My 1998 scrambler 400 went on a 8 hour trip in -32degree weather. When it arrived it struggled to start, but after persuasion and a new plug it did. I flew around the fields and was heading out into the next field when it suddenly died. I have put a new plug in and it didn't help. The fuel is brand new. We have taken the carb apart completely and it is clean and seems like it it is working properly. It will turn over forever, and there is spark at the spark plug, but it will not fire. Even after turning it over for a while, if I pull the spark plug out it is bone dry. It has been sitting in a heated garage for 7 hours now and it still isn't starting. Any ideas. It is getting very frustrating. I have owned this quad for 3 years or so and it has always fired on first push of the button.

 

a shot of ether doesn't help . can you take the fuel line off at the carb. and fuel runs out fuel shutoff may be full of crud or tank has crud in it as well

 

we tried ether into the intake and it didn't even go boom. There is fuel running freely from the gas tank.

 

could it be from a hole in the piston, or a cracked ring?

 

do a compression check if you have a guage, may be a bad piston

 

thankyou, I checked the piston and it does have a hole. So far no damage past that. Easy fix, just wrecked a weekend. Thankyou

 

This happens when you dont rejet for temp drop and air density.
You have to do a topend but not too bad of a job