CB desert sled - Page 11

Jayrod1318 · 12-10-2012, 03:15 PM

The xr650r sprocket has at least double the surface area on the shaft. the xr650l guys use them on their bikes.

I have no idea if that helps you or not.

Sweet build bTW!

Luke · 12-10-2012, 04:41 PM

Quote:

Originally Posted by MortimerSickle

I think it is likely enough to warrant never using aftermarket primaries again.

It's a moot point, OEM sprockets are unavailable.

jesusgatos · 12-10-2012, 07:42 PM

Quote:

Originally Posted by Luke

Hmmm.... I wonder if it's possible to remove the hardening from the sprocket. That'd solve two problems.

Absolutely. Easy. You should be able to anneal that with a torch or a BBQ or something. Just heat it up and then let it air-cool. Then send it out to have it heat treated after you're done. Hate the idea of custom consumable parts though. Might also try giving any of the custom sprocket mfgs a call?

Zombie_Stomp · 12-10-2012, 09:31 PM

Quote:

Originally Posted by MortimerSickle

I didn't keep track of the time involved, but once it got started it seemed to get worse at an increasing rate. I have no proof of cause, but this is a fairly common problem, at least on XRs, and the consensus on the XR forum seems to be that hard a aftermarket sprocket is the culprit.

I bought the bike used, and the sprocket that was on it was hard to get off. I didn't think to inspect the shaft at the time, but I think the damage had started with that sprocket.

After a season (two?) on the new sprocket, the damage was obvious, but less bad than in the below pic. I noticed the keeper had strange wear on it, so I pulled the sprocket, and found the damage. I foolishly hoped it would not get any worse, but after not-enough-hundred miles more, it looked like this.

I knew it was doomed, so just put it back together and kept riding. After an even shorter period of time it looked like it did in the first pic.

At that point I figured all was lost, and with nothing to lose, I welded the sprocket to the shaft to get some more mileage before changing the shaft.

The first sign of danger is a keeper that looks like this. But, I think that once the destruction starts, it will continue until it strips completely no matter what you do.

Though I can't be positive the sprocket caused this, I think it is likely enough to warrant never using aftermarket primaries again. The OEM sprocket for the XR is not only the proper hardness, but it also has a wider cross-section, or so I am told.

There also is no cush drive on XR600s or XR650Ls to dampen this kind of wear if the bikes are being used for a lot of street miles. I would love it if there were A) someone with a hardness tester to prove the varying hardness of the shaft and stock/aftermarket sprockets, and B) a more affordable cush-drive sprocket than the one made by RAD Manufacturing.

You're really going all-out by lengthening the frame, Luke. Great job. I hope to check it out in-person in a few months.

Luke · 12-11-2012, 11:17 PM

Quote:

Originally Posted by Zombie_Stomp

You're really going all-out by lengthening the frame, Luke. Great job. I hope to check it out in-person in a few months.

No one has accused me of being too conservative with this build.

You're coming back to Portland? Any guess when? It'll be good to see you.

Luke · 12-11-2012, 11:34 PM

A little more work got done today.

I pulled the bushings from the shock and measured them. I'll replace them with spherical bearings which should work better.

Ohgood had the right tip on cutting the sprocket. I put it in the big lathe, set the speed as slow as possible and it cut quite nicely. Slowly, but nicely.

I put a countershaft in the engine cases that are mounted in the frame. Then fit and adjusted the chain.

This is with the chain tension adjusted and the wheel at full extension. The slack looks pretty good, there won't be too much work for the rollers and guides to do.

It's a long bike.

Tall, too.

oregoncoast · 12-11-2012, 11:59 PM

ohgood · 12-12-2012, 01:59 AM

SWEET!! tall enough for us normal people almost! ;-)

You can check hardness of stuff with a good file.. if the edge of a good "mill" file cuts a piece easily, the piece is usually soft or not yet heat treated. If it "screams" or "sings" off the piece, its harder than a preachers dick in a ..... well you get the idea.

You can use that to check areas around welds, or welds themselves. If it gets too hard, watch out! There's a whole bunch of hard vs tough vs strong vs black magic I can't remember anymore... but it matters sometimes.

This project isssssss great!

DRjoe · 12-12-2012, 02:49 AM

Its looking good, You'll be finished by next week at this rate.

TooFast · 12-12-2012, 11:22 AM

Quote:

Originally Posted by MortimerSickle

Are you sure you want those sprockets?

Don't forget what a harder-than-stock sprocket did for me.

I bought a brand new 94 XR600, put an aftrmarket 13t c/s sprocket on and had this happen in 450 miles of two track dirt riding. I bitched to Honda USA about a having a soft c/s and they told me they have never sold a XR600 c/s. I replaced my c/s and ran the OEM 14t with more teeth on the rear sprocket to gear down without any more problems. Since I have seen 5 other c/s wearing the same way, fixed two of them...each and every one was running an aftermarket c/s sprocket. Still bugs me that Honda USA told me they have never sold a XR600/650L c/s.

Zombie_Stomp · 12-13-2012, 08:36 AM

Quote:

Originally Posted by Luke

No one has accused me of being too conservative with this build.

You're coming back to Portland? Any guess when? It'll be good to see you.

Expect me around late May.

LC Garage · 12-13-2012, 06:29 PM

Luke was so busy building and fabricating today, he forgot to take pictures!

