Author Topic: Cobra motor disassembly and rebuild (Read 107683 times)

bear · « **Reply #225 on:** February 19, 2016, 12:26:08 PM »

Bugger!
That brings back some bad memories.

I don't want be a stick in the mud.
But my experiences with welded cranks has been pretty ugly over the years as well.
You blokes might do em a bit better over there.
I hope so, you deserve a winner Billy and I've got no doubt you'll get there.

Cheers,
Brian

Bill/BentON Racing · « **Reply #226 on:** February 19, 2016, 02:48:39 PM »

That's not funny! Lol. There's over $2K sitting there not usable. This came with fresh bore,rings, pins, buttons etc.
Won't be ran on any of mine, welding will only fix the surface, not the whole thing! Damn. Oh, well drop back 20 and punt!

754 · « **Reply #227 on:** February 19, 2016, 02:55:37 PM »

Are you sure its a crack..looks more like a crack in the sand.

madmtnmotors · « **Reply #228 on:** February 19, 2016, 03:18:39 PM »

Quote from: 754 on February 19, 2016, 02:55:37 PM

Are you sure its a crack..looks more like a crack in the sand.

I was wondering the same thing...

754 · « **Reply #229 on:** February 19, 2016, 04:03:02 PM »

If its a crack it will go in not stand out..

scottly · « **Reply #230 on:** February 19, 2016, 04:39:02 PM »

I agree with Frank and Wilbur. Notice the vertical displacement of the fins on either side of the "crack". The flaw was with the mold, and mirrored in the part.

Bill/BentON Racing · « **Reply #231 on:** February 19, 2016, 04:52:51 PM »

Wanna buy a block? Haha!

scottly · « **Reply #232 on:** February 19, 2016, 04:57:54 PM »

That's not a crack, Bill. Look at the top machined surface of the block. Any crack visible?

kmb69 · « **Reply #233 on:** February 19, 2016, 05:13:13 PM »

Quote from: scottly on February 19, 2016, 04:39:02 PM

I agree with Frank and Wilbur. Notice the vertical displacement of the fins on either side of the "crack". The flaw was with the mold, and mirrored in the part.

I agree with Frank, Wilbur, and Scottly. Fractured sand in the mold reflected on the part. Part be good.

Jim F · « **Reply #234 on:** February 19, 2016, 05:31:28 PM »

It might be repairable but the only way to find out is to grind it down to the sleeves or you find where it stops. Lots of questions
It could be Laser welded or TIG welded but the later has issues with heat
Are the sleeves going to be replaced? What about oil seals? Also if yiu go with the TIG route
Then you might have to have everything re-decked
I've welded a lot of busted heads from Jerry cooper at cooper performance and they have all worked
When done
Keep us posted
By the way I could not save this rod

Jim F · « **Reply #235 on:** February 19, 2016, 05:33:43 PM »

Bingo it's not cracked
I took a closer look and it's a flaw in the mold
Your fine bill

Bill/BentON Racing · « **Reply #236 on:** February 19, 2016, 07:04:09 PM »

Jimmy, I'll need you to tell me that in person! Lol, you home this weekend? Hope so, cause I don't see RC selling a block that looks cracked! I'll bring that puppy with me and my red one to compare, let me know , thanks, Bill

madmtnmotors · « **Reply #237 on:** February 19, 2016, 07:06:31 PM »

Quote from: Jim F on February 19, 2016, 05:33:43 PM

Bingo it's not cracked
I took a closer look and it's a flaw in the mold
Your fine bill

+1

Part of the character of being "sand cast"!

Bill/BentON Racing · « **Reply #238 on:** February 19, 2016, 07:10:51 PM »

RC Scarface sandcast blocks, I get it!! ,Bill

,
I'll just work on this then!!

754 · « **Reply #239 on:** February 19, 2016, 07:56:51 PM »

Post 231 pic2..you can see the slight step in The fin .....means the sand in the mold cracked anone side moved up or down....... not a lot.

Bill/BentON Racing · « **Reply #240 on:** February 19, 2016, 08:23:20 PM »

It definitely moved. I'm on Purple Rain right now, something about case studs.....lol, Bill

NalleyRacing · « **Reply #241 on:** February 20, 2016, 12:53:28 AM »

Holy moly.. I missed this whole post! Havent seen that before.. Hope that block is good. Billy sure was excited about getting it!!

Love those HD case studs.. Cant wait to ride the new purple rain!!

Sam Green Racing · « **Reply #242 on:** February 20, 2016, 02:19:08 AM »

Quote from: Bill/BentON Racing on February 19, 2016, 07:04:09 PM

Jimmy, I'll need you to tell me that in person! Lol, you home this weekend? Hope so, cause I don't see RC selling a block that looks cracked! I'll bring that puppy with me and my red one to compare, let me know , thanks, Bill

Like you say Billy, I can't see Russ selling a block like that.
It's plain to see that it is only a casting flaw and is in no way detrimental to the block but would he have turned it out like that?
A few years ago I got a RC block sent to a mutual friend to make a copy. He would not go ahead without consulting with Russ first. As far as I know he never went ahead with the project after Russ died.
My thinking is that this block you have is a repop made in someones back yard, I'd use it, it's not as if it's a cast brake drum that your life might depend on.

Sam.

Jim F · « **Reply #243 on:** February 20, 2016, 04:43:09 AM »

I'll be in the shop all weekend with work
I can check it in the microscope
Call me if needed
Jim

Bill/BentON Racing · « **Reply #244 on:** February 20, 2016, 05:03:43 AM »

Thanks bro, I will.

, Bill

Bill/BentON Racing · « **Reply #245 on:** February 20, 2016, 08:36:14 AM »

Fixed! K, thanks for the input, Bill

bwaller · « **Reply #246 on:** February 20, 2016, 09:12:54 AM »

Easy Peasy huh Bill. Ya fixed it!

BPellerine · « **Reply #247 on:** February 20, 2016, 09:38:05 AM »

can everyone hear the sigh of relief ??haha billp

Medyo Bastos · « **Reply #248 on:** February 20, 2016, 01:57:02 PM »

or my heart start beating again

...Save a tree, eat a beaver...

dragracer · « **Reply #249 on:** February 20, 2016, 04:25:20 PM »

That's good you figured out it was just a simple casting flaw. We all were feeling down when thinking it was an actual crack. Dang shame if you put out over $2000 for something you couldn't readily use. But wow, we don't pay that much for brand new blocks and 85mm piston sets for KZ and GS motors unless it billet blocks. Hmm, I guess being a poor boy I'll stick with resleeved stock blocks for the Honda's. You're scaring the hell out of me.

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Author Topic: Cobra motor disassembly and rebuild (Read 107683 times)