Lacking power rpms

[Beau57]

1978 GS 750 with 31k miles.
I have noticed a loss of power and a reluctance to rev past 5.5-6k rpms. I have cone air filters and 4-1 Kerker exhaust. It almost seems as if the air filters are restricted (haven't cleaned them yet). I did however drain the float bowls. Have performed valve adjustment within the past 6 months and installed ne plugs. Once warm it starts fine. No missing or backfiring. No unusual exhaust smoke. Idles as good as it ever did. Going downhill is the only time it seems easier to pick up rpms which suggests a compression issue to me? Have not found the time to do compression tests yet. What puzzles me is the abrupt change and not a gradual one which helps rule out plugged air filters. Carbs were also torn down completely 6 months ago and all float levels adjusted. All work done by myself. I realize some of the things I already mentioned may in fact be my problem but time is short and if anyone has any other thoughts I would appreciate you chiming in.

 

[Guest]

Beau, Sounds like it may not be getting enough fuel. When taking the carbs apart did you soak them thoroughly and clean the small passages? All new orings? Mostly just thinking out loud. Good luck with her. Ray

 

[Big T]

You need bigger jets to compensate for the pods

However,

1. The pods may be dirty or overoiled
2. Did it run fine before you added the pods?

Cheap pods are a known source of carb issues

 

[Texasgs]

re

re

Beau, Sounds like it may not be getting enough fuel. When taking the carbs apart did you soak them thoroughly and clean the small passages? All new orings? Mostly just thinking out loud. Good luck with her. Ray

I agree, fuel starvation. If it ran good at one point, and you havent modified it, then went downhill, the jets are not the problem, If this is the case check out the fuel flow from the tank, and look to see if the fuel line is delivering a decent fuel flow.

 

[posplayr]

I have cone air filters and 4-1 Kerker exhaust. It almost seems as if the air filters are restricted (haven't cleaned them yet). .

If you bought some of those cheap K&L filters off e-bay they are very restrictive. Even though the ID of the filter fits your carb, the inner rubber is a much smaller ID.

Someone on here was recently having an issue with tuning and it got down to those restictive "cone" type filters instead of the more oval cone type.