Wristpin Bearing Upgrade?

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,843
235
63
up north now
What can anyone add?
Anyone done one? thatsdax? Norman?
Tools needed?

I have bushed engine and am contemplating the upgrade.
 

Norman

LORD VADER Moderator
Staff member
Jan 16, 2008
2,605
2
38
67
pampa texas
I will be attempting one soon I plan on making my bushing on the lathe. I want to take the engine completely apart just for the **** of it.
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,843
235
63
up north now
Refresh my memory... does the bushing press out of the rod, or what? How about the bearing going in? Do I do the old heat-the rod-freeze-the-bearing deal?
 

Norman

LORD VADER Moderator
Staff member
Jan 16, 2008
2,605
2
38
67
pampa texas
What my plans are. Press out the bushing from the rod 12 ton press ought to do the trick. I'll make a tool to push out the bushing. Make the bushing out of aluminum or bronze bushing material. freeze the bushing heat up the rod and hope It will almost drop in I will check with my uncle on the correct interference fit or what he recommends for fit and type of material to use or one of the local speed shops and see what they recommend. I've been eyeballing an arbor press at harbor freight its about $40.00 but goes on sale now and then. I'll ream the bushing to size after i get it in place. I might have to make a fixture to do that to get it straight etc.
Darn it I'm talking myself into going out in the shop tonight and start on it.
I've always sent the rods out to a machine shop for these kind of repairs so this will be my first. I hope I don't mess it up.
Norman
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,843
235
63
up north now
Well heck, I'm going to tear into this bushed job and see what there is to see....I'll be reprting back in a couple of days.
 

deacon

minor bike philosopher
Jan 15, 2008
8,117
3
0
north carolina
You guys are a lot more ambitious than me. I play **** just changing a bearing in a wheel. Good luck to both of you.
 

thatsdax

Member
Feb 22, 2008
869
1
16
www.thatsdax.com
the standard bushing type bearing is a different size than the roller. You can not replace the Bushing with a roller. They are a different sizes. Besides,, A bushing can be more reliable than a roller if the proper material is used. You can replace the roller bearing with a solid. But not the other way around. If it were me, and I had problems with too soft a solid bearing, I would consider looking for a harder material and replace the solid with a harder material...Now that all said........... It seems to me that I remember a guy that was selling replacement rollers for those that had bushing. Not sure where he got them. Not sure the guy is still around. It may be that he was able to spec some rollers that fit. Not sure.. o well.. Thats the latest as I know it. Enjoy the ride...:ride2:
 
Last edited:

Easy Rider

Santa Cruz Scooter Works
Jan 15, 2008
2,144
4
38
Nor*Cal
My motor had a bushing when I first bought it. We ended up reaming the rod out (w/ a reamer) and used a Zenoah G43 wrist pin bearing. The quality of these bearings seem to be made better than the stock ones. I knew my bushing was starting to give out when the motor started to vibrating more at high RPMs. Plus I started to lose torque when climbing hills
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,843
235
63
up north now
thatsdax, don't you sell a roller bearing for upgrade on your site? I may be mistaken, but that's why I was gonna tear this baby down. I thought I saw a bearing and I was gonna change the bushing for the bearing...
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,843
235
63
up north now
My bad....I see it DOES NOT say "upgrade", it is a replacement part.

Well, that will save me a little work.

That'sdax, do you have replacement bushings?

I DO NOT suspect it is going bad....BTW how long does this bushing last? What's the highest mileage engine you know of?
 

Norman

LORD VADER Moderator
Staff member
Jan 16, 2008
2,605
2
38
67
pampa texas
I've gave it some thought and I plan on using a bushing. Mine was loose from the get go I think, but it runs good still. needle bearings are good but why do the wrist pin and not the crank? I'm thinking maybe split the crank and have a look at that's in there as well and maybe re bush all with a quality bushing. Then again I maybe blowing smoke out of you know where. I'm going to start today as I might be back to work by tomorrow. My original plans were ride it until it drops then buy a new engine. But I got to liking this engine so I hope to breath more life into it but I might kill it on the sacrificial table to the God of speed. Well a quick look at the rest of the posts then off to the alter. rotflrotfl
Norman
aka Lord Vader( very heavy breathing and the theme song music as I walk to the shop)( and heavy meowing from the walking grease rag Rufus as we waltz off to the shop)
I need to get back to work.
 
