A friend gave me a 1979 XS650 2F a few years ago that was sitting outside. It had no title and hadn't run in many years ... Just the way we like em My brother and I picked it up and drug it back to my place. Getting old junk bikes is like Christmas morning for me and I can't wait to find and the rodent nests and spider webs packed into it. Under the seat on the XS it has the plastic document holder like a lot of the old bikes. Inside was the title signed off and notarized in the 80's I ran down to the title bureau this next morning and I was the legal owner of this gem. She's a beaut ain't she The truth is that after I got the title I let it sit in my garage at home for a couple years promising myself I would not touch it until I had an actual plan and time to do it. I've done some other bikes and opened up a new shop for work since then. Also had many ideas for what the the 650 should be in its new life. Initially it was going to be a street tracker, then a bobber, thought about a cafe for awhile too. I really like the street tracker XS650s and that was it until I was searching Craigslist one morning and happened upon this jewel. A 1987 YZ125 basket case. After seeing a few pictures on this forum of a YZ650F that someone made I was hooked. Another 650 adventure bike it was. I put that YZ in the garage for a bit while I was working on my F11. Then the owner of a regional motorcycle paper, Midwest Motorcyclist, mentioned that if I wanted to run a series of articles on a motorcycle build he would be happy to support it. That was late Spring / early Summer. We talked about what to do and he liked the adventure bike idea and a possible second set up for supermoto duty. We are in the middle of this now, but here is what we have so far. A hybrid of the XS650 frame and motor with the YZ125 front and rear suspension, monoshock and wheels.
Cool , How does the YZ suspension handle the extra weight of the XS motor ? any sag? I have been thinking about making my XS a full dual sport and YZ's pop up on C/L often with blown motors pretty cheap.
Sitting still the stock YZ spring is good with significant preload. I haven't tested it dynamically yet. Since then I picked up a YZ490 rolling chasis. That shock is the same, but the spring is nearly 1mm larger diameter. That should help quite a bit. Also I found progressive springs for the front that are the same outside diameter, about 12mm longer than the YZ. They have nea nearly twice the spring rate as the YZ. I'll need to road test it before we determine springs, but there are options. I am trying to reduce the weight as much as possible at this stage.
Here are a few more pics. A few of the electrical plate and battery box: 520 chain and sprocket mod: An aftermarket exhaust that is modified into a 2 into 1:
The long term plan is to have this as a convertible bike. I have a second set of wheels from the YZ490 that will get laced for supermoto duty. We also have an old YZ125 steel tank (approximately 1 gallon) that will get retro fit as a track day tank / seat to reduce the weight. The stock tank will serve as the everyday / ADV tank at 3.9 gallons. Someone stopped by the shop after we closed tonight who like to do "stupid shit" to his bikes I've never met him before, but we talked for a couple hours about different projects and past bikes ... he'll fit right in and already offered up good ideas about relocating the coils and mounting the smaller YZ tank.
Looks really top notch, can't wait 'til you get it on deck & give us an evaluation of the finished product! :eek1 Did the YZ frontend take much fitting?, looks like you have a couple of extra holes to move the top end of the rear shock around too? Cheers Baza
Thanks, The front end from the 1987 YZ125 was much more involved than I had thought. We ended up cutting the stem out of the original XS650 lower tree, machining the lower plate of the YZ to accept the larger XS stem and pressing the XS stem into the ZY plate. Then we had to make a shim for the upper YZ tree to fit the XS stem. We did that then I came accross the 1989 YZ490 and the top tree (rubber mounted bar mounts vice cast) fit right on the XS stem without any modification. The YZ490 lower tree might be a direct swap too, but I haven't tried to fit it just yet. Here are some pics of the front triple tree mod:
I found some pics of the rear suspension mod. The aluminum mono shock swing arm bolted right up to the XS frame after we cut the rear peg loops off. We used the XS swingarm axle and no other mods. Mounting the upper and lower shock linkage was a much more time consuming project. Most of the stock YZ linkage was used along with the frame mounts that were cut of the YZ donner frame. We needed to get the lower shock linkage mount as far forward as we could to get the travel to work and the shock not to bind. Once we got the lower mount on we could position the upper mount. I wanted to get the shock vertical to increase the effective spring rate, but we could not do that without the lower linkage binding. So we ended up just about parallel with the spine of the frame. No matter what we did the lower linkage would bind at about 4" of travel because we could not get the lower mount forward enough on the frame. So to get the full travel we had to make a shorter dog bone. That was mocked up with some aluminum plate and pins. Oh ... and a lot of trial and error:huh With this piece we can get 11" of rear travel. This is just a mockup and a friend with a CNC mill is reproducing the original with the new pivot points from the temporary piece.
