Jetting

[fsmlittler]

Ok so my Casa SS200 kit is running well once on the pipe and I’ve been clocked st 82 on the flat so it’s clearly not far off on jetting. But....if I go to wide open throttle the motor misses above 8000. If I back of a fraction it’s perfect. I’ve tried putting the choke on and it gets worse.
The set up is a 30phbh and JL3 pipe.

[rosscla]

Someone's got to ask - what jets?

[fsmlittler]

150 main jet. Av268 atomiser and 40 slide. No filter

[rosscla]

That sounds quite rich try leaning off the main a size at a time and see if it clears.

[johnny650]

if you haven't already fitted an auto advance , now might be the time to consider it .

At 8000 rpm it would over-advanced at a static 17 degrees . According to Webster and Broadhurst you would probably be needing as little as 14-15 degrees advance at 8-9000rpm
https://www.mbscooters.co.uk/info/mb-*- ... s+282.html

[fsmlittler]

I did consider some timing control but the miss is only apparent if the throttle is wide open at high revs. Back it off a fraction and it goes away and revs happily to 9000
It’s already more conservatively jetted than RLC recommend for the set up and others have got the same set up. I suspected the needle but wanted to see if anyone had the same issue?

[fsmlittler]

I’ve just put a 300 needle valve in the carb as I suspected the 200 wasn’t enough but it still sounds like a rev limiter at 8000

[db67]

Hi, sorry to hijack your thread but was just wondering did you get this sorted because I'm having a similar problem on my ts 225, 30mm dellorto, with filter, 140 main,av266 atom,55 pilot, x13 tc & 300 valve jet,runs great till you get to the top of the rev range then it starts to get the same symptoms as yours, I put a 200 valve jet in which greatly improved the problem with just a slight stutter, I've got a 250 to try at some point, will let you know if it helps good luck

[Mrnice71]

db67 .....a 200 float valve jet is to small , you need a 300 , what exhaust are you running ? On a standard TS1 a 140 main could be a bit to large

[db67]

Hi, thanks for your reply,I'm running one of the new Ron Moss clubman exhausts, I did have a 300 valve jet in I was just trying the 200 as a sort of process of elimination, if a 140 main is too large what size would you recommend? cheers