Vintage Dirt Bike Q & A

Hi all,

Does anybody know if a rear brake panel from an 82 will fit the rear wheel from an 81?
Also, if an 81 front brake panel will fit the front wheel from an 80?

The part numbers are close, but without actually paying for them and then finding out they don't fit...

Thanks!

Mark.

The rear brake panels are interchangeable but I don't think the fronts are.

Honda part numbers break down into five sections. The first two numbers are
the function number, the next three are the component number and the next
three are the parts classification number. These are the ones that have to
match for compatibility. The last three to five numbers are classification code
and color number if applicable.

The numbers on the rear hub and brake panel in question, that matter, match.

The numbers on the front hub and brake panel in question, are not compatible
and the '81 was the first year for the double leading shoe front brake, so I don't
think that brake panel will fit a "430" hub.

dogger

_________________
1973 CR250M
1979 CR250R
1993 CR250R
2008 CR500R
2009 CR250R

Hi Dogger, sorry to get back to you so late, work & kids...

Thanks for the info! What you told me about the part numbers helps alot for other things, too.
And you saved me some cash on the front brake answer, bonus.

Nice collection of bikes, wow. I'm trying to finish my '80 CR 250 that has a Sachs 175/7A fitted into it. I know, sacrilage, but I've had it all since 81 and I can't give up now. Just trying to save some $$$ and parts for the '81's and '82's are cheaper to buy.

Thanks again!!

An '81 Honda CR wth a Sachs engine - interesting combination.

Are you doing the engineering yourself? I would imagine the CS sprocket
allignment, engine mounting tabs etc. is quite a challenge.

I have been working on putting an HPP valve era CR250 (92-01) engine
into a gen 4 frame from an '08 CRF 250 for the ultimate CR250.

The latest generation frames have superior handling characteristics to
any of the aluminum frames offered when the CRs were in production.
The '08 CRF 250 has the same geometry as the '93 CR250 (best ever)
and is pounds lighter. The HPP valve engines were much stouter than
the lame RC case valve engines the last CR250s were equipped with

I am building the engine now using all the best parts ('01 cylinder, Keihin
PWK carb with TPS, V-force 3, dual map programmable ignition, billet
crank, coated superlight piston, works tranny gears, Hinson clutch, lots
of titanium and carbon fiber, etc., etc.)

Unfortunately, I have run into some problems with case width, CG, and
CS sprocket allignment. It is doable because Service Honda is turning
out quite a few CR500 AFs which is a similar concept.

I am motivated because I am tired of the overpriced, unreliable and oversized
four strokes that were forced on us by the idiots at the AMA because of a
loophole in the rules. The price of racing per season has tripled because of
bike, maintenance and parts cost. But, if you can't beat 'em, join 'em. The
new rules allow a 250 two stroke to compete heads up against the 250 four
strokes. That's a rule I like, so it's back to the "tiddler" class for me.

dogger

p.s. Anybody want to buy some CRF 450s? I have an assortment, new and used.

_________________
1973 CR250M
1979 CR250R
1993 CR250R
2008 CR500R
2009 CR250R

Hi Dogger,

Again, thanks for the reply and I really wish I had more time for everything...

Engineering, never thought of it that way, but yes, I've had 27 years to think about this one. The engine sprocket lines up perfectly with the rear wheel, but it's exactly three-eights of an inch off to the left of the center of the frame. Hopefully it won't make a huge difference. Also, with the center exhaust placement on the engine and the height it's at, the 1980 CR250 frame was the best one suited for this engine, with the double-downtube frame (compare it with the 79 and before and the 81 and after). Sure, monoshock and discs would be great, but i'm building this with the frame of mind that it's 1981 and i'm 16 years old, cutting lawns for dirtbike money. Ahhh, memories..

I could bore you with details, but if you go to this link http://www.markschell.com/dirtbike/ you can get some hopefully not too boring details at your leisure. Not updated in a while, more for my own reference. Again, not enough time, but at least you can see how I got the engine in. If I have a few hours soon I'd like to update it more; lots of pictures & what-I-did type stuff.

By the sounds of it, you're miles ahead of anything i'm doing. I've looked at some other posts in here and you seem to have an answer or advice for everything. I can see why you're putting your HPP valve engine into the '08 frame; never had either bike but from what i've read/seen, I hope it works for you. If you can, post some pics, i'd like to see this, even just what you've done so far.

For now, I just would like to finish my dual-shock, drum-brake, carburetor-fed, air-cooled Sachs-powered 1980 Honda CR250. Yeah, here comes the old-timer....

BTW, if you know of where I can get a wheel or even just a hub for a 1980 CR250R for under 200 bucks, i'd really appreciate it.

Have a great new year and keep the info coming on your bike.

All the best,

Mark

Mark,

Sounds like you have that Sachs/Honda conversion well in hand.

The problem with late model Honda conversions is the singarm
pivot bolt passes through the crankcase and is an additional
engine mount. Unless the replacement engine is the exact same
width as the original, you will have problems. Unfortunately, the
HPP valve engine I want to transplant is wider than the CRF engine
the frame, swingarm and mounting tabs were designed for.

