XR MINI RACER
RACE SHOP + FABRICATION
XR MINI RACER
In the coming months, we will be bringing many new projects to the table, such as how to install the original lay-down turtle suspensions, which we offer as a kit, for 73–76 XR75, including TIG installation, before and after, for those of you wanting to lay down the shocks at a 45-degree angle. The original turtle suspensions were built by CSCE, which stands for Custom Service Cycle Engineering, building the J&H monoshocker, wheel lacing, lightening engine parts, engine building FRANKS ROOLINK XR80.
As you can see, above the 73–76 XR75 suspension, even with these, Werk's performance shocks were only acceptable at most. Radical suspensions really had not been engineered for minis. That was all about to change when CSCE came out with this turtle suspension kit. We will take you through the steps from mild to wild. The 45-degree shock mount became the standard on many MX machines that came right from the factory. Below, at this point, you have to cut off both rear number plate holders left and right. Be sure to mark them for when to reinstall, and also cut off the original shock mounts, as you won't be needing those anymore. Use strong building magnets to install the two units to the predetermined measurements. Be very exact. Otherwise, all will be for nothing! Once positioned, run a 1/2" of aluminum rod through both ends. This is very critical, so both sides are completely plum lots of measuring! Once set, tack them in very carefully! The aluminum rod stays in throughout the complete welding process, with lots of twists and super-tight corners, and uses a size reduction unit. If you're not an accomplished TIG welder, leave it up to a professional. It's not as easy as it looks. You can see the aluminum rod and how straight the installation is compared with the seat bracket.
As you can see, above the 73–76 XR75 suspension, even with these, Werk's performance shocks were only acceptable at most. Radical suspensions really had not been engineered for minis. That was all about to change when CSCE came out with this turtle suspension kit. We will take you through the steps from mild to wild. The 45-degree shock mount became the standard on many MX machines that came right from the factory. Below, at this point, you have to cut off both rear number plate holders left and right. Be sure to mark them for when to reinstall, and also cut off the original shock mounts, as you won't be needing those anymore. Use strong building magnets to install the two units to the predetermined measurements. Be very exact. Otherwise, all will be for nothing! Once positioned, run a 1/2" of aluminum rod through both ends. This is very critical, so both sides are completely plum lots of measuring! Once set, tack them in very carefully! The aluminum rod stays in throughout the complete welding process, with lots of twists and super-tight corners, and uses a size reduction unit. If you're not an accomplished TIG welder, leave it up to a professional. It's not as easy as it looks. You can see the aluminum rod and how straight the installation is compared with the seat bracket.
OK, remember cutting off the old shock mounts? Now, you are going to drill a hole through the blank area pictured below. Make it big enough to put a 12mm bolt through. Drill at a very slow speed, or you will never get through it with lots of lubricants. On the lower arrow, which is inside, you are going to weld a 12 mm nut into place and weld it in on both sides with the bolt intact and tight. The bolt will be taken out after welding is complete.
With all the pieces back in place, there is a huge difference! With a 13-inch shock, you will get the full 5.5 inches of travel and a much more progressive suspension; we have also continued the weld all the way around the front frame member where the press fit meets the weld. This is where the tubes would crack, so the front is also stronger. Only the 73–76 need this reinforcement. Frame welding for strength and aggressive suspension seat mods were all part of standard equipment for top runners back in the day, such as Myerscough, Ward, and Brown, just to name a few. Next off to paint, front end, and wheel lacing.
With all the pieces back in place, there is a huge difference! With a 13-inch shock, you will get the full 5.5 inches of travel and a much more progressive suspension; we have also continued the weld all the way around the front frame member where the press fit meets the weld. This is where the tubes would crack, so the front is also stronger. Only the 73–76 need this reinforcement. Frame welding for strength and aggressive suspension seat mods were all part of standard equipment for top runners back in the day, such as Myerscough, Ward, and Brown, just to name a few. Next off to paint, front end, and wheel lacing.
Here's a sneak peek at our J&H monoshock. At this point, we have machined the axle pivot and bronze bushings, which are much thicker than stock and have also installed the shock. The next step is to install tapered steering bearings and rework the front end for a more rigid feel. Pro fab made both frames for DG and J&H. They were both identical except for a few mounting holes. As for the colors, DG offered theirs in gold, and the J&H came in silver.
