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A little help after 09 rebuild

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Short story - had my 09' 450 motor out over the winter. A mechanic went through it - valves all within tolerance, said it looked like new inside. I had him put new rings in and I reinstalled the motor.

Tried starting the other day and I get nothing but backfires. :banana: I mean C'mon - I don't have time for this!

As as lifetime 2-smoke rider I am befuddled on where to start in diagnosing this. Any suggestions?

The motor kicks through and has compression. I presume there is spark and fuel, because all I get are backfires.

Thanks for lending a hand - I really wanna go riding. First race is in two weeks!!

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Be careful trying to start it, it sounds like your off a tooth on the cam chain. Take it back to him and have the chain reset, if out of spec.

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Short story - had my 09' 450 motor out over the winter. A mechanic went through it - valves all within tolerance, said it looked like new inside. I had him put new rings in and I reinstalled the motor.

Tried starting the other day and I get nothing but backfires. :banana: I mean C'mon - I don't have time for this!

As as lifetime 2-smoke rider I am befuddled on where to start in diagnosing this. Any suggestions?

The motor kicks through and has compression. I presume there is spark and fuel, because all I get are backfires.

Thanks for lending a hand - I really wanna go riding. First race is in two weeks!!

First thing I'd do is double check all the wiring harness connectors as well as the main system ground at the radiator mount. This ground point (see pic below) has caused issues for a few riders, you might find that it is loose or just may need cleaning as corrosion can develop and create a hi resistance problem.

Next, double check the cam / crank timing marks to make sure no mistakes were made during re-assembly.

Ask your rebuilder if valves were re-shimmed at all as it's pretty easy to make a mistake there if you get in a hurry.

Lastly, sometimes when the fuel system has been opened up you can get some air in the lines and it can take a quite a few kicks (upwards of 40-50 kicks) to regain proper system pressure. We have heard from customers that had to tow start their injected bike to get it running after the fuel line had been removed for servicing etc.

I would strongly recommend checking the timing etc as mentioned above before trying to tow start it as you don't want to cause any damage due to trying to tow start a engine that has been incorrectly assembled.

SystemGround.gif

Good Luck! :lol:

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Check all the wires and connectors as mentioned above, along with the timing. I had the cam on my 09 off a tooth the other day and it ran fine (kinda doggy) once I got it going but it would barely fire up.

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I'd like to buy a vowel?!

Checked cam and it was off a tooth. Fair enough, put it together and Kaboom! More back fires.

Two of us looked over the wiring harness and connections and they all appear ok. Checked ground wire - ok.

Removed air filter and no obstructions. Same with exhaust pipe.

Changed spark plug to new and back to old. Same effect.

Anyone run into this before? Is it really a matter of enduring countless backfires while trying to get it to fire up?

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How many times have you kicked it? Do you have the little pressurizing tool from Honda? If not, it may take quite a few kicks. I don't have the tool and the 1st time I did a rebuild it took more than enough kicks. I don't remember it backfiring though.

Are you sure your valves are in spec?

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If you know for a fact that your engine is properly assembled I would tow it. It'll start right up unless ofcourse he did something wrong.

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