posted up in another section already.88 f1.lost compretion in #3 & 4.pulled motor,changed rings,gaskets & o rings under cylinder block sleeves.reinstalled motor.bike will not start.good fire,geting gas,set timing by the book.when turning over it spits back through the carbs.pulled valve cover & double checked timing twice.sounds like timing problems to me.this used to be my bike.i sold it to a friend.he put a good bit of hard miles on it before we lost compretion.the bike now has 25000 miles on it.what am i missing.

 

My guess would have to be timing as you suggested. I would check again, this time, make sure your not off 180 deg. Your timing marks will be on, but you may be firing on the exhaust stroke versus the compression stroke.

 

You didn't mix the exhaust and inlet cams up ?
I don't know that model, but I've seen it done before.....

 

going by the book the first com lobes should be facing away from center.thats how i have them.also did double check to make sure i did not mix up intake & exaust.thanks for the replys.any more ideas.im going look again now.confused.[:@]

 

Have you got the plug leads going to the correct cylinders?

 

yes plug wires are correct.i did have 2& 3 swiched but found italready.

 

We've all been looking at cam timing........
what about ignition timing.............?
It's adjustable on some bikes. I had a keyway break once and it moved. Burnt hole in piston
Backfiring through the carb is generally a timing issue...........

 

i dont think its ajustable.2 seperate coil packs.i will look back in the book and see if it is.

 

Dude, something tells me you've got those cams 180ยบ out of spec. There isn't much else to go on here, though. If you have fuel, fire, compression and air you should at least be firing, if not running. How much compression does each cylinder have? Is it relatively close to the manufacturers spec? Give us a couple numbers to go by.

 

yea ur right.ok.going get cmpresion tester tommorrow.i know all my timing marks are good.......i think?