Update On Oilite Bushing/Bearings Conversions of 4 Stroke Belt Drive

[Deleted Member 4613]

It occurred to me you might be making a mistake in the
assembly of the parts. There should be no 1/4 inch gap
anywhere. The large Oilite spacer washer has to be reamed
just slightly to fit over the Oilite bushing top, so when all
the parts are installed, there is only a 1/16 inch gap
between the spacer washer and the top of the clutch bell
housing. If you read my posts carefully, I mentioned I
had to do this. The 1/16 inch gap is about right. Look
at the video and you can see the gap.

 

[michael whiteman]

Thanks Mike for taking the time to keep me on track. I do appreciate it, but I am definitely 100% on the same page with you in your last two posts. I did go back and look at your video just now. Let me clarify my statement on the 1/4" air gap. The black machined piece that first goes on the Allen head bolt, I refer to as the end cap. I see you have 2 brass washers stacked on top of yours. Now measure the protrusion of the end cap that actually goes inside the Oilite bushing. Next measure the distance from the end of the bushing down to the crankshaft inside. The difference is the "air gap" where there is no support to the bushing. I realize the bushing is trapped against the crankshaft and rotates at the same rpm. I was thinking a new black end cap that reached all the way down to the crankshaft would be a better design from a support standpoint.

I notice, as Jerry did, your large pulley wobbles. Did you ever measure the runout ? My runout is 0.100 and it drags against the clutch bell for about 90* of rotation. I can't imagine the casting being "bent".... I think the shaft bore is not concentric with the machined surface the teeth mount to.

Because of this, I strived to make my clutch assy. be as far inboard toward the block as possible. Installing the clutch on the shaft backwards will move the shoes about 3/16". I installed it with the shoes far inboard. We might have a clutch from a different manufacturer because yours looks backwards to mine. Don't worry about it, really. Next I found a special thickness steel washer to slide on the shaft, followed by the Oilite bushing with the Oilite washer slid over the top. I reduced the O.D. of this washer to clear protrusions on the clutch. There is 0.020" between the outer surface of this washer and any contact point on the clutch itself.

My end cap has only one 0.062" bronze washer which allows the clutch bell (drum) to move 0.050" I feel 0.020" to be more than plenty. The more the bell travels outward the more contact area you loose for shoes. I know , it's nit-picky. My end cap will go a little deeper into my bushing than your set up.

Wednesday I will address the issue of my large pulley kissing the bell. I got a real POS trany with my kit, but I'm gonna make it the best I can, within reason. Thanks for all you help Mike. More to come............

BTW I made a new full length key for my clutch. You wouldn't believe the little one that came with it. It didn't even fit tight in the shaft's keyway, which is a real NO NO. I hope yours is better.

 

[Deleted Member 4613]

The clutch bell does not travel outward due to the closeness of the
two pulleys and the tension on the belt. The 1/16 gap is acceptable.
If there is any movement at all, and it made contact with the spacer washer,
the spacer I selected is an ultra-low friction Oilite oil impreganated washer.
You can add a couple of drops of oil between the clutch bell and the
spacer washer if you like but it is really not necessary.
So you are aware, the original greased brass bushing operates in the same way:
It is locked to the shaft and there is a gap between the flange of the
bushing and the top of the bell housing. The manufacturer applies
grease to the underside of the flange should there be any contact. I
guess you're worried about the part of the Oilite bushing that protrudes
out the top of the bell housing, but it has a spacer washer around it and
I don't see it experiencing much stress. If there was any problem with
the design, I haven't seen it so far. I'm more interested in knowing
how long the Oilite bushing lasts until it runs out of oil, which is now
an unknown. Maybe you have a different motor shaft than mine
which is causing you to invent your own solution. I don't know.

