Topic: High Performance PRIMARY Chain tensioner for CB750(MessnerMoto)

[MessnerMoto]

After first version of primary chain tensioner was testing my bike I redesigned primary tensioner. First version works but after testing I noticed that there is two much curvature in guides because of two extra links in chains.

The problem is that top guid in first version has to much curvature and chain is transmitting all the power in tight side(upper part between crank and primary drive sprockets in cb750 configuration. Because of that fact and big curvature in upper guide friction is increased in upper guide. It will last but not for more than 10000km. Thats not good enough for me... So I redesign i primary tensioner with stock number of links and with durability in mind and keeping original idea of eliminating oscillations from primary chains.

The new version has a slight curvature in upper guide but enough to eliminate oscillations and also to last more than 100k km. And also chain is nor supported all the way with guides.

And of corse material for the guides is the best you can buy. PA 46

This version on pictures has 4 M6 bolts but production version will have 2 M8 bolts. The only modification necessary  for installation of production version will be two 8mm holes in upper block. You also don't see in pictures custom made springs etc... There are more parts that are part of the kit.

This will go in my engine next week.


INSTRUCTIONS:

Upper Chain guide Instructions

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PART2 - Manual Adjuster

[Old Scrambler]

Very Interested............Is the estimated life longer than the expected life of standard chains? My new OEM chains wore out in approximately 200 miles of high-rev work (8-11,000 rpm) in my C.B.R. and the OEM tensioner with a replacement wheel froze in place somewhere in the last 50-miles. New HD chains and a tensioner are needed by next May to re-assemble the motor.......I'll keep watching your progress

[MessnerMoto]

This should outlast several times OEM tensioner. In any condition. Thats a reason why I engineered new tensioner.

I will offer this tensioner setup next week. There needs to be at least 10 people willing to buy in order for me to produce it.

If there is no interest I will be the only one to benefit

[wannabridin]

I'm always interested in producing small suppliers, especially with HIGH quality products such as yours.  Also, one of the main themes to my VERY long build is to upgrade wherever possible to be as reliable as possible and survive any upgrades to performance I do (within reason).

Anyways, please let use know the price and I might just have to throw some money at you. 

[simon#42]

how does this control the chain slack when the torque is reversed ?  from the pictures it looks very like the original design and that is the originals biggest failing  .

[MessnerMoto]

how does this control the chain slack when the torque is reversed ?  from the pictures it looks very like the original design and that is the originals biggest failing  .

The biggest mistake in original design is the use of chains instead of gear drive.

This is not like original. Completely different.

In chain drive there is always slack side and tight side. That depends in what direction torque is applied and which gear is driving gear.

When you down shift torque is reversed. Thats why in modern engines(that use chains to drive something, nowadays it is only camshafts) there is always curved guides on tight side also for when torque changes direction, torque oscillates  etc...http://auditimingchainproblem.com/img/4point2EngineTimingChainProblemSteps/step0301DiagnosticPart3DSC0854.JPG and tensioner(nowdays oil pressure controlled) is always on slack side

Curved guides prevent chain from oscillating, because curved guides artificially introduce tension in "expected" direction. And chain breaks not because slack(any chain drive needs to have desirable amount of slack, ->google) but because of violent resonance oscillations in chain that creates fatigue failure points in chain.

Honda introduces top guide in DOHCs but they still at that point did not understand benefits of curved guides.

If you look my solution both guides are curved and also important thing they follow chain path all the way eliminating any potential points for oscillation to develop. Picture is added to demonstrate added curvature.

[MessnerMoto]

Very Interested............Is the estimated life longer than the expected life of standard chains? My new OEM chains wore out in approximately 200 miles of high-rev work (8-11,000 rpm) in my C.B.R. and the OEM tensioner with a replacement wheel of PA6 froze in place somewhere in the last 50-miles. New HD chains and a tensioner are needed by next May to re-assemble the motor.......I'll keep watching your progress

please people stop using PA6(it is white in color) in hot engine oil environment. That material is not made for that environment and it will fail fast

[madmtnmotors]

Subscribed!

[simon#42]

your solution still allows the chain to get slack on the top run during deceleration , it does not look much better than standard . why not do away with the spring and design a positive manual or automatic adjuster ? 

[MessnerMoto]

your solution still allows the chain to get slack on the top run during deceleration , it does not look much better than standard . why not do away with the spring and design a positive manual or automatic adjuster ?

I think you haven't read what I wrote in previous post or you don't understand what I wrote or don't have understanding of how modern chain drive tensioners work. Please exactly state what is wrong in my previous post where I explained how my chain tensioner works.

