Author Topic: Octane Booster & Timing Question & The Story & Over It.  (Read 3749 times)

Online Tom H

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Re: Octane Booster & Timing Question.
« Reply #30 on: March 26, 2022, 04:23:19 PM »
Pressure: As I have mentioned, I wanted to use the booster as a test tool. If it changes things, then find why.

Unfortunately no consensus yet on a good one to try :sad:

Lucian: Here you go. LH 150, 160 wet. RH 155, 160 wet.

The rings are new, maybe 100 or so miles on them. I pulled the heads apart while doing the rings. Guides, valves and springs measure in spec.

In a PM it was mentioned to check the cam lift. I did but I did not have the right tool and got some odd measurements, consistent, but odd.. A dial indicator will be here shortly and see what the lift tells me about the cam.

Thanks again so far!!
Tom
2004 Cali EV Touring
1972 Eldo
1970 Ambo V1000
1973 R75/5 SWB with Toaster
2007 HD Street Bob
1953 Triumph 6T (one day it will be on the road!)

Offline pressureangle

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Re: Octane Booster & Timing Question.
« Reply #31 on: March 26, 2022, 06:10:33 PM »
This will start a fight , but octane isn't a measure of how fast or slow gasoline burns . Octane is only a measure of how resistant gasoline is to ignition . Gasoline can be blended to burn slightly slower or faster at any octane rating , although the differences are tiny . What chemists and IC engine designers are looking for are the conditions where the combustion process is complete at a certain degree of crankshaft rotation , low octane fuel ignites more readily , so in a high compression engine or in an old aircooled design that runs hot it can ignite too soon , meaning higher octane is needed to resist pre-ignition . Ethanol does tend to burn a tiny bit slower than gasoline , but that is a different discussion .

 Dusty

Never start a fight before you do your research.

Octane is *not* 'resistance to ignition'. Octane is resistance to *detonation*. It is a critical distinction.
Gasoline can be blended for *great* difference in burn rate, and also for energy density.
'Pre-Ignition' is caused by hot spots in the combustion chamber, and is not very sensitive to octane.
'Detonation' is the *un-ignited* spontaneous combustion or explosion of the fuel mixture, caused by heat and pressure beyond the combustion threshold.
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Offline lucian

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Re: Octane Booster & Timing Question.
« Reply #32 on: March 26, 2022, 06:49:23 PM »
Tom are you running the original vhb carbs? What size main jets? How are the plugs looking. I'm thinking it may be going lean at the higher rpms. Lean = more heat= more pressure = more detonation ,  Leaking valves can cause a lean condition also , do you have access to a leak down tester? I know you mentioned the valves measured in spec , but are the sealing properly? Thats all I've got tonight. All you can o is rule out the basics.  I would also try plugs one heat range lower .

Offline SoCV

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Re: Octane Booster & Timing Question.
« Reply #33 on: March 26, 2022, 07:28:10 PM »
Never start a fight before you do your research.

Octane is *not* 'resistance to ignition'. Octane is resistance to *detonation*. It is a critical distinction.
Gasoline can be blended for *great* difference in burn rate, and also for energy density.
'Pre-Ignition' is caused by hot spots in the combustion chamber, and is not very sensitive to octane.
'Detonation' is the *un-ignited* spontaneous combustion or explosion of the fuel mixture, caused by heat and pressure beyond the combustion threshold.

 What do you think is causing the detonation ? The fuel is igniting , it is caused by heat , never said it wasn't . Trust me , I know the difference . Your statement that octane is about burn rate is wrong , that is what I was trying to sort out . Octane really is just resistance to ignition no matter the source .

 Anyway , carry on .

 Dusty
Almost 900,000 in a little over 8 years in two .