 

[michael whiteman]

We have the exact 15mm crankshaft Mike. I'm questioning the fact we might not have the same clutch. Different Company ? Our endplay is nearly identical and we are both just fine. The air gap I mentioned where the bushing is not supported is located INSIDE the bushing and you have one too. On to the large pulley.................

 

[Deleted Member 4613]

I think I finally understand what you're talking about, but I'm not
sure there is one. The total length of the brass bushing that the bolt
tightens against is 24.8 mm, and the total length of the Oilite
bushing is 25 mm that the bolt tightens against, so if there is
a gap, it is about 0.2 mm. I believe it's a nothingburger issue,
at least on my motor.

 

[michael whiteman]

Unfortunately Mike, I must have not explained this "gap" well enough in the first paragraph of post #22. It was the best I could do.

My clutch installation yesterday works perfectly. I was able to stop the large pulley from kissing the bell by first removing the black steel ring on the rear. Just grab it with vise grips and twist it back and forth, it's a press fit. The teeth are actually machined into the aluminum casting and are not a separately applied component as I had previously thought. There was still minimal kissing going on which I eliminated by placing some emery cloth at that point an spinning the large pulley until it was no longer there. .It still wobbles but the belt tracks well. It tends to track on the small pulley against the bell which keeps that 1/16" endplay on the spacer washer open. Finally I have this running to my satisfaction. It would have been nice had they furnished a second end cap to go in the bore of the large pulley. If I machine a longer one someday for the clutch I will use that one. The belt dragged on the lower portion of the cover with a half inch gap on the top. Unbelievable ! You'd think they could make this fit. After elongating two screw holes and drilling a new one for the bolt the cover fits properly. It'll be a while before my bike is on the road so keep us all informed on how yours is doing.

I'm anxious to see how much extra effort is required to pedal the bike with the engine off seeing as this trany does not have a freewheel. Maybe a tapered shaft engine's 11T drive sprocket with a freewheel will fit our shaft. Something to research for sure.

 

[Deleted Member 4613]

I don't have any contact between the two pulleys. I did ride
the bike several times with the motor off to test the chain
which I was having trouble with. There is some drag caused
by the entire belt drive but not much. Maybe you should bite
the bullet and buy a replacement belt drive from BGF.

 

[kb9ezl]

Here's where I'm at for those interested. I completed the installation of
the Oilite bushing on a Chinese 4 stroke ebay kit and did some initial
testing. So far it looks like a very promising improvement over the
greased bronze bushing - no drive problems at all. I don't know
how long it will last until the bushing goes dry. Some users swear
by these Oilite bushings. All I can do is continue testing and then
inspect the parts after about 100 hours, and report the results. I
intend to make a video of the drive running to show how
stable the clutchbell is when running.

On the bearing solution, I am at a crossroads: The small Avid sealed
bearings I purchased did not fit the motor shaft, although they were
intended for a 15mm shaft. Some small amount
of material would have to be taken off the shaft to get the
bearings on, and I'm reluctant to mod the shaft. On the needle roller
bearing, it is a slip fit over the motor shaft, but I am very concerned
that the keyway groove will interefere with its operation. I could also
envision how the groove would collect grease from the bearing,
and ultimately all the grease would end up in the keyway groove.
It could be that the sealed bearings are the best solution, and on
the plus side, I now know how to easily install them on the drive.
So overall, right now, the best solution seems to be the Oilite
bushing. It's an easy fast mod, and maybe, it could last for a long
time before it has to be re-impregnated with oil.

Amazon has a bunch of oilite bearings available. Measure the ID of the clutch bell and motor shaft. The length can be
cut down and a washer used on the outside. A solid brass one really needs to be coated with high temp grease. You
don't want oil slinging onto the clutch facings. Here's the Amazon link

That bearing only spins freely until the clutch engages against the bell.

 

[michael whiteman]

Thanks for sharing this Mike. Cheaper and faster than McMaster Carr if the dimensions will work.

 

[DieselTech]

Grubee has these back in stock better act quick!