Harescramble Upgrades for 1985 XR600R

[dirtjumpordie]

Before reading this, I am not asking you whether or not I should do this with this bike.  I'm looking for tips, feedback, stories, recommendations, etc etc.   Please resist the urge to tell me to "go buy a real race bike".  I'm not doing that.  Thank you. 

Hey guys, I picked up a 1985 XR600R thats plated for the street here in Wisconsin.  Strong bike, and it has enough balls to do interstate, so I'm happy.  Its actually not that heavy of a bike compared to what I expected it to be like.  I used to race motocross and harescrambles.  I was a good rider, and I know that I could race this at harescrambles in C class if I set it up a little better than it is now (I used to be mid pack B class, sometimes a front runner, but that was 4 years ago).  Have any of you raced an XR600R, or seen anybody do it?  Anybody here ride singletrack with it?  

I have a lot of leftover 2001 YZ250 parts from a parts bike I bought.  I'm thinking about putting the XR steering stem in the YZ triple clamps and running my yamaha front wheel, brakes, and fender.  I also have a gas tank, seat, subframe, and plastics from a 2008 yz250.  I want to put those on, because I can't stand the XR gas tank and seat.  It looks stupid and makes it very awkward to move on the bike.  I'm good at fabricating stuff, and I've done similar gas tank swaps on other old steel frame bikes.

 

[Backwoods-Bomber]

Before reading this, I am not asking you whether or not I should do this with this bike.  I'm looking for tips, feedback, stories, recommendations, etc etc.   Please resist the urge to tell me to "go buy a real race bike".  I'm not doing that.  Thank you. 
Hey guys, I picked up a 1985 XR600R thats plated for the street here in Wisconsin.  Strong bike, and it has enough balls to do interstate, so I'm happy.  Its actually not that heavy of a bike compared to what I expected it to be like.  I used to race motocross and harescrambles.  I was a good rider, and I know that I could race this at harescrambles in C class if I set it up a little better than it is now (I used to be mid pack B class, sometimes a front runner, but that was 4 years ago).  Have any of you raced an XR600R, or seen anybody do it?  Anybody here ride singletrack with it?  
I have a lot of leftover 2001 YZ250 parts from a parts bike I bought.  I'm thinking about putting the XR steering stem in the YZ triple clamps and running my yamaha front wheel, brakes, and fender.  I also have a gas tank, seat, subframe, and plastics from a 2008 yz250.  I want to put those on, because I can't stand the XR gas tank and seat.  It looks stupid and makes it very awkward to move on the bike.  I'm good at fabricating stuff, and I've done similar gas tank swaps on other old steel frame bikes.
 

Do it! My 87 competes. The fork swap is the biggest improvement for trails imo.

[notoriousE-R-I-C]

Do it!
Serious motor!
Just get those carbs dialed in and you'll love it.
Like BB said. Suspension. If you're talking about seat size/moving the bike, then you will like how much better the bike moves when suspended for YOU.
I did a harescramble on a 600r 15 years ago. Stock suspension. I don't remember details.

[dirtjumpordie]

11 hours ago, Backwoods-Bomber said:

Do it! My 87 competes. The fork swap is the biggest improvement for trails imo.

Thats good to hear!! What forks did you put on it?  Did you do any work to the shock?  I have a shock from a 2001 yz250 that I could put on as well.  

Edited November 18, 2017 by dirtjumpordie

[Backwoods-Bomber]

Thats good to hear!! What forks did you put on it?  Did you do any work to the shock?  I have a shock from a 2001 yz250 that I could put on as well.  

I just used some kayaba's from an 06 cr125. They were sprung perfectly for my weight from the factory but could probably benefit from some valve work. They are kind of abrupt on square edge obstacles like roots, but the positive steering response and ability to soak up big hits is a game changer on the ol girl. It used to kind of pick the line for me as if my input was a suggestion, now it goes where I point it!

I haven't done anything to the shock other than maintenance. I suppose ignorance is bliss, but it seems to work just fine for what I do.

[dirtjumpordie]

1 hour ago, Backwoods-Bomber said:

I just used some kayaba's from an 06 cr125. They were sprung perfectly for my weight from the factory but could probably benefit from some valve work. They are kind of abrupt on square edge obstacles like roots, but the positive steering response and ability to soak up big hits is a game changer on the ol girl. It used to kind of pick the line for me as if my input was a suggestion, now it goes where I point it!

I haven't done anything to the shock other than maintenance. I suppose ignorance is bliss, but it seems to work just fine for what I do.

The way you describe the bike's handling with the stock forks is exactly how I would describe it as well.  That front fender and headlight looks great too.  

I'm thinking after I can get a decent set of forks on it, plus the gas tank/seat/subframe conversion, all it will need is some better footpegs.  I could see the bike turning out to be a nicely riding machine. 

I already own all of the parts that I want to put on the bike.  All I'm going to need to buy is a couple bushings, bolts, and some pieces of metal for fabricating adapter brackets.  No need to spend $500 on an Aloop kit when those kits already kinda look home made. 

 

Edited November 18, 2017 by dirtjumpordie

[Backwoods-Bomber]

The way you describe the bike's handling with the stock forks is exactly how I would describe it as well.  That front fender and headlight looks great too.  
I'm thinking after I can get a decent set of forks on it, plus the gas tank/seat/subframe conversion, all it will need is some better footpegs.  I could see the bike turning out to be a nicely riding machine. 
I already own all of the parts that I want to put on the bike.  All I'm going to need to buy is a couple bushings, bolts, and some pieces of metal for fabricating adapter brackets.  No need to spend $500 on an Aloop kit when those kits already kinda look home made. 
 

What tank are you looking to use?

[dirtjumpordie]

2 minutes ago, Backwoods-Bomber said:

What tank are you looking to use?

