Topic: Bent timing advancer shaft

[C5paul]

Has anyone else had a difficult time finding a replacement points "advancer" shaft for the CB650/750 engine? Bikes that fall/crash/slide on the right side often damage the shaft. The last time I was at my friends salvage yard I saw at least 6 bikes with damaged parts.

I am machining a timing shaft for the CB650 and discovered that it is fairly close in shape to the CB750. Last month my friend tried finding one and really had a tough time. He teased me that I should make one for him. Would it be worth the effort to make a replacement shaft that fits both engines?

Road racers please speak up 

[bjbuchanan]

For the simplicity of the shaft design you could support an affordable 'cult' following of the shaft replacement. You wouldn't get rich but it would be a nice thing to have. They get tweaked pretty easily

[Davez134]

I had a hard time finding one for my last bike.  Ended up someone here had a spare. I agree probablly not a lot of money to be made, but  it would be nice to have a source for them!

[C5paul]

Thank you for the feed back. My goal would not to be to "get rich" but since I have to manufacture one for the CB650 anyway, I thought it would be nice to change it a bit and also help out those who bent their CB750 shaft.

The shaft will come with new o-rings since we must use two of them side by side to fit both engines.
We should have them done soon. I will post on here (parts for sale?) so everyone who needs one can order.
They will also be on our website. The part should be inexpensive (under $20).

The CB350-550 use a bolt, but are there other Honda engines that use a thread in stud?

[bert96]

 I bought one at yamiya....


Bert

[C5paul]

 I bought one at yamiya....


Bert

If I converted the 3000 Yen correctly the shaft is about $26. Does that sound correct Bert? If so, I think my target price of $20 would not be out of line. I'm in Wisconsin so at least for U.S. residents the postage would not be bad.

[MCRider]

 I bought one at yamiya....


Bert

If I converted the 3000 Yen correctly the shaft is about $26. Does that sound correct Bert? If so, I think my target price of $20 would not be out of line. I'm in Wisconsin so at least for U.S. residents the postage would not be bad.

There is a place on Yamiya site, in the right vertical column near the top, where you can select currency. Doing so confirms your work, about $26 incl the ORing.

[chewbacca5000]

Maybe you can make one that is slightly more stout than the original?  Less wobble better timing?  If yamiya offers one for $26 I wonder what the total price would be with shipping?

[MCRider]

Maybe you can make one that is slightly more stout than the original?  Less wobble better timing?  If yamiya offers one for $26 I wonder what the total price would be with shipping?

I've ordered several times from them, usually a padded envelope of goodies. S&H runs around $18 to Indianapolis.

Funny thing is, I get Yamiya stuff usually in 3 days. Takes 5+ often to get stuff from Illinois. Like from MotoGrid.com.

[chewbacca5000]

So $44 delivered.  That should give you some wiggle room.  I know from experience if that shaft is bent you are not going to get your 1,4 and 2,3 correct.

[72 yellow]

How easy is it to remove the shaft ?

[chewbacca5000]

How easy is it to remove the shaft ?

Just double nut it and it comes out without too much fuss.

[MiGhost]

A word of caution: Those timing shafts go through the top end oil supply passage in the crank. Any restriction of the passage could cause top end oiling problems.

You may be able to adjust the placement of the o-ring to eliminate the necessity of using two o-rings. Just locate it in the middle area that the two o-rings would take up. Check the oil passage seal carefully.

[scottly]

The shaft will come with new o-rings since we must use two of them side by side to fit both engines.

Huh? Are you trying to make a shaft that fits both a 650 and a 750?? The 650 shaft is both longer and thicker than a 750 shaft in the area that fits into the advancer.

[C5paul]

A word of caution: Those timing shafts go through the top end oil supply passage in the crank. Any restriction of the passage could cause top end oiling problems.

You may be able to adjust the placement of the o-ring to eliminate the necessity of using two o-rings. Just locate it in the middle area that the two o-rings would take up. Check the oil passage seal carefully.

You are correct, and the 650-750 passage is the same (in relation to the threaded end) but NOT the same in relation to the area where the o-ring seals. I am machining a CB650 shaft that duplicates the 750 in length and diameter, except the o-ring placement in different which causes a problem.

If I move the o-ring back far enough to work on the 750, I fear it will cause an oil leak on the 650 engine. I'll take another look at it this week. THANK YOU for mentioning that as a possible option!

[C5paul]

The shaft will come with new o-rings since we must use two of them side by side to fit both engines.

Huh? Are you trying to make a shaft that fits both a 650 and a 750?? The 650 shaft is both longer and thicker than a 750 shaft in the area that fits into the advancer.

You are 100% correct, however, I am machining a CB650 shaft that is the same diameter and length as the 750, so I can install our C5 ignition kits. The CB650 shaft is both thicker, longer, and has a slightly fat area at the end of the shaft.

