2001 CR250 $pecial Restoration Part II - Recreation of a 1999-2000 Japan Honda Factory RC250M

Yeah, I realize I am a bit overboard, but I have more free time since I am semi-retired now. Many of the HRC parts I have found are exception condition so I try to keep each additional part I add at the same level of quality. It is a display bike so I try to make it as nice to gaze at as possible. What I have now is not perfection, but I may decide to live with it as it still looks quite good and I have done everything I can to try and fix the issue. It is a very old piece of 7075 that was machined probably 21+ years ago. I have looked into bright dip and other possible solutions but that is the tricky part about anodizing.. on thing that some expert anodizers told me recently is that every piece of aluminum is different when anodizing even of it the same series alloy. If I etched the part, it would address the black streaks but that gives a very flat, matte finish/ color (what most anodize shops do) and that is not correct for this build.

Jeff, I already tried that approach after the first time I ran into the problem. I took my dye and parts to four anodize shops in New Jersey (and there aren't many). They will refuse your dye. They will only use their standard color in there tanks and they would have to empty one of their dye tanks and refill with your color.. that is maybe 35 to 55 gallon tanks and very expensive and time consuming to do. They will not do it for a couple of parts.. they will only do a special color for a customers that had thousands of major parts to be anodized.. a big job.

It is not so much compromising the integrity of the metal, but you loose the dimensions/ tight tolerances for fitted parts like the steering stem and fork tubes. For the bolt holes I protect them with silicone plugs.

I have a few extra HRC parts that I won't use so I thought about displaying some of them on the wall of the man-cave. I took the old HRC front number plate and spruced it up a bit with a new HRC aluminum retainer screw and brake line guide. On my build, I had decided to use the green number plate backgrounds that the All Japan MX Nationals used up until 1999, the first year factory Honda raced the 2nd gen aluminum RC250Ms. In 2000, the 2nd year they raced this bike, they switched to red backgrounds and #6 was Honda's factory rider, Ryuichiro Takahama. He won the 2000 All Japan MX National Championship on this RC250M. Since Honda raced essentially the same bike in 1999 and 2000 with a change in a few cosmetic details and the adoption of the 51mm fork, I have used the cosmetic details that I liked the most from each year for my build. A nice red plate to display from the 2000 Japan championship winning RC250M was a natural addition.




Here is Ryuichiro Takama racing the RC250M to eventual victory in 2000. In one picture he is being congratulated by his HRC mechanic, Takashi "Sasayan", on winning the Japan 250cc MX championship.




This model RC250M sweeped the MX 250cc Championships in 2000 (Takahama) and 2001 (Atsuta) in both Japan and Europe (Frederic Bolley). Tortelli might have been able to do the same on this bike in the USA, if it weren't for one thing.... Ricky Carmichael on the Kawasaki! Ricky was supposed to race this model RC250M at the 2001 MXdN if it weren't for September 11th. His first full season with Honda he raced the 3rd gen frame and engine and we know what happened there

The top clamp anodized almost perfectly with only a small hint of smut and the color looks very close to the original red HRC clamp that I have for comparison. I did leave the part in my desmut tank a little longer this time, but the difference with the lower clamp just might have been the piece of metal, and the lower clamp might have had a bit more zinc and copper in the alloy. Anyway, the clamps look nice enough for the this build and glad I got past this headache. I think, at the least, I was able to increase my knowledge on this process to the next level. Anodizing is pretty cool, but it can be a finicky process at times. I am always happy to help anyone who wants to try this at home.

Many thanks for the cheer, Damien.. it helps provide some steam to keep at it until this build is complete.. it is getting close, though it build went far beyond what I originally intended to do. First it was just a resto with a few HRC parts, then it morphed into a replica with a mix of a couple of HRC parts and a lot of replica parts, and now it has evolved into a full blown RC250M build with all original HRC parts.

The bikes are really set up for the rider and you can change the feel for what the rider likes. Believe it or not, the biggest change to the feel is the fatter 18" rear and 20" front tires.. they really take the shock out of hard hits like with whoops and a very different feel. I like the 20" for dry, hard conditions, but it is a nightmare in mud. The factory team would switch back and forth also depending on the track conditions. Suspension is another bigger difference that you might not even notice much until the track gets rough. There were also several different engine packages and sometimes the US, Europe and Japan had different engine set ups and sometimes they would change and a rider might start using the engine set up of one of the other factory teams. What I heard was that these Japan HRC engines were set up for very wide, smooth, linear power.. very controllable over the duration of the race and nothing that pulls the arms out of the sockets, so to speak. A few years ago, I translated a Japanese magazine article on a test ride of this very RC250M that I can post so you can read what the test rider had to say about the bike. They all loved this bike and few liked the case-reed engine of the next (last) generation RC250M.

