my son has the same 4 wheeler and it's acting the same way but sometimes it will start and just run kinda bad at top end and won't idle but most the time it will not run or after i have ran it for a few mintues it will not restart any ideas out there?[img]i/expressions/face-icon-small-disgusted.gif[/img]

 

do the comp check i think 135 125 is good on that motor for stock
my sons bike runs a hi comp motor at close to 200
plus a ton of other mods also if you get an aftermarket fuel filter and replace the fuel line
Dwayne

 

The FIRST thing you need to do is do a compression test. There is no way myself or anybody else can make a call on this without a compression test. Once we get the compression test over, we will know where to go from there.

Ex.- Bad compression...........going to be bad top end, crank seals or a bad reed valve. In any event, the engine is going to have to be torn apart and one or all of these things will need to be fixed.

Ex.- Good compression.........Put a new plug in the thing and give it a shot of ether. Does it start and run for a few seconds and then die? If so, this will be a fuel issue. Plugged jet, port or fuel filter or line. If not, it's more than likely a spark issue.

Not to give you more to check or do but, these little 2 strokes will plug the muffler if the fuel to oil ratio is not on the money. I've seen these things so plugged with oil and carbon that there is no way these things would start. You can test it with air pressure and volume.

It's kinda weird that a shop won't work on it for you???? Around here, a shop will diagnosis anything if they think they can do it, and gladdy accept your money!!!!! They might tell you that they can't fix it because of parts, but they will tell you what is wrong for a price.

Get back to us with that compression test and there will be people on this board that will fix you up, and have that thing running in no time!!!!

 

Sorry it took me so long to get back to this. I got the new top end from WRH Racing. They have a web site. It is wrhracing.com. The phone number is 251-675-9906. I got a new cylinder, piston, rings, and gaskets from them for around $150.00, I don't remember the exact number. The kit they sell is a 93cc instead of the stock 83cc, but it fits right on. I have not had any trouble since doing the top end job. It is tight, but the cylinder will come out without taking the motor out of the frame. I will try to check back in a day or so if you have any more questions.

 

I'm taking my sons 4wheeler in on Thursday to get the compression check done. I really hope that tells me something.

DocTurbo - thanks for the analysis - I now know what a compression test will do for me!!

Bandits3 - thanks for the info - I'll order this weekend if that looks like it will help. Bumping up to 93cc would be fine by me! Thanks!

 

My boys eton was doing similar stuff a while back. The rings were gone. You can just hone the cylinder and put new rings and gaskets, maybe a piston if its bad. I also removed the oil injection.

 

Compression test COMPLETE!! Finally - it was so simple, I feel stupid for not doing it sooner.

Anyway, it appears to have good compression. The first stroke is about 75psi, the second takes it up to around 100psi, and the 3d (and all additional) strokes takes it to 120psi. The range mentioned earlier by someone else was 85-120. So - good compression - back to the spark plug or fuel issue?

I changed the plug a while back (but it hasn't run since then) - I will get another spark plug. Could it be wiring?

 

man all u need is air , fuel, and spark. with good comp. wicth you have take the air filter off and spray so mixed gas and 2 stroke oil in the carb and try to start it if that works you need to check to needle an seat and the floot lto see if there stuck i dont think you have a wireing problem my 5 year old races a eton 90 and ive had it in peaces top to bottom if your carb is bad i have a good used carb and they are easy to change. well dude hope i helped take care

 

Major Update - today a friend came over and we made some major headway.

I changed the spark plug again, confirmed it was firing. Emptied all the gas and put fresh gas in the tank. Blew out the carbeurator with carb cleaner (we think we found a couple of blockages) thoroughly. Took off all the plastic, removed the carbeurator, took out the reed valve. Confirmed the reed valve was fine, and cleaned it with carb cleaner. Reinstalled the reed valve, re-installed the carb (after finding an o-ring that was missing for one of the connectors). Using jumper cables to the battery, we tried to start it electrically (it has an electric start that works fine). We double checked the compression with the electric start and it topped out at 110psi. Re-installed new spark plug.

Using ether, we got a few 'coughs' from the engine. We had exhaust coming out of the back (not much, since the engine never caught, but some). Switching to the fuel/gas mix, we would get coughs when adjusting the two screws on the bottom of the carb, we got some coughing from the engine. It sounded like it wanted to catch, but just didn't.

My NEW question is: what is the standard setting for these adjustment screws on the bottom of the carb - I'm assuming that all the other bikes (eton and others) have the same or similiar carb. How many turns from the bottom should each screw be?

Here's a webpage with some pictures from today's maintenance, including some closeups of the carb. Sundiro Maintenance

 

Air screw should be 1.5-2 turns. Roll the idle screw with air filter on until quad starts. I found sarter fluid or chain lube help the process.