It will be some time before I have any progress pics to post
on this one, the engine is spread out across my workbench in
four covered piles.

I don't think you will have much luck finding a complete '80 wheel
for under $200, but you should be able to score a restorable hub
in that price range. Ebay, a want add on this site, maybe a local
swap meet in the Spring.

Good luck with it and keep us posted.

dogger

_________________
1973 CR250M
1979 CR250R
1993 CR250R
2008 CR500R
2009 CR250R

portland oregon cragslist has some one parting a 81 cr250 listed on 1-3-09 under honda cr parts

I have several 1978-1980 single leading shoe wheels, hubs and brake backing plates. If this is what you are looking for PM me. BTW, if you are thinking longer-term, take a hub and get it powder-coated, refresh the bearings and seals, and then lace it up to a new rim and stronger spokes. It costs but the stock DID (did it dent?) rims I have had my hands on were - without exception - dented, dinged or cracked.

I'll get out in the garage and see what I've got...

_________________
Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF

I know this isn't a vintage bike, but I just found out that Service honda is building
the ultimate CR250 I was talking about in a previous post.

It will be available in a few weeks and combines an '01 HPP valve engine (badest
ever) with an '09 CRF 250 roller.

I will be taking delivery of one this Spring. All I have to do is bolt on my works
suspension, put it on a Titanium diet, dial it in and instant adrenaline machine.

I found the pic on another site, probably a test mule.

dogger

[img][/img]

_________________
1973 CR250M
1979 CR250R
1993 CR250R
2008 CR500R
2009 CR250R

Hi Dogger315, Redrocket190, Badsix,

Thanks so much for all the help/info, really appreciate it. Been too long since i've gotten back to anyone, but a new job can do that to you. Busy, sometimes too busy, but with the economy the way it is i'm glad to have it.
Dogger, if that pic is along the lines of your new creation, all I can say is Wow. Trade ya any day.. not that you would. Again, your info is great, thanks so much.
Redrocket, I appreciate the offers, wish i'd read it before I went out of town for work, but when I got back two weeks ago I saw a complete 1980 rear wheel on Ebay, complete with axle, brake, all for a starting bid of 50 bucks. I put in my bid and won it for that price; I was the only bidder! The seller got back to me after I'd won and said when he was removing the tire for shipping he noticed the rim had a quarter inch crack on the edge. What to do; he offered me my money back but at that price I don't care; I can change the rim. I'll see when I get it.

I'll try and keep this post going; the thought is always there but time can be an issue...

If anyone knows of a good Sachs site, please let me know. There are days I wish I still had the original engine, parts would be easier to find! Most people I talk to have never heard of Sachs or if they have it's for the Madass, etc. Even the factory doesn't have spare parts or info on my engine. Yup, a Sachs 175/7A, went into so many European enduro's in the 70's, but that was then & this is now....

Again to all, thanks so much!

Mark.

FYI,

If you can bead blast the brake hub, i keep buying used brake hubs for 78-80 250's and after i blast them i find them to be full of cracks!! Another tip, a friend of mine who broke his backing plate on his cr480 swapped in a complete brake assymbly from an 85 YZ250, took a little grinding on the spacers but other than that it works great, and is a much better casting than the honda part. Not to mention availability is much better!!

montywa,

When you talk about cracks you find in the backing plates after you blast them,
do they look like the picture below?

If so, those are not cracks that affect structural integrity but are casting flaws
caused by production standards and the use of magnesium. Magnesium is very
strong and light but also very brittle. Among the ways to produce parts from
magnesium is sand casting (think Halibrand wheels) or investment casting (what
Honda used). It is not unusual for investment cast magnesium parts (if production
standards allow it) to have superficial cosmetic cracks. Honda knew these parts
would be painted so were unconcerned. You could media blast a NOS clutch cover
or backing plate and find these same cracks.

I know you mentioned in another post that you had a backing plate failure. If you
consider the age and the unknown history of these parts, that is not that unusual.
Also, I'm betting the Yamaha backing plate is aluminum.

One way to check if the part is sound is to take it to a shop that performs NDI
(non destructive inspection). They will apply a special dye penetrant then inspect
using a black light. Any compromise in structural integrity will be revealed. This
test is used on aicraft parts as routine and preventive maintenance. I have the
home version of this kit and use it on every questionable component of the bike
I am restoring (frame, swingarm, hubs, backing plates, triple clamps, etc). Better
safe than sorry, right? I hope you didn't throw away those old backing plates, they
may still be good

dogger

[img][/img]

_________________
1973 CR250M
1979 CR250R
1993 CR250R
2008 CR500R
2009 CR250R

the cracks are open and obvious once properly cleaned. i am well aware of the diferences between casting impressions and actual metal stress fractures and cracks. I raced two more motos this weekend on my cracked backing plate with no issues, i am up in the air on what to do at this point though. My options are to either maching a billet aluminum backing plate, or swap on a newer wheel that will allow the use of the yamaha backing plate. either way i will show the results