Ok, I know I should have done my homework better before I let Trinity build up my Raptor, but the fact is, they did and now I have to live with it. So, please no criticism on my choice of builder. I am really looking for help here.

I have a Yamaha '03 Raptor 660r. It have all of the Trinity recommended mods for their 727 build. Valves, springs, corilla rod, port, polish, dynatek ignition and FCR carbs (which is where I think the problem lies). I also have a Yoshi pipe, which Trinity said was a good pipe for their system and not worth changing out. The bike was broke-in very slowly, oil changed many times, all to the details told to me.

Here's the problem: Seemed like the bike was running decent during breakin, but obviously I wasn't hitting it extremely hard for long time then. I was also at sea level (near Trinity). Now back home, at about 2500' and having gone through a range of a dozen jet sizes, the bike run TERRIBLE. But, really only at high rpms.
Starts perfectly, idles good, seems like I may be hearing a pinging sound, but I connected an oxygen sensor and it is right on for the mixture. BUT, when I jump to full throttle, the motor cuts in and out. Like gas, no gas, and the oxygen sensor (obviously) goes from rich to lean about every second. Let go, and it idles perfectly again. Sounds like a main jet issue to me, but like I said, I have tried from 135 to 155 on the FCRs and they all act exactly the same, yes exactly.

On other item I ran across is the FCR needles. Although I would expect them to only affect midrange, the needles that came with my bike are not the ones referenced on Trinity's web (mine are OCEMR). So, I bought the ones the listed, and still no diff.

Thanks in advance for any help.

mtquader

 

It sounds like it's starving for gas.I would check the float level.
Or your not flowing enough fuel from the tank for some reason and may need a pingle dual outlet valve. Craycaft sells a nice one that has a reserve position and the price thru him is better then most if not all.

 

What jets/needle position are you running in your FCRs and are they 35mm or 39mm?

 

I am running the 35mm carbs and currently I am trying 145 jets in both carbs. But, I've tried from 135 to 155 and also tried making the right one size bigger than the left. As for needles, I am currently using OCGMR but I have also tried OCEMR which was the original set.

Thanks.

Looking at the float and fuel flow this evening, will give some feedback later.

mtquader

 

I agree with 6 6 when i rebuil my top end my float was caught up and it would cut mid - high rpms

 

Makes sense, but doesn't seem to be the problem. Tonight I took the carbs completely apart, cleaned... floats appear to be moving fine. I also emptied the gas can, cleared out the peacock and put in new gas and a new gas line. Put in 150/148 jets and set the needles at 4/5. I connected the gas to the removed carbs and pulled the throttle to watch the both carbs squirt, looks good to me although I'm no expert.

Still cuts out at high rpm.

Another detail, which may not make a difference; Trinity installed dual separate k&n air cleaners. Am I possibly getting too much air and maybe even need to go much bigger on the jets? 150 seems pretty big already.

Thanks for the suggestions so far.

mtquader

 

Keep going bigger and give it a shot . It sounds like your engine is starving for gas. Try to go bigger and see what happens. Monday you should call trinity and see what they reconmend.

 

When you say "only at high rpm", how high do you mean? Are you sure you aren't hitting the rev limiter? The rev limiter sounds like a crisp stutter at high rpm, it's constant until you let off the throttle (bra-a-a-a-a-a-a-a-a).

On my 686 w/35mm FCRs at sea level, I ran 145/145 with OCGMR needles on the 4th groove from the top. At 2500 feet, you need to jet down from where it ran good at sea level. Higher altitude has less O2 than sea level, larger mains is going in the wrong direction. With a brand new spark plug, go back to your original mains and do a full throttle plug chop without hitting the rev limiter (some can do it in 2nd, others prefer 3rd gear). After a few seconds at WOT, pull in the clutch and shut off the motor. I'll bet that your plug is dark brown. Report back and we'll get you dialed in.

 

tis happened on my bros dirt bike. What happened was on his he would idle fine and then kick into first/second and the bike would jump and go slow and stall out. What was wrong with his is the fact that his main jet was very clogged with crap. Cleaned it and now tis fine.

Basically.. when u run idle.. it stays a constant gas. When u give it throttle, the bike needs more gas.. and thats ur problem. It seems that either ya got crap in the jet, or ur jetting is messed up because of the sea leve thing u were talking about. If the jet is too small.. then it will starve it for gass and result it as being like what i described with the dirt bike. Just change the jet size and ur good. MAke sure its clean too.

 

Ok, first I want to say Thank You to all that have been helping me through this problem.

But, the sad news is, I must be missing something because it doesn't appear to be getting better. Today I went to 150/155 jets, no difference. I moved the needles to 5/6 from the top, no difference. I also removed the nuts on the bottom of the carbs and verified the floats were not stuck and they move freely.

I do have more details on the high rpm question. When I pay more attention, the poor engine performance starts about 1/2 throttle and just gets worse and worse going up. So, it doesn't look like the rev limiter.

Tried the plug chop, but the bike runs so poorly at higher speeds, it makes me nervous to run more than a couple seconds. But, when trying as close as I can get and pulling the plug, the plug is dark colored, and dry.

Thanks again,

mtquader