Hi everybody,

I have stripped my bike down and re-ground the valves.

I have put it back together but I am having problems. Please bear with me while I try to explain to see if anyone can see anything obvious.

Piston is at TDC as per Haynes manual. Timing mark set on the front of the crankcase LHS of engine.

Both crankshafts have the timing mark at the top. I am rotating the engine anti-clockwise. All return to TDC after rotation.

The problem that I am having is when, (I have put in a spark plug and rotate the engine), if I hold my hand over the inlet manifold I get suction on my hand for part of the turn then as the piston starts to come back up it blows out of the inlet??? This is when the inlet valves are open. I also get no register on the compression gauge when i use it is this because I am turning it over by hand?

I have completely rebuit it but petrol was blowing out of the inlet side hence me restripping it. I am sure its out but the haynes manual says it is ok but the pictures are sketchy to say the least.

Any thoughts and thanks in advance.

I am going to ponder it over a few beers.

Hi everybody,

I have stripped my bike down and re-ground the valves.

I have put it back together but I am having problems. Please bear with me while I try to explain to see if anyone can see anything obvious.

Piston is at TDC as per Haynes manual. Timing mark set on the front of the crankcase LHS of engine.

Both crankshafts have the timing mark at the top. I am rotating the engine anti-clockwise. All return to TDC after rotation.

The problem that I am having is when, (I have put in a spark plug and rotate the engine), if I hold my hand over the inlet manifold I get suction on my hand for part of the turn then as the piston starts to come back up it blows out of the inlet??? This is when the inlet valves are open. I also get no register on the compression gauge when i use it is this because I am turning it over by hand?

I have completely rebuit it but petrol was blowing out of the inlet side hence me restripping it. I am sure its out but the haynes manual says it is ok but the pictures are sketchy to say the least.

Any thoughts and thanks in advance.

I am going to ponder it over a few beers.

Hi there

so I guess when you set the valve timming the marks on both cams were alingned when the motor was set at LT? You need to spin the motor (not by hand) in order to get a reading via a compression gauge, if the compression is low at this point add oil to the cylinder and see if the guage increases in value, if so you will have some ring problems.. if not you may have a bent valve (or 2 or so) I'm not sure what you have done so give some more info

Regards Jim

Hi JimR

I think I may have found the problem. The haynes manual shows on the picture that alignment is at the front of the engine i.e. the alternator tdc line is lined up with the casing seam.

On the Yamaha manual it shows the alignment to take place at the rear of the block. Strange I know but I was going to try that this afternoon and have a look. I will give it a go and let you know if it works. Both camshafts were aligned as per instructions.

All the valves are ok and move freely in the head. I have had them all out and checked.

Everything in the engine is imacculate as the bike had only done 3500 miles when I bought it.

The owner had an accident (not on the bike) and it just got parked.

I had got it into my head it was the valves not seating correctly after reading the FZR common faults. But this was not the case. It was the spacers/shims on the inlet side that needed adjustment which I have done now.

I will get it done this afternoon and give feedback.

Cheers.

Hi JimR

I think I may have found the problem. The haynes manual shows on the picture that alignment is at the front of the engine i.e. the alternator tdc line is lined up with the casing seam.

On the Yamaha manual it shows the alignment to take place at the rear of the block. Strange I know but I was going to try that this afternoon and have a look. I will give it a go and let you know if it works. Both camshafts were aligned as per instructions.

All the valves are ok and move freely in the head. I have had them all out and checked.

Everything in the engine is imacculate as the bike had only done 3500 miles when I bought it.

The owner had an accident (not on the bike) and it just got parked.

I had got it into my head it was the valves not seating correctly after reading the FZR common faults. But this was not the case. It was the spacers/shims on the inlet side that needed adjustment which I have done now.

I will get it done this afternoon and give feedback.

Cheers.

Thats good let us know how you get on

Regards Jim

got it rebuilt when i put it with the timing mark at the rear it caught on valves. So sacked it and returned to the front.

both pictures are confusing. It works followed the pattern of the cams etc for intake exhaust all ok.

got compression test and no 1,2, +4= 145 psi. no 3 = 40 psi. bench tested using a dril and socket.

put petrol into intake on no 3 to see what was happening. valves leaking.

turned the engine over and the petrol came out of exhaust 3 + 4 .

nightmare. Any thoughts as to why?

know anywhere that I can get the head checked reground in Leeds / Batley area UK?

Or as suggested in the manual is it worth running it across some 600 grit sand on a flat surface?

Just got a quote from Cowburn’s Auto Engineers in cleckheaton.

£20 to skim. £25 to reseat valves, £25 to decoke, £25 to redo valves.

dont think that is a bad price.

got it rebuilt when i put it with the timing mark at the rear it caught on valves. So sacked it and returned to the front.

both pictures are confusing. It works followed the pattern of the cams etc for intake exhaust all ok.

got compression test and no 1,2, +4= 145 psi. no 3 = 40 psi. bench tested using a dril and socket.

put petrol into intake on no 3 to see what was happening. valves leaking.

turned the engine over and the petrol came out of exhaust 3 + 4 .

nightmare. Any thoughts as to why?

know anywhere that I can get the head checked reground in Leeds / Batley area UK?

Or as suggested in the manual is it worth running it across some 600 grit sand on a flat surface?

Just got a quote from Cowburn’s Auto Engineers in cleckheaton.

£20 to skim. £25 to reseat valves, £25 to decoke, £25 to redo valves.

dont think that is a bad price.

Hi there

seam to have bent a valve or 2 there by setting the valve timming incorrectly, I can send you stage by stage msgs on how to set it once you have the new valves put in, just let me know.

Regards Jim

Cheers JimR

Luckily its not the valves that are bent its aluminium that has got stuck between the valve and valve seat.

just a little bit but enough to stop it seating properly. I deburred the inlet side after I had put the valves back in. Should have done it before that really but you live and learn.

Thanks for the offer if I get it back together and run in to problems I will update you and let you know if it runs ok.