Topic: CB750 AHRMA Sportsman 750 Racer

[Old Scrambler]

Frank is 100% correct ...............nest the outer bearing-journals on two blocks of wood screwed to the box.........then use two more blocks of wood to hold the crank down..........no rattles or slides   Leave room for the rods and some packing material for the return shipment.

[calj737]

I won't if APE re-pack the crank upon return with appropriate accommodations for the rods? Surely they are not novice service people. Their website provides very good guidelines for shipment to them. Might be worth a call inbound to inquire about return shipment packaging.

[754]

Cardboard is fine for normal handling,but stuff gets dropped ..all the time.
And steel of that mass punches thru cardboard real fast.
So if you use it more than once...wood is good..

[Retro Rocket]

I use polystyrene for shipping delicate parts, not the loose stuff thats commonly used, I use polystyrene blocks, I cut the block in half , cut the shape of the part into the poly, put the part into the cavity in the poly, its relatively easy to get a good tight fit, tape the two halfs together securely , then put it into a nice thick cardboard box, I quite often use large carboard sheets to make my own boxes if its a critical part, I did this not that long ago to send a set of old style Yoshimura prepped CR31 ticklers, the buyer was impressed with the packing and unless run over by a bulldozer, its almost impossible to damage. {although there's always someone that will go out of their way to try  }   Mike Reick uses a similar method to ship engine parts....

[gschuld]

http://crankworks.com/index.php/shipping/how-to-ship

Worth a read...

George

[slikwilli420]

Got the cases split today and pulled the crank, marked the bearing halves, pulled the rods and started cleaning.

Going to build a box to ship the crank and Cycle X rods off to Cycle X for lightening, balancing and rod install this week.

Regarding bearings, does everyone generally replace all of them? Is there a source for a whole set? CMSNL has them piecemeal but was hoping for the set.

Once the crank comes back the trans will go out and that pretty much does it for the bottom end.

[754]

Cant sell as a set, because there are many different combinations..

[MRieck]

CB750 main and con bearings are available in the USA no problem.

[slikwilli420]

Looking for the roller bearings for the trans, not the crank/ rod bearings.

[Haybus]

I just got an email from CycleX about trans bearings. I would call them.

Alan

[slikwilli420]

I will get with Cycle X and see what they have. I need to order some other bottom end goodies anyway. I did find a fantastic article on replacing the trans bearings in a '76F which should be the exact same as my '77 engine, but I will make sure to use part numbers from '77 just in case. Here is the article:

https://wrenchandspanner.wordpress.com/2014/12/16/cb750f-transmission-bearings/

It seems like a simple enough process and that will give solid piece of mind when this thing is humming along at 10 grand.

[slikwilli420]

Well the crank has been separated from its home and is packed (very well I might add) and off to Cycle X to be lightened/balanced and have the Cycle X rods installed.





As I dig deeper into the lower end, what do I need to replace and what is just a nice-to-have?

I am definitely planning on the following:
- total oil pump rebuild
- oil seals throughout
- primary chains
- primary chain tensioner
- undercut trans

Things that I don't know if they are necessary:
- lower end roller bearings - how do I tell if these are still good aside from spinning and listening
- drive rubbers behind the clutch

Anything else that falls into either category that I am forgetting?

[754]

HayZuez..that is a box... Bombproof.... A bit bigger than i would have built.
 Takes the worry out of sending it away.
 I usually listen/feel the bearing while slowly turning it...look for roughness or irregular feel.
And sideplay..no excessive play. And no corrossion.

[bear]

In my opinion cush drive rubbers should always be replaced in a competition motor.

Cheers,
Brian

[Retro Rocket]

In my opinion cush drive rubbers should always be replaced in a competition motor.

Cheers,
Brian

With the better rubbers now on offer too....

[slikwilli420]

Any sources besides Cycle x?
In my opinion cush drive rubbers should always be replaced in a competition motor.

