Secondary menu

Search form

Powered by MotoTribe.com

high idle when engine is hot.

to start the bike i have to have the choke open almost everytime unless its very hot outside (by the way i live in vegas). a minute later i close the choke & it runs like a charm for 10 to 15 minutes then idle runs high, & the hotter the engine the higher the idle, & i mean very high. what can i do? plz help. last month i took it on the freeway for a 50 mile ride (it was 117 degrees that day) i suffered wind burn. a half hour after parking it in the garrage my wife told me the bike is hissing and strong gas smell in the garage, i went to check it out the hissing was comming from the gas tank cap. is it possible for the bike to run so hot that even half an hour after parking it with the engine off the gas tank is still hissing? this is my first touring bike plz help.

Topic:

15 Comments

117 deg is a hell of a hot day - you need to cover your face as you've found out - sounds like someone has changed the exhaust/air intake system and not bothered to modify the Carby Jets to suit therefore its probly running lean (BTW - the choke works by closing off the normal air/fuel intake and allowing extra fuel into the engine, therefore you CLOSE the choke to make it richer, and OPEN the choke to allow normal fuel intake) If the engine IS running rich, you can tell by removing the spark plugs and notice if they are WHITE around the central electrode - BLACK would indicate that it's running too rich. (which is unlikely)
A lean mixture will make the engine run faster and can cause damage to the valves - Check the timing to ensure that the spark is not too advanced. this will cause 'knocking' when the engine fires and cause the engine to run hot. - Its times like these when a work shop manual comes in very handy.

A few questions that may help folks be more more helpful in sorting this out -
When did the problem start? Gradually or suddenly? Did you just get the bike (in this condition?) or have you owned it for some time? Was the bike parked for an extended period of time? If so, was it with fuel in it? Did you recently do (or have performed by a shop) any maintenance on the bike prior to this problem starting?

I'm afraid that I can't speak intelligently on the effects of riding in 117 degree temps as that is something I have never done due to physiological issues related to such conditions. But I would imagine that it is possible there could be enough heat rising off of that engine to cause the fuel in the tank to expand, hence the vapors being forced out through the cap.
Either way, a little more background or history on the bike and the onset of these symptoms might be helpful to narrow down the problem. For what it's worth, the choke on the VStar does not actually close off air like a choke on most carbureted engines. It actuates an enrichment valve that allows more fuel to enter the engine.

I agree with Phil, sounds like carb/jets combination issue ... my ex was a cycle mechanic and I learned a whole lot from working with him in the garage.. Also what year is the bike?

The bike is 2006, bought it used from a dealer, just started riding it, not much experience

Sounds like the guys above are getting you on the right track.
re the gas hiss, this great 1100 website might help out with a simple check of this:
https://sites.google.com/site/vstar1100kb/home/repairs/gas-cap

Oh, and the bike service manual is here, for when you need it:
https://sites.google.com/site/vstar1100kb/home/7-library/manuals

And just to follow-on to Bobs comments, have you or anyone else had a play with the vacuum hoses or AIS system? AIS: https://sites.google.com/site/vstar1100kb/home/5-modifications/1-ai
Or anyone tweaked the carbies, changed carby jets or played with carby sync?

Cheers, Steve

Again re the hiss, you may be hearing the consequences of a blocked or squashed vent hose under the tank or surrounding area.
Parts for tank and associated bits shown here: http://www.highlandsyamaha.com/oemparts/a/yam/50045890f8700209bc793776/f...

This is general troubleshooting but, applies to bikes too.
Symptom: The engine idles too fast. After the engine has run long enough to be warm, the idle speed does not come down to normal. .
Possible causes:
1. If you have a carburetor, you may have a bad accelerator pump or power circuit.
The Fix: Replace accelerator pump or replace carburetor.
2. The engine may be overheating.
The Fix: Check and repair cooling system.
3. The fuel pressure regulator may be operating at too low a pressure.
The Fix: Check fuel pressure with a fuel pressure gauge. Replace fuel pressure regulator. (Generally not a DIY job)
4. The ignition timing may be set wrong.
The Fix: Adjust ignition timing.
5. There may be some type of ignition problem.
The Fix: Check and replace distributor cap, rotor, ignition wires and spark plugs.
6. There may be a fault in the computerized engine control system.
The Fix: Check engine control systems with a scan tool. Test circuits and repair or replace components as required. (Generally not a DIY job)
7. There may be a vacuum leak.
The Fix: Check and replace vacuum lines as required.
8. You have a bad idle speed control unit.
The Fix: Replace idle speed control unit.
9. The alternator may not be working properly.
The Fix: Replace alternator.

Its pretty hard to diagnose engine faults without actually hearing whats going on, we have many skilled mechanics, engineers etc on this site and each gets one gets an image of what likely problems may exist from a written description, as above, but a large part of diagnosing a fault is through listening to the engine running, and then past experience comes into play, the fluff of an engine running rich, the crack of the exhaust note when too lean, the white tinge around the exhaust and Spark plugs. The fact that it is necessary to use the choke when starting in hot conditions, so therefore its important to include as much background info as possible about past mods, what altitude the countryside is (I don't know how high Las Vegas is but some towns are fairly high up) this all comes into consideration when tuning an engine, as I said earlier, 117 degrees is bloody hot, not the sort of stuff I enjoy riding in, and to park the bike back in the garage after a fast run can be asking for trouble when you consider the heat coming from the engine, under a hot tank of fuel, I would be looking for a fan or a breeze to reduce the likely hood of a fire should there be a leak onto the exhaust ..... so good luck with that, and let us know when its sorted out - so often in the past, much discussion has gone into various running and steering problems, but we never learn if the problem is finally solved or where the problem really lay, frustrating !

IF the bike has been sitting up for anytime at all it is possible that the carbs need cleaning.
When I first started riding my V Star 1100 it had some of the same issues, backfiring on deceleration, fast idle when coming to a stop. Carburetor backfire when cranking.

Long story short, I ran 3 tanks of fuel with some sea form(gas treatment) additive, and I lowered my idle just a tad.
All problems went away.

I have a 1991 Nighthawk 750. She starts right up and runs great except that the hotter the engine gets, the higher the idle. I am on my 2nd tank of seafoam (i think thats the name) to clean out the carbs, but havent yet noticed a difference. I have done complete oil change including filter. Even put a new starter on it not that that would affect this issue. The idle is perfect for starting so i am afraid to do any adjusting will make it too low at the start. What would be the next best thing to try? I am in Georgia and right now the temps r in the mid 80s so not so hot outside. Thanks. Pat

Sounds like Air leaking in through the manifold when it warms up causing the mixture to lean out .
Try putting some diesel into a pump action oil can and squirting it around the Manifold joints ... if there's a leak it will get sucked in, the engine should slow down a bit and you may get some blue smoke from the exhaust indicating that that's where the fault lies ..... cheers
... If we dont get feed back on how you're doing, we wont know if its been fixed yet ....!

when engine is hot idle gets faster and blue smoke from one cylinder how can fix

Bike sounded ok then i added stabil as a friend suggested now high idle and stalls when i try to put in gear

Serviced cabs after discovering sludge in gas tank never tamper with any adjustment rear cylinder fires good clean ex flow front cylinder warm ex warm an backfires like crazy troubleshoot everything clean all contacts check harness serviced cabs again check fuel pump flow to cabs inspect an check gap check ig coil one other thing to check is pump relay

Add new comment

Please login if you already have an account or enter your details below to create one.

Your Details