I need some help troubleshooting a '17 CRF45RX...

Hello Folks,

I finally broke down and bought another dirt bike after a 30 year hiatus...and they, of course, have changed. I have a problem I can not identify and I'm hoping someone here might know what's going on.

I have a 2017, throttle body injected, CRF450RX that I bought late last summer, used. When I bought the bike, it started right up, every time. That said, over time, she started getting harder and harder to start (towards the end of season) but I could always get her started with the kick start. Then came winter and about 3 months of sitting. After the bike had sat, she would NOT start...no matter what I did. She's getting spark and fuel, so I thought maybe I had inadvertently put some bad gas in her last fall. I drained and refilled the tank and she started RIGHT UP and ran FINE that day, after some good gas had gone through the system. I did not ride it much, as I was working on the bike that day, but she fired right up before I put her away again. Only a few days later, I went out to do some more work on the bike and found she would NOT start again.

I have since changed the spark plug, along with the battery and still cannot get her started, with the switch or the kick start. Any ideas??? When I bought the bike, she would fire right up.?.?.? Thank you in advance for any help or feedback I can get on this!

UPDATE: I've torn the bike down several times looking for any potential problem. I have spark and I have fuel...and I can't see how I wouldn't have air...where's the fire??? Yesterday, after draining the fuel AGAIN, I decided to check the filter, so I pulled the pump. The main O-ring was broken into 2 pieces but it was NOT leaking fuel. Could this have ANYTHING to do with my problem??? I have NO idea with these computerized bikes. I went through all of my connectors yet again and ended up breaking the clip on to the ECU. It was brittle. I guess I'll have to use a little JB Weld to put her back together with b/c I do NOT want to replace the whole wiring harness. My fuel filter looks fine, though I have NO idea how one is supposed to know when it's dirty???

I even tried a short shot of brake cleaner in the air intake to get her to fire...no luck.?.?.?

Okiewan said:

Have you checked the valves?

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No, I have not. From all the reading I've done, folks are saying that people do this way too much on the 4 strokes??? The guy I bought it from said she had 90-100 hours on her and they supposedly tore them down each winter and went through the bike every year.

Checking the valves would be something I'd have to learn how to do. That said, I do have a manual...

Okiewan said:

Not sure I want to comment on that, lol.

This video will get you started:

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Thank you! That doesn't look too hard...and you don't have to pull the engine and tranny like you do with my HD either. I reckon I'll add some shims to my order tomorrow, so I can get this done as well. Thanks again!

Quick question...would you always try to shim to minimum specs to allow room for wear???