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The Shop
While working on the exhaust I noticed that it must be titanium. It’s just a different type than what is usually used and thicker walled as well.
This was after the bike was on the scale so Around 106,1kg
1,017kg where as the stock XR unit is 588g without the H4 bulb that the MD30 uses.
the acerbis unit can lose some weight. All the steel hardware will be replaced with titanium and carbon. And LED spot can be modified as well. No need that much material for cooling.
-40g just by drilling some 13mm holes is not to bad.
the XR250 MD30 (1995- 2005) puts out 204W at ~5000RPM, the left crankcase cover is also different due to the bigger alternator, it also uses a bigger R/R.
The XR250 headlight uses a standard 60/55W H4 bulb and is much brighter than the std 35W XR250R US unit.
Als far as I know buy rewinding the the US model stator you can get it to 150Watts max, but the RR musst be changed to match.
Here a taste of what ist to come, these are all bolts that are going on the bike. To my experience the Ti bolts that I got so fare are about 42% lighter than the steal. So the would be around 90gs saved.
The fender is 421g (shortened in the rear to clear the frame)
According to the calculations that I’ve done the final weight of the bike is going to stay somewhere about 107kgs. There is some small stuff I’m working on that will add up but I don’t think there is major savings still in store.
If I would convert it to kickstart only and the simple US model electrical system then It would go under 100kgs 😂. But then my wife won’t ride it. 😂
I would have to ride it First as removing weight would have a significant effect on the riding the bike in different environments.
The bike has safely made it to the small country in east Africa will be our new home. It’s not yet done. I have LightSpeed carbon skidplate coming and there will be some other modifications coming.
Some little updates as I’ve been getting some questions concerning the Mikuni carb I’ve been using. It will fit a standard XR really well but you’ll need to get the cables made or contact mikuni OZ they have them available for purchase. You will also need to modify the cable bracket a bit.
The performance is amazing compared to the stock carb. And you can use a 1 cable setup because it has such a strong return spring. Thus i could also cut off a part of the bracket save some grams.
On the E-start Modell it is a tight fit and requires a bit experience as it needs an adapter made. The Air-boot of the MD30 has a bigger diameter so pay attention to that. The XR400 air boot is also bigger so one has 3 size options to choose from when setting it up. When doing a big bore you should consider that a big bore pulls more air volume through the intake tract and also requires a smaller throttle opening to create the same torque. This raises the vacuum in the carb which causes a larger pressure differential between the float bowl and the venture. This pulls more fuel through the same size jet. The A/F ratio is the same but people mistakenly believe that it is leaner because of the smaller jets. The main change that you will make when increasing the engine displacement is in needle clip position and air screw setting. The main jet stays very close to the same as with a smaller bore. So the bigger one goes on the carb bore and the air boot opening, the more power you shift the power to the top of the Rpm range.
Maybe you could cut that muffler back a few cm, it would loose some weight and be easier to swing your leg over. Is the bike loud at all with the aftermarket pipe?
It’s a bit louder than the stock bike, but not crazy. I actually thought of cutting the pipe back but it’s not as straightforward because the inner tube is in cone shape. My wife is happy with the weight as it is now. It was a fun project. There will for sure be some more ideas to improve the bike later down the road.
Daniel from Malaysia is converting a XR250r to electric start for his wife. He was friendly enough to take pictures of the 2 frames side by side
Here you can see that main differences are the tank mounts CDI mount, the stearing tube.
Left the MD30 right XR/R
Hear a pic of the two swing arms. Pay attention two the different chain slider mounts. The chain slider of MD30 only allows small rear sprockets.
Left is the MD30 plug, right the XR250R plug. Pay attention to the threads.
Pit Row
Rwanda a nice place!
Latest addition is a light Speed Carbon skid. So far the bike is really good fun. I’ll be doing some more experiments with DLC on axles and internal suspension components when I’m back in Europe. Will also be trying to get a stock headlight as I’m not to happy with the LED weight wise. I was able to weigh the bike again with the fat bike tubes an some some titanium added and it is a 106kgs final weight. I would say the lightest xr250r with E-start on earth.
You don't have to answer as it's not related in any way to your awesome bike but why are you shuttling between Europe and Africa?
Yeah, that’s a good question. We work and live Rwanda but have to be in Germany every couple of years.
Final edition, still looking for a golden rear rim, I’ve got the front already.
Bravo sir.
Where in the world did you find those classic Acerbis flags!?
Dude searching eBay and other platforms every now and then for 2 years.
That is a badass XR
It‘s a bit boring during rainy season here, here’s a pic of the cut of trottle return.
some stator bolts I’m changing for titanium
there is still options to reduce some grams of the bike.
Unbelievably good thread. Incredible work.
Thanks BoxcarWilly!
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