well i have a 600 f2 that gets spark, fuel, air, and turns over great but will back fire and not start... i was told it was the timing, but what can cause the timing to just change or get off time

 

If it was a car I would say that your timing is WAY out like 180 out. But not sure how the transfers to the bike world... do you have a service manual?

*EDIT*

Looked at your service manual.. got it here: http://www.stephygee.com/

Timing is on page 16-9, might want to check it. I'll keep looking to see what else it might be.

MDFF

 

Has it sat for a long time? Maybe bad gas or trash in the carb.

 

Help us all out. The bike ran at one time and now it back fires. What happened between now and the last time it ran. Did you have any work done or did you do any work to it?

 

One thing that can cause way out timing like that is putting the spark plug wires on the wrong plugs. Check that the wires on the plugs are numbered 1-4, starting from the left as sitting on the bike.

 

yes it ran before i bought it but it was sitting for about a month, i had a shop look at it and he said that the plugs, fuel, air were ok, but i am going to change out the gas , change the plugs, GET A BOOK and go from there, like the carbs and float needles etc....

thanks to everyone for you input, keep it coming......

ps the guy who had it before me had a sputtering problem before and he let a back yard machanic clean the carbs