XL 250 head repair

[farmer58za]

Hi All.
I would like to repair the cylinder head of a 1976 Honda XL250. Both the camshaft and bearing journals in the head are worn.

Is there a way to:
1. Build up the camshaft at the bearing surfaces?
2. Re-line or line bore the head journals, or do a roller bearing conversion?

They must have sold hundreds of thousands of XL250s. I reckon someone must have worked this out already.


Thanks in advance
David

[TT5 Matt]

some places used to do that type of work back in the day and can still do your cam/rocker arms by hard faceing them but with so many low kay bikes being wrecked why not find replacement used parts as could be way cheaper in the long run,do a quick search on ebay

[farmer58za]

Matt

There's ebay stuff available, but there's always the risk that it too is er....stuffed

I did get one question answered in that Megacycle make a Roller bearing cam kit:

http://www.megacyclecams.com/catalog/Page23.pdf

I just need to find out if they supply full lineboring instructions with the kit. We have a couple of top-notch engineering shops here who should be able to do the boring.

Regards
David

[MX?]

It's hard to get line boring done in Oz....don't know why???
I had the Megacyle roller cam put in mine, but I ended up buying an old head in the US and had it shipped straight to XLint Performance to have it bored for the cam, and the valves seated. I reckon it worked out cheaper than shipping the cam out here and trying to get the boring done.

[farmer58za]

Ok, buying a 2nd hand head and getting the machine work done there is an option.
All depends on what the machine shop says.....

What's the best Megacycle cam and setup for a bit more zip than stock?
I'm thinking of a 00 grind, stock valve train, a bit of porting in the head, 290cc big bore kit and a 32mm round slide Mikuni VM carb.
What exhaust pipe dia should I use?



Regards
David

[Slakewell]

Tip 1
When buying a second hand bike or engine look for signs of silastic if you see any do not buy. People used to silastic on the rocker covers and this squeezes into the tiny oil passage behind the cam hence wrecking the cam surfaces.

I did make a tool years ago for line boring them and fitting sinterd bronze bushes so it can be done. I do have the tools for repairing the spark plug crack still.

[MX?]

Have you had a look around XLint? Lots of info there.
Click here
You may also want to consider Hard Faced rockers as well, depending on which cam you get?
I'd imagine you could also just machine up some form of bush for a simple repair job to the bearing surfaces?
This was my little box of goodies as it arrived. 

[Swiss]

Go with the 12740 cam minimum.  Everything that you do to the XL250/350 engines just makes more power everywhere.  Heck, you can use the 12790 cam for riding trails if you want to!  HA!HA!  I have for years, but everything else in the engine is changed also.  Got new Beehive design valve springs available now also.  Modern design, better than any of the older dual spring kits.  Work with any of the cams from mild all the way to maxed out!

Swiss