1983 Le Mans III

[DanPez]

Aloha Dan,
And a big time Congrats to you and your new baby! She's a beauty.
The only thing I will add, is pretty much how happy I am for you, and say ahead of time how much your going to enjoy her.
It was only a short swap, but had an ever lasting effect. After a few months, Jay got more loose with loaning her out to me.
And I been a fan ever since. For some reason, I've always just bought a new Guzzi when the right Lemans III has come to market... And she has been like my Phantom "Guzzi" girl, little peeks here and there, then turns away, for more than twenty years now. Congrats.
Aloha,
el jedi

Thanks for the kind words ....
The difference between you and me is that its having an effect on me NOW ..... very late 40's.
Call it middle age crisis? :lol:

Cheers

 

[DanPez]

Can someome please explain this?

The previous owner rebuilt the top engine and the points were changed to a Dyna III electronic ignition.
So while I was adjusting the ignition and timing gear I couldn’t match the “D” and “S” markings.
Comparing the TDC pistons and timing gear nothing matched either.
I placed a skewer stick inside the cylinder heads and physically felt the position of the piston when it was all the way to the top, checked to make sure the intake and exhaust valves were fully closed and verified the position of the ignition cam. (Hall Effect)

Just to clarify ....... I bought the bike and this is a running engine. :lol:
If I'm not mistaken the chain gear is a 96 teeth (for 360º).... please correct me if I'm wrong.
I did see other marking on the chain gear and noticed a 32 teeth advance (120º off)

Edit: As though the chain gear was installed with a 120º offset.....is it possible?

The electronic timing (Statically) was off by 1º advanced to 3º retard (right /left respectively)
The clearance on the right intake was 0.33mm instead of 0.22mm as per specs require. (Others were +/- 0.05mm off)
I re-marked the chain gear properly, adjusted the static cam housing for the ignition and adjusted the valve clearances.

How could this have happened? :huh:

 

[SED]

Mk III LeMans use 'Lean Burn' carbs. Going to 132 mains will make it run like shit. I thought AB 268's were standared atomiser size for Mk III's?
Does it have original pipes or something more 'Open'? And has it got the original airbox or pod filters? (Checked the pics, its got pods and what look like Lafranconi 'Competizzione' pipes?
If it has pods and/or open pipes going up to a 120 main *may* help a bit at the top end, plug chops will determine that. My guess is 125's are a bit big. K18's are right, you *Might* find an improvement if you raise the needle a notch.
To my mind everything else looks just about OK.
Pete

On the part list I downloaded it specifies AB268's also .... but the manuals says different. (3 hundredths mm ?)
Exactly ..... It has K&N pods and Lafranconi 'Competizzione' pipes and your right breathing a little better may need slight increase.
Infact I saw it somewhere else the use of 120 jet ....but having K27's needles on the 2nd notch as a standard setting.
The K18's specify placing it on the 3rd notch.
Thanks

Congratulations on a beautiful bike.

I followed Pete's advice on jetting and my '83 LMIII runs great. https://www.guzzitech.com/forum/160/4000.html

I found that the 50 idle jet was too lean (and I can't find where I wrote down what's in the carbs now), so my guess is that the 57s will work fine. The main jet is a 120. The atomizers are 268s with the k-18 needles. they seem to run fine, but I couldn't get the 265s when I was rebuilding the carbs so don't have a comparison.

The other change is the Euro idle mix screws with a different profile #1393-6200) and lighter carb springs (#1793-7167) and new throttle cables.

I didn't worry about the choke jet and pump jet and slide because they don't cause problems and it runs well. I remember them being an odd combination of US and Euro specs.

Yours is a beautiful example.

 

[DanPez]

Thanks Shawn for the compliment.

So far the autumn / winter project is going well.

I think I landed on one that wasn't too tampered with.
I purchased all the parts necessary to rebuild the PHF36 carburetors.
I'm starting with .....265 atomizer, K-18 needle (3rd groove), 115 main jet, 50 idle jet, 50/3 slide, 70 choke jet, 33 pump jet.
Cause of the K&N and exhaust may be a little lean but still have the 125 main jet, 57 idle jet and 75 choke jet that were removed.
I found the float adjustment on one carbs was off by a 1mm, an extra o-ring in one of the idle screws and the choke plungers were not properly adjusted. (Took it apart without realizing but 1 plunger seemed to have been constantly open)

Plugs were a little dark ..... still gotta do a leakdown test to check seats and/or rings.

