7000 RPM and there is a problem!

[jangofett]

Well, Twisted her up today and found a problem. When it gets to 7000 rpm or over, it starts missing and acting like it is not getting enough fuel? Falls below 7000 fine, gets to 7000 and rap, rap, rap? Any ideas out there. I have never changed the jets or anything, The needles have been shimmed and that is all. Damn, I was looking forward to that. It was coming alive until the problem. :x

[Rema1000]

Try setting the fuel petcock to PRI and repeat.  If it does OK, then there's probably a vacuum leak, and not enough vacuum to draw enough fuel... but that usually isn't a problem until you get up to wide-open-throttle.  Check-out the Racer's Corner for some tips on vacuum problem causing fuel starvation at high revs.

[jangofett]

Just got back and made a little progress. My brother-in-law told me to check the gap on the plugs. I set them at the top level (.035) according to the owners man. It helped. There is still a rough spot between 6000-7000 but after, hang on! It came to life. I ran her up to 9000. First time for me. It was fun. It sounded like it was going to twist apart but it was ok. Just wish I could figure out that dead spot between 6000-7000. I am no mechanic people, I am just muddling through. Just throw your ideas at me and I will try them. I'll check that PRI thing to Rema, Thanks!

[pantablo]

just did a 200 mile canyon ride today with a group and never got below 9k...oh the joy!

At one point I misshifted while at redline and hit at least 12K in neutral  before I managed to do something, like shifting. Also has my front end tuck and slide a foot or two on a corner today. Talk about joy!

[Black Snowman]

Hey Jango, I can't remember, has your bike been re-jetted? Any other mods? Sounds like it might be a lean spot in that RPM range. For a while after I did all my engine mods I had some hickups in those RPM ranges. Eventually they cleared themselves up once everything settled in.

I ended up replacing sparkplugs tinkering with the carbs, etc . . . but the main thing that corrected it was sealing the exhaust headers. I had a slight leak on one that I only noticed because I had painted the exhaust silver.

A carb ballence might be in order too. Especially if you can ballence them running near that RPM range.

[jangofett]

Hello Snowman, my carbs have the needles shimmed but that is all (about two washers). I thought it had been rejetted when I first got the bike but a subsequent call to the previous owner confirmed that it was not rejetted. So, that is exactly what is happening, a hickup at one spot around 6800 right now. I will try all of those things you mentioned and check my headers because I did have those off when I had them recoated. I know it is something that will have to be massaged out of it. It is a very small hesitation and once past it, it really turns on. It was shocking to feel that power in there that I did not know existed. Fun, Fun, Fun!

[DENVERGEE]

I am having the same problem but mine is fine at 3/4 throttle yet any further is just bogging down and dosnt want to run right it goes then starves then goes so on... I just bought it and dont even know where to start? any suj. If you could tell me how to check the plugs I would like that.

[bettingpython]

Well, Twisted her up today and found a problem. When it gets to 7000 rpm or over, it starts missing and acting like it is not getting enough fuel? Falls below 7000 fine, gets to 7000 and rap, rap, rap? Any ideas out there. I have never changed the jets or anything, The needles have been shimmed and that is all. Damn, I was looking forward to that. It was coming alive until the problem. :x

92 500e had the same problem I rejetted and set the floats to fill completely to the bowl gasket level and it still did this to me on the Highway around 80. Get rid of all the extra crap in the fuel system and block off the vacuum line to the left carb, run an inline valve and 5/16" fuel line should fix your problem.

read here my solution

I just finished a ride today with a couple of gixxer 750 riders and even the tank mounted valve is causing enough restriction that when running hard through the twisties shes sucking the floats way down when I keep her in the 8.5k to 10k rpm range for extended periods. I had to ease off in the straights to refill the bowls so I did'nt lean out in the middle of hard cornering. Check in racers corner for a pingle tank mount valve mod that will be my next step.

check Kerrys general purpose page find out how to check float level with clear poly tube.

also try using the search feature. No one person has the right answer.