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Author Topic: mystery racing engine  (Read 1217 times)

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Offline macvit7906

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mystery racing engine
« on: January 27, 2019, 08:39:20 pm »
started engine disassembly. This is a K5/K6 head, not sure which.

The springs and caps do not look stock, can anyone identify these springs? Difference from stock?
« Last Edit: February 18, 2019, 11:07:08 am by macvit7906 »

Online 754

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Re: Identification help
« Reply #1 on: January 27, 2019, 11:28:57 pm »
Probably has a high performance cam, usually they are marked on the end.
 And it looks like an adjustable cam sprocket.
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Offline ekpent

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Re: Identification help
« Reply #2 on: January 28, 2019, 05:19:44 am »
 OOOH- Somebody has some go fast parts. How far are you taking it down ? If you pop off the head look for some bigger pistons and domes on top. I would be leaving the block on so you don't mess up the rings if the bores look good. Remember also that if it does have an aftermarket hotter cam that the valve lash is set bigger then stock specs.

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Re: Identification help
« Reply #3 on: January 28, 2019, 08:05:31 am »
Check  valve clearance ..NOW..
 Write it down.
Maker of the WELDLESS 750 Frame Kit
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Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline macvit7906

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Re: Identification help
« Reply #4 on: January 28, 2019, 08:56:34 am »
Will do, thanks!

I'll check clearances before I go further.  I'm overhauling the engine,  but it's always nice to find some free performance parts.

I did notice the aftermarket cam sprocket. I think that is R/C engineering's.

I'm sending cylinders and head to MR anyways, but maybe there is a big bore kit that can be reused.

Exhaust valve #3 is completely stuck open, so the engine wont turn over right now, could be a total mess under there.

It's a k5 engine in a F0 frame, you can tell the bike was definitely raced.

Online 754

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Re: Identification help
« Reply #5 on: January 28, 2019, 11:46:44 am »
Take a good look at the portsm it may have porting work done.
The reason to check the valves, once in a while a mystery cam  shows up  if you have removed the rockers you then have no idea of what valves should be set up at.   They range from .004 to.012 of an inch.
 If the cam has a distinct grey color it may be a Norrism and they are marked , engraved on a flat spott on the cam between 2 lobe sets.
Maker of the WELDLESS 750 Frame Kit
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Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline macvit7906

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Re: Identification help
« Reply #6 on: January 31, 2019, 04:17:36 pm »
Hope everyone is well. Think I made need a good amount of identification help as I tear down.

The rocker clearances were coming in at .305mm or more - so a bit loose for stock.

Got the rockers off and the cam out.

The cam lift is coming in at 8.86mm for both intake and exhaust. No idea what type of cam this is. I'm assuming it's aftermarket - from what I've read, this could be a webcam 41 or 41A, any way to tell the difference?

The Sprocket has the R/C stamp on it.

The cam looks to be in great shape, except there seems to be a small chip on the #3 exhaust, though it looked to be put there intentionally. What do you think?

Can anyone identify this cam by the stamps? Stamps include: D1 and CWC, K134, C1, and A7

After removing the cam holder, I also noticed the oil control orifices look completely different then stock. They look to have super small holes. has anyone seen this?

Thanks for all the help so far
« Last Edit: January 31, 2019, 05:13:11 pm by macvit7906 »

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Re: Identification help
« Reply #7 on: January 31, 2019, 09:38:07 pm »
What were the valve clearances ?
 Not sure what you mean by early but it's not a 69 head.m but it is 70 to 72.. or very early 73.
 Your cam cradles are 73 or up.
« Last Edit: January 31, 2019, 09:42:33 pm by 754 »
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline macvit7906

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Re: Identification help
« Reply #8 on: February 01, 2019, 08:56:07 am »
What were the valve clearances ?
 Not sure what you mean by early but it's not a 69 head.m but it is 70 to 72.. or very early 73.
 Your cam cradles are 73 or up.



Clearances were coming in at around .305mm or a bit more on intake.

The cam has stamps D1 and CWC, K134, C1, and A7 on it, and the lift is right around 8.86mm for intake and exhaust. 
I just want to make sure the cam would be ok for everyday street riding. I'll be using an 836cc kit.

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Re: Identification help
« Reply #9 on: February 01, 2019, 03:36:32 pm »
What us under it now ? 836 or bigger ?
 RC used that valve clearance on some of their cams..
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline macvit7906

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Re: Identification help
« Reply #10 on: February 01, 2019, 04:57:15 pm »
What us under it now ? 836 or bigger ?
 RC used that valve clearance on some of their cams..

Every time I see your picture I chuckle.

Finally got the head off the cylinder. The pistons have old style 1 piece piston oil ring. The bores measure 61.2mm so I do not think a big bore kit was used.

I'll post more pictures this weekend.

Offline macvit7906

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Re: Identification help
« Reply #11 on: February 02, 2019, 07:20:59 pm »
What us under it now ? 836 or bigger ?
 RC used that valve clearance on some of their cams..

Here are the pistons it was running. The measure 61mm.

I also took the alternator cover off to discover the alternator has been lightened and micro polished. I'm hoping the crank is too!

