Topic: 1978 CB750 Chain and sprockets direct replacement.

[crousos]

Well.. just to add a happy ending to this thread I decided to stay with the stock 630/15/41I found the full setup fairly cheap in my area ! thank you all for a very helpful and informative discussion ;-)

[Wobbly]

I always used the original Honda endless chain (88 links) on my 77 K7, and I would replace chain and sprocket at the same time--it's the tradition where I come from  --instead of mixing new and old.
After 200,000 miles and 37 years, I am still waiting for the horrible damage that the 630 chain is supposed to do to my bike. But I have patience, and will keep waiting for that to happen.

[BobbyR]

I always used the original Honda endless chain (88 links) on my 77 K7, and I would replace chain and sprocket at the same time--it's the tradition where I come from  --instead of mixing new and old.
After 200,000 miles and 37 years, I am still waiting for the horrible damage that the 630 chain is supposed to do to my bike. But I have patience, and will keep waiting for that to happen.

And you will not. The K7 and K8 750's were intended to use the 630 chain. Some people like to distribute old or incorrect information.

[lucky]

Lucky, if you think a 630 chain will break you have rocks in your head. Honda went up to a 630 because the old 530's were breaking cases when they failed for whatever reason they were failing. Use your brain for once...

Nothing wrong with using a 630 if the OP decides to go stock, if the bike is being ridden on the street I bet the difference in the rotating mass of a 530 set up might not be really noticeable to most people.

IF you hold a #630 chain in one hand and a #530 chain in the other hand,
Your mind will be made up. That #630 chain is ridiculously heavy for that bike.

There is nothing wrong with a 630 chain Lucky, yes it's heavier than a 530 but it works just fine in street applications. Quit trying to scare people into believing its going to break, it's plenty strong. Just because you don't like it doesn't mean there's anything wrong with it.

For the record I'm actually switching over too a 520 setup, not because there's anything wrong with my 630. I got a set locally for cheap as well as a 520 chain, otherwise I'd happily stick to my 630 setup. I'm trying to lighten up the old bike without hacking things off of it. 520 setup, aluminum wheels, drilled rotor, billet motor mounts from 745.

Very strange, you say there is nothing wrong with a #630 sprocket and chain set up and you go with the lightest weight of all, the #520. 
You say you are putting your bike on a diet.
Don't like that big heavy #630 chain do you.


I am NOT trying to scare anyone. Just facts.

 Just ask Cycle Exchange in Wisconsin how many CB750 engine cases they come across that have a hole in them. The 1977-78 CB750 engine cases even had a thicker engine case in that area . One of the 21 improvements in that last two years of the CB750 SOHC.

[TwoTired]

I am NOT trying to scare anyone. Just facts.

Imo, I think your facts are faulty or misrepresented.

The pre-77 SOHC4 750s did get a reputation for holing cases.  These all had 530 chains, and usually were neglected regarding maintenance.  Worse, the battery vent tube was also often mis-routed and dripped battery acid on the chain. Replacing lube with battery acid pretty much leads to steel link failure.

Honda finally understood that owners would neglect the chains to failure and then blame Honda.  Owners always think its the mechanic's or the designer's fault that the machine doesn't compensate for owner induced issues.  A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools.
So, beginning in 77, 630 O ring chains were introduced, which have the best record for sustaining operation with owner abuse than just about any chain made available to that date.  People were touring cross country and deferring chain maintenance.  The 630 oring can take this.  The F models did the same while putting more power through the chain.  Finally, case replacement became a rare event.

Is it still possible to wad up a chain and break the case?  Of course.  Any machine can fail.  But, you have to REALLY try hard to do so with a 630.

 I've seen several holed/broken cases from 530 chain failure.  Never one that was due to 630 chain failure.

I would like you, Lucky, to document a broken case directly attributable to a 630 chain failure.  Not just any old 750 case that you can find as broken.  And not just regurgitated hearsay of some lore you think you might have heard.   But, one that you actually KNOW had a thrown 630 chain associated with it.

