Topic: My 'primary' concern right now... is 'linked' to the bottom end.

[fang]

Lets talk about upgrading our primary chains. 

I mentioned that I have two big bore motors on the bench right now, and I have been spending a lot of time thinking about those darn cam and primary chains. 

While the primaries only rarely break and fail, per se, they do stretch and make a racket, and then they maybe do not stretch in a balanced way.  A far as race engines go, a finely tuned, lightened, and balanced bottom end will see greatly increased strain -- in significantly higher RPMs, in additional reciprocating forces during more aggressive acceleration and deceleration, not to mention the actual power increase.  And that does not even consider possible increased engine and bearing journal deflection under this increased strain ....  Race motors are put through the ringer, and the primary chains are supposed to hold that ring together.   Yet we rarely -- if ever - discuss them.   I am interested in details about why the primary dampener gear is split in two pieces, why/how this actually helps things, and how improved primary chains might interact in this system.   I am curious about what the more experienced CB750 racers and race engine builders have experienced, and what has been done to make their bottom ends more bullet proof.

There was a good discussion started by AshimotoK0, where KOS, Nippon, and others hammered out the virtue of various replacement primary rubber dampers....  LINK  But it never satisfactorily got back on the discussion of upgraded primary chains and how they might impact the rubbers.  As far as I could tell, it was implied that successful racers should do something about their rubbers and then semi-regularly replace their primary chains.  It was full of good thoughts, but I felt it just touched the surface of what I would like to know.  I also don't want to regularly replace my primary chains.


I am aware that Classic Cycle City offers their unique upgraded/heavy duty primary chains and HERE for the CCC spec sheet as a .pdf, but they're a bit pricey -- currently $335 a set (shipping included) from their eBay store. 
As far as I know this is the ONLY option available for improved CB750 primary chains, and while their data indicates their product is an excellent option, I would like to explore the subject a little further.

With all these things in mind, I have been spending some time trying to speak with folks who are more knowledgeable about chain technology than I about possible alternative options for upgraded primary chains.   Sadly my short list of motorcycle chain reps and other experts have not had much to contribute on the subject. 

When the 'real experts' fail you, its time to turn to the the 'other guys,' and this seems like a good place to start a thoughtful discussion about the SOHC CB750's interior chains.

[mec]

the primary chains had never been an issue in the old sohc750 (contrary to the conrods).
i raced two 1000ccm engines that way....no problems.

before you have to replace the chains, you have to replace 4th gear wheel twice.

new carillos, OEM chains and rubbers and you have done the best to your bottom end.

the camchain is a weak link in the 750sohc however. put in the best you can get (including tensioner and guide).

my2cents

mec

[MRieck]

Get the heavy duty chains and pay to have a mold made to make primary rubbers in the -- range.

[MRieck]

the primary chains had never been an issue in the old sohc750 (contrary to the conrods).
i raced two 1000ccm engines that way....no problems.

before you have to replace the chains, you have to replace 4th gear wheel twice.

new carillos, OEM chains and rubbers and you have done the best to your bottom end.

the camchain is a weak link in the 750sohc however. put in the best you can get (including tensioner and guide).

my2cents

mec

My chains were very loose in less than 5,000 miles. Sam Green can verify that. 4th gear is still OK

[nippon]

I cannot agree.
How many miles did you "race" them?
I have used the stock RK chains four years ago in my K1 with 75hp at the wheel. After 7000 miles the "new" RK chains stretched to 71mm. Honda recommend to replace them at 70mm.
Did not have to replace my 4. gear wheel twice meanwhile. 

Well known that new RK chains start rattling again after 4000 miles.

Mec, i know it's racing, but take your time for an accurate shifting, especially into the 4. gear.  It will last longer.


nippon

[Sam Green Racing]

I think you have to look at the bigger picture here and look at the power that some motors are putting out and the type of use that the motor is subjected to under different conditions.
Although I campaigned the old CR750 in sprint and drag events for three seasons without any problems and only used stock OEM chains, just look at the abuse that Brian Williams (bear) subjects his chains to with his methanol burning 129bhp sidecar outfit. In Brian's case, the gearbox fails well before the primary chains.
If you look what the majority of tuned motors are putting out and the type of use they are subjected too, you will find stock chains are good for quite a few miles up to around 85 bhp.
Push it up to 98bhp as in Mikes case and the chains don't last as long.
In Brian's case, he probably changes his primary when the gearbox fails.
It's horses for courses.
I talked to my chain man a couple of years ago about a decent primary chain for the high performance motors and he said there was a German chain that would be more than up to the job.
I never persued it any further when my rider Chris decided to sell the bike and I went down the automatic route. I will contact him again for prices and performance data if there is enough interest.

Sam.

[MCRider]

Cryogenics may be the in-between. I know its hard to get objective data on things like this. Anecdotal evidence abounds. Its used on trans, dragster crankcases, crankshafts, essentially all metal parts that receive stress from operations. Including chains.

