I just picked up a Honda TRX300ex 2001 on craigslist for only $150. Although im starting to find out why it was so cheap. Idk what the old owner was trying to do but he had lots of parts from a 2006 250ex on it. by the look of it he was trying to put the 250 carb, but it would never fit, but he had the old carb so whatever. The worst issues is it looks like most of the old cables where a bit meted by a fire or something. Then he tried to fix it with the 250 wiring harness, but nothing is the same and he ripped some plugs off and i need some help figuring out what to do using the lest amount of money. I dont care too much about getting the lights or anything to work. I just want to be able to run even if i had to hot wire it to start. I have added some links to the 250 and og 300 wiring harness (the one on the 300ex is the 250 harness and the one on the wood floor is the OG 300s cables)

I can provide more photos or info you need.
https://photos.app.goo.gl/c2mH8LAPdbV4maEy1 - photos of both wiring harnesses

Thanks in advance

 

You may be lucky and find a good 300EX wiring harness from a breaker. Or you can make your own using the old one as a base, just replacing any damaged wires once the black insulation tape shroud is removed. A new harness is $128, which is the easiest route to sorting your wiring out.

 

I think i am just going to buy a new CDI, and make a much more simple circuit with no safety on it.

 

Trouble with that is you need some of the wiring plugs, so have to hack the old loom up so badly you could never get it back to standard, then find one of those safety circuits is needed to make the CDI work. Lots of people have tried that on Chinese Kids Quads, with simpler systems, and lots of them fail.

 

I have got the engine to make a spark now, but the issue is that i cant get it to actually fire now. When i hold open the throttle a bit a feel a slight tug and i think i saw some mist/smoke come out the carb. The exhaust almost feels like its sucking too when im trying to start it.

 

Check compression, it is possible a valve has stuck with standing, or the original fault may have been incorrect valve adjustment. The carb may need sorting out too.

 

I have not fully checked the compression, but I know that it is blowing air out of the spark plug. I will try to reset the valve lash and see if that helps anything.