Valve Clearance Guide

[Haydn]

Quick question. Ive checked the valve clearances on the rear today. This is what I found.

Cylinder 1

Inlet

0.20 - 0.18

Exhaust

0.30 - 0.33


Cylinder 3

Inlet

0.21 - 0.19

Exhaust

0.30 - 0.31

Now i thought the clearances would get smaller as the engine wears so why are all mine either on the upper tolerance or too large?? It has been a track bike for many years raced in Formula 400, would anyone have done this intentionally?

Cheers
Haydn

[CMSMJ1]

yes - the HRC manual has the clearances set pretty loose..though the exhausts on yours are bloody loose! I bet it is a noisy mofo.

[Haydn]

That's the strange thing, it isn't particularly noisy, sounds really well. I'm only checking as I had the carbs off. The tolerance is obviously there for a reason so is it worth re shimming to bring it in, the engine is spotless inside with no signs of wear due to loose clearances. I did check the clearance between cam and rocker and they are all bang on so I think somebody may have set the clearances that way in the past.

The HRC tolerances are:

0.15-0.20 for inlet. Making it 0.01 over on cylinder 3.
0.25-0.30 for exhaust. Which makes it 0.03 over on cylinder 1.

Appreciate your input

Haydn

[porndoguk]

Carbon build up on the valve seats will cause the loosening/increase in clearance

[Haydn]

The bike has been running excessively rich for some time so that may have contributed to it.

[CMSMJ1]

That's the strange thing, it isn't particularly noisy, sounds really well. I'm only checking as I had the carbs off. The tolerance is obviously there for a reason so is it worth re shimming to bring it in, the engine is spotless inside with no signs of wear due to loose clearances. I did check the clearance between cam and rocker and they are all bang on so I think somebody may have set the clearances that way in the past.

The HRC tolerances are:

0.15-0.20 for inlet. Making it 0.01 over on cylinder 3.
0.25-0.30 for exhaust. Which makes it 0.03 over on cylinder 1.

Appreciate your input

Haydn

You surely mean the finger and the shim?

[Haydn]

You've read that wrong. You didn't read the post before. I also checked between the cam and rocker after just out of curiosity, I thought the previous owner may of been mistaken by the Haynes manual photo and set the valve clearances between the rocker and cam. The measurements all came within the tolerances so I was suspicious thats all.

Thanks for the help
Haydn

[hawk2993]

Does one have to replace the crankcase O-ring? I read in the haynes' that a new one must be used

[Cammo]

Does one have to replace the crankcase O-ring? I read in the haynes' that a new one must be used

You mean the timing inspection cover o-ring? Probably not absolutely necessary if yours looks fine.

Personally though I would replace it as it could be 20+ years old and it's only a few bucks new: http://www.davidsilverspares.co.uk/part ... mber_6957/

[bizzle3]

hi
First of all thank you viper for this detailed guide it looks simple enough to do, my question is, excuse me if i missed it in previous post (ive been through all 18 pages) what to do if your valve clearances do not match up? some people have addressed this issue but nobody has said anything about the procedure to rectify this? im worried my exhaust valve are out.