I am concerned if I make the the 650 o-ring slot too close to the threads it will block the oiling hole, and I don't have a complete engine for test fitting, only 750's.

When we machined the first 650 shaft I pulled the shaft from my 750 just to compare. I was amazed at  how close they are in size. 

These are are easy enough to change with basic tools, as Chewbacca5000 indicated in his reply.

[754]

It's at the end of crank, should not be oil supply problem.. The oil ring just prevents external leaking.
 Often they come out easy, but I got at least one that won't come out..even with aluminum shimmed vise grips near motor end of shaft.. Turning it hard enough that double Nutting would twist the shaft off.

[MiGhost]

The shaft will come with new o-rings since we must use two of them side by side to fit both engines.

Huh? Are you trying to make a shaft that fits both a 650 and a 750?? The 650 shaft is both longer and thicker than a 750 shaft in the area that fits into the advancer.

You are 100% correct, however, I am machining a CB650 shaft that is the same diameter and length as the 750, so I can install our C5 ignition kits. The CB650 shaft is both thicker, longer, and has a slightly fat area at the end of the shaft.

I am concerned if I make the the 650 o-ring slot too close to the threads it will block the oiling hole, and I don't have a complete engine for test fitting, only 750's.

When we machined the first 650 shaft I pulled the shaft from my 750 just to compare. I was amazed at  how close they are in size. 

These are are easy enough to change with basic tools, as Chewbacca5000 indicated in his reply.

If you can get you hands on a crank bearing. You can compare the location of the oil feed hole. If you figure the shoulder on the threaded part as the inside edge of the oil passage. You can then determine the minimum space needed to clear the oil passage.

I would not think that moving the o-ring inward 2-3mm on the 650 would be as much of an issue as moving the o-ring outward on the 750.

[C5paul]

It's at the end of crank, should not be oil supply problem.. The oil ring just prevents external leaking.
 Often they come out easy, but I got at least one that won't come out..even with aluminum shimmed vise grips near motor end of shaft.. Turning it hard enough that double Nutting would twist the shaft off.

If you move the o-ring too far toward the crank, the o-ring would no longer ride on the "sealing" surface of the cases. It would also be right next to (or over the top of) the cross drilled holes.
For removal of the shaft most come right out, and one required mild torch work and vice grips.
 
We had a 650 engine to measure for about an hour, so it's a bit tough to redesign unless I go find another engine.
I know that moving our existing o-ring slot backwards about 3mm would be perfect for the 750, but no so confident that it would still fit the 650 (which is why I made this in the first place).
Back to the junkyard to find a 650 engine to measure! Thank you gentleman.

[scottly]

Sorry, but the differences on the crank end of the shaft simply will not allow a shaft that will properly fit both a 750, and a 650 with your 750 rotor, regardless of the O ring; if the crank end fits the 750, the rotor end would be too short on a 650, as the shaft would be sunk deeper into the crank. If the shaft matches the 650 crank end, the shoulder sits proud of the rotor mating surface.

[scottly]

We had a 650 engine to measure for about an hour, so it's a bit tough to redesign unless I go find another engine.

Back to the junkyard to find a 650 engine to measure! Thank you gentleman.

So you have never fitted one of your ignitions to a 650 before?

[C5paul]

Sorry, but the differences on the crank end of the shaft simply will not allow a shaft that will properly fit both a 750, and a 650 with your 750 rotor, regardless of the O ring; if the crank end fits the 750, the rotor end would be too short on a 650, as the shaft would be sunk deeper into the crank. If the shaft matches the 650 crank end, the shoulder sits proud of the rotor mating surface.

Is that a 650 shaft in the 750 engine?

[scottly]

Yes

[C5paul]

Yes

Both parts are at our machinist right now. I'm fairly sure that we've figured out a way to make our part function in a 750 engine using OEM ignition parts, and still work with our C5 ignition in the CB650 engine. We'd have to trim off about 10mm of shaft for a 750 customer, but the rest of the shaft could remain unchanged.

I should have the parts back later this week. I'll post better pictures so you can see them.

[MiGhost]

Looking into this futher I have to agree with Scottly. It will not be possible to make one shaft to work in both engines.

The problem is the outside shoulder for the o-ring. That shoulder sits against the advancer, and locates the advancer in relation to the crankshaft. This is where the approx 10mm difference comes in. Not at the advancer end of the shaft. For that shoulder to be moved outward on the 750. It would also move the advancer outward away from the crankshaft. It is highly likely that your ignition system also uses the shoulder/crankshaft to locate the trigger wheel. My thought of changing the o-ring position will not work. 

However, As you have already gone throught the process of developing the shaft. It would make sense to make it available as an aftermarket replacement also. I am sure that it would be most welcomed due to the fact that they are nearly impossible to find. Maybe a nice introduction to your ignition system??