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Author Topic: Engine upgrades?  (Read 2063 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.
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Offline 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.
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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 »

Offline napoleonb

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Re: Engine upgrades?
« Reply #36 on: February 13, 2019, 01:24:21 pm »
After the gear the axle itself was ready for a makeover, reducing the overall weight off the axle by a little more than 1/3.
« Last Edit: February 13, 2019, 01:50:17 pm by napoleonb »

Offline kmb69

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Re: Engine upgrades?
« Reply #37 on: February 13, 2019, 06:47:10 pm »
Nice, Nap!

Offline 754

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Re: Engine upgrades?
« Reply #38 on: February 14, 2019, 12:52:48 am »
 Did you cast your own brake pedal. . I see it in the background..
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Offline napoleonb

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Re: Engine upgrades?
« Reply #39 on: February 14, 2019, 01:36:49 am »
That's indeed a homecast brake pedal, but for a CR110 we did some CR750 parts as well like the clutch perch and pedals.
Ronald Groenendijk from GRP (http://hondaclassicracing.blogspot.com/) does al the actual casting, i made some of the specific moulds.
We did also make some CR110 clutch components for a side project of mine.

Offline MessnerMoto

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Re: Engine upgrades?
« Reply #40 on: February 14, 2019, 03:27:50 am »
Exceptional level of details. I am just concern a little bit with how long this will last :)

Offline napoleonb

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Re: Engine upgrades?
« Reply #41 on: February 14, 2019, 03:42:40 am »
I did some preliminary strength calculations and it should be fine, that's part of the reason why i kept the support side in the clutch cover relatively long.
The axle itself will be stationary and the forces directed onto the gear by the clutch and oilpump are minimal.
So if there is some sort of excessive load (debris in the pump) the axle will deflect a bit but the gears will still make contact.

Offline MRieck

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Re: Engine upgrades?
« Reply #42 on: February 14, 2019, 06:30:56 am »
 I think that will be plenty strong enough.
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Offline scottly

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Re: Engine upgrades?
« Reply #43 on: February 14, 2019, 03:49:20 pm »
What is the actual weight savings from your kick-start delete mods in grams? 8) 
Don't fix it if it ain't broke!
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Offline napoleonb

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Re: Engine upgrades?
« Reply #44 on: February 14, 2019, 11:18:09 pm »
The shaft savings are about 135 grams (or close to that) if memory serves me right.
I will weigh all the parts this weekend and check for the overall savings.
Somebody ones told me that unspring weight counts double and rotating mass triple, so the "real" savings are in the gear and not the flange and axle.
« Last Edit: February 14, 2019, 11:21:37 pm by napoleonb »

Offline napoleonb

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Re: Engine upgrades?
« Reply #45 on: February 17, 2019, 04:11:37 am »
I weighed the adapted parts and compared them to the original weighing's, first value is the old one
Adapted parts:
Shaft 314.9g > 223.9g = -91g (29% actual savings)
Gear 548.3g > 409.6g = -138.7g (25% actual savings)
Flange 152.5g > 68.1g = -84.4g (55% actual savings)

Deleted parts:
Pawl kickstarter -9.3g
Spring kickstarter ratchet -2.0g
Spring kickstarter return -88.3g

Added parts:
Grub screw for positioning the axle tbd
Plug to close the clutch cover tbd

So in total I think this solution is about 380-400g lighter when finished (removed 413.7g)
But besides the actual static weight savings, the rotating mass is reduced considerable imo without weakening the part for its intended function in my engine.
« Last Edit: February 17, 2019, 04:18:08 am by napoleonb »

Offline MRieck

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Re: Engine upgrades?
« Reply #46 on: February 17, 2019, 05:31:51 am »
 Where will you be putting the grub screw?
Owner of the "Million Dollar CB"

Offline napoleonb

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Re: Engine upgrades?
« Reply #47 on: February 17, 2019, 06:12:23 am »
I was thinking about grinding a small flat on the shaft and drilling/tapping in the lower crankcase.
This surface isn't normally being sealed so it should work fine.

Probably not all that necessary but I want to positively eliminate any chance of the shaft rotating and losing the gravity fed lubrication to the gear.
Now that I think of it if I can make a small hole in the shaft and use a stepped grub screw I can eliminate the pesky roll pin which weighs more than the screw...
« Last Edit: February 17, 2019, 06:57:46 am by napoleonb »

Offline MRieck

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Re: Engine upgrades?
« Reply #48 on: February 17, 2019, 05:48:20 pm »
That's pretty much what I figured. I have thought about what you have done a number of times over the past15 or 20 years....glad you actually did it as I have always been wrapped up in other stuff.
 My next....and probably my last incarnation of a CB engine will incorporate this removal of the kick starter
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Offline slikwilli420

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Re: Engine upgrades?
« Reply #49 on: February 17, 2019, 07:11:40 pm »
Absolutely no reason for that grub screw. The shoulder on the shaft goes against the inside of the clutch cover and prevents any movement.
All you gotta do is do what you gotta do.

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