DR 600 probs (no compression)

[G]

Well after much banging with hammers I found there was two internal bolts under the tappet covers (doh).

Got the head off to find a rather loose camchain, now with two ends.
Going to get a replacement ordered today.
I know some drive chain riveters claim to do cam chains as well, is this likely to be what I need?
Will I need to 'run in' a cam chain at all?

Also, one of the tappets has an adjuster missing (the bit that actually pushes down on the spring).

I can nab one from the spare engine in the short term, but does anyone how I should adjust it etc? Never worked with valves at all really, never mind tappets etc.

[Kickstart]

Hi

Not really sure how much good it will do running a cam chain in. Probably worth taking it easy then checking the tensioner is working (or adjust it if it is a manual tensioner).

The principle is exactly the same for a cam chain. However given that it is a single the cam chain must be at the end of the crank so I would be tempted to just use an endless chain.

The tappet is likely to just be a bolt with a lock nut (in effect). You just slacken the lock nut then turn the bolt to get the valve clearance correct then tighten up the lock nut again, then double check the clearance (and do the whole thing again as tightening the lock nut up moved the bolt ).

All the best

Keith
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[Robby]

I changed the camchain on my cb250, which was a single, and used an endless one.

Change the tensioner too.

I had the head and barrell off anyway, but basically just undo it at the top, take the side panel off and undo what you need at the bottom to get the chain out. Get the new one in and pull it up the tunnel with a bit of string. Set up the timing, and THEN put the tensioner in. Very hard (but possible) to set up the cam timing with the tensioner in place.

[G]

Cheers .

The camchain I've ordered is an endless one, but also comes with a rivvet link.

I presume setting the timing means matching up marks on appropriate gears that the chain goes around?

So, how exactly do I set up the valve clearances?

I have a manual, but it's a scanned german one.

[mr jamez]

Well if they are anything like mine Turn the engine over until the valve is fully closed (easiest to put it in top gear and push the bike or use the clutch to *jerk* the egine over) then use a feeler gauge to measure the gap between the valve stem and rocker arm, it should slide in with some resistance, kind of like a smooth stiff sliding. If it is incorrect, undo the nut on the adjustment stud, and turn the screw. I triple checked mine, as kickstart said when you tighten the locknut back up it usualy turns the adjustment stud.

On my car, I had to do this in sequence e.g. valve no 8 fully open then check and adjust valve no 1

[Robby]

Yup, pretty much as mr. jamez said. Best thing is to turn the engine on the crank bolt - make sure you turn it the right way, and take the spark plug out first so you're not fighting compression.

Measure the biggest gap between the rocker arm and top of the valve on SOHC engines as I remember, or measure the gap between the cam and the tappet with the cam lobe pointing upwards on DOHC engines, or OHC engines without rockers.

Never actually done the valves on a bike myself, did the ones on my golf though. The manual will show you pictures and tell you the clearances, which will be different for inlet and exhaust normally.

Setting the timing is normally just a case of lining up marks. Sometimes the marks are easy and obvious (mercedes car) and sometimes they are rather less obvious (honda bike). Make sure you turn the engine over a couple of times afterwards to make sure it is set up right.

[Smoto Bob]

Easy if you have another engine to look at lol and it you can turn it over by the crank then thats a good sign as well :p

What they all said
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[Guest]

There'll probably be a couple of marks on the timing plate - 't' and 'f'

't' will be when the crank is at top dead centre. Line this up and the valves should be shut. There'll be a line scribed on the cam sprocket and it'll probably line up with the flat face of the cylider head when both valves are closed. Get these two marks right and it should be ok - turn it over a couple of times (on the crank with the plug out as said) and then re-check they're still lined up.

This'll be where you check the valve clearances as well.

No need to run-in the chain, just take it easy for a few miles to make sure everything's ok as said.

[Kickstart]

Hi

As mentioned the crank and the cam should be marked. Remember not to turn the crank if the cam is in position with the valves open.

With 4 cylinder cars the rule of 5 normally applies. You adjust the inlets on one cylinder and the exhausts on another cylinder at the same time with the cylinder numbers adding up to 5.

All the best

Keith
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[G]

Well, got it all put back together.

