that.
Edit  not the leaking, the poor running

[guzziart]

It's not uncommon for the four-speed to leak from the throw-out bearing outer body area. The outer body is sealed with an o-ring and that could be old and hardened, or there could be a groove worn into the transmission rear cover where it slides in and out. The o-ring can be replacing with am "X-ring" which seals better. If there a groove worn, that's a lot more work - the transmission needs to be removed and partly disassembled, then the bore the outer body slides in sleeved (Patrick Hayes can do that for you).

Hey Charlie,
Can the the x-ring be used on Loop/Tonti 5 spd?  If so, can you recommend a size or p/n and vendor?
Thank you,
Art

[Antietam Classic Cycle]

Hey Charlie,
Can the the x-ring be used on Loop/Tonti 5 spd?  If so, can you recommend a size or p/n and vendor?
Thank you,
Art

I'm sure an x-ring can be used on a 5 spd, you would just need to find the correct size to use. The size for the 20 mm outer body on early 4 spds is on Greg's website:
https://www.thisoldtractor.com/moto_guzzi_loopframe__for_sealing_the_outer_body_of_the_throw-out_bearing_assembly.html

I haven't tried one on the larger 22 mm outer body yet since it fairly uncommon for the 5 spd rear cover to wear the bore like the 4 spd. I normally use the aftermarket dual o-ring outer body anyway. This size >might< possibly work:
https://www.mcmaster.com/90025K236/

[neetones]

The oil leak can be solved with the transmission in place.  Remove the swingarm and the throwout system will be fully exposed.  You can replace or improve the o-ring.  Good idea to check the quality of the throwout bearing.  Not a lifetime item.  If the bearing failed in a prior life then it may have torn up the inside of the rear cover bore hole.  That is much more complex to correct.

It was hard to see, but it looks like you do have vacuum ports on the intake manifolds. Can you post a picture?  If you do have vacuum ports then use those to manage the minute adjustment of carb settings.  Using vacuum comparison is much more accurate for balancing and synchronizing the carbs.

Patrick Hayes
Fremont CA

Thank you! Yes, it does have vacuum ports though I need to figure out what size they are to find a nipple that will fit.

Also, just woke up to a puddle of oil that appears to be coming out of the smaller tube of the breather box. Oil level may be too high - hard to tell as I have an aftermarket engine temp dipstick.

[Tom H]

3 Quarts of engine oil is all it needs.

The fittings should be m6X1.0 if they are factory drilled. A zirk fitting with the check ball removed works well.

Tom

[Tom]

Are you using synthetic oil?  It could be too slippery and accelerate the oil leakage.  The same for the gear lube.  It will be clunky when you shift.  You have to shift gears with a very positive input to the shift lever.  It won't be as smooth as a Japanese bike or later Moto Guzzis.

[Antietam Classic Cycle]

Thank you! Yes, it does have vacuum ports though I need to figure out what size they are to find a nipple that will fit.

Also, just woke up to a puddle of oil that appears to be coming out of the smaller tube of the breather box. Oil level may be too high - hard to tell as I have an aftermarket engine temp dipstick.

Those clamps looked like they have "bottomed-out" before they squeezed the hose sufficiently. I use these instead:
https://www.mcmaster.com/53175k86/ Also available at auto parts stores as "fuel injection" clamps.

Like Tom H wrote: 3 qts. only (it helps the sump to drain more completely if the front wheel is raised approx. 4") and make a new mark on the dipstick.

As Tom wrote: skip the synthetics. Since the transmission gears all run on bronze bushings, I feel it is important to use GL-4 gear oil or other oils that specifically state "safe for yellow metals" on the label.

[Tom H]

On the GL-4.....

Charlie.....What brand are you finding GL-4 from? StaLube used to be readily available, now seems only GL-5.

Lucas clams to have a GL-5 conventional gear oil that says in a spec on it that it is safe for yellow metals. It was reasonably priced, so I gave it a shot for my R75's and Guzzi 4 speed.

Tom

[Antietam Classic Cycle]

On the GL-4.....

Charlie.....What brand are you finding GL-4 from? StaLube used to be readily available, now seems only GL-5.

Lucas clams to have a GL-5 conventional gear oil that says in a spec on it that it is safe for yellow metals. It was reasonably priced, so I gave it a shot for my R75's and Guzzi 4 speed.

Tom

I had been buying the CRC Sta-Lube as well. To tell the truth, it's been so long since I've needed any (rarely any Ambos through the shop lately) that I haven't kept up with what's available.

[Moparnut72]

Also any gear oil approved for a NV 4500 5 speed manual transmission  in a 1st generation Dodge with a Cummins engine will be fine. I used a Pennsoil product in mine but I don't remember which.
kk

[Antietam Classic Cycle]

From a quick Google search:

VP Racing Classic: https://www.summitracing.com/parts/vpr-2703
PennGrade Multipurpose Classic: https://www.summitracing.com/parts/bpo-77296
Valvoline: https://www.valvolineglobal.com/en-ksa/gear-gl-4/