And I really don't see how this looks like original two you. I think you should start by drawing on paper how chain travels inside the original drive. Let just start by pointing that OEM tensioner system does not have top guide. And than lets go to point that OEM tensioner shoe is wheel pressing chain in one point. My version has a long guide on slack side supporting chain almost all the way from sprocket to sprocket. Also lower tensioner guide will pick up any slack developed during down shifting. But this goes in to deeper analyses of how forces are transferred in chain drive system.

There is a version that is already in my engine. And it is tested and there is no rattle coming from engine or as you call it slack... when you accelerate hard down shift hard etc. Now it has 3000km. Much much better then OEM. Please search this part of forum you have discussion and pictures.

This is upgraded version

Also spring is automatic adjuster. I designed and made special springs for this version. Also I don't recommend putting bolt adjusted tensioner. It is easy to ruin bearings... and like I said chain drive needs to have a little play in tensioner.

[Old Scrambler]

My mistake..........or bad assumption.........I corrected my earlier post regarding PA6..........my tensioner wheel is white but not of that material.........the center shaft is what failed/froze.......the wheel was fine until then.

[simon#42]

yes i have read what you wrote in a previous post , and yes i did understand what you wrote , i also do understand how modern chain drive tensioners work . i just think this is not a proper solution to the problem .
you cannot control the chain when the torque is reversed with your tensioner . 

[slikwilli420]

How much we talking here Mirko? That would be a nice addition to my cam chain tensioner.

[MessnerMoto]

How much we talking here Mirko? That would be a nice addition to my cam chain tensioner.

Not sure. There is a lot of parts here involved. I need to get a quote from four shops. I will inform interested people as soon as I get rough number.

[RAZZ]

Hi mirko im temted here, but is it correct, I Will need special chains  aswell ? (I already new CC HD chains on the shelf, waiting for my new engine build)


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[MessnerMoto]

Yep you need HD chains in OEM length... 68 links. So no special chains expect they need to be straight plated

for those who don't have "HD" chains... they can buy them here

https://www.ebay.com/itm/Steuerkette-SWAG-30-93-9962-/161555573484?rmvSB=true

100eu for a pair.

[eli]

Mirko, I'm in again.
eli

[Tracksnblades1]

Will these chains work with your tensioner. Just got them from Germany, I believe they are Yamiya HD primary Chains. Considerably more expensive too.

Maybe you could design (dream) a two stage spring tensioner. One that holds correct tension for acceleration torque and a higher second stage spring that prevents rapid tensioner travel (over travel) on de-acceleration torque. And since I'm dreaming, one that maintains (repositions) those stages automatically (ratcheting stop?) during the service limits of the primary chains.

I'm hoping you get that primary gear Idler perfected with some back lash shims and alignment shims provisions. With Three parallel shaft planes in the alignment game, it would be convenient to be able to adjust (compromise) accordingly if Honda didn't have their game hat on when boring in parallel planes.

While this wouldn't eliminate your Idler gear from experiencing side loading during torque and torque reversals (if the Honda bores were not quite parallel). it may minimize some side loading by halving any bore errors.

I'll be in for your cam chain guide. I'll read your post on your oil pump rotors and do a single shipment purchase.
 
Thanks for your efforts.

https://www.ebay.com/itm/Honda-CB750-SOHC-K0-K1-K2-K6-K7-F3-Heavy-Duty-Reinforced-Primary-Chains-CR750/163261038083?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649

[scottly]

It will last but not for more than 10000km. Thats not good enough for me...

No, that's not very good at all; an OEM chain and tensioner in a stock bike can be good for over 256,000km, as documented by a member here. Perhaps you should do some testing on the new style before going into production?

[MessnerMoto]

Will these chains work with your tensioner. Just got them from Germany, I believe they are Yamiya HD primary Chains. Considerably more expensive too.

Maybe you could design (dream) a two stage spring tensioner. One that holds correct tension for acceleration torque and a higher second stage spring that prevents rapid tensioner travel (over travel) on de-acceleration torque. And since I'm dreaming, one that maintains (repositions) those stages automatically (ratcheting stop?) during the service limits of the primary chains.

I'm hoping you get that primary gear Idler perfected with some back lash shims and alignment shims provisions. With Three parallel shaft planes in the alignment game, it would be convenient to be able to adjust (compromise) accordingly if Honda didn't have their game hat on when boring in parallel planes.

While this wouldn't eliminate your Idler gear from experiencing side loading during torque and torque reversals (if the Honda bores were not quite parallel). it may minimize some side loading by halving any bore errors.

I'll be in for your cam chain guide. I'll read your post on your oil pump rotors and do a single shipment purchase.
 
