Helix won't keep running

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Helix won't keep running

Postby zookeepwr » Mon Dec 17, 2018 7:55 am

This is my first time using this forum so I hope this the right place to ask for this help. I have a 1996 Honda Helix 250 that will start in the idle position and then die after about 2 seconds. I have taken the carb. off and cleaned it completely and replaced the electronic valve on top of the carb. and the gas filter but nothing has changed. If I put my hand over the carb. intake and close it off by about 90% I can get it to run all day long, to me that sounds like it's not getting gas. Where do I look next, what could be the problem? Any help would be very much appreciated.
Thank You
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Re: Helix won't keep running

Postby wilsongj » Mon Dec 17, 2018 12:47 pm

Hi there, have you got a good fuel flow carb side of the fuel filter?
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Re: Helix won't keep running

Postby zookeepwr » Mon Dec 17, 2018 1:47 pm

I can see the fuel running thru the filter. The filter is about half full but maybe what I think is good flow is instead vibration?
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Re: Helix won't keep running

Postby zookeepwr » Tue Dec 18, 2018 9:58 am

Any other suggestions?
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Re: Helix won't keep running

Postby Squeazel » Tue Dec 18, 2018 11:14 am

OK, to reiterate...

-It starts and runs for a couple of seconds, then dies (presumably when cold- does it run long enough to get warmed up?)
-When you cover the intake with your hand, it will continue to run.

That sounds mightily that the mixture is too lean at idle for some reason. Some possibilities are:

- Crack or leak in the intake coupler (common problem) letting in too much air. A careful inspection is in order.
- One of the passages in the carb is still blocked. And there are many of them. Did you completely disassemble the carb and blow out all the passages when you rebuilt it? If it were this, I would suspect the one that goes from the idle mixture screw to the tiny hole just past the butterfly. Or the bystarter passage.
- Float level is way too low- bent float. Check the float drop.
- One of the vacuum hoses is disconnected and letting in way too much air.

Anyway, a cheap solution is to just buy a Chinese carb on Ebay and put it on. If it fixes the problem, you're halfway there. If not, you have a source of cheap carb replacement parts and gaskets. (They're missing one vacuum port, so it's not a permanent solution.)
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Re: Helix won't keep running

Postby zookeepwr » Tue Dec 18, 2018 12:58 pm

Thank You. I did not check the intake coupler so I will do that and if its ok I will take the carb. apart again to make sure I didn't miss anything. Thank you again. I will let you know what happened.
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Re: Helix won't keep running

Postby Squeazel » Tue Dec 18, 2018 3:45 pm

A bit more information could be helpful to better diagnose the problem, too. Did it change suddenly? Like one day it ran fine, and the next it wouldn't idle? Or was is slowly degenerative, like it had some symptoms like stalling at stoplights, then got worse and worse, then wouldn't idle at all?

Does it rev up at all? Or does it stall immediately, as soon as you try to crack the throttle? Even when you partially cover the intake?

I know that my bike will sputter upon revving if the plastic intake u-tube is not attached.
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Re: Helix won't keep running

Postby zookeepwr » Tue Dec 18, 2018 3:56 pm

This sat for about 3 years without running but when it was put away it was running fine. When I start it and try to crack the throttle it dies immediatetly. If I don't touch the throttle it will run for about two seconds. If I cover the intake on the carb. by about 90% I can get it to run forever. It acts the same way if the plastic tube is on or off.
Thank You
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Re: Helix won't keep running

Postby Squeazel » Wed Dec 19, 2018 10:50 am

OK, that makes sense then- sitting for a few years will very much gunk up the carb. To the extent that you may not be able to clean it because the blockage could be corrosion rather than something that dissolves in carb cleaner. Worst case, you may need a new carb.

But, try another cleaning, being careful to remove all the jets and screws, and try to run little wires through all the passages you can, blowing them out with compressed air. Professionals will drill out the little caps that block the holes where the original passages were bored, then put new caps on after cleaning. But before I do that, I'd just get a Chinese replacement carb on ebay for $30 shipped.
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Re: Helix won't keep running

Postby birdmannn101 » Thu Dec 20, 2018 8:28 am

Squeazel wrote:Professionals will drill out the little caps that block the holes where the original passages were bored, then put new caps on after cleaning. But before I do that, I'd just get a Chinese replacement carb on ebay for $30 shipped.


Never heard of that before. I do know if you drill out a jet, that doesn't work either.

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Re: Helix won't keep running

Postby Dan_Lockwood » Thu Dec 20, 2018 10:35 am

Years ago when I did marina outboard mechanical work, way back in the 60's, a carb rebuild kit came with new soft plugs. They're usually aluminum and were quite easy to pop out and replace. They're convex and when install the dome is on the outside. You then just tap in the middle and they expand to re-seal the cavity.

I can attest to the MANY passages in one of these carbs. I had a 2004 Honda Rebel a few years ago that had just 97 miles on it when I bought it. It ran, but not very well and it was a bugger to get started. I took the carb off several times before I finally got the one last passage that was giving me fits.

So don't give up yet, just try to hit every passage that you can find. I will take a single wire from a wire brush and use that to clean out some of the passages. Once you get a hole through, it's a lot easier to finally get them cleaned out.

Good luck with you project.
Dan

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Re: Helix won't keep running

Postby Squeazel » Thu Dec 20, 2018 12:42 pm

I didn't mean drill out the jets- those are calibrated as to hole diameter and just need to be unscrewed and cleaned. But when the carb is manufactured, there are lots of channels drilled in the body that can't be drilled straight from one direction. Those are drilled in two stages- once in one direction and once again in another direction, to connect the two places with a channel through the carb body. They'll have a brass dome cap on the outside of the body where the two holes were drilled from the outside, to seal the holes from the outside. Professional carb rebuilders will drill out those caps to access the holes, clean them, then put a new cap back on. You'll see a bunch of those caps on your carb. Even if I knew where to get the new caps, I wouldn't trust my ability to seal them properly after replacement. So I just either work a wire through all the holes I can find, and if that doesn't work I say "screw it" and buy a new carb.

From your symptoms, I'd say it's the idle jet passage that's blocked, which runs from the idle jet to the mixture screw, to a tiny hole in the throat of the carburetor on the manifold side of the butterfly. At closed throttle, the fuel is sucked through the jet from the bowl, metered by the mixture screw, then it squirts through the hole in the throat. There's another hole that allows air through; I don't think that one is blocked because blocking off the air with your hand makes it run; it's getting plenty of air.
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Re: Helix won't keep running

Postby zookeepwr » Thu Dec 27, 2018 7:41 pm

After taking the carb. apart again and using a small wire on all the small openings, soaking it and blowing it out. (this took some time) I am happy to say that it now runs like a top. Thank you so much for the advice. This forum was well worth joining, thank you again.
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Re: Helix won't keep running

Postby slonaker » Thu Dec 27, 2018 7:52 pm

I'm glad you found the forum useful!

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Re: Helix won't keep running

Postby Squeazel » Wed Jan 02, 2019 11:01 am

Glad we can help! Thanks for posting the result of your work, and have fun!
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