Author Topic: Cobra motor disassembly and rebuild (Read 107734 times)

Ericcb750 · « **Reply #450 on:** July 07, 2016, 06:16:22 AM »

Thanks Bill, I appreciate that. It's my first hot rod honda so excited is an understatement. I'm used to running my sportster so even the stock 736 gets boogy'n pretty good above 5K.... My Sporty would be ready to explode where the Inline 4 is just waking up...ha-ha.

Here's what I've got so far, I'm going to do a build thread too.
836cc Wiseco 10.5;1
Stage 2+ JMR ported head (oversize intakes), new hd springs, guides (iron), early retainers, cycle x super flow valves
Cycle X Super Rods (couldn't afford the Carillo's) - they're really nice
WebCam 63A
Balanced Crank
Classic Cycle City HD Primary Chains
HD Cam Chain (wish I had bought a couple Tsubaki's years ago)...
New Tensioners (primary) .... I still need to order my cam chain tensioners
APE HD Studs (both Cylinder and Main bearing)
APE Clutch
Dyna Ignition - still have to get the 0.5 ohm coils and new wires though... no biggie
Going with completely re-built stock 657B carbs ( have a whole bunch of different jets)
Moto Gpwerks stainless exhaust
K&N Pods

Have to measure my crank and rods for the bearning shells, so a few more things to iron out but i'm almost done gathering parts, time to start building!!!

Also piecing together a full GSXR Front setup - galfer wave rotors.... the whole schebang... Pretty much trying to re-build my 78K the way I should have originally... The first time around was a learning experience. This is hopefully going to be a good sleeper.....Give some modern rice a run for their money (maybe)...

That Cobra Motor is pretty Sweet Bill.... What is the size of the Cylinders ( sorry don't know too much about them)... i love that plate on the valve cover. I've watched your You-tube videos and that thing (both the black and purple rain one) sound like a beast!!!!

Do you recommend using a valve cover with the cam tower supports? I've seen them on Kenny's site and i honestly think they look so cool so that's worth it alone.... I want this motor to be a very strong runner and hopefully as reliable as possible so I thought it may be a good idea. I'll have to look into some better carbs down the road too, I'm hoping my stockers when jetted properly should work ok.

Ericcb750 · « **Reply #451 on:** July 07, 2016, 06:57:57 AM »

Here's a couple photos...Sorry not trying to Thread Jack you Bill...

Bill/BentON Racing · « **Reply #452 on:** July 07, 2016, 07:13:10 AM »

It's cool and so is your build. I like the cam cover for the cool factor! Needed? Nah, not really, sure doesn't hurt though. It won't be the sleeper if a knowledgeable person sees them either, but they so cool. Also I like the old school welded covers ,bit I admit I haven't tried one of the newer style ones. Keep us posted and G'luck, Bill

POPS 911 · « **Reply #453 on:** July 07, 2016, 02:34:33 PM »

I can't wait for Memphis to see the PACE or THE COBRA HEAD put numbers on the board = with that DA and maybe a cool night run and a tail wind maybe BILLY BLING will have a good day at the track [ or night run ]. I would think that two batteries would be need for a high point motor, remember your hurt leg at Valdosta kick starting. In 1977 was that Butch bike a bar bike with a slick that ran 10.19 at 136mph

? Blinkster IS A NO BAR BIKE with a Shinko street tire, 395 pounder scale weight AND WITH ALL THOSE HIGH DOLLAR PARTS should run 10 flat in 1320'.

Bill/BentON Racing · « **Reply #454 on:** July 08, 2016, 02:55:37 PM »

We'll see. I bet you that Pace bike had wheelie bars and dual Webers! And a distributor or magneto! And quite possibly a stroker. Don't matter, we'll see what we can do soon enough. Putting this on also. So close, stay tuned.

gschuld · « **Reply #455 on:** July 08, 2016, 03:44:34 PM »

Well, the record states the displacement at 1162 for the Pace 11/74 A/A record, so yes, sounds like a stroker motor to me unless it had some huge sleeves and pistons shoved in there somehow.

George

Bill/BentON Racing · « **Reply #456 on:** July 08, 2016, 04:41:52 PM »

Yo, last time I did the math, it took a 73.75mm piston to hit 1080. Someone please do the math for 73, 73.25, 73.50 and 73.75mm's, thanks. I think when I said it was 1062 at 73mm, Medyo said that was 1054. Thanks, Bill
I'm driving, lol.

Jerry Rxman Griffin aka MuthaF'er · « **Reply #457 on:** July 08, 2016, 06:36:24 PM »

Billy, I like that starter clutch holder!

