Trouble With First Start

Mar 16, 2016
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I have a brand new engine with a centrifugal clutch, pull start, and shift kit. The pull start is because i can't turn the engine over pedaling because the shift kit gears down the power from pedaling so much. I also had to make a makeshift intake because the engine fits too high up on the frame. I made it from copper pipes jb welded together. It's a little longer (about 2 inches) than stock but they make extended intakes so i didn't think it would be an issue. I'm getting spark and gas it getting into the cylinder. I've pulled on the thing for about half an hour. I don't know how much pulling needs to be done to start it for the first time if anyone has a pull start that's done this before. Or if there's an actual issue with either the homemade intake or something else. Any help is appreciated, thanks!
 

crassius

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Sep 30, 2012
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I'd first try a few drops of fuel thru plug hole before even starting to check gaskets and things.
 
Mar 16, 2016
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Gas in the plug didnt work. I'm using 16:1 btw. There was a popping sound and some white smoke came out of the carb at one point before i tried the fuel in the plug. Not sure what that means.
 
Mar 16, 2016
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I'e tried in the middle, leanest and richest. I'll switch out the gas as well and try it again. I'm goin to get another plug anyways so ill change the gap on that one.
 
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crassius

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Sep 30, 2012
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no pop with fuel in hole often means bad plug or loose head gasket (carb & bottom end gasket aren't involved at that point)
 

Tyler6357

Well-Known Member
Mar 15, 2012
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Santa Barbara, CA
The plug is sparking so ill tighten the head down as well.
Yeah, don't tighten it too much. The head nuts should be torqued at about 15 foot pounds. Over tightening fasteners has caused more problems than any other one thing with these kits. In the case of the cylinder head too loose or too tight can cause you further problems. Use a torque wrench, if you don't have one, get one because you are going to want to check it often.

brnot
 

crassius

Well-Known Member
Sep 30, 2012
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a fouled plug can spark in air, but not under compression - you could try any plug that is not too long just for testing

many auto parts stores will loan a compression tester for free to check that
 
Mar 16, 2016
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Replaced the spark plug and switched the gas to 32:1. The head is properly tightened and there aren't any leaks elsewhere that i can see. Not sure what else to check at this point.
 
Jan 21, 2015
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Portland, Oregon
Are you using the acorn head nuts that came with it? They have a tendency to bottom out on the studs before they are actually tight. Try replacing them with normal nuts and re-tightening.
 

crassius

Well-Known Member
Sep 30, 2012
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I've got a thread somewhere here (probably under electrical) about making a timing mark to check CDI timing, but it is rare to get good spark at wrong time

if someone is near you with a CDI to borrow, I usually just try one to eliminate that

19 times out of 20, it is some really simple thing, but with all the changes you made, it may be hard to find, like if rotor was off to put in pull start, maybe it went back on backwards or without woodruff key or a lack of enough head stud washers so nuts are tight but head is too loose

did you try a cold compression test?
 
Mar 16, 2016
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The nuts are tight i checked that when i checked the torque. I have another bike so i can check the cdi with that one in a couple days. I'll double check to see if the rotor is on the right way but i am getting a spark which i wouldn't if that was backwards correct? Or would it just be mistimed? Definitely didn't forget the woodruf key I double checked that lol What is a cold compression test?
 
Jan 21, 2015
610
21
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Portland, Oregon
The nuts are tight i checked that when i checked the torque. I have another bike so i can check the cdi with that one in a couple days. I'll double check to see if the rotor is on the right way but i am getting a spark which i wouldn't if that was backwards correct? Or would it just be mistimed? Definitely didn't forget the woodruf key I double checked that lol What is a cold compression test?
If you're using the stock acorn nuts, the nuts may be tight because they are bottoming out on the studs, instead of because they are holding the cylinder head in place.