The one example my source liked to keep giving me was the crankcases on a funnycar based here in INDY. They used to get 3 to 5 runs. After cryoing they get 15 to 20 runs. The problem was the cases would go out of true and would have to be line bored. This is a pretty fast turnover of stress exposures, with lots of experience. The testing was measuring a critical area with precision instruments. Not exactly a bona-fide experiment but pretty close. They knew what they had to begin with and what they had after cryoing. AS they would measure after each run.

I've had all my moving parts cryod except the crankshaft and rods, and the fancypants chains I got from ClassicCycle City. The crank/rods combo is already overkill for my engine. I was going to have the chains cryo'd but i couldn't match my assembly schedule with the cryo guys schedule, and those chains are stronger than I'll ever wear out, so i went ahead without.

I did cryo the new HD cam chain, all the sprockets, all valve train, pistons, rings, trans, etc. A lot of sports car guys do it claiming they get a lot more out of their trans which would normally last less than a season.  Google it if you have time.

So, you could buy new OEM chains, have them cryo'd with the hope that you increase their life by 50 to 100% and leave it at that.

Just an unsupported thought. Assuming you don't want to pop for CCC chains.

PS: my prior bike had first an 836, then an 888. Total mileage about 80,000, Mostly heavy laden touring, and I wasn't easy on it. The chains wre at service limit, but more important was the tensioner was trashed, had lost all its ability to tension the chains. That's why it was so noisy. We have discussed Rob/Voxonda's idea of shimming up the tensioner to make it more quiet. However this won't make it last longer, maybe shorter, and that's a big source of chain noise.

[Retro Rocket]

I talked to my chain man a couple of years ago about a decent primary chain for the high performance motors and he said there was a German chain that would be more than up to the job.

Thats probably the chains that nippon has Sam, i have a set and will be buying more, you can tell as soon as you look at them that they are stronger and the spec sheet is very impressive. I think its been posted before but in the interest of this thread could you post the specs for these please Thomas....

[MCRider]

I talked to my chain man a couple of years ago about a decent primary chain for the high performance motors and he said there was a German chain that would be more than up to the job.

Thats probably the chains that nippon has Sam, i have a set and will be buying more, you can tell as soon as you look at them that they are stronger and the spec sheet is very impressive. I think its been posted before but in the interest of this thread could you post the specs for these please Thomas....

In Fang's first post, he provides the links to all of CCCs chain data. Especially in the "HERE" link.

[Retro Rocket]

Thanks Ron, i didn't look at the links ...    I was thinking about the added effect of cryo....

I think the primary rubbers would wear out faster with more horsepower but if you are just changing out the chain for a heavy duty model,  the rubber life should be unaffected

[Sam Green Racing]

I never persued it with my chain man after Chris sold the bike, I doubt it was the same chain that Ted sells as the price was quite a bit less. I'll contact him about them and see what sort of a price he can come up with.
The Cryo Idea makes sense.

Sam.

[MCRider]

Thanks Ron, i didn't look at the links ...    I was thinking about the added effect of cryo....

I think the primary rubbers would wear out faster with more horsepower but if you are just changing out the chain for a heavy duty model,  the rubber life should be unaffected

My mainshaft hub with the primary rubbers in it had discernable play, you could feel the play just buy grabbing one part with one hand and the other part with the other hand and twist as the chains would. It "clicks" with about 1/8 inch rotation. I had a low mileage mainshaft from a parts bike, with no discernable play. Sent it to the cryo to get the teeth of the sprocket treated, as well as the whole shaft. They claim the cryo doesn't hurt the rubber bits, even ORings on drive chains.

I've noticed that KOS has primary rubbers listed for sale, so i guess they wear out faster in a racebike. Don't know how you get in there though, drill and rivet?

[mick7504]

Here is an out of the packet comparison showing an OEM and a HD side by side.
I think that picture says it all. 
Terry and myself were only talking about these just this week. 
Mick

[MRieck]

Cryogenics may be the in-between. I know its hard to get objective data on things like this. Anecdotal evidence abounds. Its used on trans, dragster crankcases, crankshafts, essentially all metal parts that receive stress from operations. Including chains.

The one example my source liked to keep giving me was the crankcases on a funnycar based here in INDY. They used to get 3 to 5 runs. After cryoing they get 15 to 20 runs. The problem was the cases would go out of true and would have to be line bored. This is a pretty fast turnover of stress exposures, with lots of experience. The testing was measuring a critical area with precision instruments. Not exactly a bona-fide experiment but pretty close. They knew what they had to begin with and what they had after cryoing. AS they would measure after each run.

I've had all my moving parts cryod except the crankshaft and rods, and the fancypants chains I got from ClassicCycle City. The crank/rods combo is already overkill for my engine. I was going to have the chains cryo'd but i couldn't match my assembly schedule with the cryo guys schedule, and those chains are stronger than I'll ever wear out, so i went ahead without.

