Heavy duty hyvo primary chain

[Orcade-Ian]

Tried using the search facility without success and unless I dreamt it, someone posted a link to a source of a heavy duty HYVO primary chain (was it for a Kawasaki?). I'm doing my spare 350/4 engine and thought I might try one - not sure why really as a new genuine Honda one will easily see me out!   

Ian

[K2-K6]

Mentioned in here and reference to Bryan.

Thought it was a like for like unit not HD, just cheaper through Kawasaki supply line in comparison to Honda.

https://www.sohc.co.uk/index.php/topic,29234.0.html#msg280031

[AshimotoK0]

Might have been this link but check with Bryan.

https://www.motorcyclespareparts.eu/en/kawasaki-parts/920571011

[XS850]

This is what I used - 920571011 from MSP (I may have had to shorten it but can’t remember!) - New Year memory lapse - it was of course the cam chain I had to shorten not this primary (that would have been difficult to say the least!!).
Bruce

[K2-K6]

I completely forgot to put the link Ash 

[Laverda Dave]

It is a like for like replacement but as previously stated it's half the price of the original Honda part.
 I used one in my 400 rebuild and it's absolutely fine. I purchased mine from Daytona Motorcycles, it did have to be ordered in but was here within three days.

[Orcade-Ian]

Thanks for the link and info chaps, I'm probably mixing HD with cam chains, not primary - another age thing, no doubt.  This is technically a spare engine anyway, although it was the one that came with the bike and appears on the V5c.  Didn't change it in case I ever got round to doing this one and swapping back.

Ian

[Bryanj]

Yup 350,400,500,550 all same but change the damper rubbers in primary drive
I get chain from Fowlers and dampers from Nurse Julie.

Its not HD just half the price and cheaper as genuine Kawasaki than a pattern Tourmax from other sellers

[Orcade-Ian]

Thanks Bryan,
Everything is just about ready for assembly, so I'll get those bits ordered.  Bloody cold in the workshop today but might warm up soon!

Ian

[Seabeowner]

Been using the Kawasaki chain for 9 years, but only about 6000 miles and all good. Recently built an engine using the best parts of two and I readily moved it on to that engine. It is used in much more powerful bikes right up to the late 90s, but they may have had a tensioner.

[K2-K6]

They're more or less heavy duty in design spec, particularly for the 350/400 installation.

Some of their attributes and limitations aren't readily apparent in casual observation though.

The bearing pins, along with the holes they run in, are quite smal in surface area. Oil replenishment and its film strength being critical to longevity.

Originally developed to run in 5 viscosity transmission oils, are pushed into compromise a little in these engine oil applications.  Because of restricted access into and out of the bearing sites, any impediment effectively starves those of competent lubrication. That resulting in the oil breaking down its film strength (shearing capacity) to both wear and overheat the pins.
Oil flow and low fuel dilution (shear performance reduction) are the prerequisite needs to give long life.
They are in effect self tensioning as the tooth form change along with centrifuge action causes them to moderate their own excess movement and generally not flap around. This effect part of their original designation as "silent" chain type, before development by Borg Warner into the more common usage for transmissions generally, named by them I believe as "HyVo" installation.

Ideally they'd use lowest viscosity engine oil in bringing it closer to the Auto transmission fluid they developed it with for high speed applications.  But other restrictions apply here in our shere of regime operation.  Cleam undiluted oil though, eminently sensible for all,engine function.

[AshimotoK0]

Interesting that the 1968 CB750 prototype that is up for auction at Mecum this month had a Morse / Hyvo primary chain drive....description not entirely correct as the CB750 SOHC Automatic had a Morse / Hyvo primary drive.

https://www.mecum.com/lots/1157654/1968-honda-cb750-prototype/

https://www.cb750prototype.com/

https://www.cb750prototype.com/parts

[SteveD CB500K0]

Gosh.

Expected sale price?


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[AshimotoK0]

Gosh.

Expected sale price?


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My estimate is £250-£500k

[Orcade-Ian]

Hi Ash,
Thanks for that link, very interesting!

Just for fun I've copied the link to the 3x CBX man here in Orkney - he likes rare stuff with pipes on both sides🤓

Ian