LM III Clutch - flywheel question

[jerryS]

Hi, This is really an extension of the most helpful discussion https://wildguzzi.com/forum/index.php?topic=114590.0 but as the last post of that thread was 2022, I thought I'd start fresh.
I've just pulled my LMIII clutch and as expected the hub and flywheel are both ridged. After following the discussion it seems clear that the SD TEC deep splined replacement is the way to go.. I'll need a new flywheel as well. I measured mine of the kitchen scale (oops) and it comes in at 3323g.. The Stein Dinse site has 3 flywheels, 4250, 3300 & 2450.. I'ma bit confused about this.. I assume that mine is original (the bike is pretty much unmodified). . I can't imagine putting in  heavier flywheel than original.. Unfortunately the 3300 is currently unavailable (delivery time unknown).. I'm looking at maybe the 2450 option.. there seems to be more positive than negative reports on the lighter flywheel. If I went down this route, would I also need to replace the pressure plate and/or the ring-gear? Both appear to be in good condition (at least to the naked eye). I've taken on board the other comments about the dual o-ring clutch thrust doohicky.. and will replace crank seal and gearbox input & output shaft seals..
I'd be most grateful if anyone has any other wisdom on this.
While I have the box off, I'm considering popping off the cover to replace the gearshift return spring.. I've noticed some missed gearchanges which I think is due to the gearshift not always coming back to centre. Is the spring a common issue?
My Lemon has done 55k km. I've owned it for a short time and going through sorting it out and bringing it back to life.

[Dukedesmo]

Not got into the clutch/flywheel on my LM2 (it's only done around 18k miles so hopefully won't need to) but, from previous experiences with Ducatis, if I was replacing the flywheel, I'd go for a lighter rather than heavier everytime.


Obviously 1970s Guzzi engines are 'lazier' than 1990s Ducatis but, other than being a little prone to stalling when cold, I have seen no downsides to a lighter flywheel on both mine - more responsive on both revving up and down (so more engine braking) and, as such feel livelier. Plus losing weight (especially rotating) from your bike is always a good thing.


I have no idea how heavy the flywheel (or crankshaft) on my LM2 is but, it is definitely heavy and large diameter so carries a lot of stored energy. 

[BMCMOTO]

Others may differ but, internet pictures being what they are, I think your flywheel is probably fine, the hub definitely needs to be replaced. If you replace with the lighter factory flywheel you will notice some difference but not very much, after all it was issued by the factory for some bike. The custom skeletonized, lightened, flywheels that some offer, make a very noticeable difference, those are a different kettle of fish altogether. 
Good luck with this!

Brian

[wirespokes]

I'm with bmcmoto - the flywheel doesn't look bad to me either. However, cleaning up the teeth and a new photo would help a lot. It's difficult determining how notched it might be in the current state.

[jerryS]

Thanks for your responses. That gives me more confidence going for the lighter Guzzi flywheel.
Here are some more images of my flywheel.. after cleaning.. 
You can see the driving





 face of each tooth is worn. I think it would be wise to replace. What do you reckon?

[yackee]

I've had no problems at all with my lighter flywheel installed as part of a ram clutch conversion. No stalling in cold temps, engine tics over very regularly at idle, shifts are smooth. That said I also haven't sensed much impact in overall performance "feel". The lighter clutch is definitely noticeable, but the "spinning up faster" doesn't seem super-noticeable to me at least.

[Frenchfrog]

You would possibly get away with that flywheel Jerry.But if you do high mileage and are keeping the bike long term I'd swap it out because doing a clutch/flywheel job is such a pita.

[wirespokes]

Now that I see the wear, I agree it should be replaced.

[jerryS]

Thank you for all your replies.. That's great confirmation.. I'll get a new flywheel for sure.. I really don't want to be doing this again..
While I'm in there, my clutch springs are technically out of spec. .I have a range of free lengths of 27.29 to 27.84. The spec says 27.97 - 28.00 (workshop_manual_g5_ sp.pdf) . .So, I will replace those too.. watch this space 

[Antietam Classic Cycle]

I've not had good luck with aftermarket springs, especially with the S-D Tech friction plates, which are slightly thicker than stock. Some made the clutch pull super heavy, one set would coil bind before the clutch released, another set that was advertised as "wrist relief" was still heavier than stock springs. My advice: find o.e. or new-old-stock Guzzi springs, or simply reuse the originals even though they are slightly out of spec.

[jerryS]

Thanks Antietam,
I like this advice.. The original clutch was showing no signs of slipping.. and new plates will be thicker by all accounts.. I don't fancy the idea of stiffening the clutch action..

[Stevex]

I replaced my LM2 flywheel with a lightened one. To me it improves the ride and I would even think about going lighter. My lightened flywheel came with the timing marks machined off, which was an advantage, as I etched them back on using a timing wheel and piston stop, so I know they are 100% accurate now.
Use Viton replacement seals.

[jerryS]

Thanks Steve,
I did wonder about the timing marks on my original flywheel.. the stamped marks are around 6deg off.. I assumed that it had been put on wrong in the past but looking at how it goes together I can't imagine how a bad assembly could lead to such a small error.. there are 6 mounting bolts, so a bad assembly would lead to a 60deg error (360 / 6).. I can only assume that the timing marks are wrong.
.. and thanks for the tip about seals.. I see there are several brands on offer at a variety of prices.