Topic: CB 650 primary chain tensionerin in to CB 550 ?

[50BMG]

What is the best way to install the cb650 primary chain tensioner in to the cb550 block ? I can't even find pic's of it installed in the cb650

[Tim2005]

The primary tensioner on the 650 attaches to a lug that does not exist in the 550 cases, so you'd need to weld one in there somehow.

Maybe someone has a pic of the 650 cases that will help?

[paulages]

You can make a bolt-on piece pretty easy. One bolt goes through the case with a copper sealing washer, and the other goes into a hole drilled and tapped inside the case. The bolt with the copper washer here (incidental in this picture and not necessary) is the latter. the bolt on the right holds the tensioner.

[turboguzzi]

hei 50, what about introducing yourself?

if you use paul's solution you will need to use also a 650 sump, the tensioner will touch the shallower 550 sump.

TG

[bwaller]

Because the 650 oil pan is deeper you'll need to modify the 550 oil pickup to maintain the oil feed for the trochoid transmission pump. I think some have used the 650 pickup, (which doesn't have the nipple) but I don't know what happens to that pump without oil.


stock 550 left, 650 right

[paulages]

Because the 650 oil pan is deeper you'll need to modify the 550 oil pickup to maintain the oil feed for the trochoid transmission pump. I think some have used the 650 pickup, (which doesn't have the nipple) but I don't know what happens to that pump without oil.


stock 550 left, 650 right

Excuse me while I think out loud, Brent, but how necessary do you think the deeper pick-up is? Using the 550 dipstick, won't the oil level still be at the same point relative to the pickup screen even with a deeper sump? I thought a lot about this when I put my engine together and reasoned that if anything the heavier sediment in the sump pan would be even farther away from the screen.

The biggest worry for me was that the pick-up would fall out of its hole without some method of retaining, and to be honest... I forgot about it until a few oil changes later when it ocurred to me that I hadn't dealt with the issue. In any case, the O-ring seems to hold it there just fine, and I get the oil feed to the countershaft pump. Of course, one could easily drill a couple holes in the bottom case for a little retainer clip.

[bwaller]

Paul as you know the three "legs" are cast into the bottom of the 650 pan to maintain the pickup distance off the bottom just in case to some it looks like it sits flush. I feared the further off the pan bottom the more the hot oil would slosh, but the biggest reason was to make sure it didn't drop out. With all the fury and heat in the pan I wouldn't take a chance!

You mentioned an o-ring, but the stock 550 piece doesn't have unless you cut a groove for one. I welded in a long neck section from a CB400 part that already used a single o-ring and I figure it helps seal for the longer reach. Another option I suppose would be to braze a nipple into the 650 pickup.

[paulages]

Well now you have me wondering exactly which set up I went with, because I thought I remembered having an oring. I do know this: that little oil line going to the trochoid pump is pretty stubborn to remove on purpose.    In any case, I'll likely try the retainer clip route, though it has held in place quite well so far.

Regarding the hot oil... do you think picking the oil up from that level negates the benefit of a deep sump? more oil= diluted circulation of hot oil either way, right? it's hard to imagine it not mixing pretty fast inside that pan while riding anyway. If it really does stratify into a hotter and cooler layer then the deeper pick up would clearly be better..

[bwaller]

It probably doesn't make much difference. I was thinking of race conditions, hard acceleration & heavy braking, better to have it on the bottom just so the pump doesn't ever cavitate, but you're right the stock piece is emersed in the same amount of oil. The baffle in the 650 pan certainly helps too.

[paulages]

The baffle in the 650 pan certainly helps too.

Definitely. I've seen this trap sediment is well. Ok, I'm convinced... I'l find some way to retain mine or weld in a section like you did before reassembly (if that ever happens..  ).

[CB500Four]

Hello at all!

I have done this modification in the early ninetieths.
It works very well since that time.


This pic shows the situation in the CB650 case.


Here you can see some measurements i have done on a CB650 case.


These are the things you need. An oilpan from the CB650, the tensioner unit and the pickup from the CB650.


I have brazed a nipple to the CB650 pickup. It could be done with a bored mild steel pin.
I have done this on a lathe. It reaches down to the screen of the pickup.


