WTF, jetting on FCR carb.

[Fast350ex]

I have a 99 400ex with a full Curtis Sparks engine (x-6 pipe) in it, and a Keihin FCR carb.(piece of $hit) I can't get the damn jetting right on the $hit. I've tried 162, 168, and 170 main jets, and nothing is working, I've also tried turning the mixture screw out 2 1/2 turns and it makes no difference, it just leaks a $****load of expensive gas. It makes a sharp sucking/ popping noise through the air filter at idle and shuts off. It also has a hard time starting, my battery drains before I can get it started sometimes. When I try to start it the starter makes a grinding/ stripping noise (doesn't sound good). And yes, the timing is right

It's really starting to f'ing piss me off:mad:

Any jetting opinions and what I should do about the starting situation:confused:?

Please help :( , I really want to ride because I just got it.

[EPDP99]

what mods and what size carb. most people i hear of have a 50 pilot and a 165-175 main on 416-440. they have alot of adjustments but colby from c&d says DO NOT mess with them. Only use pilot, needle, main, and fuel screw to adjust. also alot of people do a accelerator pump mod so it only squirts gas for under 1 second. I am going to do this on my 41 mm soon.

[Fast350ex]

I'm not shure what size carb. it's a 39mm- 41mm but it has CURTIS SPARKS x-6 pipe, race cam, heavy duty cam chain, heavy duty valve spring kit, port work, 416 piston and a heavy duty clutch kit.

I'll try the pilot at 50, but the main jet will have to be over 170.
Anyone know about the starting issue.

Please help:(

[cals400ex]

we have best luck with a 52 pilot jet. also, look at both air boots close. make sure neither one has a crack in it. you need to look close though. make sure all the clamps on the boots are tight too. you may have an air leak. are you running a stock ignition box?

[Fast350ex]

I just took the carb. off and cleaned it, I also inspected both boots, they are fine and tight. I not shure about the ignition box, I bought it used and I think it still has the stock one. Is this bad, would it cause it not to start?

Please help:(

[cals400ex]

an aftermarket ignition box could make it hard to start. i would take it off and look at it.

[Jonas]

fcr carbs are the best you can buy. Tell us what your all of your jetting specs are now.

1. Slow jet?
2. Needle setting?
3. Main jet?
4. Air mixture screw?
5. What does the carb say on it?
Also:
6. What elevation do you ride at?
7. Also what type of gas do you run?
8. What does your cdi say on it?
8. Any info. is good.

[DannyB]

fast350x, I ran across the sparks setup for their 39mm fcr, I don't know what elevation this setup is for ,but it was a 165main 50 or 52 pilot,and the pilot screw was turned all the way in,and this was for the sparks x-6 pipe with threir cam. I had a starting problem as you described and it was a worn out starter sprag,bearing that mounts in the back of the flywheel,it causes the starter to clang and clatter and turns the engine over intermittently,making it very hard to start.hope this helps, dannyb