Eton 90 Thunder full speed ahead

[fungonefishin]

Hi folks:

I am new to this forum and thought you may be able to help me with a problem, as my own research and efforts have failed to resolve this issue. Efforts are somewhat further complicated due to the fact that I do not know the history or have the direct hands on experience with this quad to fall back on as it was literally sitting on my doorstep ---- along side the owner.

A couple of days ago, there was a knock at my door only to find my next door neighbor and his blue Eton Thunder 90 quad used by his youngest son. His youngest son had just got a new quad for his birthday and my neighbor was unwilling to invest any more time and money in this quad which he purchased used from a previous owner. He said he has spent the purchase price once over in trying to keep it running. I am the go to fix it guy on the street with a garage that looks like a hardware store, so he said it was mine to do with as I please. I said cool, new project.

The only reference I have to it being a Eton thunder 90 is on the faded key tag. the quad itself still has Eton and somewhere on the plastic. My neighbor said the biggest problem with the quad was ideling, accelerating hesitation, stalling, etc. Since it had been sitting for a while, I removed inspected and cleaned the carborator, flushed the tank, inspected and cleaned the plug and reinstalled using the same parts that I started with. Before investing in parts, I wanted a little assurance something major was not wrong with it.

Put it back together without incident, open the gas cock, and opened the bowl bleed valve to flush air and fill. I got a little screwdriver expecting to make some adjustments to the idle screw, stood on the side of the quad, turned the key and gave it a kick. Before my foot reached the bottom of the stroke the quad kicked over full speed ahead. With both breaks sqeezed to the handle bars the little quad was still pulling me forward, so I hit the kill switch. Got on the quad this time, turned the idle screw out a turn grabed the brakes and gave it anothe kick. Again instantly full speed ahead and I hit the kill switch. Needless to say I tried a few more adjustments with no change as throttle lever had no effect nor did turning the idle screw.

I remvoved the carburetor again to make sure everything was inplace, rechecked float, and reset the air screw to factory specs. I reinstallled and no difference. The problem of course is how to get the idle down to normal? Although I do not have any history with this quad, I did make some observations that may help in troubleshooting this problem. Tje observations are as follows:

1. Based on the Eton home site, it appears the Eton Thunder 90 series uses the same carburetor on all models.
2 When comparing the internal parts to the ETon diagram, it appears the Pilot screw (air screw) looks different than the drawing. The breakout drawing sows the pilot screw to tapper at the end with horozontal cuts to offer three different diamaters and it also looks like a small ruber washer is but up agains the spring. The one on the quad has a general cone like taper at the end and has no washer against the spring. Could this be the problem or just a different design with the rebuild kit?
3. With the air filter off and the engine off, I tried to observe the reaction of the jet needle to throttle cable movement from idle positon to full throttle. My observation was that the jet needle moved very little in relation to the distance the throttle lever moves. Is this normal?
I observed that the engine ran much closer to normal with the air filter off as the easier flow of air in effect leaned the carberator out. When I put my fingers over the intake, the engine would race again towards full throttle.
4. The Carburetor has an electric choke and the battery is dead. Would this have any effect on the idle problem? Obviously the engine is getting adequate spark when kicked over.
5 I have made no adjustments to the jet needle and left it as I found it.

I will leave it at that and see what you think.
Thanks in advance for any assisstance you may offer.

[mywifesquad]

Welcome to the forum fungonefishin!

Sweet project and the price was perfect...This carb youve got... is the slide operated by the cable? or is the cable attached to a lever on the out side of the carb? My first thought was maybe the slide isnt returning to the bottom of its bore.. Then I read about disconnecting the filter making it better. Is the filter real dirty? got to much oil on it?

[vindell]

remove slide, re-install 180 degrees. Same thing happened to me, full throttlr into the back of my pick up. hurt like h[.ll with air filter off, make sure slide is down, not stuck up at full throttle.

[LT80]

I agree w/vindell. The slide is not in the correct position.

[fourwheeldrive]

Just a bump on the slide position being the problem. Remove, spin 180 degrees and replace, just as vindell said. Should get you going.

[fungonefishin]

Hello Mywifesquad, vindell, LT80 and fourwheeldrive. thanks for the quick response on this experts thread, and as I expected, hands on experience offers a great advantage over research and figures.

Mywifesquad was headed in the right direction discribing the throttle assemble as stuck as it was indeed stuck exactly how vindell described it being a 180 degrees backwards. That view was in concurrence with with LT80 and fourwheel drive.

A note on Mywifesquad's statement on the air filter. What I think happened when I took off the air filter and realized a lower RPM was with the throttle stuck in full throttle position, the air filter acted as a means of enriching the mixture by partially restricting the air. When it was removed, there was no restriction which leaned out the mix a little and reduced the RPM. Putting my fingers by the intake restricted flow and enriched the mix again increasing acceleration.

I probably took that carburetor off a half dozen times and for the life of me could not conceive how that thin jet needle and the nose of the idel screw could have any effect on anything. I am used to carburetors with the flapper that closes when choked and opens when running. All I could figure is the electric choke must compensate for all of that, When the throttle assembly was installed the correct way and for the first time dropped down into the throat to the point where it rested on the idle screw point, now we had the restricted flow and the idle screw that would raise or lowrer the throttle assemble. Now when I pushed the throttle lever, the assembly responded by moving up and it all made sense.

It started up, needed a slight adjustment of the idle screw and road like a champ, even though I exceeded the recommended weight by a few pounds. It had to be those clip on sunglasses that threw me over

Putting the throttle assemble in 180 backwards might just be the ticket for a 100 yard dash. While everyone else has got their engines running, head down and waiting for the green light. your standing on your kick start and as soon as you start down and a spark is made, your out of the hole at 100 percent throttle with tears streaming out of your eyes from the record shattering speed as you cross the finish line where you pull the rip cord releasing the parachute and push the kill switch to bring the rocket to a stop do you can break your death grip from the handle bars and proceed to the winnners circle for first place and collect your prize.

Again thanks for the quick and accurate responses. I would have replied earlier had I not lost my post not once but twice and hopefully this third attempt will be the charm and post.

Next venture is to tighten the chain. How hard can that be . Tell you what, if I can't figure it out, you all will be the first to know.

Cheers!

[fourwheeldrive]

Glad you got it going. If you get into a bind and need some further advice or assistance, I can't think of a better place to come than here. Much cheaper than going to a shop and probably just as quick on the answers, plus the advice is usually right the first time.

Anyway, good luck with your project.

4WD