Using a Rear Head for the Front Cylinder. I know it's been discussed a few times before, but never attempted that I know of. I got my old Bridgeport mill running today and decided I would try it on a rear head I had on the shelf.

Comparison: The castings look the same, with only the Cam Chain Tensioner location being different. On the rear head, the CCT mount blank is there, but it's a rough casting.







The first thing I needed to do was machine the face flat where the gasket seals. The lucky thing was that the two opposing CCT mounts are parallel. This made it easier to mount the head on the table with the CCT blank level. I put the biggest mill in I could find and had to make a few passes to clean up the surface.





The next step was to bore the hole where the tensioner would go into. The other CCT hole measured about 0.985". I didn't have a bit that precise, but I found a 1" drill bit I could use.







I used a gasket to measure the hole spacing. I put the gasket in place and located the first hole by hand, then using the measurement I took I moved the table and drilled the second hole, followed by tapping them for the M6 bolts used.





I tried bolting on the Manual CCT I had on hand and the bolts were just a little wide. My measurement was a little off. I drilled the MCCT holes a little to 1/4" and it bolted up.





Looks to me like it's going to work. Next I'm going to make a cover for the unused CCT mount on the other side of the head.

Who wants to be the guinea pig? Anyone need a head for a front replacement?

 

There is no reason that will not work.. quite simply, all the CCT does is push against the chain guide.. You could almost just drill a hole in the non machined casting and tap it, then thread a bolt in to push against the guide... Not enough materiel thickness in the rough casting at the unfinished CCT hole to do that reliable, but you get the idea.

 

I believe there is also a hole for a fairing stay bolt that needs to be drilled, tapped and faced.

 

Thanks, I'll look it over more closely tomorrow to see if that's true. I also thought I should check that the coolant passages have the same exact design/outlets.

 

it is the same casting.
there is nothing to gain performance wise.
i also dont think the tensioner will work correctly on that
side of the chain.
i may also be mistaking.

 

You are definitely mistaking. This is the number one performance mod. There is an enormous power and torque gain to be realized when swapping your failed front head with bent valves for a functional rear head. You literally transform your thumper into a Ducati-esque V-twin. It's like painting it yellow or something. Or adding a cylinder.

 

Yes sir I believe you misunderstand on several points.

1: this is a modification of a rear head assembly so it can be used as a repair part on the front cylinder.
2: as modified and used on the front, the new cam chain tension mount location recently machined is in the stock (standard ie normal) location and will function exactly as stock.

 

doh! that's what I get for posting so early!
reading comprehension much?

 

I'm actually going to put two chain tensioners on. That way it will hold twice as much combustion pressure.

 

Yeah, but once you move it to the front, it will fail twice as fast.

 

Hells yeah. Everyone is going with two chains nowadays. Even rappers!

 

That's why he has the second one for backup.

 

...so it all evens out! Remove head from ***, check.

 

Eff that logic, I'm going the other direction then. I'm going to take my CCT's out and reduce the risk of CCT failure by 100%

 

I'll buy them.

 

Plug drain hole?

 

What about it?

Its on the "down hill" side of the head, no matter if you move the front head to rear or rear head to front.. Because you have to also rotate the head, not just move it fore or aft.

 

Just to clarify, I will NOT be putting two CCT's on....you never know who might read this and take it seriously...The CCT needs to be on the loose side of the cam chain. With the motor rotation being counter clockwise when viewed from the left side the cam chain is loose towards the rear of the motor. So when you rotate the rear head 180* to put on the front cylinder you need the opposite side CCT location.

I wasn't sure which hole you were talking about. If it was the old CCT hole, no I didn't make a block off plate for it today, got busy cleaning the shop.

 

The head has a drain hole for the spark plug well... I assume that is what NZSpokes is asking about, stating, questioning