Vintage Dirt Bike Q & A

I have a 1979 yz400 that i just rebuilt, but it will not start cold unless you put fuel in the cylinder. once you have had it running it will restart first try. any ideas? thanks Todd

You may have slightly low compression. If that were the case, it could make it difficult to suck fuel through the carburetor into the cylinder when using the kick starter. Have you tried bump starting while it's cold? I would recommend checking the compression and see if it is up to spec.

haven't tried bump starting but will check compression again. the bike has a new top end.

hi, would also do a leak down preasure test. the bottom end seals and bearings could be bad,terry

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Terry


79 RM 400 (2), 79 CR250, 80 CR250, 80 CR125, 82 Husky WR430, 72 Rickman 125, 71 Hod 100 SR, 73 X75, 76 Hon TL125, 74 XL350, 79 XL500, 00 KX250, 00 YZF426, 04, 06, & 08 CRF450, 06 CR250, 05 CR85, 74 GT550, 85 350X, 83 200X, 80 Yam 125.

will give that a try thanks.

Once check the compression and pressure and can get good result...

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