Cheers

 

[DanPez]

I picked this up from one of the sites written by Rolf Johansen concerning the "Cush drive"

"Judging from forum discussions and what is written in Guzziology, a popular modification to increase the damping effect of the cush-drive is to drill two or three holes in the rubber dampers, some even remove every other of them and some even do both!"
Drilling holes of 10mm and 6mm respectively.

They are rock hard rubber ‘dampers’ and when I opened the hub I notice they are in need of some lubrication.
Correct me if I'm out on left field .......but the reason for greasing will help! (won't seize, free play, easier future maintenance, anti-corrosion)

What is the riding advantage when the holes are drilled? (besides damping or less force on the drive train))
Won't the rubbers collapse over time?
Any experiences?

Thanks

 

[rolf j]

They are rock hard rubber ‘dampers’ and when I opened the hub I notice they are in need of some lubrication.
Correct me if I'm out on left field .......but the reason for greasing will help! (won't seize, free play, easier future maintenance, anti-corrosion)

What is the riding advantage when the holes are drilled? (besides damping or less force on the drive train))
Won't the rubbers collapse over time?
Any experiences?
Thanks

I bought my LM3 street bike brand new and it came off the factory line with no lubrication in the cush drive - stuck! Just remember you should use a silicone sealand on the narrow surface of the rim in contact with the plate/ring when you close it up again. You may otherwise get grease leakage messing up the rim/tyre while driving. I tried a couple of selants at this loacation, but the only one that actually worked was silicone. Not a drop has been seen from there ever since, and I probably never have to open it again. As for modifications to soften the rubber - such as removing every other or drilling holes - you will not notice any difference when driving, but will be a bit more kind to the drive train when it actually works as intended.

Btw all splines for the prop shaft in the rear fork were also DRY from the factory line - NO lube! I caught it in time, they were already balls of rust, but not yet eaten up.

 

[DanPez]

Rolf J
What a coincidence!
Gotta tell you …. found the DK.Archive site?, You guys …... like my kids would say “ROCK”.
I’m reading up on the procedures and tips for the Tonti …… they are nicely written and very easy to follow.
May not mean anything coming from me …. but nice work!

While removing the hub, I myself felt the coupling disc stuck to the rubber dampers ….. Definitely needs lube.

Just remember you should use a silicone sealand on the narrow surface of the rim in contact with the plate/ring when you close it up again. You may otherwise get grease leakage messing up the rim/tyre while driving.

I’ll be cleaning the disc with solvent then silicone as you mentioned.

As for modifications to soften the rubber - such as removing every other or drilling holes - you will not notice any difference when driving, but will be a bit more kind to the drive train when it actually works as intended.

While in a curve and the engine is under compression, does the bike have a tendency to drift?

Btw all splines for the prop shaft in the rear fork were also DRY from the factory line - NO lube! I caught it in time, they were already balls of rust, but not yet eaten up.

Actually that was next on my check list… thanks

 

[Series4]

Didn't notice mine drift at all when going through the French/Italian Alps and the Massif Centrale recently. I could feel the back working but it seemed to track OK. Make sure you set up the rear suspension properly (I had my man do it for me) and you won't have a problem.

Peter

 

[rolf j]

Rolf J
What a coincidence!
Gotta tell you …. found the DK.Archive site?, You guys …... like my kids would say “ROCK”.
I’m reading up on the procedures and tips for the Tonti …… they are nicely written and very easy to follow.
May not mean anything coming from me …. but nice work!

Thanks for kind words! You'll find that those articles of technical&complicated stuff, such as e.g. engine strip and gearbox shimming, Pete Roper provided the method, knowledge and experience and I tried to make it as presentable as I could using simple means of layout&editing. Pete is a fabulous source of knowledge that he parts with so generously! It was great fun doing this and I'm happy that Greg Bender accepted to take over and upload the lot from Jens Lyck when he closed his guzzitech.dk web site. On the sam site you will also find some useful tables of all small part like seals, bearings etc and in many cases with reference numbers you canb take to your local machine shop. A friend of mine here in Norway, Rolf Halvorsen, compiled and uploaded this information. Rolf H is the same fellow who offers some fantastic tools for entering into the gearbox and engine of the big twins. They cost a bit, but the quality is superior as Pete has also noted on occasions. Comparing with the price you have to pay a shop-man to earn a decent living, the price for the tools is actually not bad at all, so if you are ready to take on the challenge it's the way to go, and it is fun when it all work out fine!

