Jetting my FCR

[EPDP99]

I have a 41mm FCR on my stroker motor. Engine was dyno with "the right" jets and produced decent power. but jetting is definitally off. It sputters and surges down low to maybe 1/4 throttle then cleans out. Dyno was ran with this in the test description. fcr carb ocemr #5 182m 48p. But i dont know what the ocemr #5 means, maybe needle clip. I think my pilot may be too lean. but im not sure. quad puts out 52.6HP and 37.5lb-ft tq. not bad but expected the numbers to be more opposite. Dyno sheet to come. but need suggestions on jetting.

[K_Fulk]

This will take care of your bottom end sputtering. It did mine and everyone else ive talked to with one.

http://www.mxsouth.com/factoryrd/fac11p-38li.htm

[hook]

i use the rad plate too but still had to goup with a 52 pilot

[cals400ex]

does that piece fit fcr40mm's?

the ocemr is the needle that is in the carb. i believe i only ran the needle clip in the 4th position, but maybe it was the 5th. i really can't remember. the fcr's do tend to hesitate a bit if floored from lower rpms. i have had great luck with the 52 pilot jet as well. we also run a smaller mainjet. however,i am not too sure what your mods are.

[K_Fulk]

Originally posted by cals400ex
does that piece fit fcr40mm's?

Yeah it will fit but, Im not sure if they will help as much on the 40's though. The 40's are supposed to have a better accelerator pump. I'm not sure how true that is though.

[EPDP99]

mods= 465 stroker motor(440 stroked +4mm) 12.5:1 comp piston, web 479 cam port and polish full trinity racing exhaust, big gun rev box, 41mm fcr. its not only when you give full throtle, if you are just riding in the low throttle range and it does it all the time not only on hard acceleration. like when just starting off in first gear and rolling. or just cruising in like 3rd gear with throttle barely open it surges. like when going through camp sites slow, it surges, pops, and stumbles.all the way to 1/4 throttle possibly a little more. where should I go with jetting before I worry about pump.

[K_Fulk]

I would try going to a 50 pilot first then play with your needle settings.

[EPDP99]

ill give it a whirl. Thanks for the info also.

[MIKE400EX]

I agree with KFULK, put the #50 pilot in there first. Adjust the idle screw (get a zip-ty one) for best response and idle. Then adjust the slow air screw to get best response just past idle - that'll probably get rid of that flat spot below 1/4 throttle. The slow air screw is in the hole on the left bottom looking into the venturi entrance. #5 usually means the 5th clip position from the top. That 182 main seems a little fat especially with the clip that low and a 479 cam, but you did get great numbers. Why did you expect the numbers to be more opposite? Sounds like peak torque was at about 7000 rpm and probably had a wide powerband. Should run very well!

[cals400ex]

yes, i would go up on thepilot for sure. i ran a 50 and it even seemed a bit small but who knows. my buddy runs a 52 with great success. i noticed on my bike if i was anything over idle, my needle make the most difference.