Will not rev past 7K

[chronoman]

My GS450 will not rev past 7K it started about 2 months ago, since thinking it was a fuel issue, I have rebuilt and then replace the carbs, new fuel line w/ no inline filter and checked the intank filter for problems and it all seems to be good.Compression and valve adj is also good. I'm thinking the problem is in the ignition(electronic ignition), I also installed and gap new plugs and caps. Can the coils be going bad, or the electronic module, if so what is the best way to check them, according to my Clydes manual it all checks good.
1987 GS450l 32K miles.

Claude

[Dave8338]

Are your main jets sized correctly? That would be the first thing to check if it runs well through all other ranges up to 7000RPM.

[Steve]

Actually it's a little-known safety device that was installed on a select few bikes. :shock:

It is designed to keep your speeds down to a sane level so you can enjoy the ride. 8-[


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[Dave8338]

Actually it's a little-known safety device that was installed on a select few bikes. :shock:

It is designed to keep your speeds down to a sane level so you can enjoy the ride. 8-[


.

Yo...STEVE...what's behind door number 3 ?????? A goat???? :-D \\/

[Steve]

Sure, I'll take a Goat. :shock:
















A nice shiny red 1967 Pontiac version, if you don't mind. \\/


.

[Dave8338]

Great taste in Vintage muscle, Steve! :twisted: \\/

[chronoman]

The jets are ok, the bike ran well and then all of the sudden, well no more past 7K
If the bike has such a device that would limit the RPM's where would it be located, not that I would want to disable it or anything like that

Claude

[Dave8338]

The jets are ok, the bike ran well and then all of the sudden, well no more past 7K
If the bike has such a device that would limit the RPM's where would it be located, not that I would want to disable it or anything like that

Claude

Now look what you've done Steve...:---) There is no such device (on older bikes). If there is, I'd like to see it. My guess is that there is an ignition issue at work. Anyone else have any thoughts?

[KEITH KRAUSE]

Will it rev to redline when in neutral?
Trying to determine if it's fuel or air/vacuum related.
If fuel flow related, typical symptom is it will rev well in neutral/no load, but will have limited rev's while in gear/under load/accelerating.
If air/vacuum related, such as a semi-blocked air filter housing, dirty filter or poor air box sealing/rotting seals, then it will rev equally poor/limited in both no load/load conditions.
Many owners have serviced carbs and the disturbance to the filter housing creates leaks and loss of power because the CV carbs are so finicky about an air tight box.

[chronoman]

Well I have figured it out, by accident but never the less its fixed.
I went for a ride Saturday morning, As the light turned green I took off, again as soon as I hit 7K the bike shut off and came back on again. frustrated I pulled the clutch and gave it some gas until it hit 7k and keeped it there, and all of the sudden the bike died, Hit the starter button as I was coasting ,and nothing the bike would not even turn over, I shifted into neutral hit the starter and the bike came back to life, well I had to try that again in 4th I pulled the clutch and gave it gas till it hit 7k and the bike died again, pulled over, pulled in the clutch and noting no starter, put it in neutral, it started right up.What was the problem. stay tune for next time,(just kidding) it turns out that the KICK Stand spring is weak and for some reason when the motor hit around 7k(vibration or something) the kick stand would come down just enough to shut the bike off as soon as the motor shut it self off the kick stand would go back up and come back to life. Go figure.
You can almost say Steve was right, my bike had a rev limiter.

[Dave8338]

Well I have figured it out, by accident but never the less its fixed.
I went for a ride Saturday morning, As the light turned green I took off, again as soon as I hit 7K the bike shut off and came back on again. frustrated I pulled the clutch and gave it some gas until it hit 7k and keeped it there, and all of the sudden the bike died, Hit the starter button as I was coasting ,and nothing the bike would not even turn over, I shifted into neutral hit the starter and the bike came back to life, well I had to try that again in 4th I pulled the clutch and gave it gas till it hit 7k and the bike died again, pulled over, pulled in the clutch and noting no starter, put it in neutral, it started right up.What was the problem. stay tune for next time,(just kidding) it turns out that the KICK Stand spring is weak and for some reason when the motor hit around 7k(vibration or something) the kick stand would come down just enough to shut the bike off as soon as the motor shut it self off the kick stand would go back up and come back to life. Go figure.
You can almost say Steve was right, my bike had a rev limiter.

Gremlins...you've got to love them. This could have been one of those issues that might have plagued you forever, had you not thrown a healthy dose of LOGIC at the problem! \\/ NICE WORK WATSON....:-D

[chef1366]

Happy endings \\/

[KEITH KRAUSE]

The way the problem was described, he said the bike wouldn't rev past 7K. That to me did not sound like he was trying to say it completely died/shut off. Immediate shut down always points to an electrical issue.
He even said it seemed fuel related. He sure threw me with the poor description.
I'm glad it's fixed though.

[chronoman]

Keith
I'm sorry, I should have said that it hit 7K and oscillated between 7000 and 6500 rpms. in other word it would go to 7k and then drop on its own to 6500 and go back to 7k and the process would continue until I back off the throttle.