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Re: Octane Booster & Timing Question.
« Reply #33 on: March 26, 2022, 07:28:10 PM »

Offline Shorty

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Re: Octane Booster & Timing Question.
« Reply #34 on: March 26, 2022, 11:32:31 PM »
You probably already did this, but: run the engine up to the condition where the trouble starts. Then see if one jug gets noticeably hotter than the other. If yes, you have taken step one to isolate the problem. If no, it lies in a system that effects both cylinders equally. Shade tree 101.  Does the engine run cleanly up to high RPM in nuetral? Have you tried a new coil?  The only octane boost I ever noticed a difference with on a tired engine was racing fuel from the local hot rod shop, or AVgas.
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Offline Road Rocket

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Re: Octane Booster & Timing Question.
« Reply #35 on: March 27, 2022, 11:19:04 AM »
 More…this article was written by the head engineer of GM engine development…

       http://www.contactmagazine.com/Issue54/EngineBasics.html
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Online Tom H

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Re: Octane Booster & Timing Question & The Story.
« Reply #36 on: March 27, 2022, 11:28:21 AM »
RR: I'll give that a read latter today.

When I was working with my Dyna III. I found a real good site on coils and ignition parts. Long but good read.

Tom
2004 Cali EV Touring
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1970 Ambo V1000
1973 R75/5 SWB with Toaster
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Offline Road Rocket

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Re: Octane Booster & Timing Question & The Story.
« Reply #37 on: March 27, 2022, 11:58:15 AM »
And it gets more complicated…The author of this forum response is chief engineer at a company doing advanced engine research

     Re: High octane fuel burns slower?
Report Quote Like
Post  by David Redszus » Sat Jan 03, 2015 6:39 pm

jmarkaudio wrote:
I can tell you that it is possible to have a higher octane fuel that will evaporate at a lower temp and as a result burn faster than a lower octane fuel. So you can not assume one goes hand in hand with the other.
You can have a higher octane fuel with any number of boiling points and igntion points. They have nothing to do with burning faster.

Fuel octane values (either RON or MON) have NOTHING to do with combustion flame speed. They are completely unrelated.

If we run an engine on the dyno using straight “isooctane” (224TriMethylPentane) it would have RON and MON values of 100. Interestingly, there are actually 18 different isomers for isooctane with different octane values.
We could then add measured amounts of Tetra Methyl Lead(TML) to increase the octane values in steps. We would find:

TML
g/gal ........ MON .......... RON
0 ........ 100 .......... 100
2 ........ 108.6 ........ 108.6
4 ........ 118.0 ........ 118.0
6 ........ 120.3 ........ 120.3

While the fuel octane values are increasing, there would be absolutely no change in engine performance or in ignition temperature, flame temperature, laminar flame speed, peak combustion pressure angle and total burn angle.

Fuel octane alone does not change these combustion values. But a change in blend composition is another matter. It is possible to have two fuel blends with the same octane numbers, but they will behave quite differently in the combustion chamber. This is due to the fuel blend components and not to their octane values.

Different fuel blend components do have a substantial effect on combustion properties.

................... .................. nHeptane .... Methanol .... Toluene .... Isooctane

Laminar flame speed ................. 42.4 ....... 52.3 .......... 38.6 .........37.7
(cm/s)

A/F ratio for max FS .................. 122 ........ 101 ........... 105 ......... 106
(% of stoich)

Ignition temp ................... ........ 476 ........ 878 .......... 1052 ......... 874
(F)

Flame temp ................... ......... 3525 ........ 5050 ........ 3759 ........ 4193
(F)

Laminar flame speed is not affected by octane value but is a function of fuel blend components. Laminar flame speed is much too slow to burn properly in modern engines; chamber turbulence is necessary. When chamber turbulence (primarily squish velocity) is added to laminar flame speed, turbulent flame speed is the result. That is what will determine combustion burn angle, peak combustion pressure location, flame temperature and engine performance.

Laminar flame speeds are on the order of about 40cm/s (.4m/s). Squish velocity is on the order of 40m/s or about 100 times that of laminar flame speed. Combined turbulent flame speed would be 40.4m/s; the laminar flame speed having contributed very little to burn time or burn angle.

The ignition temperature of the fuel will determine the ignition delay period. The flame temperature of the fuel will affect the flame speed and combustion pressure.

