I need advice on a top-end rebuild

[Larry S]

I have a Combat Wombat that has been reeded. It's a dog. My Super Rat will run circles around it. I assumed the DPO bolted on a reed intake and called it good.

I tore the engine down and was surprised to find the top end is Super Combat - piston, barrel and head. The reed intake is 32 mm, but for a regular two bolt carb, not a spigot carb. The carb on it is the 28 mm Combat Wombat.

The reason it was running bad, the piston ring had about 2 mm end cap and came out in three pieces. The barrel is .020 over with .006 piston clearance.

The easy thing to do is bore it to .030 with a new piston and ring, but I would like to put the engine back to piston port.

I would like to race the bike in the AHRMA Classic 125 class and bang handlebars with Captain Eddie. All advice from the brethren will be greatly appreciated.

Larry S

[Bullfrog]

Larry,

Hot dang that sounds like fun! I have photos around here showing how I put Harry's advice to work and converted a reeded cylinder back to piston-port - it was a CW cylinder which had been ported for reeds. It will take me a bit to find the photos and send 'em, but it can be done.

NOTE: You could end up with a pretty pipey engine (road racer reeeeealllly pipey?) with that SC cylinder converted to piston port! (In fact, based on my knowledge base from the last century . . . I just wouldn't do it.)

Ed

[dirty_rat]

If it has already been ported for reeds, there is really no way to run that cylinder any other way. The best solution would be to get a new combat cylinder, piston, etc. and return it to stock, if you want to race classic.

[olddogs]

I will bet you could find someone who would want to swap CW parts for your SC parts. Less work and better results.

[Bullfrog]

Dirty_Rat - we agree and we disagree. I agree that the "best" route here is to find a CW cylinder to work with, the engine will be wayeeee more fun to ride in Classic Class than a piston-port Super Combat. But we disagree on the concept of not being able to go back to piston-port induction with a reed modified cylinder. I was doubtful when I was told about it. But I followed instructions and successfully changed a "reed modified" CW cylinder back to piston-port induction . . . and rode it in competition for two or three seasons - including at Hodaka Days. (Hmmmm, this discussion may prompt a Resonator article.) I'm testing (also known as "playing with") a different cylinder right now, but the "JB Weld" epoxy modified cylinder WILL be going back on the engine before too long.
Ed

[Larry S]

It seems finding CW parts and putting it back to stock would be the way to go. I would be interested in a swap.

Larry S

[Larry S]

After searching part numbers, I found my cylinder head is CW and NOT a SC , so I will be keeping that. I still have a SC barrel and reed manifold to trade for a CW barrel and manifold.

Larry S

[Larry S]

I need contact information for California Hodaka. Greg - Kelly ?

Larry S

[racerclam]

Its not that big of a deal converting back to piston port. And making the engine more friendly than pipey can be improved alot by adding venturi dividers .in the carb, 3 on each side , six in all is best. I recently did a cerb for Henry Gregorich and his combat wombat while also going up to a 34mm carb and his performance was improved from off idle to wot. His testimony can be seen on my web site richstaylordporting,com. Oh what pipe are you using?

Rich

[Larry S]

Thanks Rich for your input. The pipe is the stock early CW flame thrower. I'm not really interested in putting the SC barrel back to piston port. I think its' too valuable for that. My plan for it is to bore to the next oversize with new piston and ring and use it for trading material.

What I want is a good used CW barrel. Bore it if necessary, and new piston and ring.

Larry S