2001 Yamaha GP1200R, intermitant bog!!

SKYWALKER

SKYWALKER

X-
Location
Hutchinson,KS
I built this motor out of random decent parts off of other 1200's, just so you know that up front. From a dead stop sometimes it will take off like it should and hit about 7500 rpms, other times it flat lines at 5000 rpms. Used to be if you hopped the ski a little, it would then take off, wierd. The ski is bone stock. Issue happens cold or hot, runs awesome when it isn't acting up. Sometimes it will run great on and off the gas for a couple min., then it will act up again.

Things I have changed or done allready:

- Compression is around 110 on all cylinders
- plugs have been changed
- fuel trap door removed
- converter changed (due to the one in it had broken loose)
- waterboxed changed, found some debrit from old converter in it
- carbs were taken appart and checked prior to reassembly( still not out of the ? yet)
- main fuel filter clean
- cdi box changed

I am unsure on how the sensor right after the converter works. I plug it in and the ski runs like crap, i unplug it and it still runs like crap. The old converter wipe bent the sensor for the converter that was on it when I first tested it. Thn I put on a converter system(brand new), but I dont know what year it is. Im thinkn the old sensor was busted and wasnt working right, and the new one doesnt match the cdi, am i thinking wrong? Superramjet has the bypass chip I am going to try tomorrow. I haven't ruled out the stator, and I have one anothor one of those. When it starts running bad I can pull the wires off one at a time, and all they all seem to still be running. So I am 95% positive there isnt a miss, just limited power.

Hope someone can help me, or might know about this problem

Thanks


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ANT

ANT

Just ride
Location
Sea Isle City, NJ
a lot of times the powervalves hang up on them making it seem like its dropping a cylinder. it's only a tiny little servo motor that opens them up so all it takes is a little carbon to hang it up and it will kick in and out sometimes. pop off the covers, disconnect the linkages and check each valve individually, you should be able to open and close them by hand easily.
 
Jumper

Jumper

What! What!
Location
Orlando biatches!
Hey bro! Check the wires and the caps. I used to have a similar problem from time to time with my Blaster. It was when the caps were not making a good connection with the plugs. I zip tied the caps around the plugs and have not had that prob any more. Good luck buddy!
 
Kaveman

Kaveman

Born in USA(not Kenya)
Location
texas but soon tejas
SKYWALKER said:
When it starts running bad I can pull the wires off one at a time, and all they all seem to still be running. So I am 95% positive there isnt a miss, just limited power.-
Click to expand...

In the future, I would strongly recommend against this type of "cylinder drop test". When the coil sends out a signal it searches for a ground, the spark plug. If it doesn't find one it can try to ground through the cdi and fry it.

The sensor beyond the catalytic converter is a heat sensor which will signal the cdi to signal the meter to beep if the temperature after the cat is too high or too low. The chip you are installing will only serve to tell the cdi that the temperature after the cat is within the operating parameters. Probably an R&D sensor chip.

I just had one of these engines in an XR1800 sport boat do something similar. What I found was the check ball for the exit of the accelerator pump had become stuck, not allowing that shot of fuel needed to overcome the negative pressure caused by opening the throttle (it would run lean.) You may have a problem with the accelerator pump...faulty diaphragm, stuck check ball either on the supply side or the exit side or possibly a loose hose or a hole in one of them. Most technicians NEVER even check (some don't even know what it is) the accelerator pump. It is located in the rear carbureters metering side cover.
 
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