Lack of horsepower

[Bdogginit]

I’m trying to diagnose a problem with my 1982 gsx1100, the timing is set properly, all the valves are set at .004”, compression in all cylinders 135-138 psi, carburator was taken apart and inspected and all seems fine, air filters are clean, spark plugs are gapped to .025”. The oil isn’t over full,Everything seems to be in spec.

It starts up and idles pretty good, the exhaust temperatures for 1 and 4 are the same and 2 and 3 are the same and it sounds fine in neutral, but when I take it on a road test it has trouble going up a slight hill, and can only really drive it in 1st gear unless I’m going down a hill.

Over the winter I had replaced the stator and upgraded the regulator rectifier, and also replaced one of my ignition coils as cyl #3 wasn’t firing. Any suggestions on what to do next?

[Brendan W]

Hi Bdogginit and Welcome to the Forum
Is the fuel flow sufficient?
Clogged in-tank strainers, failing petcock and an inline filter for pumped fuel systems fitted are the usual suspects.

[Bdogginit]

Thanks Brendan, the tank strainer and inline filter look fine visually. I don’t know about the petcock, it is starting to leak so I will probably rebuild it, but I don’t know how to tell if the fuel flow is restricted

[cowboyup3371]

So two things - petcock rebuild kits fail regularly over 95% of the time here; order a new one and be done with it.

Secondly, when you say you inspected the carbs, how did you do that? There are passages in the carbs you can't see just from removing the float bowls that need a major (12-24 hours) dip cleaning and each jet needs to have a wire pushed through the holes. Go to http://members.dslextreme.com/users/bikecliff, download the tutorial, and really make sure they are clean.

[salty_monk]

It can only be fuel or ignition.... You have the electronic advance ignition on that model so upgrade choices are more costly. I would expect it to be fuel related first, Cowboy makes some good points about carb cleaning. You also need to replace all the O rings, make sure the floats are correct and inlet valves are sealing properly.
Intake O rings / boots & airbox boots are another thing you could look at too....

With regards to the valves - it's better to be on the higher end of tolerance than the tight end. They close up with use...

There is a newbie thread here (you're obviously more knowledgeable than a total newb so don't take offence) that I think might help you as it has a step by step list.

Good luck!

[Brendan W]

Thanks Brendan, the tank strainer and inline filter look fine visually. I don’t know about the petcock, it is starting to leak so I will probably rebuild it, but I don’t know how to tell if the fuel flow is restricted

If the inline filter is less than 25mm in diameter it's probably a pumped system type and will not flow enough for a gravity feed system. Worth checking it out in any case.
You could check the flow after the filter, it should be well over half a liter a minute if memory serves.

[gustovh]

Another possibility is plugged gas cap vent. Yes you have to remove the plastic plug under the cover.

V