Topic: Heavy Duty primary chains from M3...

[lordmoonpie]

To sum this all up...we are a racing team and company that has travelled all over the world to race the best and are constantly striving to go faster, make more HP and win races. Doing this, we break parts, we improve them, we break other parts..on and on.

And this is exactly what it's all about and why people like Mark are good for our sport and our hobby. Not everyone has the resources to experiment and change things making them better until they work, it's a time and money consuming process but at the end of the day, it's us little guys that benefit from the technological advancement.

I have to say, I'm going to continue with my version of the Hy-vo system (mainly because I have a beautifully balanced and lightened crank that uses it and if it was good enough for M3 to go to datona with, it's more than good enough for me  ) and I'll see what the results are. If things go awry, I know where to come for the upgrade.

Just as a matter of interest - has anyone tried running a true duplex chain instead of two single chains. I've seen duplex chains running on some of the older classics as final drive chains but running a duplex as a primary may give more strength and even wear rate - any thoughts?

[kos]

It is all the run Down Under in Classic series...ALCOHOL.

Mark @ m3

[MRieck]

As for his HP 1200cc's on achohol...140 at crank is not unrealistic, and he has the benefit of running that big 1200cc engine at much lower RPM and that helps with the Hy Vo chains living longer. 8000-8500 RPM is a lot beter than 10,500-11,000.

Mark @ M3

I agree....at the crank especially with alcohol. You can run a bit more compression too which certainly helps (until you get to much engine braking but than there's a slipper clutch to rectify that problem). Rex's 1200 must produce good torque #'s which would, again, help reduce the need for big RPM's when racing.

[HondaMan]

Just as a matter of interest - has anyone tried running a true duplex chain instead of two single chains. I've seen duplex chains running on some of the older classics as final drive chains but running a duplex as a primary may give more strength and even wear rate - any thoughts?

I had the discussion with DID many years ago, when they were offering a dual-row drive chain for the 750. It seems the spacing between the sprockets on the crank and clutch are just right to disallow use of a dual chain. What whould have had to happen was an extra plate of a non-standard thickness, or all of the plates made up of a much greater thickness, to make the roller spacing come out right.

When you look at the mechanics of the dual-row chain, it's apparent that this style will also introduce harmonic vibration. While I'm impressed with Honda's 1960s designers, I don't think this particular item was on their mind at the time: I think the cost of 2 cheap single chains was more likely the guiding factor for the design.

[voxonda]

Think the, extra, weight of a duplex chain will not contribute to a longer life of the primary drive. Have driven with a 1/2" duplex secundairy drive chain, back when there were no O- or X-ring chains and the chains, although had a better strength, they did not last longer. The weight of the sprockets did not help either, fot the rubbers on the transmission damper in the rear wheel had a hard time, also the front sprocket gave the bearings a hard time, specially if things where not lined properly. Must have a photo of the set somewhere.

[speedracer741]

Also, I have worked with a guy from Indiana that builds sawed off (ie: no gear box) CB750 SOHC engines on alcohol that run in TQ midget cars. He runs at 836cc (12.5/1 compression) and dynos at crank 118-120 HP. He has a comination of 71mm bore with 52.8mm stroke that bhe was going to try, but I never heard how far he went with this, but I'll check on it and come back if there are any details.
Mark @ M3

Mark:
Is this an older guy (like me) with a backburn (maybe still) and bald top, named "Jeff" or "Jack" (or something with a "J"), who was also doing this with these engines in the early 1970s? If so, I know him, but he was in southern Illinois then. I helped build a 16,000 RPM version of one back then for a midget car.

I think he might be talking about Randy Literal of Literal Racing in Fortville, IN. I bought some 14:1 alcohol Arias 836 pistons and Falicon rods from him a few years back.

[bwaller]

Here is that Rex Wolfenden article from Old Bike Journal.....1997, so it's way out of date, but I thought it might be an interesting read for some. Thanks to scondon for the coaching, and if like me you can't read it here, don't ask me how to fix the damn thing 

[754]

I looked over the parts today, and both crank and hub were in phase.

But the clutch hub sprocket teeth can move independent of each other  .. easily, you can push one with your finger!

At the time way back when I noticed one chain tight on top the other on the bottom, I concluded that Honda figured a way to keep contant tension on the assembly. No idea which year motor I saw that in or how many miles were on it..

[scondon]

..... and if like me you can't read it here, don't ask me how to fix the damn thing 

"The undisputed king of Australia's flourishing Post Classic roadracing class is the K&W Honda CB110R of Melbourne-based bike dealer Rex Wolfenden. Actually, the king could be any one of the 10 clones of his original CB750-based high-barred roadracer that the 40-something former motocrosser and Aussie Rules footballer has been persuaded to build for chums and customers since he started sweeping the big-bore Post Classic honors aboard his own bike in the early '90s..... "

   Just need to fix the wingnut in front of your computer Brent. Yer aaaaalllllllmmmoooooostttt there

[bwaller]

I hear u seanman! 