Thanks for your efforts.

https://www.ebay.com/itm/Honda-CB750-SOHC-K0-K1-K2-K6-K7-F3-Heavy-Duty-Reinforced-Primary-Chains-CR750/163261038083?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649

https://www.ebay.com/itm/Honda-CB750-SOHC-K0-K1-K2-K6-K7-F3-Heavy-Duty-Reinforced-Primary-Chains-CR750/163261038083?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649

those chains are completely the same like this one.

https://www.ebay.com/itm/Steuerkette-SWAG-30-93-9962-/161555573484?rmvSB=true

you just over paid them

I wanted to try to make separate tensioner for each chain... there is no space in cases.

ratcheting is bad solution. Harley implemented this in there primary tensioner several years ago... completely destroyed chains and guide. You can not account for thermal expansion etc... In order to work ratcheting need to go also the other way. A lot of Harley primary failure topics on internet because of this...

I made custom spring for tensioner from thicker wire. 2.9mm tick wire in OEM, in mine it is 3.8mm. Several times stronger. It can be stronger because it is spreading the load on 8-9 links. Combined with upper guid it will minimize the "slack" how people are calling this

It will last but not for more than 10000km. Thats not good enough for me...

No, that's not very good at all; an OEM chain and tensioner in a stock bike can be good for over 256,000km, as documented by a member here. Perhaps you should do some testing on the new style before going into production?

Testing was done if you read it in first post. I am not a Audi or GM... to invest 100 000 $ or millions in testing some parts... I do extrapolation testing.

I am doing the best for what people will want to spend on this. There is no money here. This is not a product that will be sold in thousands and make me reach. I am enjoying designing new part and solving existing problems. Side benefits is that people from SOHC community will benefit from my work.

 If you want to enjoy this bike and drive it all over the range and in all the conditions. OEM will not last long. If you race OEM system(cam and primary) it will last several races top. Or in some cases it does not last one race. I have seen now probably 10 cb750 engines apart. All way below 100k km. Haven't seen one tensioner/chain in good reusable condition. But if you get from your bike and push it on the street it can probably go 1M km

[PeWe]

My stock primary chains had increased their slack to 67.5mm (from 65.0mm new) when measure as the Honda manual describe. This after around 35.000 km. I doubt they should have done 35.000 more to reach service level of max 70mm when measure slack. This with 836cc mostly used as a tourer. The first set replaced after 65.000km stock engine. Those chains rattled.

My new K2 build got these chains, not as strong as above but stronger than stock. Correct lenght 68 links. The design look exact as those chains CycleX sells
https://www.autoteileprofi.de/bmw-ersatzteile/5-e39/10025/10511/steuerkette

I could do that thanks to the very technical TS MessnerMoto's thread where this was imvestigated and published
http://forums.sohc4.net/index.php/topic,154183.100.html

The old rotten/hard cush rubbers in primary hub not to be forgotten.

[Tracksnblades1]

Sorry Mirko,

I was only dreaming. Not of the Harley type Rachet adjuster either. More of a variable rate or two stage spring assembly that just the spring assembly could compensate for chain and substraight wear and not impede or limit total tensioner travel. The lighter stage spring would address the harmonics you describe in detail and wouldn't lend to accerated sub-straight or chain wear. The second heavier spring rate, only to slow or dampen the sudden torque reversal shock the chain transfers to the tensioner assembly when it becomes the tight side.

Probably all here have witnessed an out board spring loaded chain adjusters used in various other applications and their reactions to sudden torque reversals.

 Without installing a camera in the cases, it's all theoretical conjecture based off of available known knowledge-technology and their applied failures.

My own thoughts, as mentioned above, the original tensioner design (Honda Idle Noise Bandaid) and location on the outside of the chain circle can only effectively address acceration torque slack.

 With space being the killer, I think the compromise may lie within the chain circle where both torques could be addressed.

All dreams are unique and some like me have trouble expressing what we visualize. You have taken yours to reality. I believe your on top of your game and will succeed within the restrictions Honda has placed. I will be patient and quietly watch (gear Idler too).

Thanks for your efforts

[MessnerMoto]

Sorry Mirko,

I was only dreaming. Not of the Harley type Rachet adjuster either. More of a variable rate or two stage spring assembly that just the spring assembly could compensate for chain and substraight wear and not impede or limit total tensioner travel. The lighter stage spring would address the harmonics you describe in detail and wouldn't lend to accerated sub-straight or chain wear. The second heavier spring rate, only to slow or dampen the sudden torque reversal shock the chain transfers to the tensioner assembly when it becomes the tight side.

Probably all here have witnessed an out board spring loaded chain adjusters used in various other applications and their reactions to sudden torque reversals.

