Hey everyone,
This is a tad of a long post so I apologize in advance! ATV is an '06 Jetmoto Desert Storm 250cc 5 speed Utility quad with the Honda style twin cylinder engine.


I bought it knowing it needed some carb adjustments and such.. It would run fine but wouldn't idle unless throttle was applied, I tightened the idle adjustment all the way and it still wanted to die. Also was leaking gas from the bowl overflow heavily and was randomly high reving on its own. I've rebuilt a ton of two stroke carbs, This was my first four stroke rebuild but think I handled it well. The pilot jets on both carbs were clogged to the point were even after soaking in carb cleaner over night they wouldn't budge... Tried a wire brush bristle, fine finish nail etc... After many attempts I got aggravated and drilled them out with a very very fine drill bit, not sure of the # but fine enough to where I didn't hurt any of the brass on the screw only what was inside... Cleaned everything up, all jets, inlets etc and re assembled... Installed in the ATV, opened the petcock turned it over a few times to let the carbs fill up... No more leaks from the overflow, nice that's a plus already... Started right up (needed the choke to start, but it's cold out) Still wont idle correctly but ran a lot better with slight throttle applied to keep from stalling.

I took it for a ride in the snow (on private land) and it ran great till about 5 minutes into the ride when I was going slow coming to a stop with the clutch in and it stalled on me, I may have caused the stall by letting rpms get too low.... No biggie started right back up.... 2 minutes later I'm just creeping along in the snow and it stalled on me.... would not start back up... every few tries it would make a faint put like it wanted to but no go... Walked to get my Jeep and pulled the ATV back to the house about 300 yards away. Pretty much killed my brand new battery with re-start attempts, tried it a few more times and could hear it wanting to start more and more, eventually she roared to life like it didn't happen, took it around the yard, stalled it (due to the idle problem) but it fired right back up......... What's wrong? Carb is clean! I need help, I got the day off tomorrow and snow on the ground!

I don't understand how to adjust/fine tune the mixture screw on each of the carbs, Not sure how I would tell a difference.

Thanks and sorry for the long post,
Mike

attached is a pic of the motor, just so you guys get an idea of it... It's very similar to a Honda Rebel twin cyl. style 250. Also attached is a pic of the type of carbs, They're similar to this set up. I borrowed the pic from google since I don't have a pic of my carbs at the moment.

 

I had a problem like that on my son's old 300ex,it was stored for almost 2 years. The carb was gunked up, had to push a wire brush bristle through a plugged pilot just like you. It also needed throttle to keep running, turned out the passage the pilot jet screwed into was also plugged, took severa tries with carb cleaner and air gun, but finally got it open, then it started and ran normally without opening the throttle at idle. You may need to pull the carbs, remove the pilot jet, put the carb spray straw in the hole and make sure the passage is clear, you should see carb cleaner squirting into the throttle body from a tiny hole near the slide.

 

Start with the fuel screws at 2.5 turns out.. then go to 3.. did it get any better?

My other thought.. if the pilot jet was clogged.. Is the pilot jet circuit clogged also? did you spray carb cleaner into the holes the pilot jets came out of.. did it come out inside the carb? In other words was the hole clear when you were done?

 

What spark plugs are in this?

 

when they run gas out like your saying is the needle on top of your float inside carb is not seding right to shut the gas off or you have a pin hole in your float take out your float and shake it to see if you hear anything in side or dry it off then shake it to see if it gets wet if it;s dry it;s your needle on top of float isn;t going up far enuf to shut gas off from over flowing.do that first then clean your jets out they have little holes in them .i use a twist tie burn off the plactic of it and use the little wire inside it works great for them little holes i;ve done hunderds of them over the years try that should take care of your problem.

 

Thanks for the replies fellas, sounds like another more intense carb clean is in order just to be sure all passages are clear because I honestly may have missed blasting the passages out correctly.

I haven't pulled them yet but will do tomorrow as I'm sure they need replacing anyways, However I doubt they're the correct plugs because the last owner supposedly cleaned the carb, and well... It's obvious he didn't or slacked on it real bad! So I'm sure the plugs are probably wrong. Would you happen to know the correct size that's in your in-laws Desert Storm 250? Googling info on this ATV is next to impossible!

Thanks again guys.

Mike

 

NGK C7HSA

Gap.. .028