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Hey guys, I'm trying to trouble shoot a 2003 Honda Rancher. I don't know a lot about it. It was a non-running machine when my friend bought it and I've been trying to get it going for him. I began by checking the spark which seemed to be good to me. Next I turned to the carb. I took it apart, cleaned everything, then put it back on. It still wouldn't start. I tore it back down a second time, this time noticing a small hole in the diaphragm on top. The carb looked like it had seen better days, so I opted to order a new OEM carb. I put it on today and it still won't start. All I can get it to do is occasionally backfire. The engine seems to have good compression. The carb is sucking in and the exhaust is pushing out while the engine is turning over which leads me to believe it isn't a valve issue. Could it possibly be the CDI box? Would I even be getting spark if it was faulty? Thanks for the help!
 

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No, you wouldn't be getting any spark at the spark plug if the CDI was faulty. You might try hooking up a timing light and see if it fires on the timing mark like it's supposed to. If that checks out OK, I would move on to something else.
 

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OK< well I will have to dis agree about the CDI, , I know for a fact when mine went, I had GOOD spark, but had back firing and other idling like issue's that were all CDI related,
that;'s alos why there really isn;t a test for a CDI< only way is to swap out with a KNOWN good one?

IF you do BUY a new CDI< DON"T buy an aftermarket one, electronic's are NOT the place to go aftermarket IMO!

Now without knowing reason atv wasn't run in a long time or NOT running when you got it.

you could have a motor out of time, causing NON firing and back firing, it its a high mile or hr motor, this can happen!
or it could have been a Sunk motor and compression isn't enough to run /start right!

I would do a compression test to KNOW where its at, simple and cheap, and rules out one thing?
 

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I would have put a new NGK spark plug in it before doing anything...
Alleluia on that !



When you cleaned the carb was the bowl funky , you could have funk in you tank and just reintroduced old gas , water and dirt right back into the cleaned out carb and them into the new one , you didn't mention if it was a new carb or after market , after market is ok with me , but some will send you something close and not necessarily the exact replacement or send you a piece of crap ------ I would do a compression test , " seems ok " to me would get it , read the manual on compression testing that engine , I think it has a decompression device on the cam for easy starting and if you don't do the right procedure you will get false readings ------- my favorite way to narrow down fuel problems is to hit it with a short burst of starting fluid and see if it pops on that
 

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Spray a quick burst of starting fluid into the intake and see if it fires up, if it does keep looking at fuel. If it doesn't look more at timing before thinking cdi box, last resort a new Oem box but it sucks to spend the money on a box and not fix the problem.


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