90 GT200 low rpm's

[Melton Jason]

Hi guys, I need some suggestion/help with a issue.

My 90 Johnson GT200 is only getting about 4800rpms and speed has dropped way off.

It has been slowly getting worse every time I take it out. The engine has new spark plugs(champions), new fuel line, fuel filter and primer bulb (all bombardier). The power pack and timer base was replaced late last year due to a short in the timer base. I decarbed it with seafoam, and checked compression, compression is low of 85 to high of 90.

I took it into my mechanic as I am on vacation this week and really wanting to get out. He found that one of the timer rollers on the front top was missing half the plastic around it. Took it to the lake and still same issue, The problem doesn't appear to be fuel as even when missing I can push the choke in and actually bogs it down a touch.

Mechanic said he has checked the timing and its ok. He also said the coils was ok. My question is there any other electrical components that could be causing this?

one more question, I bought some xd100 (was using the quicksilver oil and i premix)and put fresh gas(premium) in it and i noticed that it idling higher now. Is this normal?

[Bassmeister]

Pull the air box and verify that you're getting wot, butterflies perpendicular to the throats. While wot, see if you can move the two bottom ones with your fingers.

[Melton Jason]

Thanks Bassmeister, I have checked that already and they are fully opening at WOT, but I didn't know about being able to move the bottom ones with your fingers, will have to check that. If the bottom doesn't move what does that mean?

[ChampioNman]

The bottom butterflies on each throttle body are connected via a rod and secured with allen screws.

[Bassmeister]

The bottom 2 don't move is good. sometimes they will work loose and the vacumn from the engine won't let 'em open.

[Melton Jason]

OK, I checked them and they don't move at all.

Just for the "fun" of it. I took the carbs off yesterday and gave them a cleaning, (They looked great by the way no dirt or signs of varnish in them), issue is still persisting though. You guys have any other ideals?

One more question, I have noticed you guys posting about changing the jets in the carbs, If I remember correctly mine had 62d's in them. does this sound right?

OK, Maybe one more question going back to my original question. Would switching over to the XD100 cause the engine to idle higher?

Thanks again guys.

[guisertj]

[Bassmeister]

I don't think the 90 models were prone to the maladies of the later 90's big block.Changing to xd-100 will not cause the engine to idle higher. I suspect an air leak some where causing a lean condition. Spray some wd-40 around the base of the carbs to check for an air leak.

[Melton Jason]

Thanks for the suggestion. Will give it a try and let you guys know what happens