Above, here's a little trick for those wanting to lace your rims. This particular pattern is a 2 cross pattern; there are 2 different bend types of spokes to be installed on each wheel: an inner and an outer. The exaggerated 90 is always the outside, and the shorter bend is always the inner. Always install the inner first on both sides, then the outer; once you have done that, it is time to do the pattern. Always start with the outer spoke, count 4 holes to the right on the hub, then cross with the inner; the outer spoke will always have to be crossed over the inner spoke; pay attention to that! Tape it at approximate width. Once that's done, the outer will appear again. Do the same count over and over again, taping each as you do both sides, and the upper left picture is what you will have. Position the rim over the pattern and carefully fit it; if nothing matches, don't panic! Just turn the rim over and try again, carefully assemble all spokes loosely, and center the drum with measuring while finger-tightening the spokes. WOW, you are now ready for balancing. These will be our J&H monoshock rims. Polished and brushed hubs with all-aluminum Excel rims with stainless spokes and nipples are a beautiful combination.
Above, well, if you have made it this far, no stopping now! The whole point when first centering the hub with lots of measuring while hand tightening the spokes was to limit the up and down out of round when the initial wheelset is in balancer; this will save lots of time. Start by slowly turning the wheel; you can hold something as simple as a paint stick in place, as shown above. We like to gauge the up and down out of round first. If the rim goes low, that means you must tighten the spokes on both sides evenly to pull the rim up; 1/2 turn increments are the norm. It just takes patience! Once the up and down are true, it’s time for side-to-side action, as in the picture above. If the rim starts hitting on LEFT, you tighten only the outer RIGHT; this will pull the rim away. Whichever side you are more comfortable with, left or right, stick to one side. Once it gets close, you can use dial indicators, but, not necessary. It’s really pretty fun watching it come together once true. Always tighten to Manufacturing specs. WOW, you did it! Now go mount those tires! Next, the stress test doesn’t scratch those $550 super trick Buchannon aluminum rims XMR.
Above the floating backing plate eliminated rear-wheel hop by drilling out the existing bushing pictured at left and machining a bronze bushing and a new female spacer to predetermined measurements that slid through the hub and over it pictured right; this kept the plate free-floating on the bearing inside the hub. The original unmodified hub was fixed once tightened, and it was in a locked-in position; upon heavy braking and compression, the wheel would lock up with premature braking because the brake actuator changed axis with up and down movement, now with the semi-floater even at full compression the plate would self-adjust with up and down compression keeping the brake actuator in virtually the same position because of the now free-floating plate kit, making a big difference in the XRs handling dept. Again, standard equipment for the top runners like Ward, Myerscough, and Brown. The kit was another C.S.C.E product. Above right, the J&H is now a rolling chassis complete with a floating brake package and reworked fork internals. Soon, we will be ready for the killer XR motor.
While we are boring out our jug and getting it ready for our monster 54mm sleeve insert, here's the heart of our J&H racer. At this point, we have bored the cases to accept the new size and also drilled and tapped the oil cooler outlet fitting, which will be a must for this size engine, a fully stroked and lightened crankshaft, and our 54mm 11:5:1 high-performance piston—next, some careful reassembly of the bottom end.
With the bottom end carefully assembled, here's one last look before we assemble the top end, polished valves fully ported cylinder with valve guides machined inside the ports for clear passage, high lift modified camshaft to fit needle bearing cam tower heavy-duty valve springs 24mm Mikuni carb, electronic ignition Lockhart oil cooler, rocker arms have also been cut and lightened, stay tuned as the J&H monster comes together.
One last look at the top end before it all comes together. After complete port polish, we did some extensive machining and installed a 1mm oversized intake valve; this monster will now breathe easy with valve guides ground smooth in both passageways, a nice match to our 54mm high-performance 11;5;1 piston and one of our super high lift camshafts, the 120cc super modified motor will be a far cry from the original 72cc stocker stay tuned as the fun stuff begins.
Finally, with the killer motor tucked very nicely into the J&H frame, many handcrafted pieces had to be made, such as a trick tubular brake pedal, bottom tubular case saver, aluminum motor mounts, and new super trick fully adjustable Heim joint rear brake stay, which will also be available in our online store! We are now ready for some oil cooler plumbing ignition wiring and, of course, the J&B pipe, which the J&H monoshock ran back in the day.
The J&H complete monoshock package racer, running a full-blown 120cc XR mini racer full race motor, you have been with us from the very start, from wheel lacing to complete motor building to finish and cosmetics a great build and unique in its own way. One of our favorite old-school purebred racers and still one of the trickiest of the hot-rodded XRs; more detailed pictures on the homepage.
Polishing some parts is a must. The local polisher in our neighborhood does extremely detailed work and has done so for many years. Call for parts polishing prices.
