200x altitude tuning help

[Tnsejed]

New to the forum and having some issues with my trikes.

I grew up on an 84 200x. Built an 85 200x before leaving for college. Stopped riding in 1999.
Anyways I just got both my trikes back. I now live in Colorado at 8700 ft. elevation.

They both sat for about the last 11 years. So I got them last week. Pulled the carbs off and cleaned them. The 85 carb still looked brand new inside. But I wired every port after soaking, blew air through everything. New float and new needles. New gaskets. On Both carbs.
Did oil changes and replaced the fuel lines. Cleaned the tanks. Etc.

Anyways got them running. I'm looking for jetting help at this elevation. Both trikes ran well at sea level years ago. The jets were a 108 in the '84, and a 110 in the '85. The 85 is bored with aftermarket exhaust. I cannot remember the rest of the engine mods I did, if any. I'm also very rusty with these carbs as far as tuning goes. I've been out of this game for awhile.

I got the trikes running with a 102 in the 84 and a 105 in the 85. Both needle clips on the 4th groove. The trikes won't idle at all. I've also got popping out the exhaust on decel. They runout pretty good though. Plugs look light tan. I do feel like the midrange on both is a bit lacking, but my memory of how they originally felt is sketchy at best.

Any help or guidance is good. I need to get them idleing and atleast in the ballpark. The adjustment screw does just about nothing right now. So I've left it at factory 1 3/4 turns out.

[barnett468]

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ok, if they started fine at sea level then i would drop the pilot jet 2 sizes and try that . . you will have to mess with the fuel mix screw . . you should also run a slide with a different cutaway.

your bikes will have at least 25% less power due to the extreme elevation.

you loose around 5 psi of compression for every 1000 foot increase in elevation, so if we multiply 5 x 7 to be fairly conservative, you should have 35 psi less compression in each engine . . you can look up the factory compression for these bikes in the link below but they are around 155 at seal level when new, if they are not new, they would be less, so subtract 35 from 155 and you get 120 psi of cranking compression which affects the running [dynamic] compression compression.

basically, to make them run anywhere near the way they used to at seal level, you need to increase the compression . . this can be done by simply installing higher compression pistons . . i would check the bore before doing this and bore them at the same time if necessary.

[barnett468]

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did you raise or lower the needle?

[Tnsejed]

I've got the needles back at the settings they were at from sea level. 4th groove. Which I believe is stock.

The 2 jet sizes down is what I did to get them running. Just got to workout the idle and the popping on decel. I did toss in a 108 into the 85 just to get a feel for one jet size down. Bike ran like crap and the popping was much wetter sounder, so I think I'm getting close with the 2 jet sizes down. But I can't get either bike to idle.

Explain to me the slide cutaway your talking about. Is there a different slide offered?

[barnett468]

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a bigger cutaway makes it leaner in the beginning and middle and a smaller one makes it richer.

you can probably get it jetted with the slide you have.

if it burbles/sputters on acceleration, it is rich . . if it just hesitates lie it is simply out of gas, it is lean . . i do not jet bikes for decelleration . . the point is to jet it for acceleration and let the decelleration fall where it may or simply deal with it last.