1981 Yamaha YZ-250H

The Screaming Yellow Zonker!

(Hold your cursor over the photo's for commentary. Click on photo's for enlarge

                                                        As originally found:                                                           

Home at last. I have wanted a Yz-250G or H since they came out. Now I have one. What to do with it...Hmmm.    

I had wanted a G or H model YZ250 since they came out, way back when I was in High School. I never got one then. Now I do!    

Simmons forks and nice front rim.    This is the ugliest area of the bike. The clutch actuator seems to have had it's vent brazed shut, the frame is ugly, and the countershaft sprocket is wacked.     Excellent rear rim. Wheel bearings aren't bad. Sprockets need replacing. Time for a new tire as well.

   These shots were taken the day I bought it. It was pretty much all there, but it seriously needed some TLC.

(Make sure you hold your cursor over each pic for a description. Click on the pic to enlarge the image)   

    

The gentleman I bought this bike from is a fellow Vintage racer.  He wanted to make sure the bike found a home where it would be fixed up and raced, rather than parted out. It found that home.

 

The Resurection:

Part One: The Analysis

Stripped of her tank, seat, side panels, rear fender, pipe, and cylinder we get a look at what we have to work with. Very promising.    After plucking the engine from the frame we get ready to spend some money.    Examining the motor. Crank looks great, clutch isn't too bad...Decision? Go with it!    

The first thing I did was strip her down and fondle all her parts. Duh!

  Cylinder after Dan Cragle honed and mic'ed it. 71mm and largly square. Time for a 4th over piston!!! Looks to have been ported and had some extra boost ports added at some time. Will this be a rooster?

March '04

I have about a gazillion dollars worth of new parts on order at this time, including a new Maier front fender, a Wiseco piston kit, a new chain and sprocket set, new gaskets, some bearings, some misc. nuts and bolts, and a new Uni Two stage air-filter. I am looking for some original 43mm forks and triples, but may end up using either these Simmons units, or the stock 38mm front end from my '80 465 (seen in background in left most photo above). The motor surprised me and everyone I had look at it. I was expecting to have to replace the crank bearings and seals, but they all look and feel fine. Same with the bore. It is within factory spec of being square, and, after a little honing is ready for a new piston. 

Things are looking so good with this bike that the temptation to throw it all back together and go riding is very strong. I must resist long enough to get the frame powder coated...What's that dear? My money has run out??? DOH! What will we do? Wait for the powder coating? Or spend an evening with a black rattle can???

 

Part Two: The Phoenix Rises

April '04

After debating the pro's & con's of painting versus powder-coating, I decided to paint the frame. The cost of powder-coating was significant, but not the final reason for this choice. Rather it was the specter of a future frame crack. If I had powder coated the frame, such a crack might not be as easily detected, and could result in catastrophic consequences. I thought long and hard on this, along with the spectre of hidden corrosion, and obviously, the cost. All of these factors together led me to the spray can. 

Once I had sanded the frame down and inspected it, it was on to the spray can. Good results can come from a rattle can with patience. For once I actually had  some. It turned out pretty nice. I am going to put two more coats on, then several coats of Clear for protection, and then we start re-bolting the beast back together.

I have installed some 43mm forks from an '83 YZ-490, and have a line on the correct brake backing plate for them. Yamaha changed the angle of the brake stay tab on the forks sometime between '81 and '83, and they are not intrinsically compatible. The '81 originally had 43mm forks, but the Simmons this bike came with were only 38mm. I got a great deal on the '83, so that's what this one ends up with for now. 

I am toying with the idea of ditching all the stock plastic (except the tank), all of which is in pretty good shape actually, and going totally with Maier side-panels and rear fender to augment the front Maier fender I already have. I would prefer to stay stock, but it would be nice to have uniform sheen from stem to stern. The stock side panels need to be stripped of stickers, and sanded, and I'm not sure I want to do that on this project. Someone drilled additional air intake holes through one of the side panels as well. Performance increase? Maybe. Ugly increase? Definitely. I'm pitching it. 

I ended up selling the Simmons forks to another VDR racer for a project he is working on. They were only 38mm, and, while legendary, I just didn't like the yellow. 

I need to find out who has good replacement OEM style seat covers. All the repros I see don't have the YAMAHA logo's on all three sides like stock. There are some nice ones with only the sides, but...Anyone? 

I haven't decided if I am going to use the period DG pipe (a few  minor dents and blemishes, but overall in good shape), or go with one of the nice hand-made cone section pipes I see all over the Web. Once again $$$ will be the deciding factor. 

