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Author Topic: Engine upgrades?  (Read 1223 times)

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Offline MessnerMoto

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Re: Clutch upgrade?
« Reply #25 on: December 26, 2018, 04:41:17 am »
I'm still collecting parts and info before putting the engine together.
I've got some primary drives, clutch baskets and will use the best of those for refurbishment. Following the tips above I will get new OEM clutch plates, springs etc.
We just got a 2.5D waterjet at work so I might cut some alu clutchplates in downtime :D for giggles and comparison later on.
When I've got the clutch parts redone I was thinking of getting them balanced.

Now I would like some input on the next parts I'm looking at:
The final drive had some versions over the years.
23520-300-020 SHAFT, final driven weighs 396.2 gram (early style hollow axle with chain oiler)
23520-300-030 SHAFT, final driven weighs 462.6 gram (later K version)
I was thinking of using the older type shaft and blocking of the end with a custom machined and staked alu plug to save on rotating mass.

Which bearing do you guys recommend?
91007-300-008 BEARING, ball, special 6305
91008-300-008 BEARING, ball, special 5206
both are listed for these shafts, whereas the first is for a 25mm ID 62mm OD and the thickness is 17mm (which doesn't fit my shaft)
The latter is 30mm ID which fits my shaft but the thickness is 23.8mm, comparable you can buy a 6206 bearing which is 16mm thick but otherwise fits.
Perhaps I have to come up with some special washer for this bearing as well, but that's no problem for me.

Longevity aside a smaller single bearing should reduce drag and alignment issues if I've understood correctly.
Is it worth the hassle?

Here is a link to a page on which I've put some of my CAD models where the later version solid shaft with double row bearing is posted.
https://grabcad.com/library/honda-cr750-cb750r-final-driven-shaft-1

did not know that it was you. Really nice! Is that transmission gears completely accurate?

I can provide you help... I have several scans

« Last Edit: December 26, 2018, 04:45:18 am by MessnerMoto »

Offline napoleonb

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Re: Engine upgrades?
« Reply #26 on: December 26, 2018, 04:47:15 am »
The gear tooths are a guestimate because I didn't bother drawing and calculating the evolute, also I didn't make up for wear as I have no real interest in the gears itself other then calculating rotating mass and general fit and function. So the drawing is accurate enough for my purposes but you cant use it to fabricate gears.

I havent modelled the drum yet (CR750 item is mirrored) so I would like your scans!
« Last Edit: December 26, 2018, 04:49:13 am by napoleonb »

Offline MessnerMoto

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Re: Engine upgrades?
« Reply #27 on: December 26, 2018, 05:19:38 am »
The gear tooths are a guestimate because I didn't bother drawing and calculating the evolute, also I didn't make up for wear as I have no real interest in the gears itself other then calculating rotating mass and general fit and function. So the drawing is accurate enough for my purposes but you cant use it to fabricate gears.

I havent modelled the drum yet (CR750 item is mirrored) so I would like your scans!

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Offline MessnerMoto

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Re: Engine upgrades?
« Reply #28 on: December 26, 2018, 05:38:09 am »
Also one more thing you have error on oil pump assembly. One measurement


it is not 85.77 it is 86... I measured on case, on oil pump and from 3d scan of lower block

but then again maybe I am wrong ;)

Offline napoleonb

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Re: Engine upgrades?
« Reply #29 on: December 26, 2018, 07:03:14 am »
Thanks for the heads-up, I will correct it and reupload the file.
The crankcases are up next so that should have revealed the problem, also gives me an opportunity to redesign the kickstarter gear and shaft.

Offline napoleonb

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Re: Clutch upgrade?
« Reply #30 on: January 04, 2019, 01:49:21 pm »
Does anybody have a good idea what the best solution is in terms of weight and performance?

Now I would like some input on the next parts I'm looking at:
The final drive had some versions over the years.
23520-300-020 SHAFT, final driven weighs 396.2 gram (early style hollow axle with chain oiler)
23520-300-030 SHAFT, final driven weighs 462.6 gram (later K version)
I was thinking of using the older type shaft and blocking of the end with a custom machined and staked alu plug to save on rotating mass.

Which bearing do you guys recommend?
91007-300-008 BEARING, ball, special 6305
91008-300-008 BEARING, ball, special 5206
both are listed for these shafts, whereas the first is for a 25mm ID 62mm OD and the thickness is 17mm (which doesn't fit my shaft)
The latter is 30mm ID which fits my shaft but the thickness is 23.8mm, comparable you can buy a 6206 bearing which is 16mm thick but otherwise fits.
Perhaps I have to come up with some special washer for this bearing as well, but that's no problem for me.

Longevity aside a smaller single bearing should reduce drag and alignment issues if I've understood correctly.
Is it worth the hassle?


Offline scottly

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Re: Clutch upgrade?
« Reply #31 on: January 04, 2019, 09:24:24 pm »
Does anybody have a good idea what the best solution is in terms of weight and performance?

Now I would like some input on the next parts I'm looking at:
The final drive had some versions over the years.
23520-300-020 SHAFT, final driven weighs 396.2 gram (early style hollow axle with chain oiler)
23520-300-030 SHAFT, final driven weighs 462.6 gram (later K version)
I was thinking of using the older type shaft and blocking of the end with a custom machined and staked alu plug to save on rotating mass.


I machined an aluminum plug for the oiler. For even less weight, enlarge the hole on the inside end, where the OD is greater than at the splined end, and thread it for a plug: air is lighter than oil.
Don't fix it if it ain't broke!
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Offline Old Scrambler

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Re: Engine upgrades?
« Reply #32 on: January 07, 2019, 04:54:12 pm »
If you remove the small oil-tray just below this shaft when you have split the cases for any internal work, you will no longer have oil available to the shaft unless the bike is laying down.
Dennis in Wisconsin
'64 Triumph Cub & '74 Honda CB750 Bonneville Salt Flats AMA Record Holder (6)
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Online PeWe

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Re: Engine upgrades?
« Reply #33 on: January 08, 2019, 02:48:00 am »
If you remove the small oil-tray just below this shaft when you have split the cases for any internal work, you will no longer have oil available to the shaft unless the bike is laying down.
That little oil tray only supply the chain with, right?

It has another function, hold the shaft in place while assembling the cases with cylinders aiming upwards, as it sit in the bike. Upper case has the final shaft.
CB750 K6-76 1005cc JMR Billet block.
CB750 K2-75 stock looking project started 2017

Offline napoleonb

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Re: Engine upgrades?
« Reply #34 on: January 08, 2019, 01:34:03 pm »
I don't want to risk the oil getting out unless through a breather box and catch so I will be plugging it anyway.
As I disassembled the enige the metal tray wasn't there anymore so I'll have to check if its worth buying and installing it or just leave it and fiddle some more when bonding the crankcases together.

Offline napoleonb

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Re: Engine upgrades?
« Reply #35 on: January 13, 2019, 11:54:35 am »
I wont be needing the kickstarter so the ratchet could be removed.
While I'm already at it I decided upon removing any excess material from the flange and gear. (that gear surface is really hard...)
The shaft will be modified later on by shortening and welding the clutch cover shut.

To prevent the shaft from rotating I will also be installing a grub screw in the crankcase.
This was normally done by the spring in the flange and a positive stop in the crankcase
For additional oil flow to the gear I made the hole a little larger and made a groove to aid the oil entering the gear from above.
(the hollow shaft will receive oil from the bearing next to it and disperse it to the bottom of the gear bushing)
« Last Edit: January 13, 2019, 12:22:37 pm by napoleonb »

 

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