Author Topic: CB engine (Read 3888 times)

Bodain · « **on:** April 06, 2008, 08:21:27 AM »

I just picked up a CB engine. Much to my suprise there is no serial number on it?

?

OldSchool_IsCool · « **Reply #1 on:** April 06, 2008, 08:26:03 AM »

I think that if an engine is swapped out by the dealer, that the new engine would not have a serial number.

okie · « **Reply #2 on:** April 06, 2008, 08:33:05 AM »

The replacement engine WOULD have a serial number. Replacement engines are the main reason for the increasing gap between frame numbers and engine numbers.

scondon · « **Reply #3 on:** April 06, 2008, 08:37:29 AM »

Quote from: okie on April 06, 2008, 08:33:05 AM

The replacement engine WOULD have a serial number. Replacement engines are the main reason for the increasing gap between frame numbers and engine numbers.

When cases are replaced by the dealer they do not have a # stamped on them. Don't know whether this applies to the whole engine or not, but I think it does.

Bodain · « **Reply #4 on:** April 06, 2008, 08:48:42 AM »

Quote from: scondon on April 06, 2008, 08:37:29 AM

Quote from: okie on April 06, 2008, 08:33:05 AM
The replacement engine WOULD have a serial number. Replacement engines are the main reason for the increasing gap between frame numbers and engine numbers.

When cases are replaced by the dealer they do not have a # stamped on them. Don't know whether this applies to the whole engine or not, but I think it does.

I only bought this engine cause it was dirt cheap and planned to simply resale it. I thought I aught to know exactly what I'm selling. Wouldn't want to sell a jewel 69 for $300.00 bucks.

In 69 one of the primary faults with the units was the weak chains. The dealers were commonly replacing cases because of this. If this were true then there could be sandcast units out there that couldn't be identified as such.

Gordon · « **Reply #5 on:** April 06, 2008, 08:51:16 AM »

Quote from: Bodain on April 06, 2008, 08:48:42 AM

In 69 one of the primary faults with the units was the weak chains. The dealers were commonly replacing cases because of this. If this were true then there could be sandcast units out there that couldn't be identified as such.

If the cases have been replaced, then they're not sandcasts anymore.

754 · « **Reply #6 on:** April 06, 2008, 09:10:40 AM »

Gordon, there was and is sandcast replacement cases.

My 73 had cases replaced, no numbers, used to pack the recipt around.. still have that engine..

754 · « **Reply #7 on:** April 06, 2008, 09:15:05 AM »

Look at the head from the side, 4 round bars in the fins, 72 & earlier, 3 thicker bars..73 & up.

Carbs with linkage 71 & later

The cases in the pic look pretty smooth..

I have seen one excetion to that on here, but only time I ever seen that

Bodain · « **Reply #8 on:** April 06, 2008, 09:25:08 AM »

Ok... Now there are some tips...

10 Clutch screws.....Non sandcast

4 round bars in the fins = pre 73

I just looked at my 78 F..... 3 bars........

HondaMan · « **Reply #9 on:** April 06, 2008, 09:57:00 AM »

When we had to replace cases where the customer had pitched the chain around the alternator, the new cases we got from Honda didn't have serial numbers. We were supposed to stamp the original number into the little box, but no one had stamps, so we never did.

Gordon · « **Reply #10 on:** April 06, 2008, 11:37:23 AM »

Quote from: 754 on April 06, 2008, 09:10:40 AM

Gordon, there was and is sandcast replacement cases.

My 73 had cases replaced, no numbers, used to pack the recipt around.. still have that engine..

Sorry, my bad.

754 · « **Reply #11 on:** April 06, 2008, 09:34:58 PM »

Bodain,
2 more clues..

Shift pattern in shifter cover 75 and later

Sprocket shaft with no keeper groove 77 or 78. those engines will have studs for the exhaust, but so will F models, after 75.

mystic_1 · « **Reply #12 on:** April 06, 2008, 10:11:17 PM »

Well technically, the replacement cases are themselves not sandcast. They are die-cast replacements FOR sandcast motors, but even that's overstating things. In the end they are replacement cases for early CB750's.

Just another example of the 'sandcast' term taking on a life of it's own.

mystic_1

754 · « **Reply #13 on:** April 06, 2008, 10:19:21 PM »

bull...

Honda does have replacement parts, and did back then.

They no longer have sandcast replacements, but they did back then & one member on here has a set..and there are others on the Sandcast registry..

mystic_1 · « **Reply #14 on:** April 06, 2008, 10:22:51 PM »

This would be the first I've heard about replacement cases that were actually themselves sandcast. The one pictured above is certainly not "sandcast" even though it may be made to the same specs and design as the original sandcast cases.

So is your 73 a sandcast now?

mystic_1

Terry in Australia · « **Reply #15 on:** April 06, 2008, 10:27:45 PM »

A friend of mine in Oregon has a 1969 CB750K0 with unstamped cases, he bought it from the original owner who said the same thing as Hondaman. The local dealer rebuilt his engine after a chain let go and smashed the old ones, but the dealers weren't given stamps, so it went out unstamped.

He told me the replacement cases were "diecast" though, as the damage was done long after the sandcast production finished. SteveK0 here has a "sandcast" with replacement cases (stamped with his original numbers, from memory) but they're diecast too with the extra screw hole for the later clutch cover. Cheers, Terry.