It is most unfortunate that when race fuels are mentioned, even by fuel company marketing reps, octane seems to be the only fuel property that is mentioned. We very often find fuel company marketing reps to be very underinformed regarding their fuels. While every true race fuel refinery has fuel blenders and fuel chemists on staff, they are mostly kept out of sight and contact with race fuel customers. And the promotional literature is commonly written by some ad agency copy gal who knows only the buzz words and little else.

Fuel companies could provide real data regarding their products to help racers make the right decisions. But then, who would listen? :(
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Online Tom H

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Re: Octane Booster & Timing Question & The Story.
« Reply #38 on: March 27, 2022, 12:13:41 PM »
The story.

I bought a complete but disassembled engine from a reputable Guzzi shop. I was told to assemble as is (bearings and all) and ride. There was slight confusion on rings, I thought he said don't change, but he said change. Compression was about 150 with the old rings.

I cleaned up everything. I replaced the big end rod bearings, timing chain (used the stock manual tensioner), seals/gaskets and the like. I was told all the bearings were perfect fitting. Since I was in there I did the big end.

I'm running VHB30's with 40 slides (also have tried 60's) V9 second notch, 50 pilot and 130 IIRR main (Guzziology recommended specs). Original non leaking floats with new needles. I do believe I also tried larger mains, but I don't remember what at the moment. I even tried another set of carbs, no change.

Started with a Loop single point dist.. Had my issue. Changed to Tonti dual point with Dyna III and stock pair of Tonti coils. No change and tried Busch Blue's. No change. Went back to single point. No change.

Changed to Valtec style tensioner and reconfirmed my cam timing marks as well as the flywheel TDC marks on my Loop flywheel.

Changed heads to a set of decent, not perfect Loop heads. Had to open up the push rod hole to use them. No change. Went back to Tonti heads. BTW: per specs the Loop and Tonti heads are the same except the exhaust header mounting. Casting numbers are the same. Even tried a good used set of rocker pins just in case there was an issue there. No change.

Recently I brought my cylinders and pistons to the shop. He said they looked oily. He asked about the heads and rings. He said he told me to change the rings. Now has new rings.

The Tonti heads. Pulled them apart and measured the valves and guides. Measured the guides with a 8mm ream. Perfect fit. Valves were all within the book specs. 3 on the high side and 1 on the low side. Measured at the tip and where it rides in the guide. Same size all the way.

I had thought my issue was a rattle. Checked everything, components, bolts, wires, stands, headers anything that could rattle. No change.

Right now I'm working on trying to figure out what cam I have without pulling it out.

Cam measurement question. Lift measurement and Guzziology. Is the lift measurement how much the push rod is lifted??? OR.....how much the valve is pressed down????

I read that cam builders rate the lift at the valve, not how much the push rod is lifted. DID I misread this????

If it is the push rod lift, and I'm measuring right. I possibly have a V7 Sport cam??????? BUT..... I am going to make sure that my measurement is correct.

If this engine sounds like it does under 4000rpm, when I'm over 4000rpm. This is the sweetest sounding engine I've had except my Hydro. I didn't put this in a Loop frame to have a great city bike. It was to be my go anywhere at up to 80mph. I can't do that with how it sounds.

The noise does seem to start at about 4000rpm. I have had it show up in lower gears at lower speeds. Harder to hear due to just general high rpm exhaust and the like noise. 5th and the freeway it's quiet enough to easily hear it. If I try to rev it in the garage, it either doesn't do it or I cant hear it. But remember, if I ever so slightly let off the throttle or go down a freeway slope at 4000+, the noise goes away.

Trying a booster was a thought on how to see if it was ignition. Maybe lean?

Thanks again,
Tom
« Last Edit: March 27, 2022, 01:13:22 PM by Tom H »
2004 Cali EV Touring
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1970 Ambo V1000
1973 R75/5 SWB with Toaster
2007 HD Street Bob
1953 Triumph 6T (one day it will be on the road!)

