Topic: 1978 CB750K — Post 836 OIL PRESSURE - not good

[seanbarney41]

What I have done in the past is have the raised portion ground off on one side by a machinist...grinding works better than milling as most sprockets are case hardened

[seanbarney41]

did not know that the standard 530 early sprocket would grind the case, was just worried about sprocket alignment and full thread engagement of the front sprocket bolt

[SKTP]

Sorry If I was not clear. My 630 Sprocket was on the wrong-way-round and was grinding.

I have not successfully converted to the 530 set-up due to the 1976 sprocket not fitting. I may have to grind the 1976 one, if the "conversion" one doesn't fit. Will know later this week/weekend.

[seanbarney41]

ahhhh, that makes more sense

[madmtnmotors]

The CB650 (79' or 80' I think) front sprocket in 530 pitch matches the thickness/shoulder as the later CB750 630 pitch front sprocket. Check the dimensional diagrams for both on JT sprockets page. I am using the 530 pitch front sprockets for the CB650 on my K8 CB 750's. Rear sprockets are easier to figure out, but some sprocket makers have resorted to "dishing" the center section making them thinner and more difficult to tighten securely before the nut bottoms out on the unthreaded portion of the sprocket mounting stud.

[SKTP]

Thanks...I will investigate

Why can't I find a 530 "Clip style" master link?

[madmtnmotors]

Thanks...I will investigate

Why can't I find a 530 "Clip style" master link?

You're welcome, but I can't take credit for the discovery. I think it was a post by Jerry RxMan that pointed me towards the CB650 sprockets. As for the master link, I noticed most chains were the rivet type as well. I just ordered extra rivet links and bought the riveting tool just in case I wanted to remove the chain without having to remove the swingarm. The tire/wheel can still be removed while leaving the riveted chain intact so I'm good with it.

[Tintop]

Most clip type 530's are for 'O'ring type chains.  A quick Ebay search also showed some for non o-ring chains.

[SKTP]

I bought the fancy DID X-ring...Can't find anything...I guess it will be the Rivit type

[754]

Your 630 only fitting one way is a surpise to me, i thought they were flat.

Regarding the 76 sprocket I THINK IT should fit.
 I used a  72 or 73 sprocket on a 77 motor back in about 81.
 Now the middle may be wider, not sure what I did there, doubt that I ground it. I may have added a washer so the stock one did not dish inward when I tightened it.
 After a long time running it I realized it made the back sprocket out of line..

[SKTP]

The 76 is definitely wider that the drive shaft...if that makes sense? It would need one of the LOBES or whatever they are called ground down as discussed above. That's the solution if the "conversion" one I just bought today won't work.

Here's how I have my 630 PHOTO BELOW. IT IS WRONG. SHOULD HAVE BEEN FLIPPED...I asked the forum 2 years ago, but I guess I didn't understand or make it clear....it's all good either way..I will figure this out. Next is electronic ignition...wish me luck

http://forums.sohc4.net/index.php/topic,68423.msg1765442.html#msg1765442

[Jerry Rxman Griffin aka MuthaF'er]

The CB650 (79' or 80' I think) front sprocket in 530 pitch matches the thickness/shoulder as the later CB750 630 pitch front sprocket. Check the dimensional diagrams for both on JT sprockets page. I am using the 530 pitch front sprockets for the CB650 on my K8 CB 750's. Rear sprockets are easier to figure out, but some sprocket makers have resorted to "dishing" the center section making them thinner and more difficult to tighten securely before the nut bottoms out on the unthreaded portion of the sprocket mounting stud.

+1. The 650 sprocket only has a shoulder on one side. I did the same on my 75 CB750F parts bike with a 78 K engine (as well as later model pieces behind to make up the offset.

[madmtnmotors]

The 76 is definitely wider that the drive shaft...if that makes sense?

Yes, the 76' has a raised shoulder on both sides. I have used them (before I learned of the CB650 sprockets) by using a 2mm thick washer under the larger washer. The bolt still wants to work loose with that setup though.

Here's how I have my 630 PHOTO BELOW. IT IS WRONG. SHOULD HAVE BEEN FLIPPED

True. The later model 750 with the 630 chain only has a shoulder on one side and should face inward with the flat side out. The CB650 sprocket in the 530 pitch will have a shoulder on one side only as well.

[754]

The one shown in the pic is aftermarket.
 I have a new one kicking around did not remember seeing the bump.