[seanbarney41]

+1, those 630 chains are pretty indestructible imo...I have always had early k models until fairly recently...I got an f3.  The bike has 19,000 miles on the original chain that sat around for years inside, outside, then used only for doing burnouts...I cleaned the damn thing up, lubed it and it works great!

[BobbyR]

I am NOT trying to scare anyone. Just facts.

The pre-77 SOHC4 750s did get a reputation for holing cases.  These all had 530 chains, and usually were neglected regarding maintenance.  Worse, the battery vent tube was also often mis-routed and dripped battery acid on the chain. Replacing lube with battery acid pretty much leads to steel link failure.

I read your mention of the vent tube before. I realized you were correct. I just bought an AGM battery for that reason among others.

Lucky, you seem to be very good hearted, but sometimes things you say make my teeth hurt.

[lucky]

I am NOT trying to scare anyone. Just facts.

Imo, I think your facts are faulty or misrepresented.

The pre-77 SOHC4 750s did get a reputation for holing cases.  These all had 530 chains, and usually were neglected regarding maintenance.  Worse, the battery vent tube was also often mis-routed and dripped battery acid on the chain. Replacing lube with battery acid pretty much leads to steel link failure.

Honda finally understood that owners would neglect the chains to failure and then blame Honda.  Owners always think its the mechanic's or the designer's fault that the machine doesn't compensate for owner induced issues.  A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools.
So, beginning in 77, 630 O ring chains were introduced, which have the best record for sustaining operation with owner abuse than just about any chain made available to that date.  People were touring cross country and deferring chain maintenance.  The 630 oring can take this.  The F models did the same while putting more power through the chain.  Finally, case replacement became a rare event.

Is it still possible to wad up a chain and break the case?  Of course.  Any machine can fail.  But, you have to REALLY try hard to do so with a 630.

 I've seen several holed/broken cases from 530 chain failure.  Never one that was due to 630 chain failure.

I would like you, Lucky, to document a broken case directly attributable to a 630 chain failure.  Not just any old 750 case that you can find as broken.  And not just regurgitated hearsay of some lore you think you might have heard.   But, one that you actually KNOW had a thrown 630 chain associated with it.

Luckily I have my own as an example.
It was a 1978 model with #630 chain. Hole in the engine case.
Cycle Exchange  rebuilt my engine. The chain was fine.
I never said the chains will break. they almost never break.
But they do put holes in engine cases when they get loose.

"O" ring chains were not even invented in 1977.


If you do not like my ideas just move on tho the next post.

[lucky]

+1, those 630 chains are pretty indestructible imo...I have always had early k models until fairly recently...I got an f3.  The bike has 19,000 miles on the original chain that sat around for years inside, outside, then used only for doing burnouts...I cleaned the damn thing up, lubed it and it works great!

I agree those #630 chains are massive tank grade.
I never said they broke. I said the put holes in engine cases.
It is when they get loose that this happens. They grind through the engine case.

But is is the weight that is a factor in them getting loose. Massive rotating weight.

[lucky]

I always used the original Honda endless chain (88 links) on my 77 K7, and I would replace chain and sprocket at the same time--it's the tradition where I come from  --instead of mixing new and old.
After 200,000 miles and 37 years, I am still waiting for the horrible damage that the 630 chain is supposed to do to my bike. But I have patience, and will keep waiting for that to happen.

No that big heavy massive chain will probably never break. But it can grind a hole in the engine case.

Think of it like this. If you put a heavy weight on the end of a string and swing it in a circle it develops more and more force outwards.

[lucky]

I am NOT trying to scare anyone. Just facts.

The pre-77 SOHC4 750s did get a reputation for holing cases.  These all had 530 chains, and usually were neglected regarding maintenance.  Worse, the battery vent tube was also often mis-routed and dripped battery acid on the chain. Replacing lube with battery acid pretty much leads to steel link failure.

I read your mention of the vent tube before. I realized you were correct. I just bought an AGM battery for that reason among others.

Lucky, you seem to be very good hearted, but sometimes things you say make my teeth hurt.

