spitting back

[andyzed]

anybody help? ive a z650 hardtail running 107.5 mains with k&n type filters that spits back through the carbs. ive checked the timing with a strobe and set the dwell. it all seems fine except the timing plate appears to be bent! i was going to try a compression test,will this tell me if the valves are ok? any idea what the airscrews need to be set at?
one last thing anybody know where i can get some drag pipes?
thanks

[Mad Dog]

Spitting back is usually caused by valve timing.

Check yer cam chain hasn't loosened and jumped one tooth on the cam
(happened to me and I bent a few valves as a result)

[Mitch]

Are you really sure you want some drag pipes? For a few quid towards the Mitch & Mrs R Bike restoration fund, they're yours...

If so, PM me!!

[Mitch]

Spitting back is usually caused by valve timing.

Check yer cam chain hasn't loosened and jumped one tooth on the cam
(happened to me and I bent a few valves as a result)

Also happened to Mrs R's it was one tooth out, that's what was found after getting the head rebuilt (oh that and the camchain been knackered... and the rest...)

[m@rk]

years ago i set up me z550 and had the valve timing 180 degrees out(ouch)
realised after and found out id bent the valves...
never did that again...lol :( :(

[guydewdney]

spitting back can also be caused by too lean on the needle screws - 99% of the time its 1.5 - 1.75 turns out from lightly seated (ie finger tight closed, then out by 1 1/2 to 1 3/4 turns)


but thats only spitting on tickover, not all the eay through the revs - if its doing that then its the valve timing as mentioned above.