Not massive amounts of compression.

Decided a valve was probably knackered.

Took it apart again.

The valves and piston look to be fine, so, any other ideas?

[Robby]

Measure the ring end gap to see if they are knackered.

Did you grind the valves in? Could there be a lot of shit sitting on the back of one of them.

Make sure the cam timing is spot on. Was a cunt to set up on the cb250.

Does it have a decompressor cable? Will be a cable going from somewhere near the kickstart to up at the cam(s). Disconnect the cable, and make sure the actuator inside the rocker cover isn't jammed holding a valve open.

[G]

[Robby]

Make sure you have the valve clearance adjusted proplerly if you've had the adjuster apart too.

[Kickstart]

Hi

If the head is still off, take the cam/s out. In this way the valves are closed. Then fill one of the ports with petrol and see if any leaks past into the combustion chamber, then do the other port.

Also possible that the head is cracked, the head gasket badly screwed, decompressor stuck, dead rings or the cam timing wrong.

All the best

Keith
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[G]

The clearances being the tappet adjusters?

If so, yea.

They were definetely fully out at appropriate points... I was turning over the engine with the tappet adjuster covers off and the vavles were fully closed then.

[G]

Well, think I found the problem.

The valves are not fine.
I can see some light between the exhaust ones when they should be closed.

Looks like they are quite rusty on top as well.

It would seem there is a hole on the head casing between the two exhausts . I presume this was there when I got it . You can't really see it without taking the casing off thanks to the positioning of the frame.

I presume the rust has happened while it has been sitting out in the damp.


What to do now then?
I'm thinking I might try and find a new head, complete, as I don't really feel confident playing with valves (and don't have any of the tools suggested in the manual). I was also wondering about just giving the head to a garage and saying 'sort it'; the local good garage probably doesn't have the 6 week waiting lists it has in summer.

[Kickstart]

Hi

Where can you see the light?

Only real tools you need are a valve spring compressor (someone must have one local to you, if not £35 from Halfords I think) and a bit of wood with a sucker on the end to grind the valves in.

All the best

Keith
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[Robby]

Halfords have a cheap laser valve spring compressor for about 20 quid - tried it on the merc springs and the tool broke before the springs began to compress.

Then the little stick keith mentioned costs 2 quid, and the paste to grind them in costs another 3 quid. All in halfords.

[Hex]

Drill and grinding paste, saves HOURS on lapping valves in.

Put the valve stem in the drill and make sure theres paste on the valve and turn on the drill. Then simply pull the valve to the seat and away and to and away etc etc etc till the majority of the lapping is done. Then finish by hand, ensuring there is an unbroken ring around the valve seat where it has been lapped in.
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[G]

I can see light where the valve should be sealing in the cylinder head.

Remember, one head's got a big hole in it. Though I'll consider getting one sans-valves if I can't find a complete one.

[Smoto Bob]

[G]

I'm not talking the head as in the bit that actually seals the cylinder.

But the hole is in the section of casing that includes the head.

On the outside, between the two exhaust ports, there is another hole, opening the engine internals to the 'outisde'... not sure how it's happnened.
Can't really see it while the casing is on the engine (in the bike) because of the positioning of the frame etc.
Did try and take a pic yesterday, but my camera battery's dead

You can see the side of the valve springs through this hole, so it's moderately substantial (about 2cm accross by 1cm high maybe); enough that I could get my finger in.

[Smoto Bob]

so i guessing its not actually in the rocker cover lol

And its not in the head and downward so you can see into the combustion chamber

Then its not that bad lol, some high temp araldight

Like here but on the front i am guessing, only seals it from outside world doesnt realy do anything high teck didnt loads of oil come out lol
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[G]

Yea, as you describe. There was a bit of oil around the area when I first looked, but I couldn't see where it was coming from, as it had had a recent rebuild I was thinking it that the head bolts may need re-torquing.
I think the hole's going to be a bit to big for just araldite; a bit of metal welded accross would probably do it, but it may well be cheaper to just get a new one.

It obviosuly /was/ running ok before, so can't be that bad in that respect.

[Hex]

Bit of epoxy metal... bodgery at its best mate.
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