[Terry in Australia]

It is all the run Down Under in Classic series...ALCOHOL.

Mark @ m3

Ha ha, that's very true Mark, what we can't drink we put in our bikes! The Phillip Island Classic is on this weekend, and last year the air was so thick with the smell of a combination of Alcohol and Castrol "R" fumes, that at times it was getting hard to breathe!

Give Rex a call on 011 61 3 9457 5411, I'm sure he'd love to have a chat. Cheers, Terry.

[kos]

Thanks for that number...I will call him today.

KOS

[nippon]

Hi,
we just want to give you some more detailed informations about the reinforced primary chains.
We, the Classic Cycle City, LLC. is the exclusive distributor of the high performance primary chains discussed in this thread.
Compared with the CB750 OEM primary chains, please take a look at the pictures below.
Finally, a primary design limitation on the racing SOHC CB750 has been lifted with a cost-effective
essential component that is easily installed and duplicable over any number of engines.

Technical background:
These chains are newly developed using state of the art technology. The two important benefits of our new chains are

Improved max. fluctuating tension:
precisely manufactured seamless bushes and stronger bolts.
These chains have a higher load capacity and offer more reliability against chain breakage in high performance engines.
Better wear behavior due to larger joint surface and extremely wear-resistant surfaces of bushes and bolts.
Chain stretch is minimized over the whole engine life.
These high performance chains are used in highly stressed chain drives of diesel engines. Besides high forces,
these chains are also abrasive stressed by diesel particles. These chains are designed for lifetime durability
(no exchange).
The stock chains (by RK) are the state of 1968, designed for use in gasoline engines.

fluctuating tension:
The important factor in chain breakage in engines is the maximum fluctuating tension, not the maximum tensile strength. The tensile strength in general is a multiple over the maximum occurring forces in an engine. Chains do not break because the tensile strength is exceeded, but because of material fatigue due to excess fluctuating tension.

weight each chain:
stock  chain:      377.1 gr / 13.302 oz   
reinforced chain: 371.1 gr. / 13.090 oz !!!

Please address requests for information to info@ClassicCycleCity.com.

BTW, we have just have finished our adjustable primary chain tensioner prototype,
fully adjustable from the outside of the oil pan.
Things come together.
       
nippon

[nippon]

...more details

nippon

[HondaMan]

Wow, very cool!
I can say for sure that the 50,000 miles on a CB750K engine does some mighty long stretching of the chains. My own experience has been that in particular, the outside chain stretches about 2% in 50k miles, while the inside chain is a little over 1%. They always stretch unevenly in the stock chains, due probably to the alignment issues of the mainshaft vs. the crank, at high RPM.

[lordmoonpie]

Nippon - any pictures or details of that primary chain tensioner prototype? Sounds very interesting...

[UnCrash]

Wow, very cool!
I can say for sure that the 50,000 miles on a CB750K engine does some mighty long stretching of the chains. My own experience has been that in particular, the outside chain stretches about 2% in 50k miles, while the inside chain is a little over 1%. They always stretch unevenly in the stock chains, due probably to the alignment issues of the mainshaft vs. the crank, at high RPM.

Maybe that's what the unpleasant noise from the bottom of my F3 motor is.  Could be a stretched cam chain too...

[nippon]

Yes, it is very interesting, Pics not yet in the thread. But after the first tests we can say, ...you never heard a quiter CB750 engine. Rattle is gone completely and it will never come back,...it's adjustable. Stay tuned, the primary chains with the tensioner is a very fine combination. Of course the chains alone are a big improvement and they are quiter too.

nippon

[Gamma]

mmmmm!   bit late for this motor, maybe on my next one then!!!

[mrosso]

Nippon, can we get some info on price and availability?

[nippon]

Sorry, I did not see it before.
Price per pair is $ 370.00 incl. Free shipping to SOHC members.
(You can use them almost forever).
We only have the last two sets in stock.
New production will last up to 8 or 10 weeks, but only in case of interest.

nippon

[Retro Rocket]

Hi Nippon, how is the tensioner coming along?

Mick

[nippon]

Hi,

currently, we are trying to replace the two seperate ball bearing nitrated sprockets in the cage with a chain guide in order to lower the costs of production with equal functionality. So, we are working on the perfect shape of the chain guide.
Within the next two weeks, I try to upload a movie / soundfile of our test K2 with the chains and the tensioner (sprocket version). You won't believe it, that you hear no primary chain rattle anymore.  Just a quit,......'sssssssssss'. 

nippon

[cben750f0]

man i a sooooo,looking forwad to this..

great work Mate

peace

[Retro Rocket]

Interesting, i would still like to know how much the sprocket version is...

Mick