XS650 engine rattle - help needed please

**Pussy** · 29th May 2007, 19:42

Hey Surfer, I just did some searching on the web (googled), and found some good info to refresh my memory. Try 650wiki.org, found the valve clearances as: inlet, 0.06mm(0.0024"), and exhaust, 0.15mm(0.006"). Hope this helps

**surfer** · 30th May 2007, 09:18

Originally Posted by Pussy

Hey Surfer, I just did some searching on the web (googled), and found some good info to refresh my memory. Try 650wiki.org, found the valve clearances as: inlet, 0.06mm(0.0024"), and exhaust, 0.15mm(0.006"). Hope this helps

Cheers for this, it is 1981 SH model. Never looked at this particular site before.

**surfer** · 15th June 2007, 15:38

The slight rattle sound coming from the cylinders has got worse and is now a chig ching ching ching sound. Like hitting a hammer against a fire extinguisher. Really lound, more than the exhaust note which is a loud exhaust. I reckon I only did 300km to go from rattle to ching ching. This was after a new cam chain went in.

I have checked the cam chain tension and made sure it is set to the manual specs.

I have reset the valve clearances as these were shut tight at TDC on right hand side piston which is the noisy one and too big on the inlet other side. The exhaust left side was ok. The clearances on the right hand side seem to have been set ok but before TDC.

Compression test is way down at 110 one side and 60 the noisy side. Engine ratio is 8:1 so I reckon it should be 15 to 20 times this, up around 140/150 which it was before the ching ching ching arrived.

I have dumped the oil and found no plastic so I don't think it is the front cam chain guard disintegrating. Also I found metal shavings and flakes of metal stuck on the oil magnetic drain plugs, about almost half a level teaspoonful (for the cooks out there)...not good sign I'm thinking.

Started it again and still got the ching ching ching sound.

I am suspecting the oil has been contaminated by petrol leaking through the carbs. The oil feels a bit thin. I reckon I have shagged the pistons.

I reckon engine tear down time, any thoughts?

**tri boy** · 15th June 2007, 15:47

Compression at 110/60. Noises.
Pull it down. Check top end, but also pay close inspection to rods and big end clearance. Good luck.

**Paul in NZ** · 15th June 2007, 16:34

If it runs a filter you 'might' be OK but frankly - I'd pull it right down NOW before it spits out a rod or something expensive (well MORE expensive)

**surfer** · 15th June 2007, 18:05

Cheers for the replies tri boy and Paul in NZ. Will be doing just that.

**Pussy** · 15th June 2007, 18:12

Pull down time, I'm afraid, Surfer. The crank, as no doubt you know, is a built up one, can be repaired a bit more easily than a plain crank, although best for your arse pocket if it doesn't have to be. The oil filters on XS650 motors will only filter out stone sized objects. Check the bottom strainer in the sump, it will be knackered. Top end overhaul isn't too bad to do on the 650. Sing out if I can be of any assistance

**surfer** · 15th June 2007, 18:42

Originally Posted by Pussy

Pull down time, I'm afraid, Surfer. The crank, as no doubt you know, is a built up one, can be repaired a bit more easily than a plain crank, although best for your arse pocket if it doesn't have to be. The oil filters on XS650 motors will only filter out stone sized objects. Check the bottom strainer in the sump, it will be knackered. Top end overhaul isn't too bad to do on the 650. Sing out if I can be of any assistance

Cheers for this dude, will do.

**Rhino** · 15th June 2007, 20:04

As Tri boy has said, pull it down now. They are quite simple to work on. I agree with Motu's comments that they are "overengineered" It takes a fair amount of damage for them to actually grind to a halt.

Your mention of metal filings on the sump plug is worrying. Pay close attention to rings, main bearings, big ends, small ends and cam bearings.

As Pussy has said, the crank can be repaired, but hopefully that isn't necessary.

**Kickaha** · 16th June 2007, 08:08

Have you rechecked the cam timing? could be a piston to valve clearance issuse

**surfer** · 20th November 2007, 22:22

Hello there,

Finally got to pulling the engine apart and got as far as the pistons. I reckon the loud knocking sound coming from the engine was caused by the valves hitting the top of the piston. Attached is a picture of part of the top of the right hand piston. Left hand side piston is fine.

There is no scuffing on the inside of the cylinder. Although there is a groove at about two thirds of the way down that looks like it was carved in there. It runs half way around the cylinder. I think it is lower than where the piston goes.

There is no upward movement from the pistons. That is there is no slack, I can't move them up or down without turning the crank round. So I don't think a big end or small end bearing has gone.

My questions are...

1. Is the groove in the cylinder anything to worry about?

2. Should I take the pistons out and check connecting rod tolerances anyway? And if I do this is it worth sticking new piston rings in?

3. Can I still use this piston or do I need to get another one? As you can see from the picture there is a shiny metal indentation where the valve has bashed it.

4. What should I clean the piston with to get rid of carbon build up and does this really make a difference to the engine?

5. What would cause the valve to bash the top of the piston? Timing out/valve clearance wrong? Bent valve?

Cheers for your help

**xwhatsit** · 21st November 2007, 00:39

Can't really tell wtf that picture is to be honest, but if the piston just has a little dent in the top of it... I've been using a piston in my CB with a pair of dents from exhaust valves for ~10,000kms now.

As for pulling the barrel off and checking the bottom end condition, that's not really that much more work, even for a complete n00b like me (and only one gasket). Getting the piston and rings back in wasn't too bad, but might be a pain in the tit with two cylinders.

**Warr** · 21st November 2007, 01:14

Are you convinced that the valve/s are hitting the piston?
Can be measures by putting plasterceen ?? if you can still get it.
Make a ball of the stuff up and stick it to the valve / or the piston and assemble and turn it over a couple of times. Cant remember what I was recommended when I was doing it in a 351 Clevedon, but something like 1mm clearance from memory.

**surfer** · 21st November 2007, 10:26

Originally Posted by xerxesdaphat

Can't really tell wtf that picture is to be honest, but if the piston just has a little dent in the top of it... I've been using a piston in my CB with a pair of dents from exhaust valves for ~10,000kms now.

As for pulling the barrel off and checking the bottom end condition, that's not really that much more work, even for a complete n00b like me (and only one gasket). Getting the piston and rings back in wasn't too bad, but might be a pain in the tit with two cylinders.

Hope this clarifies what the picture shows.

The picture is a close up of the piston. What you are looking at is the top of the piston inside the cylinder. The darker patch is the indent where the valve goes (normal) and the shiny white bit (not normal) is where the valve has been hitting the top of the piston. There is a smaller dent on the other side of the same piston where the other valve has been bashing at the top of the piston as well.

I will pull the piston out and inspect the bottom end. Cheers.

Originally Posted by Warr

Are you convinced that the valve/s are hitting the piston?
Can be measures by putting plasterceen ?? if you can still get it.
Make a ball of the stuff up and stick it to the valve / or the piston and assemble and turn it over a couple of times. Cant remember what I was recommended when I was doing it in a 351 Clevedon, but something like 1mm clearance from memory.

Yep, pretty sure the piston is hitting the valves. But not sure why.

**psyguy** · 21st November 2007, 16:25

hi there surfer
by no means an expert, i'll speak from what i learnt from others while rebuilding my gs