Here the parts are sticked together as they will be screwed into the case.

The tensioner will not fit with the CB500/550 oilpan. It reachs too far down.
Perhaps it´s possible to modify the tensioner at the bottom so it could be used with the CB500/550
oilpan and the CB500/550 pickup.
I haven´t attempted this since yet but i should do it.


Regards, Heinz

[CB500Four]

Here some pics of my modified CB550 case.




Here you could see the modifications on the CB500/550 case which are necessary to bold on
the adapter which will carry the tensioner unit.


Here are the adapter and the tensioner screwed into the case.
 

The adapter should be flush with the sealing surface for the oilpan. The bolt on the left side
which is screwed into the inner lug of the case should be also flush with this surface.
You must sink the bolt´s head into the adapter. If you don´t do that the inner cooling fins of
the CB650 oilpan will collide with this bolt´s head.

I´m on the way to do a little bit better solution.
For that i will post a drawing and some other pictures here.

Regards, Heinz

[paulages]

Funny, I was at the shop last night and it occurred to me to weld in a nipple onto the 650 pick up like you did, then you post pictures of this very thing. You're always one step ahead, Heinz!

[turboguzzi]

guys

built such a motor but cant figure out what you need that nipple for. What am i missing?

TG

[paulages]

guys

built such a motor but cant figure out what you need that nipple for. What am i missing?

TG

The 550 and 650 transmissions have a little trochoid oil pump on the needle bearing end of the countershaft. This little nipple feeds it.

[CB500Four]

Hello TG!

The nipple is necessary to feed the small oilpump on the countershaft in later CB550 engines.
A rubber hose connect the pump with the oil-pickup over this nipple.
The CB500 unfortunately hasn´t this cute little pump which lubricates the gears directly.

Datum/Zeit: Heute um 15:59:06Autor: paulages
Funny, I was at the shop last night and it occurred to me to weld in a nipple onto the 650 pick up like you did, then you post pictures of this very thing. You're always one step ahead, Heinz!

I´m sorry about that, Paul!
Shame over me, i should have posted this thing in my thread many times ago.
But i didn´t   !

Regards, Heinz

[CB500Four]

Uuuups!

Now you are the step ahead, paul!
I´m sorry to correct you, but at one point you are wrong:
The CB650 hasn´t this little pump.
The CB650 feeds the countershaft directly over the normal oil pump.
Below the oil pressure switch of the CB650 oil pump begins
a connection/ oil line to the countershaft mainshaft.

Regards, Heinz

[paulages]

Uuuups!

Now you are the step ahead, paul!
I´m sorry to correct you, but at one point you are wrong:
The CB650 hasn´t this little pump.
The CB650 feeds the countershaft directly over the normal oil pump.
Below the oil pressure switch of the CB650 oil pump begins
a connection/ oil line to the countershaft mainshaft.

Regards, Heinz

whoops! is this the oil passage that prevents the cb650 oil pump from fitting the 550 case?

[CB500Four]

whoops! is this the oil passage that prevents the cb650 oil pump from fitting the 550 case?

Yessir!

But you can grind down the thread for the oil pressure switch
so that the connection to this passage disappears.
Perhaps you must cut the thread a bit deeper, i don´t remember.
It´s a conical self sealing thread.
Then the CB650 oil pump fits to the CB500/550 case.
I have done so.
The CB650 oil pump increases the oil advancement because it´s a bit wider.

Regards, Heinz


 

[50BMG]

Thanks to all for the info It has made my build a little less of a pain in the A** -- At least i stoped banging my head on the work bench.

[Howell]

Why is this all neccessary ?
Do you all have problems with the primary chain tension ?
When the chain is worn out , replace it !

[turboguzzi]

howell, i am running without one too, but it certainly makes the life of the chain easier, less backlash in on-off throttle, less noise, etc., not bad reasons at all actually.

The chain becomes pretty slack after not much use, well before its worn out and its not that much fun opening the cases just because of that.

Lets not even talk about the primary chain cutting through the oil gallery.... mine was touching it already even if the bike was functioning really well.

Just to prove the poitn, both Honda (in the CB650) and kawasaki (in the KZ750) introduced primary chain tensioners as the basic models developed.