MCRider · « **Reply #458 on:** July 09, 2016, 06:20:43 AM »

Quote from: Bill/BentON Racing on July 08, 2016, 04:41:52 PM

Yo, last time I did the math, it took a 73.75mm piston to hit 1080. Someone please do the math for 73, 73.25, 73.50 and 73.75mm's, thanks. I think when I said it was 1062 at 73mm, Medyo said that was 1054. Thanks, Bill
I'm driving, lol.

http://www.nightrider.com/biketech/calc_displacement.htm

Medyo Bastos · « **Reply #459 on:** July 09, 2016, 06:39:00 AM »

70mm + 69mm stroke

gschuld · « **Reply #460 on:** July 09, 2016, 07:19:55 AM »

Technically, a 73mm bore would need a 69.3mm stroked crank to make 1162cc. Basic RC welded stroker crank/73mm combination. This is reportedly the same bore/stroke as used on the 1975 Byron Hines built Pro Stock Honda.

For reference:

Standard 63mm stroke.

70mm. 970cc
71mm. 998cc
71.25mm 1005cc
72mm. 1026cc
73mm. 1055cc
73.73mm 1076cc

George

Bill/BentON Racing · « **Reply #461 on:** July 09, 2016, 12:35:40 PM »

Cool, so Cobra Girl is 1055, Frank's is 1026cc, pretty close, Just got through taking a little over 2lbs off the bike and especially the crank! K, Thanks George Schuld and Mike Rieck and Master Zin the balancer! K, Bill

MRieck · « **Reply #462 on:** July 09, 2016, 01:16:08 PM »

Can't get that piece much lighter than that Bill. Frank has one too.

dragracer · « **Reply #463 on:** July 09, 2016, 03:53:33 PM »

Quote from: MRieck on July 09, 2016, 01:16:08 PM

Can't get that piece much lighter than that Bill. Frank has one too.

Quote from: MRieck on July 09, 2016, 01:16:08 PM

Can't get that piece much lighter than that Bill. Frank has one too.

Yes, I've got one thanks to George. Not quite as light as Bills but its a bare bone piece. Plan to use it on the motor for the project bike. I may need some head work soon Mike. Trying to salvage an old K model head.

gschuld · « **Reply #464 on:** July 09, 2016, 04:37:21 PM »

Actually Frank, yours is JUST like Bills. Perhaps yours didn't arrive yet...

George

dragracer · « **Reply #465 on:** July 10, 2016, 12:10:42 AM »

Quote from: gschuld on July 09, 2016, 04:37:21 PM

Actually Frank, yours is JUST like Bills. Perhaps yours didn't arrive yet...

George

Didn't realize the one you sent me months back had lightening holes. I had a birthday since then so excuse my feeble mind - play tricks on an old man sometimes.

gschuld · « **Reply #466 on:** July 10, 2016, 03:06:31 AM »

Frankie,

The first one was CLEARLY just a modest first effort

. No holes in that one. I got a little out of hand with the pair of "holey" ones.

George

MRieck · « **Reply #467 on:** July 10, 2016, 06:10:24 AM »

Bill's went Priority...Frank went out a slower rate as it was just a small box. Bill's had some other parts in it too.

Bill/BentON Racing · « **Reply #468 on:** July 10, 2016, 06:35:07 AM »

Some other parts......

, LMAO! Yes , it did! Hehe, Bill

gschuld · « **Reply #469 on:** July 10, 2016, 07:14:46 AM »

Quote from: MRieck on July 10, 2016, 06:10:24 AM

Bill's went Priority...Frank went out a slower rate as it was just a small box. Bill's had some other parts in it too.

Ok, cool thanks again Mike

George

Jerry Rxman Griffin aka MuthaF'er · « **Reply #470 on:** July 10, 2016, 07:51:20 AM »

Are you guys cutting down rotors or are you turning these from lightweight aluminum?

POPS 911 · « **Reply #471 on:** July 10, 2016, 08:43:20 AM »

Frank got two batteries I think, and Bill with a big cut on his head and special pistons he might need two and your right leg will take a beating self starting a ST/ET SOHC 750. Looks to me like the Blinkster [ BLINKSTAR ] will be the new number for SEL ................. 10 flat.

gschuld · « **Reply #472 on:** July 10, 2016, 10:06:50 AM »

Quote from: Jerry Rxman Griffin aka MuthaF'er on July 10, 2016, 07:51:20 AM

Are you guys cutting down rotors or are you turning these from lightweight aluminum?

Started out as factory late model rotors.

George

cbr954 · « **Reply #473 on:** July 10, 2016, 10:41:10 AM »

I did something similar but didn't go as extreme. I have since made a lighter one but dont have a photo. Been using it for a while now, nice to have a quick reving motor but still have a push button to start. 13:1 kills my leg to try and kick it, especially when hot.

Bill/BentON Racing · « **Reply #474 on:** July 10, 2016, 01:58:03 PM »

+1, LMAO, my days of kicking....will prolly be slim, Purple Rain is still kick only, Just fired the "Beast" up with lighter rotor, haha, soon as it cranked you could tell it revved quicker! K,.

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Author Topic: Cobra motor disassembly and rebuild (Read 107734 times)