754 · « **Reply #16 on:** April 06, 2008, 10:36:13 PM »

My 73 is a diecast engine.

I have had both types.

If you bought them before they ran out of sandcast spares, they were available.

Whi is it so hard to believe Honda carried spares? When they launched the 750 they worked at making it a sucess. They made the for about 5 months or more before any diecast cases were available on bikes at the factory.

By the time they were in the 600 frame serial numbers, the engines were over 730 in serial number. So there may have even been numbered cases around.

mystic_1 · « **Reply #17 on:** April 06, 2008, 10:44:55 PM »

I don't find it difficult at all to believe that honda carried spare parts. I'm just saying that if the part wasn't actually cast in sand, it's not a "sandcast".

mystic_1

Terry in Australia · « **Reply #18 on:** April 06, 2008, 10:50:57 PM »

Hmmnn, well I know that when the CB750's came out there were lines of buyers for as far as the eye could see, from memory Britain didn't get any "Sandcast" K0's at all due to short supply, (most went to the US) and it was much the same here in Oz.

From what I've heard the main reason for case replacement was chains letting go, and this situation wasn't really addressed until the F2/K7 was fitted with monster 630 chains, (although I've got an F2 bottom end with busted cases..........) but I'd imagine that not too many chains would have busted during the first 5 months of production, so that might be why not too many folk have seen "sandcast" replacement cases?

754 · « **Reply #19 on:** April 06, 2008, 11:05:51 PM »

Europe bike started after 3480 and some countries in the 5000 range.

There was lots of breakage, for 2 main reasons,
16 T front sprockets..

Chains in 69 for bike in most cases were previously never subjected to much more than 45 or 50 hp. So there were not many high strength chains.

But a lot of early bikes got raced, even in early 70, if you ordered cases, first question is Serial #, due to the clutch cover difference an early # should get a sandcast case, ubtil they ran out.

Terry in Australia · « **Reply #20 on:** April 07, 2008, 04:18:45 AM »

Actually you've got a point there Frank, I forgot about the 16T front sprocket causing chain breakage.

Gordon · « **Reply #21 on:** April 07, 2008, 05:43:30 AM »

Quote from: 754 on April 06, 2008, 11:05:51 PM

first question is Serial #, due to the clutch cover difference an early # should get a sandcast case, ubtil they ran out.

That's pretty much what I figured once I thought about it for a second. It's possible for an early production engine to have authentic sandcast replacement cases, but overall, the odds of the replacements actually being sandcast ones are most likely not all that high.

So a blanket statement that an engine with replacement cases cannot be a sandcast is untrue.

nippon · « **Reply #22 on:** April 07, 2008, 07:46:18 AM »

CMS is selling diecast crankcases for sandcast CBs
http://www.cmsnl.com/products/crankcase-assy_11010300415/

754 · « **Reply #23 on:** April 07, 2008, 07:52:42 AM »

Nippon, how much is that in US dollars? I think in 73 or 74 the ones put in my bike were around 300.. not sure now.

mystic_1 · « **Reply #24 on:** April 07, 2008, 08:31:21 AM »

Heh, they're selling A crankcase. Only one left!

It's on sale, too! Only 999 Euros (1,570.11 USD), down from 5008.50 Euros (7,872.08 USD).

mystic_1

754 · « **Reply #25 on:** April 07, 2008, 07:58:42 PM »

We need to get Swoop on here..

Terry in Australia · « **Reply #26 on:** April 07, 2008, 09:45:08 PM »

Sooooo, if those cases are for a sandcast engine, how come there's 10 screw holes?

754 · « **Reply #27 on:** April 07, 2008, 09:47:07 PM »

They said they would fit a sandcast, but they were in fact diecast..

I will try to dig up the correct part # tommorow..

754 · « **Reply #28 on:** April 08, 2008, 11:36:39 AM »

Thanks swoop,
I have sen them referred to as permanent mold castings. However as one is smooth and the other is of sandcast appearance, and they are mostly referred to as sandcast, I will keep using the term.

Terry in Australia · « **Reply #29 on:** April 08, 2008, 02:01:31 PM »

Soooo, if those "Sandcast replacement cases" are just 10 screw diecast cases, what distinguishes them from K1-K8 cases, or is CMSL just blowing smoke up potential buyers butts and pumping up the price?

754 · « **Reply #30 on:** April 08, 2008, 07:14:52 PM »

I dont know what you mean?

These are die-cast cases.. end of story. Can they be used for replacement cases for 69 thru 78 ..YES.. & that is all they are saying on there. Will they be correct for early bikes?..NO.. but all they are saying is they wqill fit, and are simply replacement cases.

754 · « **Reply #31 on:** April 08, 2008, 07:17:19 PM »

Now the bad news..

I have gotten information that suggests there was at least 4 different case sets for Sandcast 750,s

Which further muddies the mix..

HondaMan · « **Reply #32 on:** April 12, 2008, 09:37:31 PM »

Quote from: 754 on April 08, 2008, 07:17:19 PM

Now the bad news..

I have gotten information that suggests there was at least 4 different case sets for Sandcast 750,s

Which further muddies the mix..

THAT, I believe.... $:-\$ When I wrenched, we were always having to pore thru the parts catalogs to find out which K0 parts were gonna fit THIS bike...

News:

Author Topic: CB engine (Read 3888 times)

okie