 Without installing a camera in the cases, it's all theoretical conjecture based off of available known knowledge-technology and their applied failures.

My own thoughts, as mentioned above, the original tensioner design (Honda Idle Noise Bandaid) and location on the outside of the chain circle can only effectively address acceration torque slack.

 With space being the killer, I think the compromise may lie within the chain circle where both torques could be addressed.

All dreams are unique and some like me have trouble expressing what we visualize. You have taken yours to reality. I believe your on top of your game and will succeed within the restrictions Honda has placed. I will be patient and quietly watch (gear Idler too).

Thanks for your efforts

Thanks for your support. I will try to explain why I think I addressed some of the issues with my solution.

When you "power downshift" there is no torque reversal... Typical scenario when you prepare bike for a corner etc...
In a race, driver will never/'try not to' get his bike in a position where there is a torque reversal. One can conclude that weakness in OEM primary chain system, regarding the racing, does not come from torque reversal. So my system will address all the weak spots in OEM system in racing conditions.

When you "coast downshift" aka. break with engine... down shift, close the throttle and let the bike slowdown.. torque will reverse but torque amplitude will be several magnitudes smaller from the torque that engine can produce.

I agree that my system does not solve second scenario perfectly but addresses it. Firstly buy introducing artificial slack in upper side of the chain by curved guide. That curved upper guide will also absorb oscillations introduced by torque reversal. Secondly by designing lower guid with big sliding area I was able to put spring that is several times stronger than OEM spring because big sliding area reduces friction and lower shoe will not wear out. This much stronger spring is able to cope with change of slack lower chain side to lower tight side of chain, by not allowing that lower side looses to much curvature and by that not allowing slack to form in upper side of chain.

Maybe I am wrong, and this is not perfect solution, but from first 3000km I can say it is definitely much better then OEM system.

[scottly]

Testing was done if you read it in first post. I am not a Audi or GM... to invest 100 000 $ or millions in testing some parts... I do extrapolation testing.

The way I read it, the testing was done only on the first version, and since you have yet to install the new version, it hasn't been tested in actual running conditions. Please don't take what I hope to be constructive criticism the wrong way; I think you have some good ideas..

[simon#42]

Sorry Mirko,

I was only dreaming. Not of the Harley type Rachet adjuster either. More of a variable rate or two stage spring assembly that just the spring assembly could compensate for chain and substraight wear and not impede or limit total tensioner travel. The lighter stage spring would address the harmonics you describe in detail and wouldn't lend to accerated sub-straight or chain wear. The second heavier spring rate, only to slow or dampen the sudden torque reversal shock the chain transfers to the tensioner assembly when it becomes the tight side.

Probably all here have witnessed an out board spring loaded chain adjusters used in various other applications and their reactions to sudden torque reversals.

 Without installing a camera in the cases, it's all theoretical conjecture based off of available known knowledge-technology and their applied failures.

My own thoughts, as mentioned above, the original tensioner design (Honda Idle Noise Bandaid) and location on the outside of the chain circle can only effectively address acceration torque slack.

 With space being the killer, I think the compromise may lie within the chain circle where both torques could be addressed.

All dreams are unique and some like me have trouble expressing what we visualize. You have taken yours to reality. I believe your on top of your game and will succeed within the restrictions Honda has placed. I will be patient and quietly watch (gear Idler too).

Thanks for your efforts

Thanks for your support. I will try to explain why I think I addressed some of the issues with my solution.

When you "power downshift" there is no torque reversal... Typical scenario when you prepare bike for a corner etc...
In a race, driver will never/'try not to' get his bike in a position where there is a torque reversal. One can conclude that weakness in OEM primary chain system, regarding the racing, does not come from torque reversal. So my system will address all the weak spots in OEM system in racing conditions.

When you "coast downshift" aka. break with engine... down shift, close the throttle and let the bike slowdown.. torque will reverse but torque amplitude will be several magnitudes smaller from the torque that engine can produce.

I agree that my system does not solve second scenario perfectly but addresses it. Firstly buy introducing artificial slack in upper side of the chain by curved guide. That curved upper guide will also absorb oscillations introduced by torque reversal. Secondly by designing lower guid with big sliding area I was able to put spring that is several times stronger than OEM spring because big sliding area reduces friction and lower shoe will not wear out. This much stronger spring is able to cope with change of slack lower chain side to lower tight side of chain, by not allowing that lower side looses to much curvature and by that not allowing slack to form in upper side of chain.

Maybe I am wrong, and this is not perfect solution, but from first 3000km I can say it is definitely much better then OEM system.

I take it you have never raced a bike then , if you had you would know that you do exactly that entering every corner . It's known as engine braking .
Congratulations you have designed a solution for a problem you don't understand .