Offline guzzisteve

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Re: Octane Booster & Timing Question & The Story.
« Reply #39 on: March 27, 2022, 12:58:30 PM »
Time it w/timing light at 2*, like a stock smallvalve 1000 round barrel. Still make noise? Jet your carbs.
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Online Tom H

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Re: Octane Booster & Timing Question & The Story.
« Reply #40 on: March 27, 2022, 06:21:31 PM »
I played with the cam lift again.





If I'm doing it right by measuring from the lowest part of the lift to the highest part. I get a consistent .270"-.272". In the photo I tried measuring a bit different and came up with .275".

I always tried to find the lowest point on the cam. Then zero the gauge. The .275". I found the highest lift, rotated crank 360deg (S/B opposite the high end), then rotated 360deg again to the high. Now I'm pretty sure I have it right. Rotated 360 again to the low, zeroed and measured.

If I'm reading Guzziology right and measuring right, I have a 750 S cam.

Please correct me if I'm measuring wrong!!!! The only other thing I can try to confirm this is with a degree wheel. Would need to get one.

Tom
2004 Cali EV Touring
1972 Eldo
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1973 R75/5 SWB with Toaster
2007 HD Street Bob
1953 Triumph 6T (one day it will be on the road!)

Online Tom H

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Re: Octane Booster & Timing Question & The Story.
« Reply #41 on: April 04, 2022, 04:45:19 PM »
After making sure I was reading the lift right, it looks like Guzziology numbers are when you have the cam in your hand and measure it.

I borrowed a stock cam and measured the lift with my dial indicator.  It matches the lift with the one in my bike. So it's not likely a cam issue.

I've run out of ideas. I will work on jetting again and see what happens. If that doesn't solve it. I'll run it until it breaks, then I'll know what it is.

Thank you,
Tom
2004 Cali EV Touring
1972 Eldo
1970 Ambo V1000
1973 R75/5 SWB with Toaster
2007 HD Street Bob
1953 Triumph 6T (one day it will be on the road!)

Offline lucian

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Re: Octane Booster & Timing Question & The Story.
« Reply #42 on: April 04, 2022, 04:57:27 PM »
Re torque heads , adjust valves , sync carbs and try again , Pull plugs and inspect , adjust jetting accordingly , A cooler plug will sometimes help with detonation. Assuming you are running stock heat range.

Offline LowRyter

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Re: Octane Booster & Timing Question & The Story.
« Reply #43 on: April 04, 2022, 06:18:02 PM »
I suppose it's nothing simple like an air leak or lean carb condition?  Ignition timing or weak spark?

I shouldn't comment because I am so inept.   :sad:
John L 
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Re: Octane Booster & Timing Question & The Story.
« Reply #44 on: April 04, 2022, 06:50:29 PM »
Plugs: Tried 1 number hotter and colder. Even tried platinum and iridium.

Dist.: Loop and dual point with Dyna. No change with either. Also different wires and I think caps. I might try caps again, but I doubt it.

Wanted to mention. I did try the choke while it was making noise, no change. Cam timing. I did use a degree wheel and the 1.5mm valve clearance spec for this engine and the timing was "almost" spot on. Exhaust was perfect, intake off about 3 degrees open and close. If I was off just a tad on the clearance, that will change the timing.

Thank you again!
Tom
2004 Cali EV Touring
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1973 R75/5 SWB with Toaster
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Offline guzzisteve

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Re: Octane Booster & Timing Question & The Story.
« Reply #45 on: April 04, 2022, 07:07:08 PM »
Want to buy a set of base cyl shims, got a set years ago from Harpers. I'll never need them again. Finding them might take awhile.
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Offline larrys

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Re: Octane Booster & Timing Question & The Story.
« Reply #46 on: April 05, 2022, 07:22:50 AM »
Busted valve spring? Hasn't been mentioned here. My Lemans IV had a high rpm tapping noise. Found an inner valve spring was broken. Previous owner might have missed a shift...
Larry
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Offline MattP

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Re: Octane Booster & Timing Question & The Story.
« Reply #47 on: April 05, 2022, 10:26:11 AM »
retard the timing richen mixture and or install the shimes  under the cyilnders  the shimes work like a champ you will have a much nicer running engine. I have done it on a eldo . I used .062 aul shim. You will loose a coupel hourse power at the dineo at wide open throtle  when are you ever running down the road like that.

