Scrambler 400 problem

[NcMtnMan]

I have a 99 Scrambler 400 4x4 that I just did a top end rebuild on, added a RCR stage 1 kit,rebuilt carb & rejetted. Now that I got it all back together all I can get it to do when trying to start is backfire & spit. Guessing it's a timing issue, how is that adjusted on the 400 2stroke?I am getting spark & gas, tried starter fluid & only backfires. Any suggestions would be great cause I WANNA RIDE!!!!!!!!!!!!
Thanks

[gh500]

why did you have to rebuild it ? cracked or broken piston ? the factory 400 pistons were notorious for cracking & breaking drooping a pc down in the crank case and breaking / cracking the cases have you done a crank case pressure test ? that would be the first place i would start with a 400

[NcMtnMan]

It blew a head gasket, had sat for a few years, when I tore down the top end there was some scoring in the cylinder so I decided to go ahead & rebuild it so I know when everything was done & also like you said the stock piston can come apart. When you saw pressure do you mean a compression test? Tried to get a manual for it locally but no luck, so ordered one & just waiting for it to arrive, new to working on 2strokes so I'm stumped now.

[gh500]

no crank case pressure test to see if it has any air leaks even small air leaks can destroy a 2 stroke let me see if i can find a link
I know it's a jet ski site but they have tons if good info
http://www.groupk.com/tec-airleak.htm

[dwhst9]

Did you figure it out?