Valve Clearances HELP

[TSM]

I am following the haynes manual to check the valve clearances on my bike.

I did the front as per the book saying that the lobes should point away from each other and got some intresting things.
My intake and exhaust are off. They are under the specified amount. I was getting readings of .05 for the intakes and .10 for the exhaust.

Now the rear became odd.
I did not matter that the alignment was on R the lobes would never point away from eachother like on the front cylinder. They would point up. Is this normal? The piston is at the top of its stroke though and the valves are all closed.
I also got readings similer to the front.

Seems like the shims are too big on my bike. Would this be because the valves are worn down?

Im not putting the bike back together in case the shims do need to be changed.

<table border="1"><tr><td></td><td colspan="2" align="center">Front</td><td colspan="2" align="center">Rear</td></tr><tr align="center"><td></td><td>Exhaust</td><td>Intake</td><td>Intake</td><td>Exhaust</td></tr><tr align="center"><td>Right</td><td>0.15</td><td>0.10</td><td>0.10</td><td>0.15</td></tr><tr align="center"><td>Left</td><td>0.15</td><td>0.10</td><td>0.10</td><td>0.15</td></tr></table>

Basically most folks think valves "loosen" since in the old days, they did, so the general though is that they loosen. The old tappet with a nut and screw could back out or get worn, which increased clearance. Now with your SV you have a shim riding on a valve stem under a "bucket" that the cam rides on. In this arrangement they generally tighten as the valve and seat wear. Usually the first adjustment or two will be all you need, and from then on it is usually a check, but we are talking 30,000 miles.

I hope this helps, it might be in Texan, so may sound odd..........

[Sid Squid]

Are you sure you've got the cams in the right spot?

I'd forget about the marks on the crank and just turn the engine until the cam lobe in question is pointing away from the bucket completely, check it then. Anywhere, (in reason), on the base circle will be fine, and - if you have - you wouldn't be the first to get them confused.

I think you have my number, call me if in doubt.

[TSM]

Ok, yep they were pointing away from the bucket, phew.

Ok From thoes values above it looks like the exhaust shims need to be changed.

Is it far enough out that its now damaging the engine.

From what i thought, if the value is less than specified the valves are wearing into the head and therefore the need to change the shims is vital. I was just thinking about it. Not sure if its correct though.

Originally Posted by TSM

Ok, yep they were pointing away from the bucket, phew.

Ok From thoes values above it looks like the exhaust shims need to be changed.

Is it far enough out that its now damaging the engine.

From what i thought, if the value is less than specified the valves are wearing into the head and therefore the need to change the shims is vital. I was just thinking about it. Not sure if its correct though.

Correct valve clearances are required for several reasons. First the valve head can only dissapate heat when it is closed. If the valve does not close properly or for long enough, then it can overheat. Long term overheating of a valve can lead to a valve breaking up and destroying your engine. Secondly, as your engine heats up so the components expand, clearances get even smaller when the engine is at normal operating temperature. This can result in the valve not completely closing as the clearance was too small to allow for a hot engine. This leads to loss of power caused by loss of compression. This also means combustion can pass over the valves into the inlet manifold/throttle body or out into the exhaust. Not where it's supposed to be!

Having been a car mechanic for several years I came across this many times. Remove the air filter and you should hear a smooth sucking noise. If combustion is getting past the inlet valve it sounds more like an exhaust! Howver it is usually quite bad by the point you can actually hear it.

I can't advise you about tolerances of the SV650 engine, but I can warn you about the dangers of not doing anything.

Kind regards
Tim

hi TSM,

you're right about the clearance getting tighter with age.

you're also right about the difference between the checking position of the lobes on the front cylinder and those on the back:

on one cylinder, the cam lobes should point outwards , while on the other they should point inwards, i don't know which cylinder is which. It's all in the manual though. I got confused the first time too. i used to look at the peep hole for the F/T and R/T marks, but now, i do it just by sight, i just make sure the lobes are perfectly symmetrical placed (when you look to the engine head) and check 'em like that.

Normally, there's also some marks on the cam gears which should align with the cylinder head.

and for these engines there's a basic rule: too loose is better than too tight, so change those shims

[TSM]

Originally Posted by wreckah

and for these engines there's a basic rule: too loose is better than too tight, so change those shims

i thought that. Correct me if i am wrong. Too tight then will start wearing out the valve heads (damage), too loose then there is possably buildup on the valves.

How many miles has your SV done?

My K3 has knocked up 30,000 miles and I was going to take it in to have this specifically done since routine stuff like oil, air and brakes I do myself.

Bloke on the phone was surprised, said he hadn't seen a K3 with more then 15,000 on it and couldn't say if it was likely to definetly need new shims.

Apparently it'd be £120 to check the clearances and more if they need sorting.

I'm reluctant to tackle this myself as I have no garage/drive and don't want to risk foreign bodies getting inside the engine.

Anyone here definetly had to have the shims changed? What mileage was this done?

[TSM]

K2 has had a hard life, 21k.

I still dont have a definate answer on changing the shims, so the bike is still in peices.

[Sid Squid]

Originally Posted by TSM

I still dont have a definate answer on changing the shims.

Yes you do. The clearances are tight, (if you're not sure if you're measuring them right that's different thing), therefore they clearly need attention.

Assuming that the measurements you have made are correct, I'd be changing all of the shims, the inlet clearance is 0.1mm minimum, which all of yours are at, in the circumstances I'd open them one shim so that they're somewhere near the middle of their allowable range, this means that it'll likley be the longest period 'til they need changing again.

However, all of your measurements are suspiciously round numbers, and your bike has only 20,000 on it, it is unusual to say the least that there would need to be much adjustment needed at that small mileage, note I say unusual - not impossible.

Therefore I think you need to get a second opinion before doing anything more.