High idle when warm

[neverdone]

Ever since I have gotten my SX it starts fine, but once you been out beating it a little and it warms up it idles REALLY high. Anybody know why? Or have an idea why that is?

[dougspcs]

Choke plunger is likely not seating properly..running with part choke. Since on this model the choke is a bypass valve that lets extra fuel and air thru to both enrich and increase the starting idle speed at the same time.

If you haven't already and good carb cleaning is a great idea..takes a bit of a nimble hand to get that carb out and back in the 1st time. There will probable be some swearing involved..if you have any problems PM 'Fabio'. He's an old salt at this one!!

But I say do that and don't forget to clean the tank petcock screen and bowl also..maybe install a small inline fuel filter. Then you can forget about it again for a few years..

[GunsShooting]

My polaris ranger does this also, and other machines I've had. Even after cleaning the carbs and not using the choke at all.

[dougspcs]

My polaris ranger does this also, and other machines I've had. Even after cleaning the carbs and not using the choke at all.

Yeah but these are Hondas!!

Clean it right and it'll be good again for the next 10 years!!

[Poco Loco]

Also, test for a vacuum leak.

[NO-SCALES]

my sx has been doing this also. I just recently got it to stop. cleaned carb , put in inline fuel filter. still dong it. I got to noticing, it would do it at the same time , every time. then I noticed the clear inline filter I put in it was pretty empty ( sucking air ). tank was full. cap was on the on position , but cracked it open just to be sure it was getting air. still doing it. cleaned petcock ,and screen. even swapped the tank to my 185, it worked great on the 185. got to messing with the air fuel screw, turned it counter clockwise , while it was running... and it filled that filter up in a hurry. probally gave it 2 good turns on mine. they say to go 1/4 turn at a time and see how it acts though.

im no master mechanic or anything, so im not saying THIS IS YOUR PROBLEM or anything, just giving you something to check on. id for sure put an inline filter on anyways.

[neverdone]

I am probably going to start with cleaning the carb. More specifically the choke........ When I first got this I took the carb off and apart and was soaking it for days and cleaning it as best as I could. But I couldn't take the choke slide with me when I took it apart.

I am going to look for a vacuum leak just haven't had time. I generally use WD40 and spray it around to chase down vac leaks. Does anyone have a vacuum diagram for that so I know where all the hoses go if I should maybe find one missing or something??

I am sure it is not the tank screen, it is brand new when I put the tank on and the bike has only had probably 3 tanks threw it since I got it going. Also it does have a clear filter in it, there is nothing in it, but it is not completely full like I would expect it to be.... It is always atleast half full though. I thought about maybe adjusting the low end mixture a little since sometimes it is a little cold blooded even when it is warm out....

[dougspcs]

1st thing..since there are no real vacuum lines on the carb a missing tube isn't going to contribute to an air leak. The hoses are all vent lines. The only place you could have a leak if you do is the rubber carb boot or the connections between the carb and boot. Best way to tell besides spraying aerosol into the connections and boot is to wiggle the carb while it is idling. Flexing the rubber boot will cause any cracks in the rubber to open/close and change in RPM will be very apparent..

2nd..if I'm not mistaken yours is an 85..correct? Your comment that it is a cold-blooded creature is actually pretty normal..since the choke jet is very small the 85 ES/SX are known for being difficult cold start machines.

Consider contacting FlyingW and sending him your carb..he has some mad skills when it comes to carb rebuilding. Also one of the things he does is convert the choke jet size to make it better cold start..an improvement Honda put into the 86 and later model.

[tvpierce]

Does it require use of the choke/enricher to start when it's cold?

[neverdone]

Nope usually just choke it for a bit and it will start....

[tvpierce]

So that's a yes, the choke must be applied for a cold start?

[neverdone]

No it can start with out the choke unless its below like 50*. Just cranks a bit longer until it is warmed up. Once its been running for 5 minutes or so it starts perfect. But after its been ran hard for 5 to 10 minutes it idles really high.

[fastkx125]

Choke plunger is likely not seating properly..running with part choke. Since on this model the choke is a bypass valve that lets extra fuel and air thru to both enrich and increase the starting idle speed at the same time.

..

Found this thread when I noticed my 350x was idling high when warm. I had recently ordered a new idle screw and got the choke plunger instead. Got a refund on the idle screw and figured maybe this would fix my idle. It did, new choke plunger and lever. Now idles smooth before and after warm up.