I have the gas tank from a 2008 yz250, so i am going to use that one. 

I once put a 2003 yz250 fuel tank and subframe on a 1993 cr125.  I found a guy who owned a barn that was packed full of old motorcycle parts.  I got three yamaha dirtbikes all torn down in baskets with blown engines.  All he charged me was $250 for the whole shit. Two yz250 2 strokes and one 03 yz250f.  All of them were grenaded engines. 

Edited November 18, 2017 by dirtjumpordie

[Backwoods-Bomber]

I have the gas tank from a 2008 yz250, so i am going to use that one. 
I once put a 2003 yz250 fuel tank and subframe on a 1993 cr125.  I found a guy who owned a barn that was packed full of old motorcycle parts.  I got three yamaha dirtbikes all torn down in baskets with blown engines.  All he charged me was $250 for the whole shit. Two yz250 2 strokes and one 03 yz250f.  All of them were grenaded engines. 

Rad! Can't wait to see pics!

[dirtjumpordie]

4 hours ago, Backwoods-Bomber said:

Rad! Can't wait to see pics!

Yeah I am heading to my parents' house for thanksgiving next Thursday  Thats where all of my parts are stored.  I am hoping those old forks are still in okay shape!  They have been laying on a dirt floor for like 3 years because I got out of the sport for a while.

[heart_of_darkness]

I’d recommend suspension (front and rear) before seat and bodywork.  The stock suspension is so bad that the rest of the ergonomics are comparatively less important.  The forks are easy enough to swap, but the shock may be difficult.  And trying to run stiff modern forks with the stock floppy shock makes for a very unbalanced suspension.

[Backwoods-Bomber]

I believe racetech still sells a gold valve for the rear shock, so that may be an option. The problem with swapping in a newer model shock is that the dual carb air boots take up the space on both sides of the shock where an attached reservoir would need to reside. I believe you would need to find a donor shock that uses a remote reservoir.

[dirtjumpordie]

Are there any good shocks that use remote reservoirs?  I already have a shock from a 2001 yz250 in my posession.  I'm going to look at my options for mounting the shock.  

I have access to a mill, drill press, and a lathe.  So I might actually be able to find a way to mount that YZ250 shock with the reservoir pointing backwards or forwards instead of sticking out sideways.  

It might be a better strategy to experiment with that gold valve before going through the work of swapping to an entirely different shock.  Anybody have experience with the gold valve??  

[heart_of_darkness]

The issue with swapping a shock is that the XR has a dramatically different linkage ratio than most other bikes.  Even if you get another shock to fit, you may never find a correct rate spring.  And the valving will be wrong far beyond the range of any established valving specs, so it will take many revalves to get working correctly.

I don’t have any experience with the early remote reservoir shock.  But I can give some pointers that I’ve learned from the later fixed reservoir shock.

[heart_of_darkness]

I wonder if a modern remote reservoir, with both high and low speed compression adjustment, could be attached to the factory shock hose.  That, plus a high flow piston (if the stock one is restrictive), would largely give modern performance.

[creeky]

Last 600 I had was an HRC628, Yosh exhaust, WP suspension on both ends. It was a heck of a lot fun to ride, a real b---h to pick up off the ground. 

[dirtjumpordie]

I have about 90% of the parts wrangled up for this project right now.  I am not sure which one I want to use, but I have two gas tanks.  One oversized gas tank from my old 2008 yz250, and a regular sized gas tank from a 1996-2001 yz250.  The seat and subframe is from a 2001 yz250.  From experience, I know that I can make that subframe and seat work with the 2002-2018 yz250 gas tank.  

I want to keep the top of the bike flat to move around on, so the older regular sized gas tank would probably be better for keeping the top of the bike flat.  But, i also wanna use the newer shrouds that I can use with the 08 style gas tank.  And the extra fuel would be nice, since I commute on the bike.

Edited November 27, 2017 by dirtjumpordie

[dirtjumpordie]

Today I took the tank and seat off of the XR600R, and attempted to put each of the YZ250 gas tanks on the XR600R.  Neither have any hope of fitting without extensive modification.  The cylinder is too wide and too tall.  The bottom of the tank contacts the engine's valve cover wayyy before the tank is even close to sitting on the backbone of the frame.  

I was worried that this would be a problem.  Wishfull thinking made me try it anyway.  I had to see it for myself, but it is not happening.  I will probably sell both gas tanks and buy a gas tank from a 4 stroke moto bike.  I don't know which make/model gas tank I should go with, so let me know if you have ideas!  

Another possibility is to cut the bottom of one of the YZ gas tanks so that it will fit, and then do some plastic welding to close the gaping hole in the bottom of each side.  Anybody experienced with plastic welding?  How hard is it to do it well enough that the welds are strong and wont develop a crack and leak?

 

Edited December 3, 2017 by dirtjumpordie

[dirtjumpordie]

I also measured the space between the upper and lower triple clamps for the YZ setup and the XR600R triple clamps.  They are in the ballpark of eachother. 

The space between the upper and lower yz250 triple clamps is about 7.9".

The space between the upper and lower XR triple clamps is about 7.3".

I might be able to put the YZ stem in a lathe and turn it down to the diameters of the XR stem, and then press an aluminum dowel into the hollow center to reinforce its strength.

The other option is to make a bushing that will allow me to press the XR stem into the YZ lower triple clamp.

BTW, I am aware that the bike's vin pad says that the bike is a 1984 xl600r.  

 

[JoeRC51]

Is the downtube of the frame round or square ? XRs are square , XLs are round. It looks square in the pix.   As far as the tanks , the backbone of the frame is part of the oil tank and  gets pretty hot , so the tanks  needs space between it and the frame. The teams often ran the 250 tanks because the tunnel was wider.