Tl 125s alternative camshaft and head

[sherpagorri]

Hi, I have to change the head and camshaft of my old tl125s, but I can

[craig10]

Hi, I have to change the head and camshaft of my old tl125s, but I can´t found those spares. I´m thinking in other honda models parts to fit my honda. Any suggestion?. Thanks in advance.

Any of the heads with cams from the overhead cam models will fit ie CB, XL, SL, CT.

The cam timing is a bit different on the TL for better bottom end power but I'm not sure how much difference it would make.

The one pc head cams have different journal sizes to the 2 pc head cams so are not interchangeable, but a 2pc head cam will fit in any 2pc head, and a 1pc head cam will fit in any one pc head.

The early CB one piece heads have smaller valves than the later 2 piece head, not sure about the TL. The early one pc XL heads have the same size valves as the later XL and CB 2 pc heads.

This is a good TL site http://www.kaila.net/tl125/tl125faq/index.html

Is the 125s a 2-piece head 124cc engine?

Edited December 14, 2011 by craig10

[sherpagorri]

Yes, is the 124cc and two piece head. Is a free movement in the camshaft and is very difficult to do the ignition timming well. Maybe would be a good idea to try to make a bearing conversion? is it possible?

Thank you very much.

[craig10]

Yes it's possible, it depends if you have access to machining equipment and how bad the wear is in the cylinder head at the small end of the camshaft. If this end is badly worn it would need to be machined to take a needle roller bearing to do a good repair.

There are some articles on the Thumpertalk forums, dealing with fitting a bearing behind the advance/retard mechanism to stop the camshaft moving around.

First of all, you'll have to register on the Thumpertalk forums here http://www.thumpertalk.com/forum/ and sign-in so that you will see the pictures

This is an easy way of doing it, no machining required. A good, cheap solution which would be fine on a trials engine. http://www.thumpertalk.com/forum/showthread.php?t=819229&highlight=

This is how I did one with a lot of machining work http://www.thumpertalk.com/forum/showthread.php?t=940690&highlight=

If you're not seeing the pictures, do a search for user name craig10, you will see the posts there.

If you still can't see the pictures, PM me your email address and I'll send you the posts as Word documents.

I checked online, the TL 2 piece head has small valves and a dished low compression piston. If you used a head from another model you'd probably need to get a different piston as the compression ratio would be too low because the other heads have a larger combustion chamber. The only other head that would suit your TL piston would be a CB or SL one piece head.

I am about to start a bearing conversion on a 2 piece head with a needle roller at one end and a bearing at the other.

Edited December 14, 2011 by craig10

[sherpagorri]

Thanks again, craig10. I have seen the thumpertalk forum(and photos), and the modification to install the bearing behind the advance mechanism.I think that is a very good idea but maybe not definitive. I have serious problems now to put the ignition timming ok, so i

[craig10]

No hay de que Sherpagorri, the mod will definitely help stop the points cam moving around, you may find that a very small amount of oil seeps through but it shouldn't be a problem on a trials bike, it might be worth putting a small amount of sealant on the outer and inner race of the bearing.

Let us know how you get on,

Craig

Edited December 15, 2011 by craig10