 

[SED]

I picked this up from one of the sites written by Rolf Johansen concerning the "Cush drive"

What is the riding advantage when the holes are drilled? (besides damping or less force on the drive train))
Won't the rubbers collapse over time?
Any experiences?

Thanks

Dan,

I drilled the rubber cushions AND removed half of them and I noticed that the clutch seemed much less grabby. Maybe there is something wrong with my clutch, but it is certainly more tractable when in stop and go traffic because the clutch seems to engage more smoothly.

 

[Series4]

Just waking this thread up again, did some tuning work on my LM3 last week to sort out some slow running issues. Worked on atomisers and idle jets and got best results from

choke 36
throttle valve 60/3
atomiser 268AB (Guzzi manual says 265AB, Guzziology 268AB)
main 115
idle 60 (up from stock 50, also tried 55 & 58)
starter 70
pump jet 33
needle K18 3rd notch from top
idle speed screws 2.5 turns. Idle sped a little higher than normal, about 11-1200 rpm and it's now much happier

These specs are almost the same as the standard Euro specs. As far as I know the engine is stock but is fitted with big bore Kiehan mufflers which is probably why the idle jets had to come up. This might be good corroboration of a base line for your machine

Edit: standard airbox and filter

 

[Chris R]

They are rock hard rubber ‘dampers’ and when I opened the hub I notice they are in need of some lubrication.
Correct me if I'm out on left field .......but the reason for greasing will help! (won't seize, free play, easier future maintenance, anti-corrosion)

What is the riding advantage when the holes are drilled? (besides damping or less force on the drive train))
Won't the rubbers collapse over time?
Any experiences?

The reason for softening up the rubbers is long term mechanical longevity - especially the clutch drive bits. Its one of those things where you will probably see the results in 40K but given you have a sample of one you will never really know.

I greased mine with just a thin layer of good old canadian tire pink synthetic grease - any rubber compatible grease will do. If the grease leaks out I would suggest you went a bit wild. i didn't bother drilling holes - just removed half of them. The rubbers don't collapse on the ones that I have seen drilled.

In terms of riding, it changes the handling not a wit but adds that hooking the tire up feeling beloved of the drag racing crowd - I suppose it might help a bit if you miss a shift as the rear end will lock up a touch later and less brutally.

 

[DanPez]

idle speed screws 2.5 turns. Idle sped a little higher than normal, about 11-1200 rpm and it's now much happier

Today was the day!!!!
I'm proud of meself ....It started :woohoo:
After a winter in bits and pieces the LM3 rolled over.
Now I definetly have to tune it properly ..... the right cylinder is running rich ... very rich.
So rich its fouling the plug rapidly. Played around with the throttle stop screw to balance the exhaust pressure.
The manual is a little confusing ..... remove spark plug wire ... count the number of turns before stalling?
I was capable of running the bike with the left cylinder only without stalling. :shock:
Logically (Throttle screw) I will have to screw the right throttle to let more air in and/or unscrew the left.

I noticed the intake manifolds have a 6mm port hole where I can take vacumm.
Can I hookup a manometer (U-tube) and balance them this way?

My setup is with K&N pods and Lafranconi 'Competizzione' pipes.
choke 36
throttle valve 50/3
atomiser 265AB
main 115
idle 50
starter 70
pump jet 33
needle K18 3rd notch from top

I have the idle set at 1.5 turns each for now.

 

[Series4]

Well done! Nothing like the spring thaw to get the sap rising?

- Yes, plug a manometer into the manifold ports, that's why they're there
- Your fouling plug sounds like a needle and seat issue. I had a similar problem fixed by removing a piece of scale from the seat. I thought originally it was a coil or plug cap. Swap items over and see of the problem transfers.
- Mine was unrideable with a 265AB atomiser, I had to pull the choke on to make it go. The 268AB fixed it
- We got mine to idle on a 50 idle jet but it steps up to the main much more smoothly with the 60
- not sure what the smaller throttle valve will do, we didn't look at that

FWIW I reckon the LM3 works best with the standard airbox and filter. I know someone who went through the process of cut down snorkel, then K&N pods and then standard and he got best torque, rideability and economy with the standard set up.

 

[Morizzi]

The 50/3 means that it will be richer during progression, basically at lower to mid range throttle openings before the needle and atomiser become more dominant. The 50 refers to a 5mm cutaway at the bottom instead of 6mm for a 60. The smaller cutaway means the air has to travel faster through the venturi so it draws more fuel. Just make sure that a PO hasn't filed the bottom of the slide or cutaway to change it. The /3 refers to the pump ramp. Don't worry about it.

