1990 600 power problems

[Chago]

I am at my wits end now.

My 1990 kat is not delivering power smoothly. Sometimes the power comes on strong around 4500 rpm. Other times not. Also, when I blip the throttle at idle sometimes it dies. Also feels like it doesn't really want to go past 7000 rpm.

Tried to get it to die in this video (of course it didn't do it for me this time) - https://www.youtube.com/watch?v=2W2w2S5aAcs

Steps taken so far:
- Removed and clean carbs (did not take everything apart)
- Put on new vacuum caps and replaced one diaphram cap
- Sprayed about 1/2 a can of WD40 looking for vacuum leaks - not found any yet
- Synched the carbs as best I could - synch is not perfect

Known problems:
- Hole in exhaust manifold (attempted simple repair, but failed - need to find a welder). The pipe in question does not get hot at all, even just a few inches from the engine.
- Possible hole in joining section just before muffler

My questions are:
- Can syching the carbs solve this problem?
- Should I keep trying to synch the carbs even though there is a known hole in the manifold?
- Can the holes in the exhaust have such a negative effect on power output?

Thanks in advance for any help!

[RobertTravis]

The answer to most of your questions is 'no'.

The solution to most of your problems is to pull the carbs and do a proper rebuild and thorough cleaning, including soaking each one in Berryman for 24hrs. Do what is says in Carbs 101.

The problem with the newer fuel is that if it sits, stuff gets gummed up, clogged and just won't run right. I went through this a number of times with equipment...no magic spray or potion will get it to run right. The carb(s) has to come off and be properly cleaned.

[Chago]

The answer to most of your questions is 'no'.

The solution to most of your problems is to pull the carbs and do a proper rebuild and thorough cleaning, including soaking each one in Berryman for 24hrs. Do what is says in Carbs 101.

The problem with the newer fuel is that if it sits, stuff gets gummed up, clogged and just won't run right. I went through this a number of times with equipment...no magic spray or potion will get it to run right. The carb(s) has to come off and be properly cleaned.

Thanks for getting back to me.

Once I have cleaned the carbs, is it pointless to try to synch the carbs with the exhaust the way it is?

[RobertTravis]

Yes...the engine is s pump. Patch the leaks first then sync the carbs.

Maybe find a friend with a MIG welder? 5 min and it's fixed.

[Chago]

Yes...the engine is s pump. Patch the leaks first then sync the carbs.

Maybe find a friend with a MIG welder? 5 min and it's fixed.

Awesome, the hunt for the MIG begins!

[Chago]

Yes...the engine is s pump. Patch the leaks first then sync the carbs.

Maybe find a friend with a MIG welder? 5 min and it's fixed.

Patching complete. My mate had to learn to weld paper . 27 year old pipes are thin!

Now to give the carbs a balance. But my guess is that you are right. Will more than likely have to pull them apart this weekend to give them a proper clean.

[RobertTravis]

I wouldn't waste time with a sync until you clean them properly...

Plan on it running better than ever when you are done...that's the goal isn't it?

[Chago]

I wouldn't waste time with a sync until you clean them properly...

Plan on it running better than ever when you are done...that's the goal isn't it?

Yep, you are right about the sync. Guess I am just trying to get a bit of practice in for syncing the carbs. I don't have a house fan (typically cold where I live), so I need to be quick.

Stripping and cleaning the carbs this weekend.