Some new HRC parts came in for the 2nd front wheel I am building for the bike. While the HRC front hub uses oem bearings and seals, you can see the HRC bearing spacer on the left is very different from the simple oem tube on the right. You don't know this things beforehand so when trying to remove the old wheel bearings, I tried to move the spacer to the side with a hammer and long punch so I could get at the back of the opposite bearing. It wouldn't budge and now I know why! I had to use a wheel bearing puller in the end as the hammer and punch method wouldn't work as on an OEM wheel. The HRC spacer is CNC aluminum!


I got another NOS 260mm front brake disk and NOS caliper adapter that only works with the works forks. This way I can swap wheels easily and quickly without having to transfer the brake disc. Both wheel hubs are very nice, but to be honest, the Martin Honda hub is prettier and is NOS while being perhaps even rare than the HRC hub. Both are fat hubs. The again, the HRC hubs with cool, too being slightly fatter than the Martin Honda hub and I believe it must also be much stronger due to the way it is made. HRC really put an emphasis on strength and their hope is a dropped forged 7075 aluminum part that is only machined in the center section and then clear hard anodized. Making the hubs this way provides maximum strength around the spoke area, but perhaps a bit overkill. The Martin Honda hub is beautifully CNC machined all around and is a work of art, even if not as strong as the HRC design.

As for the bar mounts, this is the type the Japan factory team used on their RC250M's for many years. The one on the left is NOS HRC and the one on the right is an excellent replica made by Giuseppe Bonamigo. He makes excellent replica parts. Hard to tell them apart aside from subtle differences. Both use titanium lower mounting studs and clamp bolts. The HRC upper bar mount is clear anodized and I am guessing it is 7075 aluminum because it has the same "dirty" grain from the high zinc and copper content that gave me trouble when I anodized the lower HRC triple clamp.




The HRC front wheel I got used a heavier 9 gauge (3.6mm) spoke whereas the oem spoke on the right is a lighter 10 gauge (3.2mm) wire.

I really fussed and sweated over these clamps for the last few weeks and although there were some challenges, they do look pretty good all back together. HRC used lots of titanium on these steering parts.. all the bolts and nuts, the steering stem and the bar mount studs are titanium. I think I mentioned before the steering bearings and seals are the same size used on a CRF150 so the longevity was very short on a full size factory race bike. The HRC clamps from this era had chamfered edges, but were later changed to rounded edges soon after when HRC found that rounded edge clamps gave a smoother feel (less harsh) to the front end in the rough stuff. HRC also started drilling out the steering stops in later versions to lighten the clamps further. You can see how HRC learned and developed the factory clamps gradually over time. The HRC bar clamp is the style the Japan factory team used for many years. I think I am about ready to swap out the front end with these new factory parts.

Thanks so much! I am always wondering if I am going into details that are only interesting to myself, but you learn a lot of these details and history when you research and build a detailed factory replica like this and the learnings often don't get passed on to others. I am glad that some people are not getting bored with the details and find it enjoyable reading.

haha.. thanks Damien.. maybe I should send your wife a fruit basket or something for all your attention she has lost to a silly inanimate red bike

If you like this kind of detail, I will post a translation of a couple of Japanese MX magazine articles I did for a friend a few years back when a test rider/ retired factory rider rides these championship winning RC250Ms and reports back on what they feel like to ride and the special HRC parts on them.

Here is a test ride of Yoshitaka Atsuta's 2001 RC250M. At the same time, his team mate, Ryuichiro Takahama was on the pre-production 2002 CR250 with works goodies, and a 3rd team mate, Kazuyoshi Odagiri, was on the pre-production 2002 CRF450. Three different machines all raced together on same HRC factory team to compare and contrast against each other for the purpose of developing the OEM production machines.