Online Tom H

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Re: Octane Booster & Timing Question & The Story.
« Reply #48 on: April 05, 2022, 10:29:01 AM »
Springs are in spec. Bought a scale to test valve springs.

Tom
2004 Cali EV Touring
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1973 R75/5 SWB with Toaster
2007 HD Street Bob
1953 Triumph 6T (one day it will be on the road!)

Offline pressureangle

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Re: Octane Booster & Timing Question & The Story.
« Reply #49 on: April 05, 2022, 03:37:36 PM »
Tom,

The next diagnostic would be to discover some timing points. Idle, 2000, 3000, 4000. Perhaps the curve is simply too fast for the dynamic compression; My LM1000 has about 155psi with a Web 86b cam, and the difference between a bit of rattle and none detected was a new set of advance springs as the stockers had relaxed and worn the ends a bit. Even then, there's a bit of wear in the weight holes, so the point of entry for the heavier high-RPM spring is a few degrees late- that is to say, it doesn't control the timing until ~3* later than it might if everything was new. These are very small differences, but they do matter. So, you might simply try installing a set of LM timing springs and see if it keeps things under control. Otherwise, you could retard the timing 4*-6* and do some mid-RPM testing though your idle and top end will suffer and you don't want to keep it there beyond testing.
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Re: Octane Booster & Timing Question & The Story.
« Reply #50 on: April 05, 2022, 08:18:19 PM »
This noise has followed two Dist..

Single point and Bosch blue: Two loop springs as well as the loop loop and loop oval. No change.

Dual point with Dyna III and Bosch blue: Stock springs and LM Type that hold the advance down. Thought holding the advance down might solve it. Stock springs make it run better off the line.

I have timed it at 2 degrees AFTER TDC. The noise was almost gone, but so was performance.

As I mentioned. If I advance the timing to lets say 10deg., the noise comes in earlier in the RPM range. Retard the timing, less noise.

So if it's a mechanical issue.............. What could it be that timing would effect? Rods: small end perfect and I believe big end as well. Rocker arms?????

Again, if I float the throttle (just a hair off throttle, no gain, no significant loss of speed. Like holding speed on a small down hill), noise GONE. Get back on to hold speed, noise again.

Thank you!
Tom
2004 Cali EV Touring
1972 Eldo
1970 Ambo V1000
1973 R75/5 SWB with Toaster
2007 HD Street Bob
1953 Triumph 6T (one day it will be on the road!)

Offline pressureangle

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Re: Octane Booster & Timing Question & The Story.
« Reply #51 on: April 06, 2022, 03:25:44 PM »
I have a '68 Dodge Charger, with stroked 440. I built the engine with driveability and economy in mind; it's perfect but for one thing. To my dismay, I discovered what modern engineers had known for a long time; the engine wants 18* timing at idle, and 12* at 2000rpm. So I find myself fighting a cruise tip-in rattle if I feed too much throttle. This is an artifact of the mechanical distributor, and most of the reason they went to electronic timing. It's possible that your engine is simply tight enough that the dynamic compression is too high, and your only hope is to hold the timing down at idle spec until you get past the part where it rattles. I assume you've carefully checked both cylinders? I find the timing harder to set on the dyna than on points. I don't know what cranking compression is stock for you, so can't say whether raised compression is an issue here. Is the noise clearly only on one side, or both? You could also try installing spark plugs a range or two colder, as an inexpensive test.
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Offline MattP

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Re: Octane Booster & Timing Question & The Story.
« Reply #52 on: April 07, 2022, 11:48:32 AM »
dubble  plug it or you could use water injection. it will work or you could lower the compresion with the shims. Or as you stated just hold it where it is knocking and achive a dynamic disasembly. That is what my freind Rick did in the laverda 750 sf I sold him, I do refer to him as ricky retardo, Held it in 5th gear 40 mph. Gave him a ride on it before he blue the top off the left piston And it did not knock. he could not get it I told him to shift down. Hey what do I know,He did get to stop knocking. I did put gt pistons in it for him runs great ,I got it back a bout ten years later.

