Major 300ex Problems!!!

[RedRider55]

about a year ago, we got a 95' 300ex as kind of a project fix up quad. it would start and kinda run but every time u would try to give it gas, it would fall on it's face and die, u couldn't get it out of 1st gear. we never got around to working on it until today and now it won't even start. it acts like it isn't getting any gas but we know it is because we took the boot off and saw that it spit gas out of the carbuerator. we tried changing the plug and draining the gas and puting new in and made sure the jets weren't clogged. does anybody know what could be wrong? and if we do get it to start, does anybody know why it would act like it did? any help would be greatly appreciated, thank you

[fastkid400]

u check the valves? maybe the timing was off? what color was the plug? maybe not enough gas gettin in there?

[RedRider55]

The plug was black as can be so we put a new 1 in and it still wouldn't fire. plenty of gas was getting to it because the plug smelled like gas, alot of gas. i'll check the valves and timing.

thanks

[Xowner]

filter clean make sure all the air tubes are sealed together also make sure ur choke aint on

sounds like too much gas, on kehien carburetors the throttle comes in at the top and the long needle u can pull down a few clicks, unscrew it and pull the needle down one click and give it a try, my fiends kx 100 had the same problem and we got it fixed, we cleaned the air filter, moved the main jet down to a 123 and adjusted the needle i was talking about..the thing runs perfect now

[drifterx]

I know this might seem stupid, but do you have a kill switch on it? I have a pro-design on my 300, and it would do the same thing. It'd idle fine, then die as soon as i started going, in any gear. I found out that the coating on the wire to my kill switch, had rubbed off in one spot, and it was hitting my steering stem. I taped it up, tried again, worked like a charm. If you have a kill switch, you might check it.

[2muchquad]

it could be your reverse inhibitor unit.i hear when those go out your quad can not start at all.make sure your getting spark.

[Jay99400ex]

Start off with the basics, remove the air box, either spray gas in the carb or ether, be sure not to run it alot on just ether, if it runs fine on that then its a air or gas/carb problem, if it still runs bad on straight fuel like that then it is possibly a electrical problem or timing problem, also, i have redone engines, and the wouldn't start/run for anything till i pull started them with another quad, you can get alot higher engine turnover doing this, and open it up better.

[Rich250RRacer]

Check all your electrical connections for corrosion, especially the large plug from the handlebar switch to the main harness. This is located just above the coil. Also check the plug that goes into the CDI box, since I've seen the very small terminals in this actually rot away. I have experienced two 300ex's with this corrosion problem and both needed the entire harness replaced.

[RedRider55]

well, turns out the timing was thrown off and the piston was beating the valves out of whack.

does anybody have any suggestions on what kind of piston to buy and where to order it from? i need a 11:1 .06 over 300ex piston, a new timing chain, and a set of valves and valve guides. if anybody has some information on any of these items, i would appreciate some responses.

[Out_Sider]

www.powroll.com ;)

[Aceman]

If you want a .060 over 11-1 piston your best bet is just to replace it with a Wiseco. It's a good cheap piston that would be perfect for your needs.