Thanks for posting those extra bits of information & photos, :eek1 thinking, thinking, thinking, cogs grinding, etc. Cheers Baza
I was going to just use UNI filters on the XS, but I was affraid they would get too wet and dirty without an air box. I was going to scrap the original air box, but I did a bit of fitup and it looks like it will work with the monoshock. Here they are stock: The rear sections had to come off. I'll plug the inlet on the lower side and cut a new one up top. Need to make up a bracket for the top to support them and it should be good. I can use the stock filters andthe side covers can be used once I get the tabs back in place.
Nice work!! The stock carbs may not work to good for you. The cv part of the carb, may hang-up on you. ED XS 650 FAN!!!
I know Mikunis round slides are popular and getting away from the CV carbs might be better for lower end response. I'm sure there will be a lot of tweaking once it actually gets road worthy
I got the bracket made to hols the air boxes together and in place. Made some tabes to hang the side covers. I was not intending on using the original side covers, but I changed my mind. Unfortunately I had already cut the tabs off to mount the upper shock brace. Also started to fit the small tank. The front mounts are fine, but the tunnel doesn't clear the coils or the upper motor mount. I'll have to relocate the coils, but the upper motor mount is a funky 3 piece deal on each side. Not sure why, but Ill make a 1 piece set and the clearance issue will go away. Not much to show, but here's some pics with the stock tank and the side covers remounted: And with the small tank mocked up: I am lengthening the kick stand today, but the welder is giving mefits so that will have to wait.
Heres a XS650 motor in a XT 500 frame. Just google Hennorit 2011. Its a Dutch club who has a almost all Yamaha XT TT 350 500 600 ride each fall. About 2 weeks ago. BIG ED XT&TT&XS FAN!!
The welder was giving me trouble, but I think that is finally sorted out. It is so much easier to get things done when your equipment is working properly One of the issues with the XS650 as an ADV bike and the new suspension is that the 1979 XS650 Special had the pegs too high and too far forward. The frame does have exhaust mounts on the frame that are much closer than the stock peg mounts so I am trying to use those to lower the pegs and move them back underneath the rider. Here are a couple pics with both the stock pegs and the new locations: The toughest part abount moving the pegs for me (whether it is rear-sets on the cafe or these) is getting the rear brake pedal and the exhaust clearences to all work out. In this case I didn't need to reverse the brake pedal pivot like when you do rear-sets, but I still needed to get the brake pedal to actuate the rear brakes while still clearing the exhaust and foot pegs. Clearing the exhaust was done by building the right peg mount around it. Then it was getting the brake pedal to fit between the peg mount and the exhaust. We used the original XS650 rear brake pedal and pivot with the YZ125 cable to the rear wheel. Once I had the pegs in place we could measure the original brake pedal to section out 1/2". Here is the stock pedal where it would hit the new peg mount: And here is the sectioned lever that clears the exhaust and the peg mount: Then to make it stand on it's own the side stand needed to be extended due to the new suspension. The first time I did it it was still too short. It leaned way over and only needed a nudge to fall over on the stand side. Here is the 2nd extension. I still need to add gussets to the foot peg mounts and trim the brackets of the excess metal. I got new grade 8 bolts to mount the plates to the frame, but I'll probably add some side plates around frame mounts to stiffen it up.
Got some work done on the XS over the last couple days. To mount the mono shock with the reservoir I had to remove the horizontal frame brace from the backbone to the tail section on the right side. That is also the lower mount for the right side frame cover. I do not have a way to bend tubing so I had to find a part that I could cut to fit with the correct bend already there. An old engine guard worked out well. To reinstall the side cover the lower mount had to be moved forward on the cover. I tried to drill the spot welds holding the lower mount bracket without going through the cover. Even with the mount removed the cover had to be modified on the lower side since the new frame rail stuck out further than the original to get around the shock reservoir. With the lower mount moved forward and the bracket located on the new frame rail: One of the things I wanted to do with this bike was to have 2 different tank and seat configurations that could be swapped out easily. The stock tank for normal and longer riding and a much smaller and lighter tank for short rides. The smaller tank ended up being an MX125 tank from an early '70s Yamaha. The front mounts are the same as the XS650 Special tank. It clears the tunnel with the exception of the coils (still need to relocate them) and the 3 piece upper motor mount (another mod still coming). The tank is much shorter than the original so a second rear mount had to be added while still being able to mount the original tank. The mounts for both tanks are similar, a round grommet on the tank slides over a frame mount and is captured by a bolt through the top. I was able to use a modified lower suspension bolt I had with the YZ490 doner and weld it to the frame. It had to be short enough that I could mount the original XS tank over it. That part took a couple tries. Now both tanks can be swapped out easily. The next stem is to relocate the coils.
