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Honda 86 TRX 250R... Can't adjust idle speed

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Has been real fun:banghead:

the quad has two problems,

first, it won't idle. I can spin the idle screw all the way up or down and has no effect on idle speed. NONE. It will wind down and just die unless I give it some throttle (less then a 1/4 inch keeps her idling). I have cleaned the carb about six time. It is cleaner then an operating room :busted:. I put a inline fuel filter in, just in case dirty fuel was clogging the jet again and again. It made the problem worse until I realized it was leaking at the fuel filter. A couple SS hose clamps and it ran a little better then before. still will not idle nor can I change the idle speed with the screw. And the fact that it only need to give a little throttle pressure leads me away from a clogged pilot jet unless it is of the wrong size.

I have played with the air screw and needle so I will go back to recommended jetting of FMF (have complete system) But even then it still refused to idle and it would seem people usually suspect the air screw if the pilot jet is known to be clean. Have not specifically played with this to adjust idle speed. Tomorrow I guess.

The only other thing I could think of is the float level. Have yet to check to see if it was off with my caliper. At first I was feeling like she was starved for fuel, now it is dumping it out of the overflow tube. No adjustments have been made to the float assembly. I may have bent it on my last cleaning job. Can float level effect idle and prevent idle adjustment?

Oh, filter is freshly cleaned :busted: Any other suggestions would be great. I really want to learn how to jet my bikes and anything else for that matter. Good books or websites would be much appreciated:thumbsup:

My other issue is she does not want to rev 100%. She winds up to about 85%, I am guessing it needs a larger main jet for that but will deal with that once the idle is right.

Mods: FMF pipe and stinger, K&N air filter. Everything else is stock that I know would effect the engine. The other thought is time for a new top end but I would think that would only effect top end performance and maybe cold starts.

Thanks for any input either way:worthy:

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Clymer manual trouble shooting pg18

Engine Will not Idle or Idles Erratically

carb incorrectly adjusted

fouled or improperly gapped spark plug (No, I put in a brand new plug)

leaking head gasket or vacuum leak (haven't checked reads, no smoke from head)

weak CDI pulse generator (possible since i am also loosing top end)

ignition timing incorrect [faulty component in system]

obstructed fuel line or fuel shut off valve (can't be since the overflow tube is leaking and the problem does not get better if I give it time to fill the bowl)

Incorrect fuel air mixture (possible, changed jet. I will have numbers of both tomorrow)

thought this may help, this is the manual for the TRX 250R and ATC 250R all years

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Can float level effect idle and prevent idle adjustment?
Yes. Have you tried running it with the air box lid off?

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no, but it does have a hole in it... looks like it is from a hole saw, probably 2 to 2 1/2 inches. Should I still try?

I have checked (recently) the filter all the back to the carb. Boot is clean too.

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Yeah, still try it without the lid.

My other issue is she does not want to rev 100%. She winds up to about 85%, I am guessing it needs a larger main jet for that but will deal with that once the idle is right.

Are you sure you have the right gas/oil mixture right? Is the cylinder bored out?

The other thought is time for a new top end but I would think that would only effect top end performance and maybe cold starts.

Wrong. I would start with the top end rebuild first. You can start it cold but you need to let it warm up before you ride it or it will "cold seize", meaning the piston will freeze up due to lack of cylinder expansion.

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It sounds like you are running lean. Try going up a size on the pilot if you are not seeing a change in idle when adjusting the air screw. If you do not have extra pilots I would take a piece of duct tape and tape over the hole in the top of the airbox if the snorkel is still in place (you will still need air can't be closed completely).

Be prepared to rejet once you start opening up the airbox your jetting can change dramatically but it is worth it as the power will increase also. Just remember the more air the more fuel that you will need.

Edited by Newfoundlander
wrong work fuel screw to air screw

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