1982 GS750T Will not rev above 4000rpm

[Guest]

It does not rev above 4000RPM. I was going through the stator papers and when i attempted to rev to 5000RPM to get a reading, it hesitated at 4000RPM and went back down to idle at 1500rpm even with throtte. It idles and revs smoothly till 4000rpm.

Any ideas to what is going on?

The bike has:
-4-1 exhaust,
-Pod filters
-Rejet: Main: 120
Pilot: 45
-Inline fuel filter



I did a quick search and came up with a few possible issues...

1)Bad ignitor / cdi box
2)Valve timing
3)fuel issue
4) jetting issue

I will start my process of elimination but if anyone knows whats going on, id appreciate any info!

[mmattockx]

Will it rev past 4000 with the choke on?


Mark

[SnpGotYou]

Mark,

Thanks for the quick reply,

I will have to check tomorrow to see if itll rev past 4000 with the choke on.

What do you think will be the issue IF it does rev past 4000 vs IF it doesnt?

[mmattockx]

Mark,

Thanks for the quick reply,

I will have to check tomorrow to see if itll rev past 4000 with the choke on.

What do you think will be the issue IF it does rev past 4000 vs IF it doesnt?

If it will pull through on the choke then you are lean on at least the pilot circuit. If it stumbles worse than without the choke then it is probably somewhat rich. If there is no change then jetting likely isn't your problem. Have you ridden the bike? Do you know how it runs with a load on it? It is very hard to tell much sitting in neutral since just cracking the throttle will normally cause it to rev off the tach.


Mark

[mrbill5491]

Loose the inline fuel filter and what brand are the pod filters.

[SnpGotYou]

Loose the inline fuel filter and what brand are the pod filters.

Ill try that out. Emgo pod filters

[SnpGotYou]

If it will pull through on the choke then you are lean on at least the pilot circuit. If it stumbles worse than without the choke then it is probably somewhat rich. If there is no change then jetting likely isn't your problem. Have you ridden the bike? Do you know how it runs with a load on it? It is very hard to tell much sitting in neutral since just cracking the throttle will normally cause it to rev off the tach.


Mark

stays the same with choke on. Ill have to run with load and report back.

Thanks!

[SnpGotYou]

Thanks for the help everyone!.

I took out the inline fuel filter, and reinstalled the stock air box. It runs perfectly now.

I'd have to admit that i was a bit stubborn on wanting to keep the pod filters for aesthetics, but i guess id rather have a running motorcycle..

Thanks again!

[mmattockx]

Thanks for the help everyone!.

I took out the inline fuel filter, and reinstalled the stock air box. It runs perfectly now.

I'd have to admit that i was a bit stubborn on wanting to keep the pod filters for aesthetics, but i guess id rather have a running motorcycle..

Thanks again!

You were way lean then, if the airbox solved your problems.


Mark

[SnpGotYou]

Hmm.

How many more jet sizes would you recommend?
I went up three on the main and one on the pilot prior to installing the pods..

does going up or down one jet size make a big difference?

[mmattockx]

Hmm.

How many more jet sizes would you recommend?
I went up three on the main and one on the pilot prior to installing the pods..

does going up or down one jet size make a big difference?

I'm not sure I can recommend anything, but on my 1100E the stock main jet is a 107.5 and the pilot a 47.5. I have APE pods and a Kerker 4-1 installed, the pilot is still the same 47.5 and the main jet is now a 142.5, so 14 steps bigger. I am at 3400ft elevation, too. If I was at sea level I would probably be another size or two bigger on the main.


Mark

[SnpGotYou]

Decided to go for a ride today... But it died when i gave it some throttle. It seemed to have stared and idled better with the pods. I might just order the next 5 set sizes and go from there. What are your thoughts?

[mmattockx]

Decided to go for a ride today... But it died when i gave it some throttle. It seemed to have stared and idled better with the pods. I might just order the next 5 set sizes and go from there. What are your thoughts?

Did you go back to stock jetting to match with the airbox? With a 4-1 exhaust and the full airbox you will only need to step up one or two main jet sizes at most from stock and slightly retune your mixture screws for the pilot circuit.


Mark

[SnpGotYou]

Yea, im going to have to reorder the stock jet sizes. The heads was on the verge of stripping when i got it. But..i also plan on ordering larger jet sizes to experiment with the pods.

Thanks for all the help and info!. I really appreciate it!.

[mmattockx]

You will also need an adjustable jet needle if you don't have one.


Mark