engine overhaul

A small scratch might be insignificant, but I would recommend that you take the complete head with the cam holders and cams to a engine machining shop. They'll be able to measure the clearances and to tell if the head needs to be repaired or changed.

Cylinder head bearing surfaces can be filled up by welding and then regrounded to correct size. Obviously this is a specialist job and it might cost quite a lot. A second hand replacement could be cheaper option if you can find one.

FYI FWIW

http://www.cylinderheadshop.co.uk/

http://www.motorcycl...co.uk/index.htm

dunno if any good, as you're in Sweden!
From what I remember of the custom scene over there you gotta have some people near you who could probably do the required work, in their garage, for a beer, and to a higher standard than most professional machine shops over here

(bet I trod on some toes with that comment )

Managed to get some pics online
It's not discoloured (as it might show ont the pic) so I guess it didn't get hot.


(is there any better place to put some pics online?

Hmm don't look too bad from pics but then its never the same as having it there in the flesh!
Others may disagree but from photoI'd check clearance with plastigauge and if all good rebuild as is (once valves done etc of course!)
Tho' check all oil ways clear first.
Honda CM / CB125 twins were notorious for trashing heads and cams like that

Actually I've just had better look at pics, and theres a spot on RHS of bearing surface that looks dodgy, if it aint a shadow it loks like there's a chunk outta bearing surface, in which case ignore everything I've written above!!!

Edited by jht, 13 February 2007 - 10:07 pm.

Unfortunately Shamrock, I think the damaged head bearing surface will cause you further problems in the future - it is quite badly marked.
.........and without putting a downer on things even more - I'd be concerned about how the crankshaft and big end bearings are if the head is damaged that way.......

Had another look on the head.
The spot is i bit of material sitting there left by the shaft after it took away material elsewhere.
I could remove it with my fingernail.
The damage is only appearent on one shaft support, all the other ones look fine.
I did notice that the bolt for the head cover is screwed in on top of the bearing, so if something falls in that hole
ends up directly into the bearing (shaft-support). Not a smart construction.

It don't look that bad to me

when I did my valves at 58K, the inlet cam cap & journal on the LHS cylinder was quite badly damaged.
As it is not easily repairable I just cleaned it up best I could
It looked like it had been starved of oil. Metal had been displaced to such a degree that it was stopping the bucket from being lifted out of the head to get at the shim, and I had to cut metal of with stanley knife in order to get the bucket out.
The cam cap was also distorted so much, that when I tigthend it back down it was was locking solid onto the cam
In the end I put some wet & dry round a socket of a suitable size and cleaned / opened up the cam cap, and cam journal in the head, so that the cam would rotate when the cam cap was torqued dowm
It lasted until I crashed it at 74K with no issues

I bought a set of cams and cam caps second hand off ebay, as the cam caps aren't available seperatley from Yamaha (they come as a set with the head) to replace my badly distorted cam cap.
This second hand set were showing signs of the same problem although nowhere near as bad
Therefore I can only conclude, now seeing yours, that it is a problem on this engine.

As mine was much worse than yours looks, I'd put it back together with no worries. Jsut make sure the cam will rotate freely when the cam caps are torqued down.

Edited by GuyGraham, 14 February 2007 - 12:52 pm.

Maybe on the mkII's. I havent seen anything like that on the 4 mkI heads I have looked at.

Cylinder head and cam caps are machined as a pair at the factory. That's why Yamaha won't sell the caps separately, and they should never be mixed with another head.



Shamrock since you live in Sweden perhaps you should give Spinning Wheel a call. They had a few TDM's in bits around two years ago, I bought a swing arm from them. As Dandy said there could be even more serious damage at the lower end ... Maybe it would be smarter to ride it as long as it lasts and then find a replacement engine?

Yeah I know but as there was quite significant damage anyway any slight differences in machined dia's etc wouldn't have mattered.
If I didn't know better I'd have sworn that small metal had been removed from the clamp face of the cam cap, it was that distorted which was why is was allowing the the cam cap to clamp down on to the cam when it was tightened up.
The oil gallery hole in the cam journal in the head was nearly blocked from smeared AL.


anyway, my point was that mine was much much worse than this, yet it lasted another 16K miles without any issues

As a side note, I always rememebr when I started biking how oldish 4 strokes always have cam rattle from worn cylinders (partly due to crap oil of the early eighties) but they keep going even with cam rattle around with excessive journal clearance

Just my $0.02 worth
I'd have no problem putting it back together as is, nowing what I know now.
Just make sure the oil hole is clear

try http://photobucket.com

Ok. My experience was from a friends early 90ies GSXR1100. We tried fitting cam caps from a different engine (same year) but the bearing surfaces were off by 0.4mm !

Hi,

Finally after almost two months I got the head, cylinder and pistons back. (lack of manpower they said)
Total cost was about 350 euro's where they did a complete overhaul on the head and measured and honed the cylinders.
1 cylinder was a bit funny, taper was the other way around being below limit at the lower end of the barrel, but total taper was within limits.
Valve clearance was way off so head to order new shims, for inlet shaft only.
The pistons where refit with new rings.
Today I put everything together being very thorough and clean.
Everything seemed to fit properly besides the T mark on the flywheel was a bit ahead of the mark on the cover if the camshafts were lined up.
The difference I noticed during removal as well and appears to be about half a tooth on one of the the camshaft sprockets, which is impossible to get rid off.
Anyway, rotating the driveshaft slowly everything appeared normal.
Took the bike out having full confidence everything was fine and started the engine, it started on the first attemt but after 2 seconds dropped
in rpm and I noticed cooling fluid was spraying from the exhasut pipe at the cylinder.
You can imagine how I felt, just not crying yet.
First thought was I f#¤¤#ed up with the top gasked or maybe even forgotten to tighten the nuts on the right. (it was the right cylinder pumping the fluid out)
Within the hour had the thing apart again and retorqued the head but everything was ok.
Maybe the gasked failed, so continued to take the top off but the gasked appeared ok. The was quite some fluid in the cylinder though so it was not a small leak.
I guess the only thing left to do is to have the head and cylinderblock grind again. They did do the top but didn't do the cylinderblock.
I assume they would have told be if this was necessary.
Can this cause such a leak?
The other question was if I can reuse the gaskets or has anyone tried this? The engine ran less then a minute and the gasked (top) appears fine and you can still feel the indentations?

Thanks!

I'm sure I remember something about the head gasked supposed to be good for a couple of uses

I sure hope so cause these things cost an arm and a leg. Here in Sweden about 110 euro for foot and top gasket.

Its not leaking from where the coolant exits the cylinder via a small pipe to the water pump is it?

which pipe is that, the one on top of the valve cover?
Tomorrow I'll give it another try paying special attention to clean mating surfaces and proper torque. (using the 'old' gaskets)

where the coolant pipe goes into the cylinder head its held in by a collar with a Allen screw there is a O ring to seal that for coolant leakage ,If you take cam cover off you will notice that there is a gasket underneath where the pipe enters ,this gasket feeds the coolant in to the block if that gasket is worn prob get leak into inlet valves and pistons.
though in the service manual it says to be replaced each time cover is taken off it is not listed in the 2000 parts list PDF on JBX's web site.Its are not even listed on the parts list at Fowlers of Bristol cause i asked for one. im going to seal mine with gasket sealant under the old one.

Edited by aytcat1, 07 May 2007 - 07:18 am.

isn't that seal to prevent fluid from coming out?

Nah - its on the front of the barrels, on the RH side