Like I said I first converted one around 1981, and probably added a spacer behind the washer.

Back to the rubbing problem, the lip looks like around 2 mm. Did it cause chain rub on the case, or sprocket rub against the seal boss.
 It certainly does not hurt to give everything a spin after you assembled it to make sure you got clearance .
 I hope you are happy with the bike now..

[SKTP]

Ok..here's what arrived today. I still need to measure it but the guy a bought it from over the phone measured it.

Can I use this? I would put the spacer between the motor and the sproket (as the shoulder). I have found the CB650 sprocket online and it appears to be what I was after to begin with...Would having a spacer be really loud or do damage to the case?

530 with the spacer:




and here's the CB650 530 sprocket...seems just liek what I now have but with the shoulder/spacer built into it


Slowly figuring this out

EDIT: Link to the rear tire thread http://forums.sohc4.net/index.php/topic,172567.0.html

[SKTP]

530 chain conversion complete (DID 530VX)...that was MUCH more difficult than expected. I will add all the details later but It took ordering 3 different front sprockets before finally getting one that worked (the CB650 one was too wide despite what the online specs said) I ended up using one I had the guys at http://sprocketspecialists.com/ measure for me... I CANNOT BELIEVE HOW MUCH BETTER MY BIKE SOUNDS!!!! The chain noise before was insane...I had no idea how quiet a chain could be. Very happy I switched.

Now I need become a master of adjusting it.

[SOHC4 Cafe Racer Fan]

I CANNOT BELIEVE HOW MUCH BETTER MY BIKE SOUNDS!!!!

Thumbs up. Should be super quiet (now). Now ride the living jeepers out of it!

[SKTP]

https://4into1.com/electronic-ignition-kit-dynatek-honda-cb750-1969-1978/

I bought this. Doubt I can install it until 2 weekends from now....hoping it fixes my Lag issue when I really lay on the gas...

[SKTP]

Ok..here's what arrived today. I still need to measure it but the guy a bought it from over the phone measured it.

Can I use this? I would put the spacer between the motor and the sproket (as the shoulder). I have found the CB650 sprocket online and it appears to be what I was after to begin with...Would having a spacer be really loud or do damage to the case?

530 with the spacer:




and here's the CB650 530 sprocket...seems just liek what I now have but with the shoulder/spacer built into it


Slowly figuring this out

EDIT: Link to the rear tire thread http://forums.sohc4.net/index.php/topic,172567.0.html

Just thought I would update if anybody else is converting from 630 to 530....that CB650 530 sprocket JT sproket was too wide (says 10.7mm but it was like 11.2 or something). It was not with in the spec listed on that diagram...I returned it and used the one with the separate spacer.

[Bankerdanny]

https://4into1.com/electronic-ignition-kit-dynatek-honda-cb750-1969-1978/

I bought this. Doubt I can install it until 2 weekends from now....hoping it fixes my Lag issue when I really lay on the gas...

I don't see why it would. Throttle response is typically a function of how fast the fuel delivery can ramp up in response to added air from opening the throttle. The EI might improve starting and overall smoothness, but if you have a flat spot I can't see how a new ignition would really improve that.

[Rnobx67]

Super, You are going forward quick !

[SKTP]

Wow! I don't know what was wrong with my bike before...but the new coils and electronic ignition has made a DRASTIC improvement. It pulls like never before!!! Extremely happy!!!

[algophobe]

Wow! I don't know what was wrong with my bike before...but the new coils and electronic ignition has made a DRASTIC improvement. It pulls like never before!!! Extremely happy!!!

i just switched from the pamco to the dynatech today on my K2.. i agree, it sounds more solid... even though i haven't finished the timing yet.

[goaarongo]

Just thought I would update if anybody else is converting from 630 to 530....that CB650 530 sprocket JT sproket was too wide (says 10.7mm but it was like 11.2 or something). It was not with in the spec listed on that diagram...I returned it and used the one with the separate spacer.

I'm in the middle of doing this too - Thanks for posting about it.  I just emailed the site you mention. 
I'm actually dropping a '78 motor into an earlier model setup.  It's an adventure.

[SOHC4 Cafe Racer Fan]

Wow! I don't know what was wrong with my bike before...but the new coils and electronic ignition has made a DRASTIC improvement. It pulls like never before!!! Extremely happy!!!

Glad that pepped up your engine, Chris!  Nice seeing you last weekend, if only briefly.  Great photos of the races and congrats!