Hi guys. I've got this '98 Xplorer that I have been putting back together. I've got it almost reassembled but am have a problem getting it running. I've got two compression gauges. One is a cheapy (got it at Harbor Frieght) and the other is a decent one I got from the autoparts store. When I do a compression check I get about 100 PSI on the cheapy and exactly 115 on the one from the auto parts store. The reason I'm checking compression is that I can get the engine to run on a squirt of starter fluid but as soon as the starter fluid runs out it dies. My fuel lines are clear and my carb bowl is full of fuel. I just overhauled my carb so I know its clean inside and out. I suspected my compression was low and wasn't pulling fuel/air into the combustion chamber but according to all I've read here and the specs I have in my manual the service limit for these engines is around 100 psi. The only thing that is bugging me is that I can't determine if this is a compression issue or something else. Also, when I got this bike it was somewhat dissasembled. There is a brass fitting on the right-hand side of the carb (if your sitting on the bike) that is parallel to the ground. This fitting I suspect is a vacum fitting for the carb but I can figure out where the hose should connect to on the other end? Any thoughts would be appreciated. I am inclined to go with the compression reading from the gauge I got at the auto parts store as it has proven to be much more accurate over the years. So any ideas why it would run on starter fluid but die once it ran out? I think I've narrowed it down to compression or carb issue, but any input would be appreciated. Thanks.[img]i/expressions/face-icon-small-confused.gif[/img]

 

it isnt a compression issue w/ 100 psi to 115psi for sure. by any chance that fitting suppose to have a rubber cap over it to. im guessing here, but wouldnt that be a vacume port not being used and if it is used i would think it would to the base some where. just some idears.

 

I don't think that outlet is supposed to have a rubber cap. My clymer manual shows it in one picture with a hose coming out of it going somewhere, but I don't know where. Does anybody have a 300 Xplorer that they can take the seat off and find out where this hose goes to?

 

Wow, I remember my Xplorer, it was my second quad.

Do they have a chain driven propshaft and chain gearcase (pretty much what they used back then)
I cant remember..

 

Yep. It's my second as well. Any chance you remember where the hose referenced above is supposed to go?

 

im working on a 400 right now and i think they are very similar. do you know any history on it, the bike im working on the fellow ran it out of mix oil. it showed 100psi and would barely run with a little fuel in the spark plug hole. i took it apart, the piston is melted on the exhaust side and theskirts are coming off. on this bike they said it needed at least 115psi. as for the vac line i will look and contact you. being it is a two stroke im guessing it could be a piston problem but you never know.
joe

 

i agree that it should be in the 135 psi and above area, but i would think it would run. at least i know a 2 stroke sled will but you never know i guess.

 

I used my borescope and checked the piston crown and sidewalls of the cylinder. It all looks pretty good. I did notice a little scoring on the cylinder walls but I've yet to see a 2-stroke without a little light scoring. Since my original post I took my compressor and shot a short blast of air through this side outlet in the carb. when I did it, the engine ran. I really think this is some type of pulse or vacum fitting that has to be hooked up to push gas through the carb. I just need to find where this hose goes. DRDIRT11, if you can let me know what yours looks like, I'd sure appreciate it. I think my compression is okay so I really think its this pulse line.

 

i looked on the 400 and i dont see anything, only the choke, have you tryed plugging it?
joe

 

Yeah, I tried plugging it and that didn't do any good. The only thing that works is when I blow a short shot of compressed air through it as I turn it over. That's why I think it must be a pulse line of some type. It's located right in front of the choke plunger. There is a black plastic fitting that takes the same size hose but that fitting I believe is the overflow/vent for the choke that connects to the t-fitting and the overflow on the bowl. This is a brass fitting that is parallel to the ground and is closest to the rider as seated on the ATV.