250es idle issues

[dblungshot]

1985 250es
I replaced the carb with a very clean used carb and installed all new jets and seals (carb kit). My trike will start without a choke pretty quickly but not on the first attempt (no biggy). It seems after the trike is warmed up the idle increases in RPM's randomly. It takes a few throttle rev's to bring it down to normal idle, but some times I can't get it to come down (which makes shifting a biotch). Any ideas what jet or what the problem is??? I've read and reviewed the carb 101 and can't figure it out. I live at sea level and the carb location I replaced it was used from the east coast (unknown elevation). The jets were all replaced though and I thought were replaced correctly. Is this a fuel mixture screw that needs adjustment?

Also, this may lead to the answer or not? After my trike is warmed up or has run for a few minutes it begins to die. If I open the gas cap (with a suction), the fuel begins to flow into the carb, replacing the engine die with a normal idle. I'm assuming my gas cap is stuck in the "off" position stopping the fuel flow. Is this assumption without a doubt correct or may this be linked to my carb???

Any help will be appreciated. I've fixed everything else on this 85' and want it to be running like a dream instead of not. Any input will be awesome!!

Gig Harbor, WA.
1985 250es
1972 Rokon Trailbreaker

[cattle-dog]

i would say your vent isnt working in your cap.

[Thorpe]

How does it cold start with the gas cap open? Why arent you using you choke? Its a Honda, they are cold blooded machines...

[dblungshot]

Thanks gentleman for the quick responses:
The gas cap I'm sure has a bad valve. If I open my tank that bypasses the engine dying problem (problem solved). The real answer I need is why my idle increases after the engine is warm (forget about the gas cap - imagine I replaced it with a brand new one with a good valve)??? After I rev it 3 or 4 times the idle comes back down to normal. But not always can I get it to come down with the rev's. Sometimes I have to turn the engine off and re-start it for the idle to be normal.

I understand the gas cap problem but don't understand the idle problem. Any suggestions????

[Thorpe]

Check the routing of your throttle cable... Also make sure your cable is in good shape. I am having similar issues right now with my BR, but I know the cablehousing is trashed and its not really letting the slide down to rest like its supposed to...

[dblungshot]

The throttle cable is good, and so is the throttle adjustment setting on the carb (checked before buttoning up the carb). Again, the idle is high when it's initially started but comes down like it should there after. But after the engine has been rev'd up for a few openings (runs) or has been idleing for a while it soon creeps up slowly to a faster idle. The only way to get the idle to come down is a few dry rev's which sometimes works but other times it doesn't. Could this be a choke cable issue???? The choke cable and assembly were replaced and I don't know the perticular setting (if there is one). I simply put the needle in the hole, shoved it down and screwed the assembly nut until it stopped. This may be the issue??? Any other suggestions?

[tri again]

1985 250es
I replaced the carb with a very clean used carb and installed all new jets and seals (carb kit). My trike will start without a choke pretty quickly but not on the first attempt (no biggy). It seems after the trike is warmed up the idle increases in RPM's randomly. It takes a few throttle rev's to bring it down to normal idle, but some times I can't get it to come down (which makes shifting a biotch). Any ideas what jet or what the problem is??? I've read and reviewed the carb 101 and can't figure it out. I live at sea level and the carb location I replaced it was used from the east coast (unknown elevation). The jets were all replaced though and I thought were replaced correctly. Is this a fuel mixture screw that needs adjustment?

Also, this may lead to the answer or not? After my trike is warmed up or has run for a few minutes it begins to die. If I open the gas cap (with a suction), the fuel begins to flow into the carb, replacing the engine die with a normal idle. I'm assuming my gas cap is stuck in the "off" position stopping the fuel flow. Is this assumption without a doubt correct or may this be linked to my carb???

Any help will be appreciated. I've fixed everything else on this 85' and want it to be running like a dream instead of not. Any input will be awesome!!

Gig Harbor, WA.
1985 250es
1972 Rokon Trailbreaker

Hi

First of all, if your old carb did the same thing, I'd be happy to buy one of them from you to save you some duplicate heartache. I have an impossible early 85 'cold start recall' carb with NO hope.

I have 2 85's and they ARE dream machines when they run right, but I digress.

For some reason, I had my hands on a pulse generator/sensor thing up near the camshafts.

They love to throw a fine orange rust dust around. Now I'm not sure what year that was from but it did have some springs in there like from an old style centrifugal advance.

If that;s the case, the advance spring things might be hanging up and messing with your idle speed.

Prob THE easiest thing to check/clean/fix. 2 screws on the cover that says "cdi".

then again, yours might have an electronic advance, I'm not sure but those things like to be cleaned and lubed anyway.

They say that rustdust can short out something or other but it sounds like we have other fish to fry at the moment.

Vacuum leaks can be real weird too, and I have seen them cycle up and down and hang like you describe.

I've heard that you spray around the intake areas and clamps with carb cleaner or start fluid to see if the idle changes but pretty sure starting fluid is flashy flammable and THAT would really be a bad addition to your existing challenge.

The mix screw you can mess with is the one that hangs straight down.

I usually cut a piece of that black carb overflow drain tubing and just slip an inch or 2 on that screw so you ca turn it easily.

Nice of the engineers to think of that.

Roughly 1 and a half turns out, and then screw IN till it runs lousy and then screw OUT till it runs lousy and then go back somewhere in the middle, but that is really vacuum sensitive so you might want to rule out vac leak first.

Lets see, what else could cause that 'hunting' idle fluctuation?

I gotta go put my wheelers away for the night but I'll come back if I think of anything significant.

good luck

ps

the east coast really has no altitude places except random mountains so it's not like it came from Denver or Tahoe.

Did you happen to note the numbers on the jets?

[goodgreenbandit]

Can't help much 'cept to say my 85250ES runs about the same as described. I'll try the CDI thing and get back. Also have to figure out why the kickstart isn't working, read some threads, got an idea. About the gas cap. Mine would die after awhile of running when I first got it a couple of months ago. It wouldn't start back up till I took the cap off. So the next day the sun came out and warmed my tank. As I moved the switch from on to off it hissed in the middle, and not at either on or off. So for now I leave it in the middle and it stays running. Need to find a way to clean that cap. Been thinkin' bout soakin it in gas? carb cleaner? not too sure what's inside, and if I remember right, it's pressed together.

Don't use carb cleaner to check for leaks, use brake cleaner, that's how I was taught and do it. Your engine will bog down if there is a vacuum leak. Works for chainsaws, spray under the clutch and in pull start cover to check crank bearings.

[tri again]

I got a stoopid with my fuel pet. same kinda deal.
seems like all these honda are different than each other and I have about 10.. some shift up some down etcetc

...so I blow INTO the fuel petcock with fuel line to see which way is on or off.

on is on
off is off

reserve is OFF!

beTWEEN reserve and off is ON

I do'nt usually keep more than a gallon or so in them so I always run them on res.

this one drove me nutts for almost a 12 pack