FCR carb prob on big bore/stroker '04

[Axo24]

I've read various threads on FCR carbs with mixed results. I've got an '04 that has a big bore/stroker kit (542cc). Its got an FCR carb on it that has what apprears to be the common issue of an annoying hesitation issue when you rap the throttle off idle. It will actually shut the motor off if you do it long enough. I dont know much about the carb,but it appears to measure 42mm. The jetting was 160 main...48 pilot...80 leak. I went to a 180 main...52 pilot...and the 80 leak. Seemed to help alittle with the hesitation,and might definetly didnt loose any power,but noticed a pop or two at high rpms. Also has a tendency to shut off at low rpms just puttin around. Havent got a chance to take it down the road a 1/2 mile at speed to check the plug...but wanna see if anyone might be able to steer me in the right direction with jetting on this big bore/stroker. The 80 leak jet concerns me....and I dont know anything about the accelerator pump except it has a boyesen cover on the bottom. No clue if its adjusted properly or how to do it. I've read and heard thats just the way these carbs are. I want this thing to work about 100% perfect....and if this carb wont do it....I'll be in the market for another,but before I do...I wanna see if I can get this one to work. Any help would be greatly appreciated!!

[eastside 400]

try around 165-172 main, 42-48 pilot, 50-55 leak jet, oring or wire mod the accel pump and grind the nub on the diaphram and switch back to a stock accel pump cover...you can buy a accel pump rebuild kit from honda for like 25 bucks that comes with a diaphram, cover, and rod. fuel screw around 2 turns out. i also suggest replacing the seal that goes where the slide plate is, it deforms easily, honda doesnt offer it seperate from the wear plate but yamaha does, just order one from a yzf250 or 450. When jetted and setup properly the FCR shouldnt have any bogs, they can be one of the snappiest setups available, its been said before that the only reason the fcr's got a bad rep is because people couldnt set them up right. Once they are setup they should work just as clean as FI but give you more power in the end

[Axo24]

Thanks man!....i was actually going to back the main down a bit and try a 50 leak and put the 48 pilot back in....ill work on it tonight.

[Axo24]

Ok...put in 172 main...48 pilot...and 65 leak(thats all shop had). It actually made it a tad worse again. I wasnt sure exactly what you meant about oring or wire mod the accel pump. I dont have the stock cover either. I did play with the set screw adjuster on it,but ended up putting it back to where it was. Keep in mind too...it does really "bog"...it just dies when flicking the throttle quickly. Slider plate seal also looks good. I tried th needle from the middle(4th) and 3rd and 2nd ring up from the bottom with no improvement. Any other suggestions? Thanks!

Also...I noticed a nipple on the right side(the side with the throttle cable) of the carb with nothing attached to it and a nipple on top of the crankcase with nothing hooked to it. Its rearward from where the breather from the airbox attaches to the crankcase. What goes on those?

[audioworks04]

180 still sounds lean to me, An adjustable leak jet is a great thing to have for tunning these things. I would butmp your pilot up to a 50 and main to a 195 leave the 65 leak in. The leak is fed from the pilot so the pilot will affect the leak.

[eastside 400]

you do know that he is using a FCR right? 190 on a FCR is way too rich.. Search thumpertalk and google and youtube for FCR Oring mod and you will find what i am talking about.

[01boneless]

adjust the ac pump

[Ruf Racing]

Originally posted by audioworks04
An adjustable leak jet is a great thing to have for tunning these things.

^^ Agreed ^^ Also remember the smaller the number leak jet, the less fuel, goes back to the bowl. Meaning more gas supplied to the AP. Sounds like this is what you need. :)
http://i532.photobucket.com/albums/ee328/RideRed187/450R%20Pics%20Parts/RDAccellatorPump.jpg

[d3ktrix]

If you cant find a smaller leak jet, just totally plug the hole where the jet goes with a screw. That is what I did.
Even with a 45leak I was still getting a horrible bog when I snapped the throttle, like u said the bike would almost shut off. I plugged the leak jet with a allen head cap screw and it totally fixed the problem.

Like eastside400 said, it sounds like you need to go down in side on ur main/pilot jets and increase the strength of ur accerator pump squirt.

The bog when u snap the throttle is from a lean condition, and the popping when ur wide open is from a rich condition.

If it gives u can idea I have a 471cc ported head 43mm FCR carb and I run a 172 main, 45 pilot and a plugged leak jet.
And I still need to go leaner on the main because my plug is always black.

And if u don't already, I'd get that head ported, u have some serious displacement trying to suck air through a tinny stock head. Killing a lot of potential.

[Axo24]

Alright guys....GOOD news. Its working perfect now. I checked for that squirt from the ac pump....and nothin,so I ripped it all down to figure it out. It appeared the nozzle that squirt into the carb tunnel may have been blocked,so I cleaned that out. I reassembled everything and it work at tad better,but still not perfect. I did however have good squirtage now. I then worked on the oring/wire mod trick since I notice the acuator was seperating from the adjustment screw......wired it fast temporarily...and WAMMO. No hesitation,dying,or bogging at all!!!

Got some minor jet work to do now,but nothing major. Seems to load up a bit at idle or just putting around,should be an easy air screw or pilot adjustment. Seems perfect on top for now,but has a tendency to stall out puttin around out of the blue. And I'm still learning its starting charactoristics,but its damn hard to restart now. Might need a leak jetting too.....but overall Its running decent and that crazy hesitation/cutting out issue (never really bogged) seems to be totally gone....and that kicks ***. Thanks guys!!!! I would have never even thought about that oring/wire mod thing if you wouldnt have mentioned it eastside....so thanks man...its much appreciated. :)