www.zxrworld.co.uk

try to keep this short, oo bad weather we havein, eeerrrrr sorry

right got a zxr 4 rollong chassis, and got a motor ! before i fitted motor i had it checked ! low compresion on two cylinders. found two exhaust valves slitcking open !
mechanic took engine away to do a test on it ( i do trust the guy know him for years ). bottom end fine. he says it has the wrong head fitted ! would he mean it has an H head and an L bottom or other way round etc. either way he says i need a head to suit my bottom end.

dont know any numbers as yet but will get info when i see him. dose this make any sense !

any help would be greatfull or advise please

( p.s. it is going to be a track bike ) yeah i know with pedals at the mo

I'm prepared to bet that H and L heads are interchangeable........................Two sticking valves.............they could be bent ? or broken.

Has the head been skimmed ? Could it be a botched job ? too much removed ? and valves are hiting the top of the piston or even the top of the barrel

Could it be a head off a zx400.......................? but then it's the same engine as a ZXR isn't it ?

i dont know that much about the zxr 4 yet really i am learning as i go ! all i know is we checked the valves and 1 of No. one exhaust was no clearence at all and 1 of No. 3 exhaust there was no clearence at all. all the others were ok for clearence. so we, well my mechanic put it down to shims ( i had heard this word but was unsure what the part was ) so he took motor away to do shim clearences. before he started he checked the rest of the motor over and said everything looked and felt fine but the head was the wrong one for the bottom ??? its been machined wrong ? this is where i need a little help ?

i was just putting the question out there just in case anyone else had come across this.

ok got engine number now GEO15441 ? i know the chassis is an l model 1992.

as far as im aware, H and L heads are interchangeable, and ZX4's are identical to H model heads for definite (got one of each stripped on the bench atm)

my bike had low compression due to incorrect valve clearances, with no gap holding the valves open causing the low compression.change the shims as neccassary and see what the compression is then........other things can cause low compression other than an incorrect head.