Online seanbarney41

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Re: Identification help
« Reply #12 on: February 02, 2019, 08:17:16 pm »
Whoa!  RSC?  Are those pistons what I think they are?
If it works good, it looks good...

Offline macvit7906

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Re: Identification help
« Reply #13 on: February 02, 2019, 08:40:34 pm »
Whoa!  RSC?  Are those pistons what I think they are?

Please tell me what you think they are! Besides some carbon they are in phenomenal shape. 

I picked this bike up for $400. It sat in a garage since 88' - had about 2 inches of dust on it. The only info I have on in it is "It was raced." I'm overhauling the engine and building a high performance street and everyday riding bike but it looks like I got a rocket ship to work with. Need some help determining what to keep and what to save or sell.

I can already tell alternator was lightened. I'm cracking the cases tomorrow but I wont be surprised if if find an old "pork chopped" crank and many other goodies.

More pictures to come.

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Re: Identification help
« Reply #14 on: February 02, 2019, 08:41:27 pm »
Those look Maybe....like old Yoshi ... slipper pistons..   2 ring.. probably racing stuff..
  Must of been a hot motor in the day...
 .
« Last Edit: February 02, 2019, 08:43:28 pm by 754 »
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline macvit7906

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Re: Identification help
« Reply #15 on: February 02, 2019, 08:58:31 pm »
Those look Maybe....like old Yoshi ... slipper pistons..   2 ring.. probably racing stuff..
  Must of been a hot motor in the day...
 .

Would you recommend saving or selling these and going with different pistons for everyday street riding?

Online seanbarney41

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Re: Parts - Identification help - mystery racing engine
« Reply #16 on: February 02, 2019, 09:34:36 pm »
RSC (Racing Service Center) was the name of Honda's factory racing parts program.  I am not sure if RSC parts were sold to the general public or not.  If not :o, you are gonna want to start doing some research on the history of your bike. :D
If it works good, it looks good...

Offline PeWe

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Re: Parts - Identification help - mystery racing engine
« Reply #17 on: February 03, 2019, 02:27:51 am »
Cam has no stamps on the ends?
Look at the cyl 4 end where the notch used for correct timing is located.
I have a cam that has marks under its washer.
Other place is the cam sprocket flange.
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Offline Tim2005

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Re: Parts - Identification help - mystery racing engine
« Reply #18 on: February 03, 2019, 03:04:48 am »
RSC (Racing Service Center) was the name of Honda's factory racing parts program.  I am not sure if RSC parts were sold to the general public or not.  If not :o, you are gonna want to start doing some research on the history of your bike. :D

Some RSC stuff was available to outside the factory teams, I don't have much detail of it except I know one of my 750s has RSC rods in it that were installed new by a performance shop back in the day. Also there were some RSC parts made for 400Fs, but I don't think there was ever a factory 400F racer.

I wonder what rods this one has?

Offline macvit7906

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Re: Parts - Identification help - mystery racing engine
« Reply #19 on: February 03, 2019, 12:29:01 pm »
RSC (Racing Service Center) was the name of Honda's factory racing parts program.  I am not sure if RSC parts were sold to the general public or not.  If not :o, you are gonna want to start doing some research on the history of your bike. :D

Some RSC stuff was available to outside the factory teams, I don't have much detail of it except I know one of my 750s has RSC rods in it that were installed new by a performance shop back in the day. Also there were some RSC parts made for 400Fs, but I don't think there was ever a factory 400F racer.

I wonder what rods this one has?

Interesting. Yeah pistons definitely say RSC. I'll take the washer off the cam and see what we got.

I'm cracking the case today and I'll post some pics. Definitely some nice performance parts in this bike.
Unfortunately, not sure how I could find out anymore history about it. The owner passed away and this was acquired at an estate sale. At first it look like a pile of dust!

Here is the lightened alternator. NICE. Would you guys recommend keeping this for everyday street riding?



Online 754

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Re: Parts - Identification help - mystery racing engine
« Reply #20 on: February 03, 2019, 01:11:03 pm »
 First off, any evidence it was a track bike, if it has lighting and a plate holder, it was likely on the street.
 Nothing there  yet that does not look streetable.
 What carbs ? Is there a thin bronze bushing in the small end of the rods?
 Look for that and the rod bolt heads vs stock..
Maker of the WELDLESS 750 Frame Kit
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Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Online smacd11

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Re: Parts - Identification help - mystery racing engine
« Reply #21 on: February 03, 2019, 04:57:33 pm »
I believe that is a Norris cam - I have one I think has similar markings on it.  It was hard to find but there was a flat machined spot that had Norris Cycles hand vibropeened on it. 


Online 754

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Re: Parts - Identification help - mystery racing engine
« Reply #22 on: February 03, 2019, 05:50:51 pm »
Yeah that is what my Norris had.  First you can spot a Norris by the grey color..
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Online smacd11

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Re: Parts - Identification help - mystery racing engine
« Reply #23 on: February 03, 2019, 06:01:15 pm »
Still trying to find specs on it.

Online 754

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Re: Parts - Identification help - mystery racing engine
« Reply #24 on: February 03, 2019, 09:04:03 pm »
Does it say 750 D ?
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

 

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