Translation;
1., 2. Atsuta’s RC250M engine may become the production unit in the future, and includes specifications from both Europe and the United States. By running Takahama 's new (’02) RC together with the older RCs, the team’s objective is to collect comparative data.
3.,4. Atsuta’s “00 engine adopted the '99 RC WGP specifications, but in the second half of '01, it included the AMA National specifications. In off-season testing, Akita instantly liked it. The '00 spec engine has good top-end power, but the low end was rather weak. So in '01, while maintaining the top-end power, they were able to make improvements in the complete power band. The crank is the same as before, but the shape of the inner cases is different. A V Force reed valve was adopted from round 9 in Shikoku, so they only ran it for the last two races, but the effect is great for slippery tracks like Sugo. For the current engine specification, the V Force and the TMX (carb) go together as a set, and is what Tortelli liked using in the AMA Nationals. The characteristics of Atsuta’s set up is close to his (Tortelli’s).
5. The frame on Atsuta’s machine is reinforced with patches. The frame is basically a carryover from the '99 RC250M, but has been significantly strengthened around the steering head and the foot pegs. A special thin-walled, translucent (fuel) tank was adopted for weight reduction over the thick (walled) mass-produced black (fuel) tanks. Fuel capacity has also been increased by carefully thinning (the tanks), but the increase is not the original purpose.
6. A carbon (fiber) silencer was adopted for saving weight, and the shape is almost the same as that from a '00 RC with the bottom of the silencer indented to keep it from hitting the brake caliper.
7. The under guard is a hidden part, but provides reinforcement the way it folds up between the frame rails towards the engine. The shape of the (rear) link has been changed, adopting a different ratio. Atsuta prefers the same (rear) link ratio as the production '00 CR250R.
8. Atsuta’s machine has a button to operate a dedicated start (timing) program mounted on the left side of the handlebars. Used only for the start, it is speculated that it has a mechanism that detects a downshift and then automatically restores the timing. After changing the ignition timing to bring out the near maximum power (for starts), it returns it to normal ignition timing to avoid detonation. The (ignition timing) program can be easily modified.
9. The works hub looks fat and heavy, but it is lighter and stronger than production as it is mostly hollowed out. The spokes are also special with a larger diameter than the mass production parts. It uses the same number of spokes and has the same width dimensions as the mass produced (hub). It is one part that may find its way onto production machines in the future.
10. Among the three HRC work machines, Atsuta’s machine is the only one that used a 20 inch front / 18 inch rear tire this racing season. The rear tire sits on a wide 2.75 rim. The suspension responds to changes in tire diameter along with a change in the length of the rear shock.

Here I just translated the part comparing the 2nd gen piston port RC250M with the all new 3rd gen case reed engine RC250M. Japanese don't like to say anything negative, but it was apparent enough that the test rider didn't like the new case reed engine that was powering Takahama's RC250M.



Translation;
With piston reed, crankcase reed, and 4 stroke SOHC engines, the 3 HRC works machines running in the 2001 season can be said to be completely different. Shoki Ishii test rides (them all) to compare the differences.

This test ride of the ’01 HRC works machines is different from past years in that we test the All Japan Champion RC250M (Atsuta’s bike) first, then the CRF450R (Odagiri’s bike), and the RC250M (Takahama’s bike). Also in attendance were the mechanics responsible for the 3 bikes, the works trailer, as well as the 3 works riders. We check on the state of machine development at the end of the (racing) season. The test course was Moto Sportsland Shidoki.

-CRF450R #21 Kazuyoshi Odagiri
The first bike we tested was the CRF which was easy to ride. The engine was smooth with a long torque curve. XX REST OF THIS SECTION NOT TRANSLATED XX

-RC250M #2 Yoshitaka Atsuta
Next we test Atsuta’s RC250M. The engine characteristics make it feel somewhere between a 125 and 250. From low rpm to the top of the power curve, the power is very flat. No matter where it is in the torque curve, there is no surge in power, no change in delivery. It (power delivery) is similar to the CRF, but if I had to choose, I prefer the 2 stroke. The RC250M is more flexible.

When you half-clutch it in a corner, it stands up and moves without wasted motion like the 4 stroke. Because of this, it is unusual to miss (make a mistake) with this 2 stroke. When you watch Atsuta ride, he appears very smooth. It is probably not only his riding style, but also this machine that factors into this. It feels like a complete works machine.

He has been riding an RC250M for 3 years since 1999, but the suspension has evolved quite a bit over this time. The suspension is firm, but there is no longer any shock transferred to the hands like before. It is not because the initial (fork) travel is soft, but because it directly follows the track surface so well. There is no wasted movement and it doesn’t feel stiff. Atsuta’s machine has a perfect balance between the front and rear suspension and the frame’s rigidity. Following Takahama’s 2000 championship, it has been the championship winning machine for 2 years in a row. This is a machine without flaws.

-RC250M #1 Ryuichiro Takahama
Comparing Takahama’s ’01 RC250M (note: 2002 pre-production) with Atsuta’s, it feels like a machine that is still under development. With the change in the way the engine breathes from the former piston reed to the crankcase reed, the power delivery feels different. The power really comes on strong at the high rpm, however that cannot be said for the low and mid-power and you have to be more careful with gear selection. The spread between 2nd and 3rd gear is wide and if you are in too high of a gear, it forces you to half-clutch it in the corners to get back into the power band which causes the bike to stand up and lose traction.