So its not a must, but a (very) "nice to have".

[paulages]

Why is this all neccessary ?
Do you all have problems with the primary chain tension ?
When the chain is worn out , replace it !

At $90-100 a chain? Worthy modification in my opinion.

[Spikeybike]

hey heinz , do you have any shots of the other side of this bracket ... looks like a pretty easy mod as long as you have all the parts (witch i do )

[bwaller]

I can hop in here with a pic that shows a bit more although I don't have one of the opposite side of the bracket.

You can see one relief cut, there are two actually to allow the tensioner to sit tight on the bracket. The tensioner itself could have been ground to do the same thing but I didn't want to weaken it any.

Don't mind the screws, this was just to make sure everything fit.

[CB500Four]

hey heinz , do you have any shots of the other side of this bracket ... looks like a pretty easy mod as long as you have all the parts (witch i do )

Hey Spikeybike!

I think you will see the surface side of the bracket which touchs the case.
Unfortunately i haven´t a pic which shows this. And the bracket is build in .
But as i mentioned i will do a drawing of the slight modified bracket.
My shown bracket is made of mild steel but the new one will be made
from aluminium 7075 with a third bolt for fixing in case.

As bwaller mentioned you should not grind the tensioner (perhaps a very little bit).
You must cut a relief in the bracket which meets nearly the shape of the tensioner.


Regards, Heinz

[paulages]

hey heinz , do you have any shots of the other side of this bracket ... looks like a pretty easy mod as long as you have all the parts (witch i do )

Hey Spikeybike!

I think you will see the surface side of the bracket which touchs the case.
Unfortunately i haven´t a pic which shows this. And the bracket is build in .
But as i mentioned i will do a drawing of the slight modified bracket.
My shown bracket is made of mild steel but the new one will be made
from aluminium 7075 with a third bolt for fixing in case.

As bwaller mentioned you should not grind the tensioner (perhaps a very little bit).
You must cut a relief in the bracket which meets nearly the shape of the tensioner.


Regards, Heinz

I used 7075 with the third bolt. It's such a small piece, and 10mm or so thick (if I remember right). Surely the aluminum will be strong enough..

[50BMG]

Would it be better to Heli Arc Weld an Aluminium block in the case rather then drilling -- tapping and bolting

[paulages]

Would it be better to Heli Arc Weld an Aluminium block in the case rather then drilling -- tapping and bolting

Sure, just be careful not to distort the mating surface of the sump pan. The drilling and tapping is not difficult, though welding would remove the hole through the case that needs to be sealed with a copper washer.

[kayaker43]

Anything to take backlash out of the drive train is a good thing. As long as the spring is stiff enough to do that?? I suspect the spring is stiff enough to keep the chain from whipping around but not strong enough to prevent backlash on downshifts.

I wonder about converting to a fixed but adjustable tensioner? Kind of like a manual cam chain tensioner. Shouldn't need adjustment often, and would have a little less drag than a spring. It could eleimnate backlash though..

[cwchan]

how much deeper is the 650 pan compared to the 550?  Any exhaust clearance issues?

[bwaller]

how much deeper is the 650 pan compared to the 550?  Any exhaust clearance issues?

It's about 5/8" (16mm) deeper & yea it can interfere with your exhaust. 

[CB500Four]

Hi there!

Here are the promissed pix an the drawing.
Iwill fill in some lyrics later.

Regards, Heinz

[CB500Four]

Next bunch of pix.  

[CB500Four]

And here is a drawing with some measures.
I hope it will help someone.
As mentioned i´ll do some lyrics later.

Regards, Heinz

[Raef]

Thanks for sharing guys, you are awesome, I will be adding this to my current 550- 650 motor build

Mark

[FunJimmy]

Excellent update Heinz.
Thanks for the shop drawings too.

Looking forward to this mod.

[lukeyb]

Amazing info guys, thanks! I have a loose primary chain and i plan on doing this mod as a fix (i don't have the time or space at the moment to replace).

I am going to drop the engine out of the bike but keep it intact. How did you guys drill the holes in the casing? It look's like there isn't enough clearance to fit a drill in and drill a straight hole.