Offline LowRyter

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Re: Octane Booster & Timing Question & The Story.
« Reply #53 on: April 07, 2022, 11:50:53 AM »
could there be carbon build up on piston or combustion chamber?
John L 
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Offline Chuck in Indiana

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Re: Octane Booster & Timing Question & The Story.
« Reply #54 on: April 07, 2022, 04:00:05 PM »
Quote
if I ever so slightly let off the throttle or go down a freeway slope at 4000+, the noise goes away.

That sounds like rod bearings to me.. (shrug)
Chuck in (Elwood) Indiana/sometimes SoCal
 
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Online Tom H

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Re: Octane Booster & Timing Question & The Story.
« Reply #55 on: April 07, 2022, 04:18:03 PM »
Rod bearing. When I bought the engine, I was told both rod bearing were perfect as well as the fit to the pin and crank. Is a maybe, but don't think so?

The question again. Would increasing the advance make the noise of a rod bearing show up earlier in the revs? Decreasing advance make it latter.

And again, at about 3500/65mph, the engine is perfect sounding. If this were the days of the 55mph speed limit I would never have known there was a problem. If I wanted to stick to 65mph and under, I would do a round trip across the US in a heartbeat. It sounds that good.

Also I had the heads off recently, just needed to wipe off and a little wire brushing of the piston and head. No real build up.

Thanks again!!!!
Tom
2004 Cali EV Touring
1972 Eldo
1970 Ambo V1000
1973 R75/5 SWB with Toaster
2007 HD Street Bob
1953 Triumph 6T (one day it will be on the road!)

Offline Road Rocket

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Re: Octane Booster & Timing Question & The Story.
« Reply #56 on: April 08, 2022, 04:28:47 AM »
Rod bearings are usually noisy on the over run…..Tom says he applied the choke and no change? Fattening the mixture that much should eliminate or at least lessen part throttle detonation…
 if you have not tried high octane fuel yet now is the time to do it…..And what you describe ,regardless of new parts ,sounds like loose piston pins….
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Offline Chuck in Indiana

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Re: Octane Booster & Timing Question & The Story.
« Reply #57 on: April 08, 2022, 10:07:32 AM »
Rod bearings are usually noisy on the over run…..Tom says he applied the choke and no change? Fattening the mixture that much should eliminate or at least lessen part throttle detonation…
 if you have not tried high octane fuel yet now is the time to do it…..And what you describe ,regardless of new parts ,sounds like loose piston pins….
Yeah, rod bearing/pin. Hard to say over a computer.  :smiley:
Chuck in (Elwood) Indiana/sometimes SoCal
 
87 AeroLario
95 Skorpion tour
22 Royal Enfield Classic 3 fiddy
 "Two things are infinite: the universe and human stupidity; and I'm not sure about the universe."
Albert Einstein

Online Tom H

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Re: Octane Booster & Timing Question & The Story.
« Reply #58 on: April 08, 2022, 10:26:23 AM »
So your saying that the rod bearing can be quiet at 3500rpm and make noise at 4000rpm on a steady throttle? Would more or less advance change this?

Thanks!
Tom
2004 Cali EV Touring
1972 Eldo
1970 Ambo V1000
1973 R75/5 SWB with Toaster
2007 HD Street Bob
1953 Triumph 6T (one day it will be on the road!)

Offline Chuck in Indiana

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Re: Octane Booster & Timing Question & The Story.
« Reply #59 on: April 08, 2022, 10:29:58 AM »
So your saying that the rod bearing can be quiet at 3500rpm and make noise at 4000rpm on a steady throttle? Would more or less advance change this?

Thanks!
Tom
No. They make noise when the load is removed, even a smidgen. (technical term)
Chuck in (Elwood) Indiana/sometimes SoCal
 
87 AeroLario
95 Skorpion tour
22 Royal Enfield Classic 3 fiddy
 "Two things are infinite: the universe and human stupidity; and I'm not sure about the universe."
Albert Einstein

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