In contrast to the ’00 RC250M, Takahama’s bike uses a 19” rear wheel and I am guessing it is because it better matches this engine’s power characteristics. Takahama’s engine still has most of the characteristics of the production bike so it is lacking low end and mid-range power. However, it makes more peak power than Atsuta’s machine. The rider has to adjust to the machine’s characteristics and if you can master the power, you can probably win (with either).

As for the chassis, the suspension is smooth and feels good. While these 3 bikes share suspension, Takahama’s RC uses the same frame as the production ’02 CR250R. The production frame has more flex and requires a stiffer suspension setup.

Works machines have the image of being special (altogether different breed). Having gone through this test session, that is the definite feeling I came away with, even though the works machines are based on the production bikes. There is a connection between HRC and the development of future production CRs/ CRFs.

If you like the reading above.. I will post a few more translated articles.

The front end is done with more HRC parts on the way and it looks like I may achieve a complete RC250M build by March with all original and period/ model correct HRC parts with the exception of the engine internals which I never saw value in doing. It is a newly rebuilt engine with NOS parts though and runs great.


Many of the HRC parts bolt right on in place of the OEM parts but there are a few parts such as the rear wheel and triple clamps and forks that are a pain and require special parts and figuring out what the special parts are. I don't have the benefit of a manual or a parts catalogue to figure what special parts are needed. I usually run into a problem unaware and then need to figure out what is the right set up to make all the parts work and line up.

In the case of the triple clamps, the bearing race are specially machined for the smaller diameter HRC titanium steering stem. There are also a number of types of HRC steering bearings.. from zero offset to a various number of offsets. The HRC bearing races are also much taller than the OEM races.
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The OEM bearings sit down in the frame and the seal, seals off the top of the frame with the bearing sitting well below it. When I installed the HRC bearings, the stuck out of the frame by 1mm on both the top and the bottom.


Then I had to ask myself if they were supposed to be like that or did HRC modify the frame such that they machined the bearing bores deeper for the taller bearing race? I was thinking there is no way the seals can work like that. Not easy to confirm and I reached out to others who have installed these bearings on their own builds. The steering stem seals for the HRC look exactly like OEM except for the smaller ID. In spite of that, they do not seal the same way as the OEM seals. I mentioned that the OEM seal seals off the hole in the frame, while with the HRC set up, the seal only seals off the top of the bearing. As you can see when I put the top seal on, it covers it perfectly.. you would not know the bearing race is sticking out and looks OEM even though it is not. The lip on the OEM seal seals against the inside of the frame. The HRC seal seals against the inside of the bearing race.


Here is the bike all back together with the new RC front end. After all was said and done.. the anodized clamps looked great on the bike..




A lot of the HRC parts have holes drilled in them for safety wire, even ones that I personally never had come lose over decades of motocross.. it seems like overkill and that is the impression when you viewed the factory bike in those days.. so much overkill that it made you feel they did everything they could do to the bike to make sure it could win a championship. I safety wired the top steering nut...


And I got these titanium safety wire posts to safety wire the engine oil filler cap. HRC used the OEM oil filler cap and drilled two holes in them for the wire.



I also picked up another NOS HRC front brake rotor for the 2nd wheel I am building along with another NOS HRC brake caliper adapter for the 260mm discs I have. I had 3 different sized HRC brake caliper adapters and best I can figure out is that the disc sizes they were intended for are 240mm, 254mm, and 260mm. I never knew that HRC had a 254mm disc option at one time. These adapters only work with the factory forks.

As much as I love the Martin Honda hubs, I still picked up an HRC front hub to throw on the bike for a while. Both hubs are the "fat hub" design and really stand out as a works only item on the bike. The HRC fat front hub was laced up to an nos 20” rim and spokes. This is probably the last 20” rim and spokes that Honda had in stock.. I bought all the spokes available from Honda US, Honda Europe, and eBay to put together 36 nos 20” spokes which are 227mm long. I also got another NOS 260mm front brake disc and a very difficult to find nos Dunlop D756 20” tire. The hub was rebuilt with nos Honda bearings and seals so the wheel is all new again. Both hubs are rare and cooling looking pieces, but I think the Martin hub is the prettiest of them both and eventually may revert back to that.





The disc side HRC wheel spacer is tiny compared to the oem spacer. .




Bike is getting close to completion.. I have a works billet shock and HRC billet suspension linkage on their way and will be added soon.
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