Need shims bigger than 3.50.

[Randle]

Great work Zimm. You may be onto something.... The camshaft definitely have a small slot/groove in that journal.
What is the purpose of that journal? It does not run in the head like the other bearing surfaces on the camshaft. But it does slot into a recess in the camshaft cap.
Is it to prevent the camshafts floating sideways? Acting like a shoulder for left and right limit?
Strange to see why they needed to slot that part for more oil when it does not have to have a tight clearance up and down. Maybe the oil can feed down onto the shoulders better in extreme racing conditions.??
Have I just answered my own question? Ha.

The cams do not have slotted sprockets though, like in the race manual.

I measured the camshaft lobes and they do appear small compared to what the manual says. They are roughly 1mm under service limit. This may be the problem.
It appears race camshafts are slightly bigger on the cam lobe measurements, for more valve lift I guess.

So looks like possible worn camshaft lobes........but larger shim clearances should be ok as per race manual, that gives me some comfort if it comes to rebuilding with the biggest shims I can get and leaving a large clearance.
The engine sounded fine before.

[zimm]

yeh, they could be cams that were modded and had the original sprockets adjusted (PB mag did an article in 1993(?) about doing this when they ran a zxr in the 400ss championship) as its the timing thats as important as the lift/duration, inlet timing most important of all ..

but 1mm under service limit does look like they're just worn out.. maybe they were starved of oil for a bit if the engine was run with the snapped cam cap ?

be sure to warm her up thoroughly if you build back up with the larger clearances (race bike dont get ridden cold) as they do clatter a bit and wear will be increased.. fwiw, I set my old racebike up in between the two sets of clearances given as it always ran cold anyway and the clattering annoyed me (plus extra clearance is lost lift/duration)

[Randle]

Its interesting what you mention about timing. I was just about to take some pictures of how the cam timing was set on this bike. It was one tooth out, on the inlet sprocket I think.
Have you heard of that being done for a reason?
It made the numbers of links between the 2 cam sprockets marks 1 more than standard. I think it was 31 links instead of 30 between marks.
I intend to set it back to standard, unless I hear different.

[zimm]

set it standard .. 1 tooth out is miles (comparatively speaking) shouldn't have bent a valve though if it was set such that the inlet cam was retarded

generally speaking ;

advancing intake cam improves the bottom end
retarding it improves the topend

but we're only talking +- a few degree's here .. can't recall how many teeth on a cam sprocket but 1 tooth is more than that ..

[thomp1983]

if they are aftermarket kent cams they will have kaw15 stamped on the sprocket end. kent will be able to supply the shims you need either way

chris

[Randle]

Well, for now, I am having a go at just moving around the existing shims to give a broad 'loose' spread of clearances.
This will have the effect of closing up the biggest of the clearances and also making a tight exhaust clearance loose now, which is important.
However all clearances will be out of spec, but they were before anyway, and it sounded fine, so we will see how it runs.

Below is a screenshot of a Microsoft Excel spreadsheet I use to help organize the numbers - so you can see whats what.
This just shows the clearances now and the shims fitted now, not as it was originally.

[cargo]

you are obviously very competant.....................but something has occured to me


I have NEVER been able to find a set of metric feeler guages that would have small enough differences between each feeler guage to get an accurate clearance figure.

I measure using a set of imperial guages....................I'm wondering could it be that you are not getting an accurate measure and thus have your shim sizing problem.

I can measure with my imperial guages in to half a thou accuracy which I find works very well for me.

Just thinking out loud

[Randle]

Hmmm.....not sure what you mean.
The set of feeler gauges I use have enough variety of thicknesses for me to make every number I have needed.
And I take my time to find a thickness that will not fit and a thickness 0.01 below that that does fit, and write that one down as the clearance.
From memory, I think they have 0.05, 0.06, 0.08, 0.09, 0.10, 0.13, 0.15, 0.18, 0.20, 0.23, 0.25, 0.28, 0.30, 0.33
They are a very basic set. I would have thought the sizing range was common. I don't know how I got them. I must have owned them over 15 years.
I was thinking about getting some new ones tonight as the print on them is wearing out.

If you are referring to the accuracy of the feeler gauge set, well, I do not know about that. I could check with a micrometer that gets calibrated each year.

As for using imperial, I will leave that to you. How did you pick that up? Did you work in a trade that uses imperial?

[cargo]

I just lost a long winded explaination by clicking wrong button.....................bored now cant be bothered better things to do

[Randle]

I have had an engineer at work explain to me the accuracy of imperial, over the simplicity of metric.

[thomp1983]

as i said earlier kent will get you the sizes you need, they machine them themselves there just not cheap and you need to figure out why if you've got stock cams you need such big shims.

chris

[Randle]

Yes, thanks for the recommendation about Kent cams.
I had a look on Kent's web site, but could not see anything there. I realize I would have to place an order with them, and I saw another post where someone had said shims were expensive.
The lad whose bike it is told me not to spend any more money, so when the new cam chain arrived I thought I would have a go at putting it together making best use of the shims I have.
This would not be my approach if it were my bike. I would probably change the cams, if I could find some at a reasonable price, because the cams measure 1mm smaller on all of the lobes.
But the lad wants his bike back now. If he wants to take it further then maybe something could be ordered in advance.

I have just had the bike fired up for the first time in 2 weeks in order to get the carbs balanced. The engine is running nice enough, but it is a bit noisy from the top end with all those large clearances.
Plus the patch I welded on the holes in the exhaust is blowing from 1 hole amongst all my spot welds. Damn. I should be able to just add another spot weld over the area. Good result overall though.

[Randle]

Cargo..... I have looked for metric feeler gauges that will allow accurate reading of clearances and you are right, they are not common. You usually just get 0.05, 0.10, 0.15 etc....useless.

However, I have found some Draper Expert 32 Blade Metric/imperial feeler gauges that do seem to offer a comprehensive range of sizes. These should allow for accurate reading of the clearances.

Ebay number : 190587847847 £15.50 including postage.

Anyone using these?? Can anyone find a lower price??

[cargo]

For those who wish to work in metric I'm sure they will be fine...............but my dear old imperial feeler guages "borrowed" from work about 20 years ago will do me just fine.

Good to see someone with a bit of common on here

[stevi5]

Hi mate if you need larger shims let me know what size you want and I can make them for you from hardened and nitrided pins. You may have Kent cams in your bike, these will generally have adjuastable chain wheels as the inlet shaft needs to be retimed. Kent camshafts will also be stamped up KAW 15 on the end. The bearing journals in the pics have not been modified but the transverse location piece has, as shown in the race manual and is clearly a complete waste of time where as the same mod to the journals themselves is a worthwhile mod as it helps lubrication and reduces friction.