Posting a few pics of his work today on the new sub frame, he can provide the narrative;

Luke · 12-13-2012, 11:35 PM

I had some help from another friend today. We measured, cut, measured, measured, filed, measured, clamped, clamped, measured,welded, measured, measured, cut, measured, clamped, measured, welded, measured, measured, bent, measured. (I'm getting a lot of use out of my big L-square.) And ended up with a rear frame part that belongs on a tube frame bike, not the pressed sheet frame that I've got. Oh well, better hide it with some black paint.

The stock shock mounts were in the wrong place and were the wrong size, so it seemed easier to just cut the whole rear part of the frame off and build a new one from scratch. It'l all cut up, but only two of the joints are welded so far. The top and down tubes were offset on the cross tube to make fabrication easier. That makes the cross tube weaker since it has more bending applied to it from the shocks than if the top tubes were further out. To compensate, it's much thicker than the other tubes. I'll make some spindles on the lathe to mount the shocks to and they'll get welded into the cross tube.

The big problem now is that I look at the bike and think about putting the gas tank under the seat and the air box over the motor. Putting 0 pound/gallon stuff up high and 6 pound/gallon stuff down low sounds nice. The question is if there's enough room and if it can be built quickly.

oregoncoast · 12-14-2012, 04:42 AM

Quote:

Originally Posted by Luke

The big problem now is that I look at the bike and think about putting the gas tank under the seat and the air box over the motor. Putting 0 pound/gallon stuff up high and 6 pound/gallon stuff down low sounds nice. The question is if there's enough room and if it can be built quickly.

134 Days until race day. 19 weeks.

Loud Al · 12-14-2012, 08:19 AM

Quote:

Originally Posted by oregoncoast

134 Days until race day. 19 weeks.

Plenty of time, if Kelly Johnson can design and build the U2 in 8 months you should be able to get this done in 19 weeks

12-10-2012, 03:15 PM	#151
Jayrod1318 Studly Adventurer Joined: Jun 2011 Location: Here and there and stuff. Oddometer: 519	The xr650r sprocket has at least double the surface area on the shaft. the xr650l guys use them on their bikes. I have no idea if that helps you or not. Sweet build bTW! __________________

12-11-2012, 11:59 PM	#157
oregoncoast Racing Like a Noob Joined: May 2007 Location: Duh! Oddometer: 4,290	__________________ Racing a Subaru in the 2013 Mexican 1000

12-12-2012, 01:59 AM	#158
ohgood Studly Adventurer Joined: Sep 2010 Location: alabama Oddometer: 794	SWEET!! tall enough for us normal people almost! ;-) You can check hardness of stuff with a good file.. if the edge of a good "mill" file cuts a piece easily, the piece is usually soft or not yet heat treated. If it "screams" or "sings" off the piece, its harder than a preachers dick in a ..... well you get the idea. You can use that to check areas around welds, or welds themselves. If it gets too hard, watch out! There's a whole bunch of hard vs tough vs strong vs black magic I can't remember anymore... but it matters sometimes. This project isssssss great! __________________ Crazy_Dave just made it into my sigline, and I agree: I fall down alot.

12-13-2012, 06:29 PM	#162
LC Garage On Any Sunday Joined: Mar 2011 Location: Columbia County Oddometer: 591	Rear Sub Frame Pics Luke was so busy building and fabricating today, he forgot to take pictures! Posting a few pics of his work today on the new sub frame, he can provide the narrative; __________________ "Nothing can stop us but fear and common sense”

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12-11-2012, 11:34 PM	#156
Luke ^OP GPoET&P Joined: Aug 2004 Location: Idiotville, OR Oddometer: 3,774	A little more work got done today. I pulled the bushings from the shock and measured them. I'll replace them with spherical bearings which should work better. Ohgood had the right tip on cutting the sprocket. I put it in the big lathe, set the speed as slow as possible and it cut quite nicely. Slowly, but nicely. I put a countershaft in the engine cases that are mounted in the frame. Then fit and adjusted the chain. This is with the chain tension adjusted and the wheel at full extension. The slack looks pretty good, there won't be too much work for the rollers and guides to do. It's a long bike. Tall, too.

12-12-2012, 02:49 AM	#159
DRjoe Beastly Adventurer Joined: Sep 2007 Location: Sunshine coast qld Oddometer: 4,294	Its looking good, You'll be finished by next week at this rate.

12-13-2012, 11:35 PM	#163
Luke ^OP GPoET&P Joined: Aug 2004 Location: Idiotville, OR Oddometer: 3,774	I had some help from another friend today. We measured, cut, measured, measured, filed, measured, clamped, clamped, measured,welded, measured, measured, cut, measured, clamped, measured, welded, measured, measured, bent, measured. (I'm getting a lot of use out of my big L-square.) And ended up with a rear frame part that belongs on a tube frame bike, not the pressed sheet frame that I've got. Oh well, better hide it with some black paint. The stock shock mounts were in the wrong place and were the wrong size, so it seemed easier to just cut the whole rear part of the frame off and build a new one from scratch. It'l all cut up, but only two of the joints are welded so far. The top and down tubes were offset on the cross tube to make fabrication easier. That makes the cross tube weaker since it has more bending applied to it from the shocks than if the top tubes were further out. To compensate, it's much thicker than the other tubes. I'll make some spindles on the lathe to mount the shocks to and they'll get welded into the cross tube. The big problem now is that I look at the bike and think about putting the gas tank under the seat and the air box over the motor. Putting 0 pound/gallon stuff up high and 6 pound/gallon stuff down low sounds nice. The question is if there's enough room and if it can be built quickly.