I have never said that those massive #630 chains break.
I DID say they can put holes in engine cases. It is when they get loose.

[TwoTired]

"O" ring chains were not even invented in 1977.

You have a "unique" version of history.

Check out chapter 24 of the Honda  CB750 Shop manual.  Pg, 258.

2. DRIVE CHAIN

A. Inspection
1.  Check for damaged rollers, loose pins, or missing orings.  Replace if necessary.


I wonder why they have you inspect for missing orings in chains that weren't invented yet?

Have you ever read the shop manual? 

[lucky]

I stand corrected. Honda did have"O" ring chains.

[750K]

Lucky, if you think a 630 chain will break you have rocks in your head. Honda went up to a 630 because the old 530's were breaking cases when they failed for whatever reason they were failing. Use your brain for once...

Nothing wrong with using a 630 if the OP decides to go stock, if the bike is being ridden on the street I bet the difference in the rotating mass of a 530 set up might not be really noticeable to most people.

IF you hold a #630 chain in one hand and a #530 chain in the other hand,
Your mind will be made up. That #630 chain is ridiculously heavy for that bike.

There is nothing wrong with a 630 chain Lucky, yes it's heavier than a 530 but it works just fine in street applications. Quit trying to scare people into believing its going to break, it's plenty strong. Just because you don't like it doesn't mean there's anything wrong with it.

For the record I'm actually switching over too a 520 setup, not because there's anything wrong with my 630. I got a set locally for cheap as well as a 520 chain, otherwise I'd happily stick to my 630 setup. I'm trying to lighten up the old bike without hacking things off of it. 520 setup, aluminum wheels, drilled rotor, billet motor mounts from 745.

Very strange, you say there is nothing wrong with a #630 sprocket and chain set up and you go with the lightest weight of all, the #520. 
You say you are putting your bike on a diet.
Don't like that big heavy #630 chain do you.


I am NOT trying to scare anyone. Just facts.

Re read my post and try to understand what I said...

I'm switching to a 520 setup only because a cheap set fell into my lap, that's the only reason. If it hadn't been cheap I would still use the 630, which I'm still using by the way.

[rcracin]

I have a 78 750k that's in need of a new chaing. It's loose as hell and I can't adjust it any tighter.

Is is advisable to change the sprockets when I change the chain? Or can I leave the OEM sprockets and just buy a new 630 chain? Will the 530 chain fit on the OEM sprockets. Thanks

[Wobbly]

I have a 78 750k that's in need of a new chaing. It's loose as hell and I can't adjust it any tighter.

Is is advisable to change the sprockets when I change the chain? Or can I leave the OEM sprockets and just buy a new 630 chain? Will the 530 chain fit on the OEM sprockets. Thanks

No, the 530 won't work with the original sprockets, and, yes, you need to replace the entire set or the new chain won't last long. By the way: I never managed to wear a chain out like that. Mine, no matter what bike, would always be unevenly stretched and thus not be adjustable within specs. I can only imagine what the teeth on your sprockets must look like if your chain is like that. To be on the safe side, you should see if indeed you currently have 88 links now because it would not surprise me if some moron put  the wrong chain on--which would explain the scenario.

[rcracin]

I have a 78 750k that's in need of a new chaing. It's loose as hell and I can't adjust it any tighter.

Is is advisable to change the sprockets when I change the chain? Or can I leave the OEM sprockets and just buy a new 630 chain? Will the 530 chain fit on the OEM sprockets. Thanks

No, the 530 won't work with the original sprockets, and, yes, you need to replace the entire set or the new chain won't last long. By the way: I never managed to wear a chain out like that. Mine, no matter what bike, would always be unevenly stretched and thus not be adjustable within specs. I can only imagine what the teeth on your sprockets must look like if your chain is like that. To be on the safe side, you should see if indeed you currently have 88 links now because it would not surprise me if some moron put  the wrong chain on--which would explain the scenario.

Thanks for the response. I'll count the links and report back. I'll otherwise order a 530 chain & sprocket set. Does anyone have a link to the exact sprockets I need. I'd like to stay as close to stock as possible. Thanks