It's pretty hard not to get distracted around the shop with all our projects going on; discipline is a must. Picture at left, one of our XMR testbeds 78 XR fitted with many of our products. Many hours are spent with extensive fitting and testing for an absolutely perfect fit every time. We strive to build the best quality parts for our customers, and let's face it! There's nothing that is cooler than a fully modified XR thundering down the track with the front wheel up in the air.
Polishing some parts is a must. The local polisher in our neighborhood does extremely detailed work and has done so for many years. Call for parts polishing prices.
It's pretty hard not to get distracted around the shop with all our projects going on; discipline is a must. Picture at left, one of our XMR testbeds 78 XR fitted with many of our products. Many hours are spent with extensive fitting and testing for an absolutely perfect fit every time. We strive to build the best quality parts for our customers, and let's face it! There's nothing that is cooler than a fully modified XR thundering down the track with the front wheel up in the air.
There are tons of projects going on here at XMR. Here's a little sneak picture of the J&B package racer cosmetics and, of course, the infamous J&B style racing pipe, which is now available from XMR. The J&B racers definitely had a very distinct look and sound. You could spot them a mile away, and of course, who could forget the no. 3x ridden by the champ himself, Jeff Ward. Stay tuned; this build is lurking somewhere in the future XMR.
Slowly but surely, the J&B racer comes back to life. Running the full 120cc racing package, many hours went into the motor alone and suspension mods—next, full cradle frame Lockhart oil cooler, CDI ignition, and cosmetics. The J&B old-school racer, also one of our favorites, has a very distinct look with the trademark baby blue paint scheme, and of course, the J&B racing pipe will put the total package together.
Slowly but surely, the J&B racer comes back to life. Running the full 120cc racing package, many hours went into the motor alone and suspension mods—next, full cradle frame Lockhart oil cooler, CDI ignition, and cosmetics. The J&B old-school racer, also one of our favorites, has a very distinct look with the trademark baby blue paint scheme, and of course, the J&B racing pipe will put the total package together.
The finished J&B racer (more pictures on the homepage), many hours went into this build, turtle suspension, floating brake stay, full race motor, oil cooler, reworked fork internals tubular brake, box style aluminum swingarm seat mods, J&B race megaphone, it goes on and on. As you can see, pulling up to the starting line with one of these sweet machines was definitely a big advantage for the lucky kid who was fortunate to have one of these purebred racers XMR.
XR mini racer skunkworks division, prototyping our wild and crazy snake pipes.
On the left, in the "Werks" looking more like a full-blown open-class moto-crosser. This 74 will run a pair of machined Fox air shocks and reworked front fork internals. Of course, a full-blown race motor is standard on all XMR factory machines. More new tricks include an Aluminum tubular brake pedal, early model cr125 side plates, and, of course, a one-off XMR custom snake pipe. Stay tuned as this one develops!
Above 90% complete, hot rod 78 XMR "tuff bike," nicknamed by good friend AC, running a full line of XMR performance parts. A few, including a gold aluminum swing arm, a one-off powerbomb snake pipe, of course, a fully built race motor including a CDI for instant revs, and heavy 8-gauge stainless spokes, make this trick head-turner pretty indestructible. In progress are the custom-fit 77 CR125 side panels. Stay tuned; the finished bike should be pretty sick.
Another super trick part for the early XRs 73–76 was this 5-speed close-ratio transmission. The YZ80C was coming, and the aftermarket manufacturers knew it. PK was the first to introduce it, coming directly from Japan, shortly followed by J.W.R.P. adding that 5th gear made quite a difference on some of the longer and faster tracks.
The latest from XMR. Needle-bearing cam towers! Camshafts machined to fit—no more worn-out cam towers. Instant revs and no drier spot on high rev engines core exchange required cams and cam towers in stock, a must for the hardcore modified XR.
In stock. The ultimate 54mm high-performance piston kits. In stock configurations, a whopping 98cc! CASE MACHINING AND RESLEEVING NECESSARY, run in stroker configurations, turning your XR into a 120cc monster; 73–76, 77–78.
Old rival turned friend Dave T brought a complete basket case of an all-original racer from back in the day. It took some doing: mini Betor forks box rear gold swingarm, Lockhart oil cooler, a pair of old-school Ackront aluminum rims with 9 gauge spokes. Wasn't too happy when I first saw the cluster, you know what !!! Of junk parts but smooth-talking, Dave persuaded me to tackle the job. Tons of parts were also needed, including a new XMR-built motor.