Last edited:

Norman

LORD VADER Moderator
Staff member
Jan 16, 2008
2,605
2
38
67
pampa texas
The engine is off the bike and in the stand took 30 minutes to get it off the bike and on the stand now the fun will begin. Pictures will also start. I'll try to show how much slop was in the wrist pin bushing. I'm supprised it didn't come apart. Back to the shop.
Norman
 

Norman

LORD VADER Moderator
Staff member
Jan 16, 2008
2,605
2
38
67
pampa texas
Dax
Have you found that the wrist pin hole is off set in the rod?! Mine is by a few thousands I made a jig so if I replace it I can get it back in almost the same spot. Notice I said almost. The wrist pin has no up and down play. Its still has no slop in the hole but if you take the pin, and push it to one side and wiggle it it will rock about 0.015. This is loose to me but I can't see any wear marks so this must of been that way from the factory as I don't have that many miles on it( mileage unknown) The piston and cylinder still look very good tiny bit of wear on the skirt at the bottom in one little spot. No blow by visible on the piston.
What type of bearing material is your wrist pin bushing made out of. I looked at your site and it says brass. Is it an alloy?
I have taken this booger all apart except for the crank as I would destroy the roller bearing getting them off to split the crank. I can see there is needle bearing on the big end so I don't think I'll mess with it and this crank has no bolt on weights its a 3 piece not counting the main shafts 2 flywheels and a main pin all pressed together best I can tell.
One thing I did find and I don't recommend anyone doing this and that is don't take the clutch pads housing off of the inner drive part its pressed together. When I pressed it apart 10,000 little renegade balls took off to the four corners of the earth and a few even acted like Curly from the three stooges. I had a long Easter egg hunt to find all of them something like 56 or so. What a time I had with that .
I'm really thinking about just putting it back together and running it cause as sure as I change that bushing my edge on Bob's bike will go away. So what do all you guys think I could show how to do the bushing but not actually do it. But what fun would that be, then again if I do I might mess it up and have a ho humm engine. I'm going to look and see what kind of bushings I can find here or stock that I can roll my own out of. that to me is the fun part.
Norman
 
Last edited:

Norman

LORD VADER Moderator
Staff member
Jan 16, 2008
2,605
2
38
67
pampa texas
I called Dax a while ago and learned some interesting things from Duane. I'm going to leave the wrist pin bearing alone as they are not as precision made as I would have liked( what is in my engine and not what he sells) and they are ran a lot looser than I like but what is the way it is. I still want to change it. I'm going on a gasket run and if I find the right bronze bushing stock I'll mess with it. I need to learn to leave things alone, sometimes I can but this is buggen me. I need to get over it. I made most of the tools to take it apart and put it back together again.
Ever have one of these days when you can't decide?! Its killing me. I took it all apart to do this now I'm not or at least I don't think I will.
I do have pictures to show you so I 'll do them soon. If I do need or decide to do the bushing later all you have to pull is the top off and not take it apart like I did. Well day is turning into night so I better get it in gear.
Norman
 

Ilikeabikea

Moderator
Staff member
Jan 27, 2008
2,323
0
36
64
Ptown, Texas
You know you want to Norm. Go for it. You didn't go back to work today. I've heard no wailing and gnashing of teeth......:D......................
 

Norman

LORD VADER Moderator
Staff member
Jan 16, 2008
2,605
2
38
67
pampa texas
Well I got a bushing and then decided not to change it as Duane talked like it was normal for the slop. Any way with the 36 tooth sprocket I will not need to wind it out like I have been doing. I'll wait and maybe do the bushing swap later I now have all the tools and jigs made to change it and the bushing I bought I'm taking back. I do have ideas on some cheap easy performace things now as well after seeing all the insides of this engine. By the way its all back together and running. I ran out of scrap gasket material and I bought some to do the crank case and it was $10.00. I was suppried at the price I almost was going to go to the gasket shop for more scrap but the round trip of 60 miles would cost that in gas.
The gasket for the crankcase is a booger to make and get right I made 4 patterns before I was happy with the results. It got the gasket right on the first try so the extra time was worth the trouble.
Norman
 

deacon

minor bike philosopher
Jan 15, 2008
8,117
3
0
north carolina
I never could get a crankcase gasket made. I used some gasket seal and let it go at that. I wanted to keep the dust out not enter it in a bike show lol. I sure hope it works for that.
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,843
235
63
up north now
Norman-

You probably know this, but next time if you want to make a troublesome gasket, spary some contact cement on the gasket material, then lay the old one on it. If you only spray it on one side, it's easy to peel the old one off and it doesn't move when drawing the pattern.