This smaller opening will help balance out between the 50 and 60 pilots.

I have two LM III's. Both have standard filter boxes. One runs completely OEM jetting the other is altered slightly.

My everyday ride has:

PHF 36's with Bell tops. I didn't change them, I just hardened up.
268AB
K18-3
60/3
Pilot 50 Had 60 in it when I purchased it. :roll:
Main 120. Had 145 in it when I purchased it. :roll:
Starter jet? Who gives a rat's!?
Pump. OEM.

Remember that unlike the first 2 850 LM's the MK III had lean burn carbs. There is very little sense in increasing the main jet too much.

I wouldn't bother with changing up to a 268AB just yet. You have a few options to try if you find it is running too lean. You could always just raise the needle to the last notch.

One side rich?
Check float heights and floats. Make sure they are both the same weight, one isn't partially filled with fuel and they are set correctly. While you are in there make sure the needle valve is sealing properly. Turn the fuel on and hold the float up. If it stops completely then it is OK.

Check both choke cable have a couple of mm slack and the plungers are clean and sealing. Check the little rubber seals on the bottom and give them a clean. Remove the filter and turn the bike over with no throttle. If the choke circuit is sucking air you usually can hear the chirp as it feeds through the thin airway.

Check the throttle cables have slack too and that both slides contact the tapered adjustment screw. Touching the screw open and close the throttle. You should feel the slide contact. Adjust the cables so that both contact simultaneously.

Put new plugs in and make sure both sides are giving you an equal spark, just to eliminate an ignition cause.

Sorry if I'm telling you how to suck lemons.

cheers

Rod

 

[Series4]

I can see now how the 50/3 + 265AB + 50 pilots might work

Best way to suck lemons is through a G&T. The best way to suck Lemans is the Mandello wind tunnel

 

[DanPez]

Thanks Rod
The carbs have been redone on the LM a couple of months ago,
Float weight/height, jets, gaskets ... etc.
A reason why I suspect the right cylinder running rich is because when the engine is stopped the left cylinder is hotter than the right and the exhaust on the right does'nt have a nice popping sound. At 3000 exhaust seems even and revs nicely to 7000 without missing a beat!

Talk about sucking lemons.
I took the compression of both jugs in January and got 150psi ..... battery well charged 170psi. (engine Stone cold)
I rechecked the compression today and got 140psi on the left and 125 on the right (hot) ...... this maybe another factor why it's rich.
Ain't sucking enough on the right.

I poured in some "Sea Foam" to clean the fuel line, chamber ..... may have uncrusted the carbon deposit or something.

 

[john zibell]

I rechecked the compression today and got 140psi on the left and 125 on the right (hot) ...... this maybe another factor why it's rich.
Ain't sucking enough on the right..

Since you have more than 10 PSI difference, I would call it time for a top end job (do both sides). No amount of tuning can compensate for a weak cylinder.

 

[Morizzi]

Dan,

I haven't followed this thread from the start so I may have missed a lot.

John has a point but I wouldn't be so hasty. The question in my mind is what happened to all that compression over a short period of time? Compression loss is usually a gradual wear issue not a catastrophic failure event. :?

What did you do to the bike in between? Hasn't the bike just been started? :? If this is the first run since a top end re-build did you re-set the valve gaps after the first few minutes of running?

Have you done a wet and dry compression check?

Did you remove the carbs or hold the throttle open for the latest check? If you haven't then I'd try this first. Check valve gaps. If they are OK then I'd re-torque the heads, restart the bike and warm it. Remove the carbs and do another dry and wet compression check.

I simply don't understand the figures. They make no sense to me. :blink:

cheers

Rod, who's every day ride is a faded silver LM III, that has a discernible wear lip in the bores and still shows 170ish each side. B)

 

[DanPez]

John , Rod
I was reading your comments and thinking at the same time. (My kids would say " You can multitask?")
Suprisingly enough I can do that. :lol:
Thinking to myself ......
- I rebuilt the carbs
- I checked the valves gaps
- I made sure everything lined up at TDC
- Adjusted the elect ign for the timing
- Took the compression in January and everything was even
- Didn't start the engine till yesterday ..... no mods, adjustments where done since then!!!!

Then I come across:
"Did you remove the carbs or hold the throttle open for the latest check?"
F&?%$/.....damm .....I forgot
I just woke up....there's my difference!!!

Thanks guys