snc scoot won't start

I'll chime in here........Hopefully after you and your buddy will find out you're low on compression. If that's the case you've got some engine rebuilding ahead of you. From my experience these motors are pretty bullet proof unless they've run out of oil and scored the piston/cylinder. I've worked on a quite a few of these 'Scoots and have had two that have had problems starting similar to what your experiencing. The fuel pump seems fine when you take it apart and even switch it out with a working one but it still will not start. Bite the bullet and buy a new fuel pump. They're around $80 bucks new. How old are these 'Scoots now? At least 25 years old. That right there is a lot of time. Just think of how much crud has built up and collected and gone through the fuel pump in that time. These motors do not have a lot of compression to drive the pump. These sleds are very tempermental when it comes to fuel delivery and with todays fuel you really need to keep after it to get these sleds running right.
 

Thanks for the input Boomer, I did get a new pump, FYI its the same pump they used in the Bravo 250 (and only $25.00) still no luck. I can't believe it could be low compression, haven't run without oil or can't think what else would cause engine damage. see what happens with the compression test.
 
Just an update, did the compression test and it had 60 psi, looks like time to pull the engine apart. Thanks everyone for the help, ill update the post when I get it done.
 
Another update if anyone is following, removed the piston and it was scored pretty bad down one side and the top ring was half missing, explains the low compression! I am going to have it bored hopefully soon and will update after that.
 
just wanted to update the post, I finally got it bored and new piston just put it back together and also cleaned the carb before trying to start it, No luck still wont start. I gave it a shot of starting fluid and got two pops then nothing, so at least something is happening. I an going to pull the entire fuel system out one more time and if it doesn't work its going in the bon fire.
 
My brother in law had a scoot a few years ago and he couldn't get it to run right. Cleaned the heck out of the carb, etc. He ended up buying a new carb and it ran like a champ after that. Tempermental little beast with the carb, but after a new carb installed, he never had anymore problems with it.
 
I did switch out the carb yesterday with my other scoot which has been running great so I don't think its a carb problem.
 
I know you said you checked the pipe but maybe try starting it with the silencer removed...... plus they sound great with just the header pipe...lol.... If the silencer is clogged the baffle with come out and you can also burn the whole pipe in a bon fire to clean it out.....Tod PS cant even tell you how many small two stroke engines have come back to life after unclogging the exhaust...... I did see you had low compression but you pipe could be blocked....
 
The silencer has been off for a few years, The rubber joint that connects the silencer tore and I never replaced it, my daughter likes the sound without it!
 
OK, finally got time to go through the fuel system. The fuel pump was not working so I replaced it with another one that I had and got it running!!! Some how the pumps got switched, I knew one was bad from previous testing. Anyway just got back from a ride, on what little snow we have here in the North East, and it screams. Big difference with the 2 over piston. I took the cylinder to a guy in Berwick Maine, LD&R Machine, he just works on motorcycle, atv and snowmobile cylinders. He found the Wiseco piston 457M04950 (which is from a Yamaha yz80 1976-1980 is an almost a perfect fit the only difference is that it is a little longer on the bottom which makes no difference on this engine all the critical spec's are identical. I have heard some guys say yo can't use the YZ piston but I figured I would trust a guy who for the past 40 years had been boring engines and modifying racing machines. The scoot ran great and much peppier on the start and faster than the other scoot my son was riding.

Thanks for all the input, I never would have guessed the compression would be that low.
After talking with the guys at Sno Scoot.com who told me the only pistons available are from them and they want $258.00 not to mention the cost of boring I was determined to find an alternative. So far this piston looks promising and only $80.00.
Again thanks everyone for the help
 
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