Bad Clutch Shudder

[RZResurection]

Usually when using 17 inch wheels you have to gear up quite a lot due to the different tire radius.
A 160/60-17 is much smaller than a 110/80 or 120/80-18.

In my 17 inch RGV conversions something like 19 / 43 is pretty equal to the stock 17 / 39 with 18 inch. With a larger 180 tire it'll be slightly different maybe 19 / 45 or so.

A good calibration point is 120 kmh in 6'th gear. Stock bikes have 6000 rpm at that point.
If you have less, then your gearing is taller. If you have more, then its shorter.

You are correct. The 19/43 is equivalent to stock. My issue is there isn't a lot of choice for an 18mm offset sprocket, so I'm going to have to use the 17T front until I can find some other options.

I knew that keeping the stock gearing and going from an 18" to 17" wheel would give me a little taller gearing. I did plug in the data from the stock bike as well as my 'current' and 'custom' into gear commander and it did show this. It shows 0.54 % in RPM

I'm thinking going to a 43T on the back. That will produce an 11% higher RPM difference from stock. I don't have to worry about speedo issues as I have a GPS speedo.

If I go with 44T = 13.5% diff higher RPM

If I go with 45T = 16% which is significant

I want to try 2 sprockets, but which ones?

I'm thinking the 43T for sure and maybe the 45T. This should give me enough of a spread to see what I prefer.

[MK]

For my race bike I simply cut and relocated the engine mount brackets.
As a result the engine is shifted to the left and I can use standard sprockets without offset.

[RZResurection]

I'm too far completed to be moving my engine.

Question - did you have any pipe fitment issues due to moving your motor?

[MK]

Yes, the outer left screw has a bit limited access.
Also for stock pipes the flange had to be ground a bit at that corner to fit between frame and the 8 mm bolt on the cylinder.

Fitting Jolly flanges was easier - they have no clearance issues and after that the pipes just need fitting/loosening the springs to handle them.

[seahorse]

This sounds a bit silly but is there some confusion about gearing up here.
Im running aprillia wheels on the 421 LC. Gearing is 18/39, Tall to stop the 421 from wheelstanding everywhere
When I have built 350 rz/s with the RGV conversions I have run 17/39, it was hard to buy the 39 rear. From memory I ran the tallest profile rear tires, to keep freeway speeds high at lower revs.
I'm running an 18 mill off set 18 tooth on the LC 421 APE, that's just how it worked out.
It was hard to find 10 mill offset 18 tooth for the RZ/RGV builds, hence I stuck with the 17 tooth on the builds I have done, and achieved taller gearing by coming down as low as I could on the rear sprocket, while keeping the rear tire as big ( in circumference ) as I could.
If your running 17 inch wheels you need a 41 rear sprocket or smaller if you can find one.

[RZResurection]

This sounds a bit silly but is there some confusion about gearing up here.
Im running aprillia wheels on the 421 LC. Gearing is 18/39, Tall to stop the 421 from wheelstanding everywhere
When I have built 350 rz/s with the RGV conversions I have run 17/39, it was hard to buy the 39 rear. From memory I ran the tallest profile rear tires, to keep freeway speeds high at lower revs.
I'm running an 18 mill off set 18 tooth on the LC 421 APE, that's just how it worked out.
It was hard to find 10 mill offset 18 tooth for the RZ/RGV builds, hence I stuck with the 17 tooth on the builds I have done, and achieved taller gearing by coming down as low as I could on the rear sprocket, while keeping the rear tire as big ( in circumference ) as I could.
If your running 17 inch wheels you need a 41 rear sprocket or smaller if you can find one.

No confusion. You're correct seahorse.

I have 17/39 stock combo now. I went with the 'stock' gearing, so that the only true difference would come from the wheel size. The correction would be to go with a smaller rear sprocket.

My thinking is that my clutch is shuddering because the motor is having trouble getting my bike to move forward quickly - partially due to the weight of the bike and the heavier back rim. I thought going up a few teeth on the rear would help reduce this problem.

[seahorse]

all good as you identified earlier an 18 front is a faster taller solution as its worth 2.5 down on the rear.
When I was chasing the 18 i'm sure they were available in both a 10 and 18mm offset.
I don't have any shudder issues with the 18/39. I did however replace both internal clutch, and shaft bushes.
I have all new shaft bearings, and I did go to some trouble to drill out my basket pins, re places the cush rubbers, and tap some countersunk allen head bolts to replace the pins. The aim was to reduce the movement of the big gear wheel attached to the basket.
I still think shudder is balance associated and feel this ties back to reducing any movement of the shaft.
You did follow the arrows from basket to face plate.
Your gear drive ratios marked on the big and small clutch gears fall within the tolerances marked in the manual?

[RZResurection]

I didn't go with any new bearings. They didn't have any noticeable play, but I did not check with any amount of accuracy (using tools).

I like you went thru the trouble to rebuild the basket dampers (same process). I thought this might have been the root cause, but I still have the same symptoms.

Yep, lined up the face plate arrow. I got stung with that one awhile back. Couldn't figure out why the clutch faceplate wouldn't compress the fiber/plates. Not an issue at this point.

I did not check tolerances.

[seahorse]

Its also worth running a spanner over your engine mounts, just to make sure they are all secure.
Its a long story but I bought a mito a few years back that had a huge shudder issue.
A bloke called evil Dwarf here in Australia convinced me to double check the engine mounts after I could not get the shudder out of the bike.
Turned out he was spot on. food for thought

[RZResurection]

I have removed/installed my engine a few times since I've discovered the shudder.

I'll give it a look over. It can't hurt. Much appreciated.

[JonW]

I guess also the mounting rubbers and the mounting spacers could be damaged...

[RZResurection]

I guess also the mounting rubbers and the mounting spacers could be damaged...

I've never investigated the engine mound dampers. Never given them much thought really. Are they rebuildable? I've never looked close enough at a parts drawing sto see if there are actually part numbers for the dampers.

I did notice that I had a broken mounting spacer last time I pulled the motor out - could have been from excessive torque on the mounts. Hmmmm.

[JonW]

Smoker did his a while back on one of his projects, made a nice tool to do it too :)

[T.RexRacing]

You need 2 of these and 2 of these.

[Bare]

I'm still amazed/struck by the fitting of a 180 Tire.
130's Rub the chain.
Is it possible the Goofy Offset Engine sprocket is The cause.
As in it's not running true and /or it's causing some weird wobble on heavily loaded startup?