231

Not really a kitten. The 21mm Oko was installed on my Sherco 3.2 4T after it was disassembled and matched to the Keihin to see where it compares. All passages were deburred (all is a must), surfaces and parts cleaned up with a file. The screw hole on the bowl that blocks the small hose was ground off. I left all settings and jetting as it came. As the carb is the same as the Keihin in all dimensions, I just bolted it on and fired it up. I figured that low speed was very close to the 28mm in jetting and idle air screw settings and was correct in my observation. I spent most of the time sorting out the float level. I arrived at lower factory setting (as described in the Sherco measuring method) to 1.0 inch. Any lower it won't start. Any higher and it floods. A couple ten thousandths count. At the level where the overflow brass hole is on the bowl worked for me. (Hint: Do this off the bike. Plug the fuel tank in and see if it floods or starves on the bench. Then proceed to fine tune it on the bike.) Idle was set but the idle air screw remained the same 1 1/4 out setting. I wanted it to start cold, hot, very hot, laying on either side, picking it up from laying it down for a while and every scenario I could throw at it. One or two kicks and it fires...every time. No hesitation when opening the throttle hard. No problems. It chugs like a 4-stroke with authority. The MJ needle is quite slim and probably runs a little fat, but with the smaller jet it runs clean to full throttle in third gear up a slope in a short burst. No leanness or back firing noted on acceleration. Probably a bit rich when the throttle is shut as it does pop. Spark plug tests showed nothing I could rely on. For the time being, this is not a concern for me. It is a dream to ride at slow speed. None of that jerky surprise. The throttle is very smooth and progressive. The power up to around 1/8-1/4 throttle is considerably (underline this) lower and not explosive one bit. It doesn't pull real hard like the 28, so giving it more throttle and working on technique gives good results. More electric. 1/2 throttle tests didn't demonstrate any noticeable difference to me. 4th gear wheelies are still available but not like the 28 pulls them. Here are the box stock specs: Oko 21mm: M.J. 103 M.J. needle: 3G9 clip set in second from the bottom (very much thinner on the bottom end than the stock allowing more fuel to flow off setting the smaller jet size) Slide: #2 P.J. 42 Idle air screw: 1 1/4 turns out Yes it can be made into a beginners bike. It is a very cost effective and easy switch that it is worth the effort. As I haven't tried it in different conditions over the year here in New Zealand, I'm sure there'll be some adjustments. I'm off riding. Bob

Thanks for your inputs. A flywheel mod will take some considerable effort and probably cost. I'm going to opt for the 21mm OKO and have ordered it today. Taming the beast is my priority allowing me to improve my riding style and skills. I'll check in with you later on the progress of the change. Bob

I have the 3.2 4T and it does have the power and it is at times hard to manage. Your suggestion that a 21mm OKO would lower the power would be a help for me. And how much of a reduction will any of the smaller carb sizes be on this bike? Will the supplied jets work with the 3.2? Bob

Wayne, I have the Sherco 2008 3.2 4T and have a question on your post. You mentioned that you were going to check the valves and torque the head. Please let me know how you got the valve cover off past the left side lower cross member of the frame to get to the left head bolts. I've tried by removing the motor mount bolts and nudging the motor down, but it won't go far enough to actually remove the cover because of the lower motor mounts and swing arm. I'm able to check the valve clearance, but only able to get the intake and right (not left) exhaust shim out. Removing the motor seems to be the reluctant choice for setting the valves and torquing the head. I hope you found a easier way. Cheers, Robert