Scooterotica

First semi long ride on RB22 and I have a problem.

Firstly it is 4-stroking at 1/4 throttle,
Secondly after riding hard(ish), the engine revs "itself" when the clutch is pulled in.

I suspect either an air leak or jetting prob.

There is no sign of any gaskets leaking, scooter is clean as a whistle (maybe too clean ie. no fuel on the floorboard)
Oil is fine, no petrol in there and the correct amount.

I stripped the carb and found that the previous ownder has botched the choke and it doesn`t seat when turned off.



This means that the choke is on at all times.

I was thinking that the 4-stroking at 1/4 throttle could be slide related, so had that out too.



Plug is a NGK R CR8E and looks ok but I think it should be pretty black considering the choke is on.



Setup;
Standard RB22, Fat mamba, mb crank.

Mikuni 35 Jets;

Needle 6EN11-47 2nd clip from top
Main 310
The weird one is pilot jet. All I manage to read on that is 02??

Carb is unfiltered.

Where should I start? and how to I test the flywheel side seal?

Needle number sounds wrong, assuming it's a TMX35?
Must have an MMW CNC head if you're using a CR 10mm plug.

Yup, TMX 35 and a MMW CNC head.

What needle should be in there?

Also, thinking out loud here, if it is a mangetto seal leak wouldn`t the engine want to race all the time? It only raced when I gave it some welly over a period of time.
i drove home on the back roads @ 50mph and pulled in the cluch just to check if the engine raced and it didn`t.

needle should be in the 50 range so urs is probably a 57? the pilot jet markings are really small, get a magnifying glass or someone with good eyes to look at it, try richening up ur main jet to see if that cures the "racing".

Mikunis are difficult to get to run clean all the way through, is it rich just before the pipe kicks in usually around 5 - 5500 revs?

i reckon it was the choke thats saved it
with the choke seated a 350 main jet and 25 pilot be nearer to where it wants to be ,if 57 try clip 3

? is it std ignition or augusto/mtec/variotronic as that will change jetting requirement alot ,what ign timing?

the mmw heads are very high corrected comp if the rb22 is std porting it may suffer pinking so will need all the fuel you can throw at it to control it so probably will be rich enough to have a bit of a burble before picking up onto pipe

if you suspect a leak i have these leakdown testing kits

http://scooterotica.org/forum/viewtopic ... 12&t=26427

I meant a 57 needle. Just a typo.

When I say it revs itself after a thash, its more (slightly) pulsing i.e. uneven revving itself

Ignition is Varitronic.

youll need 25 -27.5 pilot on varitronic

the running on at part throttle after a thrash may be nothing more than the pilot being too lean

Ahh brilliant, thanks Darrell.

When I read the Pitot jet the correct way round, its a 20.

So, It looks like my 4-stroking lower down is because it`s running with the choke on and it`s running hot because my pilot is too small?

yes ,the handlebar chokes do the same ,run fine at full throttle but splutter at part throttle

think yours will be a low rpm combination of high advance from the varitronic ,high compression,lean pilot and overheating onset by the combination

Darrel are you saying that variotronic setups in general will all require pilots of 25 plus just setting up my mugello 225 with a tmx30 and B race stealth cheers Pete