Valve Clearance Guide

[phongus]

Uhh...so I tried checking my valve clearances and stupid me I bought a feeler gauge in inches...it does have the metric equivalent for it, but lucky for me, the manual also had the clearances in inches.

Anyways opened up the rocker cover and with spark plugs removed, I turned the engine via the rear wheel while in gear (can't get the timing cover off and kind of stripped the bolt head on it ). I lined the marker on the camshaft on the right hand side to the edge marker on the rocker assembly and making sure the piston is at TDC. I double checked with the lobes on the camshaft so that the pointy bit of the lobe wasn't touching the rocker/pushing on the rocker. (I assume that's when the intake and exhaust valves are closed since the stems would not be acted upon by the rocker arm).

Using the assumption above I went ahead with squeezing the feeler gauges between the shim and rocker arm and to my surprise I got the following results. (I have not measured the shims because I don't have a micrometer...and my feeler gauge didn't go lower than 0.002"...which is equivalent to 0.051mm). The image has top numbers in inches and bottom in millimeters.



Can someone please tell me with having less than the required clearance on my intake shims, could something bad have happened? I also assume this also causes major issues with cold starts and idling and make the bike run like a bag of shit? (pardon my language).

I will borrow a mates micrometer and measure the shims since they don't have anything stamped on them. I think I might be able to swap the exhaust with the intake shims and create the proper clearances, but I will double check once I check the shim sizes.

Also...it's a pain in the ass to put the shims back in.

Looks like I'm going to have a tedious task in fixing this before race day.

[CMSMJ1]

It jsut doesn't look right to me.. You need some proper feeler gauges as the clearance of 0.051mm - that is crazy tight.

When you racing? it can be done, all of it, in a few hours as long as you have the right gear and some help, so don't worry too much!

[phongus]

It jsut doesn't look right to me.. You need some proper feeler gauges as the clearance of 0.051mm - that is crazy tight.

When you racing? it can be done, all of it, in a few hours as long as you have the right gear and some help, so don't worry too much!

Yeah it is crazy tight, but I had a look at it and there doesn't seem to be any clearance at all...seems very very tight. When I took one of the shims out, it was hard to push the rocker across to remove it compared to the exhaust side. Had to use a screwdriver and lever the rocker across. When I put the shim back in, I had to push the shim down using a flat head screw driver so that the rocker could slide over it

I will get myself a metric feeler gauge...but I doubt anything thicker than a 0.051mm will fit.

Weird thing is though, the bike ran okay when I was racing it before...but had heaps of trouble during cold starts and pretty random idle.

Racing is not for a while, it's just the money associated to get back to racing ...funds are low, so making do with what I got is priority.

Thanks for you help CMSMJ1.

[phongus]

So I got the chance to borrow a fellow racers micrometer and measured all the shims today.

I found that 7 of the 8 intake rockers were putting some pressure on the shims. I had to use a screw driver to lever the rocker inwards to remove the shims, compared to using my fingers with the exhaust rockers. When putting it back in, I had to help the rocker on by pushing down on the shim while sliding the rocker across.

Would it be safe to say that there is no clearance between the shim and rocker? I know it seems extreme, but that's what I found...and I am certain I have done the clearance check correctly. Would having them at zero clearance cause a lot of issue? If so, what damages can happen? I mean I have used it on the track the way it is...so can't be too bad right?

Also, the front exhaust shims are a pain in the arse to put back in. "Oh gravity, thou art a heatless bitch".

Anyways after a couple of hours of fiddling and cursing, the shim sizes are as followed. The red numbers are the calculated shim size required for an intake clearance of 0.15mm and exhaust clearance of 0.24mm.



If someone has a spare few minutes, could you please confirm my calculations are correct...it is nearly 2am so I am feeling a little tired. Calculations were made with the assumption that the current clearance is 0.05mm for the 7 intake valves. If we assume that the clearance is close to 0 for the 7 intake valves, then the calculated shim sizes above should be reduced by 0.05mm.

I think there are some shims I can move around to save me money...but I will think of the worst case scenario and put a budget for 12 shims.

Hopefully I can get this sorted...not used to solid lifters...only worked on cars with hydraulic lifters. Great learning experience I must say :D.

Thank you all in advance :).

Regards
Phong

[Neosophist]

Valves might not close at the correct time causing loss of power and the valve to run hotter than usual

As the valves wear more and stay open longer they might hit the piston, of drop off and wreck the bores and piston.

Get the set right, I wouldnt' even run the motor when there that bad.

[phongus]

Thanks Neo, I will be replacing them as soon as I get funds, but I am surprise that the bike manage to run about 10 race days without any noticeable damage (beside the crash) to the engine. So hopefully this will help my starting issue as well as making the bike run smoother.

EDIT: I have been looking at buying a shim kit online...but I am not certain on the shim diamater, are they 7.48mm?

[Neosophist]

yes they are 7.48

Probably best to buy them individually.. don't need millions.

Speak to Rick-O on here... here used to do a shim-exchange where you can send him the ones you no longer need and swap them for other sizes..

[phongus]

yes they are 7.48

Probably best to buy them individually.. don't need millions.

Speak to Rick-O on here... here used to do a shim-exchange where you can send him the ones you no longer need and swap them for other sizes..

Thanks Neosophist.

I got quotes for individual shims but it ended up close to AUS$80 for the 12. I have contacted Rick and the prices were about the same as the local shops.

I ended up buying a kit from the states (HotCams) and with the aussie dollar being strong I got a full kit for AUS$115 delivered :). So with 3 shims per size ranging from 1.20 - 3.50 at 0.05 increments, I can replace the shims whenever needed. Will also come in handy if I decide to get a VFR/RVF road bike too :)

[phongus]

Time for an update since I finally managed to finish the valve clearance drama after my shim kit arrived. Since the kit only came in 0.05mm increments, it was hard to aim for anything specific, so as long as I had it in tolerance, I was quiet happy.

I bought myself another set of feeler gauges...this time in metric units :D. Rechecked all the clearances prior to replacing shims just to make sure I wasn't way off last time.

After spending an hour or two fiddling with the annoying little buggers, I got the following result.



You will be shocked if you compared my old clearances to my current one. From my findings, assuming I am correct in my calculations, 7 of my intake valves didn't even have any clearances...in fact, they were slightly opened at TDC. I assume the valves wouldn't have been sticking open too far for the piston to hit it...since I haven't blown the engine up yet.

I am happy to have fixed this myself and learned something new and useful for the future. Lets just hope the bike starts without blowing up between my legs. Still surprised the bike ran with such bad clearances (granted it was a pain in the ass to start, which I hope is now fixed) without issue...even at red line .

Regards
Phong

[CMSMJ1]

Good skills Phongus

It is a good feeling and you know your bike will love you for it.