Cheers,
Brian

With the better rubbers now on offer too....

[Retro Rocket]

Any sources besides Cycle x?
In my opinion cush drive rubbers should always be replaced in a competition motor.

Cheers,
Brian

With the better rubbers now on offer too....

I'm pretty sure Brian gets his rubber dampers here I Australia, I'm sure he'll chime in soon. There is also someone who sells a complete kit for the dampers, maybe in Germany, if I can find the link i'll post it here...

I was wrong, French, not german...

http://forums.sohc4.net/index.php?topic=119730.0

http://honda60-70s.net/Pieces/23110-300-030_GB/23110-300-030_gb.html

[Old Scrambler]

If your motor has the auto drive-chain oiler, I would remove the little tin tray to delete the oil-feed. Although the K7 was an upgrade, others on this site report the K8 shifter-drum is the BEST. I assume you already have the white tensioner components for the primary and cam chains..............and then there is the consideration for stronger gear-dogs for top-gear.

[slikwilli420]

I will definitely be upgrading all the tensioner wheels for primary and cam. When you say stronger gear dogs do you mean undercut or replacement? Definitely getting the gears undercut.

[MRieck]

Any sources besides Cycle x?
In my opinion cush drive rubbers should always be replaced in a competition motor.

Cheers,
Brian

With the better rubbers now on offer too....

I'm pretty sure Brian gets his rubber dampers here I Australia, I'm sure he'll chime in soon. There is also someone who sells a complete kit for the dampers, maybe in Germany, if I can find the link i'll post it here...

I was wrong, French, not german...

http://forums.sohc4.net/index.php?topic=119730.0

http://honda60-70s.net/Pieces/23110-300-030_GB/23110-300-030_gb.html

A French fella Mick.

[Retro Rocket]

Any sources besides Cycle x?
In my opinion cush drive rubbers should always be replaced in a competition motor.

Cheers,
Brian

With the better rubbers now on offer too....

I'm pretty sure Brian gets his rubber dampers here I Australia, I'm sure he'll chime in soon. There is also someone who sells a complete kit for the dampers, maybe in Germany, if I can find the link i'll post it here...

I was wrong, French, not german...

http://forums.sohc4.net/index.php?topic=119730.0

http://honda60-70s.net/Pieces/23110-300-030_GB/23110-300-030_gb.html

A French fella Mick.

Yep, got that Mike....

[slikwilli420]

Here's the scoop gents. I have made peace with the fact that I cannot afford to finish the motor and the bike ahead of my June deadline. I decided to pick up a good street motor do now I can focus on finishing the other aspects of the bike as well as have the cash to buy riding gear and pay for the race class and entry fees.

Question is what should be done to this street motor before it hits the track? I am planning on a full oil pump seal/spring kit and am pondering a cam chain but won't be splitting the cases. Thoughts on a riveted chain?

Anything else?

[Old Scrambler]

Assuming its a K6 or earlier and you will have a few days of admiring the motor while on your bench before you insert it into the chassis................Cam-chain & tensioner kit; F2 or 41A cam; clean up the casting debri and the intake ports; do the oil-pump mostly for peace of mind; remove the anchor on the left end of the crank & shrink the cover (cut the tail off of the crank); maybe remove the electric-starter gear and motor; get 2 or more L-I batteries (1 for backup) and go total-loss ignition; use the best (high-tensil) drive chain; have a spare clutch-pack; tune and race  

[scottly]

Question is what should be done to this street motor before it hits the track?

If it's a relatively low mileage, stock motor in good condition, I wouldn't do anything more than a good tune-up.

[slikwilli420]

Old scrambler , I thought about most of that although am not going to pull the head since it was just assembled.

I hear the 41a really comes alive at higher rpms and would be a good addition do I'm thinking on that one.

All of the charging/starting bits are going away once I get the motor installed and running.

Cam I do a cam chain and rivet the link so I don't need to pull the engine down? At this point that's the only real option for this motor.