www.zxrworld.co.uk

Hello, recently picked up what I assume to be SP camshafts. Unfortunately every lobe and journal is outside of what the standard 'L' model service manual states (Even below the service limit). Both the exhaust and inlet camshaft suffer from this.

After having a good look round the net and forum i'm unable to find out much about them. Are SP camshafts just standard L model cams with adjustable sprockets? In which case I'll have to have them reground too bring within spec.

Any info would be much appreciated.

Anything in the zxr400R manual
http://www.zxrworld.co.uk/Manuals/zxr400r.pdf

It does list a camshaft lobe height but its for the F3. Wasn't sure if that is a different cam to the SP again.

SP cams are the same profile as H1/H2/L1 but with adjustable sprockets. F3 are (as you suspect) different again

yours may have been reground (which takes a bit off the base circle to increase lift/duration) by kent or whoever .. I have some like this.. If this is the case they'll need larger shims but perform fine.

if you do fit them, pay very close attention to the piston-valve clearances and dont assume that because they are on the fixed bolts that there wont be clearance issues.. I've had to retard the intake cam and advance the exhaust cam of the last couple I built to prevent internal contact. This was with genuine M4 cams and some kent items... In both cases stock cams just went in on the marks with no issues.

Thanks Zimm, I'll give them ago. I take it that if I just bolt the sprocket on in the fixed bolt position or where the timing mark is, it's the same as standard camshafts?

ish

lobe centre may differ, opening/closing speed may/will differ.

dial in and pay close attention to the min piston/valve clearance (f3 manual) using that as your indicator more than where the cams end up relative to the stock marks, if the heads been skimmed they're off anyway*

my sp with kent cams in has the intake cam retarded by a whole tooth to get sufficient piston/valve clearance, the engine locks up if its on the marks, same is true of a late L i built with genuine SP cams, although that didnt need to come back quite as far.

(*cams will be retarded from stock as a consequence of skimming the head and or skipping the base gasket and changing nothing else, this tightens the piston/valve clearance on the exhaust cam)

Both the head and cylinders have been skimmed on this engine so I'll dail them in, thanks

this may well account for the lack of compression in your other thread, cams could be upto 10' retarded with pistons just kissing exhaust valves and all the fresh charge going back up the intake through the still open intake valve instead of compressing.

Hi my head is skimmed to the point I need to run with two washers on my plugs.