Posts
198
Joined
6/21/2015
Location
Bielefeld
DE
Edited Date/Time
10/19/2022 2:15pm
I‘ve been reading here quitely and following along. I thought I would share my build. As a Familie we lived In Tanzania East Africa for the last 3 Years. The place we lived was a pretty remote area in the west, so using dirt bikes is a day today thing.
We just very recently moved back to Germany and we brought our bikes with us. One of the bikes is an 1995 XR250 MD30 Modell. We bought it from Zanzibar. Its quite unique because it's a Japanese Modell with Electric start, steel tank, high output stator. The bike was in pretty rough state when I bought It, but we got It to a ridable condition.
This how it must have looked like new
For comparison a pic of the 1996 xr250r
Before Moving to Africa I had worked with a couple of factory teams, in Europe and Australia, and from this experience I know its possible to improve and customize every bike.
The goal is to Tailor this bike to my wife's needs.
Some of the things I want to take care of:
the stock Weight of this bike is 130kgs( at least that is what Honda claims, real world is probably a bit more), Powerwise they claim 28hp output at the crank which results in aprox. about 22 at rear wheel, I’m going for just a little better suspension, just a little more adjustable front fork. Note its going to stay a XR.
One very interesting fact about this bike is that when the western world was still waiting for Honda to update the Xr250r for 1996, Japan was already riding the new model updated with E-start for a year.
We just very recently moved back to Germany and we brought our bikes with us. One of the bikes is an 1995 XR250 MD30 Modell. We bought it from Zanzibar. Its quite unique because it's a Japanese Modell with Electric start, steel tank, high output stator. The bike was in pretty rough state when I bought It, but we got It to a ridable condition.
This how it must have looked like new
For comparison a pic of the 1996 xr250r
Before Moving to Africa I had worked with a couple of factory teams, in Europe and Australia, and from this experience I know its possible to improve and customize every bike.
The goal is to Tailor this bike to my wife's needs.
Some of the things I want to take care of:
the stock Weight of this bike is 130kgs( at least that is what Honda claims, real world is probably a bit more), Powerwise they claim 28hp output at the crank which results in aprox. about 22 at rear wheel, I’m going for just a little better suspension, just a little more adjustable front fork. Note its going to stay a XR.
One very interesting fact about this bike is that when the western world was still waiting for Honda to update the Xr250r for 1996, Japan was already riding the new model updated with E-start for a year.
So I began with disassembly, do to the fact the bike was in very bad condition it took quite a while.
In Tanzania there's not to much choice in bikes so you take what you can get. If there would have been a choice I would have got a different bike. Its pretty much the same situation for parts.
Different Swing Arm with a different chain slider mount which only allows small sprocket sizes,
Main frame has different tabs do to the Steel tank, Engine mounts are lower because the engine sits in the frame a little lower than in the me ME08 models, bigger wiring harness, different steering angle, different gear ratios.
The MD30 Uses a Vacuum carb it works fine but is useless Offroad. Front fork has no adjustment what so ever. The MD30 even has a little less ground clearance the ME08 (AUS,US, EU Model). The rear Airboot has a bigger diameter.
(When swapping to the XR250R ME08 Carb you have to use the rear air-boot from the ME08 model and the carb bowl drain screw has to be changed to a flat model. Otherwise you'll run into problems with the carb touching the startermotor. Other then that you need the trottle assembly including cables). But its way better to swap to the Mikuni Flatslide TM33, with the Mikuni the Trottle Cable also need to be updated.
But the Cool thing is that all XR250 models share the same Engine cases (only the inner 2 and the clutch cover), which means that you can build your self a costum tranny. That's what I'll probably end up doing. If needed. I need to split the cases at some point anyways.
So my goal was to make the suspension action as good as possible, which includes removing unsprung weight, increasing the braking performance, just make my wife have fun and enjoy when she rides it.
Basically I'm trying to build the best XR250R, that still looks like a halfway stock XR but with Electric start a quite a bit lighter and with a little more power.
I started reducing weight where I could with carbon fiber and Titanium, and aluminium. I got an XR400 Alloy subframe and costume welded the brackets for the batterie box. The XR400 Subframe will fit the 250R without any modifications. Just this AS-alloy Subframe needs to be modified a bit to fit the 250. But there's no welding included to get this done, just removing some material.
Alloy XR 400 subframe
Titanium Brake pistons and some modifications to lighten the rear caliper and hanger.
-61g front caliper modifications+Ti
-56g rear caliper modifications+Ti
-29g rear hanger modification
Total:
-141g
on my little china mill,
The Shop
Brake pedal
new headlight
machined and stock linkage
Was able to finde a couple of Rotors the OEM had done there time, the front one saved a couple about 50 grams
The Stock battery was 1,95kg
The lithium was 490g
That alone was saving 1,460g
-500g headlight
-50g front rotor
Total for now is:
2151g
Titanium piston fitted
later I found out that 08+ YZ250F from Brake calipers fit the XR250R brake hanger, and are quite a bit lighter since thy are smaller in design and use Alloy brake pistons.