Here we are mid-April. Back to a rolling chassis. The number plates are the stock pieces from my '80 465. They might stay on this guy.     I've already had two people make offers on this bike, but I had to turn them down. This bike has really been growing on me. Of course, that's what I said about the last bike I sold...

May '04

Tomorrow (May 2nd) I am going to strip and re-paint the engine, and the DG pipe. I think I have good matches for the appropriate colors, and then it's motor mounting time! The DG pipe is in overall good condition. There is one gumball sized ding down low, but I don't know if I am going to try and remove it or not. I'm building a racer, not a museum piece, and that ding isn't enough to worry about. 

While sanding. Here you can see the largest dent just below the DG. All in all it's not a bad example of a period correct DG pipe. I was really tempted to leave it unpainted...    You can see it turned out more glossy than I was trying for. There is still some masking tape on the original metal-foil DG sticker, but that will clean off.

Refinishing the pipe was a labor intensive process. I have never liked sanding. Maybe I need a sand-blaster...

I had my doubts as to whether this was a DG pipe, or if some kid had just slapped on a sticker to look cool. The proof is in the pudding.

It is now mid-May. I have just finished bolting the motor back in place, attaching the pipe, and bolting on other misc. hardware. It is starting to look like a race bike. I am finding more and more small details I have yet to fix. Little things. Like a missing bracket here, or a missing bushing there. They are on order from the local Yamaha dealer. Last night I went through the carb and removed all sorts of old, varnished gas residue. Tonight I cleaned and affixed the throttle and front brake and clutch levers and perches. I have to sort out the electrical system, bolt on the foot pegs, attach the rear brake linkage, install the air cleaner, replace the rear sprocket, tighten a bunch of bolts, add some tranny oil, put in some gas, find a silencer, and it will be ready for the first test drive. AND I have this Friday off! It won't be finished, far from it. But it's one thing to work on a bike that is arising from the grave, and quite another to work on a bike that runs and moves! I think it will be running this weekend. It may even move!

 

Since these photo's I have replaced the rear sprocket, straightened and refinished the rear brake stay arm, procured a magneto cover gasket and bolted that cover on, replaced or added several missing or damaged bolts, procured the two frame mounted chain deflection rollers, and bolted the rear brake assembly in place. 

I still haven't started it. I found a stock silencer for this bike on Ebay, and it is on its way. Today I got the pipe manifold springs from the local Yama-shop. I think I'll start it as soon as the silencer arrives. 

May 22nd:

Today I oiled and installed the new UNI dual stage air-filter, filled the crank with oil, added a few misc. bolts here and there, put on the old, beat up spark arrestor/silencer it came with...and started her up!

That's right. I put in a gallon of pre-mix, opened the throttle wide, gently prodded it five or six times, let up on the throttle, opened the choke, and it started up strong with the 2nd kick after that! I ran it for about ten minutes at idle, but didn't ride it, as I still need to find the silly little bracket that clips the clutch cable in place on the case. Out of production/out of stock. I want to find a real one rather than fabricate one, though that wouldn't be tough. We'll see. 

Man, I am having fun with this project. I can't wait 'til it's done. 

I have a lot left to do on this bike. Though a lot of it is cosmetic, or replacing worn items that are still actually functional. IE: This phase has been the bulk assembly, next phase will be the grooming and fine tuning. But that phase will be done one part at a time, in between motos. 

July 2nd:

Things have slowed down a bit, partly do to summer, partly do to being a Dad, and partly do to lack of cash. Another factor is, I have been spending time working on the '79 RM250N. 

Tonight I bolted on the YZ490 double-leading shoe front brake, bolted on the foot-pegs, added a few missing bolts (like the seat and rear fender), and fabricated the impossible-to-find clutch cable retaining clip that goes under the carburetor. I made this out of a washer and a piece of sheet steel welded together and bent to shape. It works great. Took ten minutes to make...and to think I have been searching for this part for three months.

 My welding isn't very pretty, but it works. This part proved impossible for me to find, so I "fabbed" it in under ten minutes.         Same part with two coats of black paint. I don't really know why I am so proud of this stupid little part, but I am. :)

It's finally together, and I have been blasting around my tiny test track for the last several evenings. What a blast! I can't wait to try it on a "real" track.

 

Aug. '04:

I recently replaced the clutch friction plates, and the front and rear brake shoes. This bike screams. Now all I have to do is find time to ride it...

Feb. '05

...Then I sold it to a fine gentleman from the UK...and I never saw it again... :(

 

   

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