My Next Project Is About To Begin!!

[ricky racer]

Just thought I'd post a couple of pic's of my next project, a 1966 Bultaco Metralla. I sold my '63 Cub last Thursday and made a couple of bucks and picked up this motorcycle lift to make it easier to work on the Bultaco as well as my other motorcycles.
I was surprised to see the Bultaco had spark when I checked. Might even run if I put some fresh gas in it. But that will come soon enough. I need to go over the whole thing, piece by piece until I have the confidence that everything is as it should be. Just like restoring an old Cub, you need to take it apart piece by piece and give each piece the attention it needs to be correct before reinstalling. This project should be fun.

[Barnyard]

Nice looking project. Rosie has said "No" to me ever having another bike. And here I always thought I was in charge.

[Jackman]

Yes that looks like a fun project and the lift and the nice shop you have makes these kinda things more fun . Just curious are you going to rebiuld the crank and new seals? seems to be sevral thoughts on two stroke bikes that have sat for awhile the most popular is always do a crank rebuild yet some just wing it and have good results.

On my two bikes the Kawasaki S3 is just getting a fresh top end and crossed fingers, I hope and think it will work I really want to ride this year.. On my Kawasaki H1 I am going to do a crank rebuild since it will be a long term project it costly not too sure nessasary but thats the plan..

[Marion(57 Loboy)]

I spy a sturdy ol' Craftsman "100" Tablesaw in the 1st picture!

[ricky racer]

I spy a sturdy ol' Craftsman "100" Tablesaw in the 1st picture!

You've got a good eye there Marion.

[ricky racer]

Just curious are you going to rebiuld the crank and new seals? seems to be sevral thoughts on two stroke bikes that have sat for awhile the most popular is always do a crank rebuild yet some just wing it and have good results.

On my two bikes the Kawasaki S3 is just getting a fresh top end and crossed fingers, I hope and think it will work I really want to ride this year.. On my Kawasaki H1 I am going to do a crank rebuild since it will be a long term project it costly not too sure nessasary but thats the plan..

I don't know yet just how I will proceed. The bike has not run since the mid 70's. At some point I'll be pulling the motor down. I'll probably see how things look when I get it apart.

One thing that I have to deal with is a couple of bent cooling fins on the cylinder. I want to bend them back but I'm not sure the best way to proceed.





What I am thinking of is slipping a snug fitting spacer in between the bent fin and the fin above it, just inboard of the bend. Then using a small pry bar, slowly and carefully, pry the fin back into position. My question is do I do that with or without putting heat on the fin?? I'm not looking for guesses but possibly some practical experience.
This will be easier to do this before I pull the motor out of the frame or pull the motor down.

[Jackman]

Ewwwe thats a tough call, Ive seen busted fins but never bent fins however a bent fin is a sign that the metal is flexible and that is a good thing it means they might have enough flex to bend back, the Japanese and H-D cylinders I have seen did not have much flex when bent too far they just break off. I like your idea a spacer or wedge under all the lower fins for support while trying to straighten out the bent fin, on heat I don't know but my self I think I'd try with out heat and very very gentle tapping of a wedge under the bent fin to seen if it will go back in to place.

At an H_D shop I used to work at they did welding on antique cylinders and I do remember that after the welding was complete the cylinders were put in a metal box to have a longer slower cool down as opposed to just leaving it on the bench a quick cool down was not good not sure why but thats how it was done.

[ricky racer]

Well, with a little TLC, and some heat, I was able to straighten the fins well enough that most likely, you and I will be the ones to ever know they were bent.

I put a spacer under the fin that was directly under the bent fin. I don't know if I explained that really well. Let me try again. There was the bent fin (#1 fin), the fin directly below the bent fin (#2 fin) and I placed a snug fitting spacer between fin #2 & fin #3 (the next one down). The space distributed any load over a greater area reducing any possible flex or bending.

I heated up the fin (carefully) in the area I wanted it to bend with a MAPP Gas Torch and carefully tapped in a chisel which I used as a wedge between fin #1 and Fin #2. I'd tap in the chisel a bit and heat the fin to help stress relieve it. Tap it in a bit more and heat the fin and did this until it looked good.







I pulled the motor from the frame and set it in the wash tank awaiting disposition.

[Jackman]

Dang you do nice work those fins are perfectly straight now looks darn good..

[Tezell]

Looks good. Good job. Keep us posted.

[Jackman]

Not knowing what a Materalla is I did a google what a surprise 250cc at 32 hp that's a hot rod with a Clark Kent appearance , back in the 70's there was a few Bultacos dirt bikes around but no street bikes, in the dirt the better more experienced Pro riders had Bultacos and Husquvrne , us novices had the Japanese bikes mostly RM's my friend had a TM 400 and I had a TM 250 those bikes were rockets , after those I got several RM 125's the suspension was light years a head of the TM's..

[papermaker]

I had a neighbor that had a Bultaco dirt bike. That was several years ago. If memory serves me I think that they sounded very "throaty".