Swaped out the gearing for a rental alloy sprocket and a nice none-O ring DID chain, and then we just rode it for a while
Swaped as much bolts as I could for titanium
-126,1g
Total:
2.277g
Carbon fiber heat shield
Now she sits in Germany a waiting her new awakening
I didn’t note the weight of the stock heatshield
-160,3g
Total:
2437,4g
that's the differents between stock steel and, Alloy.
So the frame has already been swapped for a 2001 XR250R frame, and I got a plastic tank of Ebay, just need to find a tank mount that I can copy in carbon. at the moment I'm swapping out the steel bolts for titanium.
Got one of these shock collar bearings, and noticed that the Yz250F from 08 use the same shock body size but use an alloy spring collar on the top. So I'll swap that XR steel collar for an YZ alloy one.
I got ahold of a company in Japan ( Yamamoto) that are offering a full titanium exhaust system for the XR, as soon as I have some cash at hand I'll try to get one. Apparently the complete system ist only 3,2kg.
for now I'm doing the rear Wheel next, I'll swap the stock rim for Excel- Rim as the a quite a bit lighter, and go for YZ alloy nipples if they fit the XR spokes. I'll try to turn down the hub 2-3 mm as well.That will be my first attempt at turning down hubs my self.
I have a 2003 WR250F front End with a titanium axle, and Lightspeed carbon guards that I hope to fit on the XR. I think SSS suspension would be a bit overkill for the XR. I think the 46 mm OC will be fine.
-10g
-11g ( banjos)
Total:
2458,4g
Yesterday was a bit frustrating the YZ250F front brake doesn't work. It would have been quite a bit lighter though.
the caliper with the golden titanium Pistons ist the Stock XR250R one, the other one is the YZ250F 08 Modell.
Before I used a CRF250 Front master cylinder from 2008, now I' switching to a 2013 Modell which should have positive effect to the feel when using the front brake, Honda claims the bigger piston increases the brake force a couple %.
in 2001 honda changed a couple of parts on the clutch assembly making it a bit lighter( at least that is what I think). So I'll be looking for an 01-04 Complete Clutch assembly to fit to the bike.
As it is quite hard to get parts before Christmas, I started doing my homework on the engine before I start tearing it down. Its always good to have plan and some parts lined up.
Here are the gear rations:
XR250 Japan/ Baja
1st gear 2.769
2nd gear 1.882
3rd gear 1.380
4th gear 1.083
5th gear 0.923
6th gear 0.814
Drive ratios (primary/final) 3.100/3.076
this is from the Honda manual for 98
1st gear 2.769
2nd gear 1.941
3rd gear 1.450
4th gear 1.173
5th gear 0.960
6th gear 0.814
Drive ratios (primary/final) 3.100/3.692
Looking at the parts lists it seems as if the 2 shafts are the same.That means after a little bit of testing I could swap out some gears to make it custom.
the compression rations are different as well, the Jap. Modell uses 9.3:1 (maybe the Japanese don't have as good quality fuel.) Where other XRs use 10.2:1. I'm planing on going to 10.5:1 and a 75.5mm bore = 266cc. The tranny once done is going to get the REM treatment and some of the shafts in the and rockers a going to get a coating to reduce a bit of heat. I’m still looking for a stock XR250R camshaft in good shape does anyone out there have one? If can’t find one I’ll settle for hotcam stage 1.
but it was definitely designed for riding more on road than off
(I think that is the reason for the lower compression and different drive ratios)
Pit Row
Thanks,
Here’s a pic of the front end that I’m thinking of mounting
I first thought of an air fork, but I think that would be a bit overkill for a XR250. Weight wise that would be the way to go. But aside from the XR250R I’m building the this WR250F 2006
as my final enduro race bike, going to put in a newer SSS YZ fork so I have the front end for free.
here a pic of the YZ master on the XR
Total:
2.558,4g
Got the stems pressed out, and made quick Sketch. It will probably take 2-3 weeks till I get the stem done. I need to make a drawing which is not my strength. Then I need get the stem hard anodized so it doesn’t corrode.
Measurements are in mm.
I made some wheel spacer last year and got them hard anodized and the price was 90 euro's.
The price mainly consist of start up cost.
I am planning to get 4 sets of fork tubes anodized but dont have a price yet.
Maybe I'll leave it the way it is then. I trying to get everything to fit and work before I do the cosmetics. Even vapor blasting in Germany is crazy expensive.
today I spend some time weighing all the part of the two front ends,
WR250F tripple clamps +210g
WR250F Forklegs -1070g
Ti WR250F front axle -130g
WR250F front wheel = as the XR
so I've saved 990g on the front End swap which is pretty cool. Funny because on Thumper-talk a lot of people claim that the fork swap would be adding weight. The savings would be even more significant if one would go to an Air fork but I think that's a setup that takes to much time to get dialed in for my application.
What I forgot is that there still more that can be saved in using Bicycle tubes, and going for the standard excel rim (not the A60). I think it’s round about 600g per wheel just doing those two things.
Total: 3.548,4g
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