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Discussion Starter · #1 ·
i am kinda new at working on these 4 strokes, i put new cams in it and thought that i timed it right and when i went to start it it would backfire and flames would come out of the carb, so then i thought that maybe i had it 180 out tried it agian and still flames out of back of carb, it doesnt even try to start just flames, need some help here i bought the quad witht he motor apart and changed the crank and cams so i never got to hear it run when it was together any help would be much appreciated
 

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If flames are coming out the carb, it sounds like the cam timing is off.

You said the motor was aprat when you got it, so make sure that the fly wheel is marked accuratly at TDC.
 

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Discussion Starter · #3 ·
Originally posted by tersejr@Apr 17 2006, 05:30 PM
If flames are coming out the carb, it sounds like the cam timing is off.

You said the motor was aprat when you got it, so make sure that the fly wheel is marked accuratly at TDC.
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i tried a screwdriver method i put it in the spark plug hole and watched when it raised to it highest point then looked and all the marks are lined up would that be tdc
 

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Yep, that will work.

Double check your cam timing and valve clearences.

Make sure you did not forget to release the ACCT to put tension an the cam chain.
 

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At TDC on the combustion stroke the cam lobes will be facing away from each other. Are they? On the exhaust stroke you will be at TDC also, but the lobes will be facing each other.

Which way is yours?
 

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Discussion Starter · #7 ·
Originally posted by tersejr@Apr 17 2006, 07:05 PM
At TDC on the combustion stroke the cam lobes will be facing away from each other. Are they? On the exhaust stroke you will be at TDC also, but the lobes will be facing each other.

Which way is yours?
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they are facing away from each other
 

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Discussion Starter · #11 ·
Originally posted by tersejr@Apr 17 2006, 07:48 PM
Are all your electrical wires and connectors correctly connected and tight?

How is your spark plug?

Is you carb slide working as it should?
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spark plug is brand new and all electrical connections are right as for the slide it appears to be could that cause a backfire thru the carb
 

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I'm going to add something to this. It's kinda obvious but commonly overlooked.

Check and make sure the throttle cable is seated properly in the housing and in the carb. Sometimes if it's not seated properly it acts as if the gas is applied throwing too much gas into the mixture. I know..kinda stupid but hey...it's worth a look. :smile:
 

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Discussion Starter · #17 ·
Originally posted by tjiversen@Apr 21 2006, 02:18 PM
could that casue it to throw flames out of the carb tho
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ok i tried everything the timing is set to exaclty how is shows in the book and the carb is working properly, it is getting spark and fuel but stillnot turing the motor over i am lost here and do not have enough money to take it to a mechanic any help plezzz
 

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As long as you're positive it's timed properly and everything moves freely (internal motor components) have you tried to pull/push start it?

And are you positive you're getting a good, constant spark?
 

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Discussion Starter · #19 ·
Originally posted by YFZ450alterego@Apr 23 2006, 03:34 PM
As long as you're positive it's timed properly and everything moves freely (internal motor components) have you tried to pull/push start it?

And are you positive you're getting a good, constant spark?
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i havnt tried to push or pull start it would that differ from jsut using the starter, and i am pretty sure it is getting a good constant spark ipulled the plug and gorunded it to the frame and cranked it over and it is a good spark.
 

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Discussion Starter · #20 ·
Originally posted by tjiversen@Apr 23 2006, 03:45 PM
i havnt tried to push or pull start it would that differ from jsut using the starter, and i am pretty sure it is getting a good constant spark ipulled the plug and gorunded it to the frame and cranked it over and it is a good spark.
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i just tried this i had the dots on the cams flush with the head but then i rotated the exhaust cam 1 tooth clockwise and now it will back fire thru the exhaust everyonce in awhile
 
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