I did cryo the new HD cam chain, all the sprockets, all valve train, pistons, rings, trans, etc. A lot of sports car guys do it claiming they get a lot more out of their trans which would normally last less than a season.  Google it if you have time.

So, you could buy new OEM chains, have them cryo'd with the hope that you increase their life by 50 to 100% and leave it at that.

Just an unsupported thought. Assuming you don't want to pop for CCC chains.

PS: my prior bike had first an 836, then an 888. Total mileage about 80,000, Mostly heavy laden touring, and I wasn't easy on it. The chains wre at service limit, but more important was the tensioner was trashed, had lost all its ability to tension the chains. That's why it was so noisy. We have discussed Rob/Voxonda's idea of shimming up the tensioner to make it more quiet. However this won't make it last longer, maybe shorter, and that's a big source of chain noise.

Cyro treatment does work MC...good point.

[MRieck]

Thanks Ron, i didn't look at the links ...    I was thinking about the added effect of cryo....

I think the primary rubbers would wear out faster with more horsepower but if you are just changing out the chain for a heavy duty model,  the rubber life should be unaffected

Maybe somebody will introduce something a little different then what is out there now?

[MRieck]

Here is an out of the packet comparison showing an OEM and a HD side by side.
I think that picture says it all. 
Terry and myself were only talking about these just this week. 
Mick

God...it sure does.If I remember correctly the new chains aren't heavier. Am I mistaken?

[MCRider]

According to CCC data sheet, they are 14grams lighter. I'll post this and double check.

Doing the math from the specs its 12 g less (pr)
The teext says 14 g.

[MRieck]

According to CCC data sheet, they are 14grams lighter. I'll post this and double check.

No need....I'm sure you are right MC.

[mick7504]

Here is an out of the packet comparison showing an OEM and a HD side by side.
I think that picture says it all. 
Terry and myself were only talking about these just this week. 
Mick

God...it sure does.If I remember correctly the new chains aren't heavier. Am I mistaken?

You're spot on Mike.
I know that I did weigh them and wrote it down somewhere??
This is the info from CCC's site.
reinforced Classic Cycle City chains: 26.18 oz / 742.2 gr. (each 13.09 oz /371.1 gr.)
stock RK chains: 26.60 oz / 754.2 gr. (each 13.30 oz / 377.1 gr.)

[fang]

Thanks to all of you for chiming in on the chains.

 I had a great telephone conversation today with Ted over at Classic Cycle City USA (aka 'Ricky_Racer' here on the forum) .  Ted described how their chains are built strong using high-end modern components and techniques...  Click HERE for the CCC chain's spec sheet as a .pdf  I am impressed, and I believe upgrading the chains is worth the cost.  If you consider that ifyou already were going to pay $90 for a set of NOS chains, the upgraded ones are only $240 more....  doesn't that make you feel better?!

I went ahead and bought a set of CCC's chains, and may get another for the other engine later -- I understand that CCC will offer a small discount to forum members if purchased directly through them w/o eBay fees....
PM Ricky_Racer for details


While I am glad that CCC is making the chains available, and I believe theirs probably are the best option currently available, I do not want this thread to turn exclusively into a sales pitch for their fine products.  I am hoping we can continue to explore and possibly discover additional options which might become available at a less expensive price, or an option that would perhaps drive down the current price of the CCC chains.

Sam, I would be interested if you could learn/share more about the lead you mentioned earlier.

I also would like to know more about cryo treating hard parts to, er, harden them.


Peace and grease,
Steve

[Ricky_Racer]

Thanks for linking to the spec sheet for our chains, Fang. And I did enjoy our telephone conversation today; you're a very knowledgeable and intellectually curious young man. In a wired world where everyone seems to have an opinion without substantiation, your openness and will to do your homework is rare.

Our chains have been rigorously tested in real world circumstances and the results well documented. Few other products available to our small SOHC niche group have been so studied, or the advantages so clear. Perhaps some users have had their OEM chains survive heavy treatment. We have documented testing to support our assertions, not opinions from a limited sampling. Thanks to everyone who has supported our efforts. If anyone has additional questions, please feel free to PM me. RR

[Ricky_Racer]

Just one small point, Steve. We don't price the chains as they are because "we've cornered the market." They are simply expensive at every level. Unfortunate, but true.

The alternative is to do the old traditional approach of CB750 Automatic crank, Hy-Vo chain and GL clutch. In that context, our chains are less than half the price of that old style approach and can be moved from one engine to another.

Some builders may feel that they don't need heavy duty primary chains. As I told you on the phone, I won't personally ever again build an engine without them. They're a wonderful new addition to the SOHC performance arsenal that has heretofore not been available. And we're proud to offer them as an option to our community.  RR

[Retro Rocket]

Now all we need is a better tensioner....

[Ricky_Racer]

I hear ya, (other) RR. Thanks for the nudge...   RR

[BLUE71TURBO]

 Maybe these guy's could make a new tensioner roller out of their new material that they use ...........

         http://www.vansantent.com/usedparts.htm