Two Stroke Motocross

Two Stroke Motocross Forum => Technical => Topic started by: lauterbacher on December 15, 2012, 07:01:17 PM

Title: Will this work?
Post by: lauterbacher on December 15, 2012, 07:01:17 PM
I have a vintage 125 Can Am, And litterally there are no oversize pistons available from anyone. Can Am used a 18mm wrist pin on there 125 bike after there first year. I can use a modern piston such as a YZ 125 with a 15mm wrist pin if I make a 3mm steel bushing to take up the space of the 18mm wrist pin. Oh and I have checked and there is no such wrist pin bearing made that would take up the space. Question do you think this would hold up? I could probably send it off to a person who does crank work and have a 15 mm top end rod put on but at some point I have to say enough of trying to keep this motor going. Thanks
Title: Will this work?
Post by: 2T Institute on December 15, 2012, 08:00:59 PM
NO bodges just swap the rod, the needle roller bearing needs to run on a hardened surface you bush would last a matter of minutes.
Title: Will this work?
Post by: TMKIWI on December 16, 2012, 04:56:11 AM
Quote from: 2T Institute on December 16, 2012, 04:00:59 AM
NO bodges just swap the rod, the needle roller bearing needs to run on a hardened surface you bush would last a matter of minutes.

x2

Check what rods are available with your crankpin size and a 15mm small end.
Even if the length is longer you can raise the cylinder to suit.
Is the piston crown to wrist pin dimension the same with the YZ as the Can am ?
Title: Will this work?
Post by: 2T Institute on December 16, 2012, 10:09:22 AM
Can Am is beautiful engine and any time you want to sell it let me know. They have a 22mm crank pin 110mm length so a RM 125 post 05 or KTM 125. Piston IIRC has a 22mm comp height so just about ANY 125mx  piston will be fine, depending on your bore size.
Title: Will this work?
Post by: VintageBlueSmoke on December 16, 2012, 11:51:21 AM
Quote from: 2T Institute on December 16, 2012, 06:09:22 PM
Can Am is beautiful engine and any time you want to sell it let me know. They have a 22mm crank pin 110mm length so a RM 125 post 05 or KTM 125. Piston IIRC has a 22mm comp height so just about ANY 125mx  piston will be fine, depending on your bore size.

Being a Can-Am guy...

X2
Title: Will this work?
Post by: 2T Institute on December 16, 2012, 12:39:49 PM
Can-Am is a brand the engine is pure Rotax. ;D
Title: Will this work?
Post by: SachsGS on December 16, 2012, 03:06:16 PM
Rotax (was a division of Fichtel & Sachs) is now a division of Bombardier.

I have 2 Can Am (Rotax  ;)) disc valve engines. I'll see if an old Sachs 1251/ piston is compatible.
Title: Will this work?
Post by: SachsGS on December 17, 2012, 12:47:56 AM
Sachs 15mm.
Title: Will this work?
Post by: SachsGS on December 17, 2012, 01:08:24 AM
2T might skin me alive for this but could a guy bore/ream the piston from 15mm to 18mm and use buttons to locate the wrist pin? I've seen this sometimes in older Rotax sled engines. :-X
Title: Will this work?
Post by: lauterbacher on December 17, 2012, 02:52:45 AM
Is the 110 rod length measured ctr to ctr of the rod ends?
Title: Will this work?
Post by: Helmut Clasen on December 17, 2012, 06:38:11 PM
Quote from: lauterbacher on December 17, 2012, 10:52:45 AM
Is the 110 rod length measured ctr to ctr of the rod ends?


I had great luck when I send my Con.rod problems on our SACHS engines to the company : CVTech in Thetford Mines Quebec.
www.CVTech-AAB.com
I think they can do anything and everything on any engine.
Great in NICASIL plating too....
They deal with WOESSNER piston Germany .
Title: Will this work?
Post by: 2T Institute on December 17, 2012, 08:39:56 PM
Quote from: SachsGS on December 17, 2012, 09:08:24 AM
2T might skin me alive for this but could a guy bore/ream the piston from 15mm to 18mm and use buttons to locate the wrist pin? I've seen this sometimes in older Rotax sled engines. :-X

How do you put the circlip grooves back in?
Title: Will this work?
Post by: Jeram on December 17, 2012, 11:25:28 PM
the teflon buttons are common in four stroke drag bikes, but the worry with them is what is stopping the bottons from moving and catching on one of the ports???? that is a big danger.

for around 250-300 bucks you can just get a custom piston made, Id imagine this is the cheapest option as once you pay 150 for a new piston plus 200 for the modifications you will be out of pocket
Title: Will this work?
Post by: SachsGS on December 18, 2012, 03:38:06 PM
If a new rod is put in the motor (30+ year old motor, probably needs it) a guy should make sure the ring locating pin (s) on the new piston won't snag on a port.

