fcr carb problem

[njquadracer11]

ok so i just recently switched back to an fcr and me and my engine builder have been working on the jetting...right now i thought i had it jetted almost perfect...there is absolutely no bogging or hiccups what so ever and the header isnt turning red...my problem is that the bottom end power is absolutely horrible...im used to getting every holeshot with my edelbrock but with this fcr I'm dead last every time! any help would be nice, thanks

[310ESR]

You say there's no bogging so are you blowing the tires off? What are the jetting info, main, pilot, leak, needle? Just curious

[DnB_racing]

as with any modification, there is ALWAYS some compromise.... meaning you cant build a drag racing machine and expect a low end torque monster,

but that doesnt mean you cant tune it in for a better bottom end, but usually it means loosing top end,

try closing up your intake somehow(put an air-box and partial cover on) and re-jet for a more restricted intake, or play around with different exhausts, or cams

as I said when you build, its a compromise...sometimes when add in one area you loose in another. play around with a good grunt web cam, you should be able find one with the right combination of speed and power,or change the thickness of your head gasket to find just the right compression,or play around with the weight of your flywheel.

no one of us can really tell you whats perfect for you,cause in reality we all are looking to go 100 mph in 60 feet and still have a machine that could pull a stump out of the ground , but sadly in the atv would there isn't that machine made, you just have to find the combination that works best for your needs:(

for me a perfect combination is more of a mid range type of cam, with high compression piston, not too bad on top, not too bad start, but im in the mid range more then im starting and more then im topped out,

but opinions vary greatly on whats just right, this is just how I like to build mine,

[njquadracer11]

its no blowing the tires of, there is just no power

well the only reason i made this post is because i had an fcr on it before and it still had grew pull and i got every holeshot so its really confusing me

[njquadracer11]

il take apart the carb and find out all the info

[DnB_racing]

Originally posted by njquadracer11
its no blowing the tires of, there is just no power

well the only reason i made this post is because i had an fcr on it before and it still had grew pull and i got every holeshot so its really confusing me have you changed anything else besides the carb, in other words it might be combination of things causing your problem and not just carb,

if just carb then put your old one back on

if you changed more then carb, then you might not have the right combination for your riding style

[njquadracer11]

i havent changed anything, its the same set up I've had for years

[ghott]

1.) Need a list of all the modifications on your engine. What year 450R do you have?

2.) Need the size of the FCR and what it orginally came off of. Any modifications on the carb. What size is it? Is it bored? Straight or tapered? Who did the boring, etc etc.

3.) Need to know what ALL of the current jetting specs are. Pilot, slow air jet, main air jet, main, needle, clip position, and leak.

4.) Is the lack of low end power your only problem? Does the bike seem to "come alive" at some point in the RPM range like a 2-stroke? Any other problems with the carb?

[njquadracer11]

its an 05 450r, cp 98mm 13:1 piston, stage 2 hot cam, mild port job, ferrea valves and springs, crf ignition...i dont know exactly what the carb came off of but i know its a 41mm and I'm gonna take it apart today to find out the jetting specs...right now the bottom end power is just completely gone, but i would say the top end power is normal or what I'm used to...(ive never ridden a 2 stroke so i couldnt tell you lol)

[njquadracer11]

i was also wondering if it could possibly be a clutch problem? just throwing ideas out there

[njquadracer11]

ok so for ****s and giggles, i put the edelbrock back on and played with it some more and it actually ran really well, so im probably gonna hit the track tomorrow to see how it goes