In the case of the wrist pin buttons one should check if the wrist pin rises enough to interfere with the transfer port. I pulled apart a used sled of mine once only to discover that at one point in the sled's life the wrist pin had somehow walked over and scarred the cylinder wall. While the damage was ugly, because it was below the level of the transfer port it didn't affect compression.

A guy could sleeve the rod small end. A steel sleeve with a plated i.d. would work I think. One would have to calculate the tolerances for the bearing o.d., light press fit and plating thickness but if a guy didn't want to split the cases it could be done. A lot of the earlier 2Ts just had a bronze bushing for the small end.
Title: Will this work?
Post by: lauterbacher on December 19, 2012, 07:53:58 PM
I was going to go with the boring out of the piston and the plastic retainers but it won't work with my port setup. I'm still thinking of trying a bushing and having it made of 0-1 heattreatable tooling steel. I am getting the machining for the bushing for free and I will do the heattreating my self. A $900.00 dollar vintage bike is not worth a new rod and a total of about $300.00 dollars for crank work. This vintage thing can get old fast.
Title: Will this work?
Post by: 2T Institute on December 19, 2012, 08:48:04 PM
A new rod is $90 off ebay and rebuilding a single cylinder crank is a $50 job. Will be worth something in the end if done right where as a box or broken bits with bodgy fixes is worth nothing.
Title: Will this work?
Post by: lauterbacher on December 19, 2012, 10:28:51 PM
2T your putting the knife into me. I'll check out e-bay. and I'll see if there is anyone who does the $50.00 crank work
Title: Will this work?
Post by: SachsGS on December 19, 2012, 11:56:08 PM
2T is right but sometimes when you get boxed into a corner a little creativity goes a long way. If you go the bushing route I'd (light interference fit) bush the rod small end rather then try to machine a sliding fit bushing for the ID of the 18mm wrist pin bearing.
Title: Will this work?
Post by: beaner on December 20, 2012, 01:03:41 AM
I'm assuming you tried the Can-am Yahoo message board, Can-am Chris from England, Al Roberts, or vintage parts 4you?

FYI INA makes a 15 X 18 hard inner race

http://www.amazon.com/INA-IR15X18X16-Needle-Bearing-Precision/dp/B007D38NRE

It's not the best option, but I've done crazier things  ;D
Title: Will this work?
Post by: lauterbacher on December 20, 2012, 02:49:47 AM
Thanks beaner , I've been down that road and it is to narrow. It needs to be 22 mm wide. Yes I've checked all the sources. I'll find out next week after Christmas about a complete MX 1 lower end that has the 15 mm crank in it. I'm just pondering of weather to bag the 125 or go for the 250 which has all the parts for many years.
    There was that time when money flowed a little more and I would'nt hessitate about putting a new rod in it. But I'm trying to have more patience and weigh out
the future of this bike. Thanks again
Title: Will this work?
Post by: VintageBlueSmoke on December 23, 2012, 10:46:22 AM
I would be remiss if I didn't suggest you call Tony Murphy Rotax Inc. 27701 Largo Vista Rd. Valyermo, CA 93563 (661)944- 1624 Fax (661) 261-9227 Email: tmurphy440@aol.com. He has all the Can-Am knowledge bottled and is a super nice guy to talk to. He has most engine items ON THE SHELF and he packages and ships everywhere.
Title: Will this work?
Post by: 2T Institute on December 23, 2012, 11:38:27 AM
Sheeeeiiiit I forgot all about Tony. I'll back that His Rotax knowledge is unsurpassed.
Title: Will this work?
Post by: lauterbacher on December 23, 2012, 05:51:03 PM
Yep I talk and buy from tony when I need parts, He has no over size 125 18mm pistons and as for the others I've talked to no one else does eithier, He has 2 or 3 standard sized 18 mm.
     Tony does though have over size 15mm pistons, so it looks like a new rod and piston after the first.