Getting ready to build a couple of RD racers

[Vintagetz]

After a long hiatus, I am finally getting to build a couple of race bikes I have been wanting to get done.  I was able to get the wheels refurbished buy a guy in England that is a magnesium specialist, he used to work for dymag and opened his own place.  he chemically strips them to bare metal, crack tests them, soft media blasts, re-chromates, then low temp powder coats.   I had them done in the original Campi gold.  Also had him do the dry clutch primary covers.  Working on the brakes and suspension now.  hope to have both a 25o and 400 on the track this spring.. 

I intend to use a TZ125 tank and TZ250 fairing and seat on both.

[Vintagetz]

Had the cases vapor blasted and the center crank lower case machine for TZ crank circlips for crank centering.  The 400 cases are NOS, the 250 cases are late model euro so they are the same as the 400 as far as the left side of the motor.  They were in almost NOS condition.  The vapor blasting is just awesome for the finish it leaves, I am probably going to cerakote at least the top case, I will also do the electrical side cover.

[stresa]

Hi Vintagetz,
I will enjoy to read about your builds.
But which TZ125 tank will you use on a RD250/400 frame?
Regards Uwe

[busa1300]

Interested in seeing the dry clutch/trans set up
Have been wanting to build a dry clutch bottom end for my RZ for years.

[m in sc]

ooh sweet. you planning on running either or both next year?  I haven't been to a race in a few years, I need to get out there.

[rlloydm]

You racing with AHRMA or a different org? Formula 750 being the featured vintage class next year is going to be a lot of fun - should be a lot of fast riders on fast 2 strokes on the grid.

[Vintagetz]

First Thanks for the interest, I will post pics of the progress, I am accumulating the rest of the parts I need to build them, it will be a set of early next year projects.

So to answer the string of questions,

Tank, it is a later model TZ125 (late 80's aluminum) I am working on a couple of new chrome-moly frames BUT, still working with the builder, if that does not work out I will modify a couple of RD frames.  If the CROMO frames work out I am getting the main cradle fabbed with a frame builder, I am going to put the back of the frame on myself.  Right now the plans are to have the bikes to be almost 100% new.  I am using Brembo P108's on the front and a tiny Brembo rear.  I have a completely new RD250 motor build (long rod) and a well-developed RD400 motor that I will replace with a completely new one by the middle of the year (NOS cases cylinders, heads and internals) I am planning to use FZR 38mm forks with emulators and billet triple clamps, aluminum swingarm.  Hoping to end up with Ohlins on the back.  Tires are an issue as Dunlop stoped making the best vintage tire, I am going to use the new Conti tires.

Dry clutch, the 75-80 TZ system is a drop-in for the RD,  The RZ is more difficult, it is a completely new transmission and not compatible with the older TZ's or the newer 5F7.  I have two Dryclutch transmissions for RZ's, they are not cheap but you can buy one, PM me and I will discuss the details.

Planning on building them both this next spring and getting them out as soon as I can.  I am in the process of finishing an RZ350, I will be running in AHRMA in the nextgen Lwt. superbike class. I have doubts about getting the two RD's done for the first race.  I think I will have the RZ finished to run some track days and try and get my lap times competitive.

Racing,   I will run AHRMA, I may also run some WERA for the track time.

And there are some VERY FAST guys running AC RD's in F-vintage but the faster bikes are the RZ's, they are allowed to run stroker-big bore motors, much faster than an RD400.  I don't plan to run F-vintage.  After I get the RZ and RD's done I have a 1984 TZ250L I want to finish for the classic gp 250 class.

[busa1300]

Found a 85 TZ motor in Japan selling for $2100 at the moment....still looking for a TZ350 bottom end.

[Vintagetz]

That is an N model, I have a few of the next series, the S and the T, the N had smaller reeds, I would like to have at least those cases,  All of the rest of the motor is the same from the 1981 - 1989 as far as the drive train, transmission, etc.  BTW the frame, tank swingarm, and shock is for sale for that bike.

you can build a brand new TZ350, I could help with the cases.  There are two sources for brand new better than original aftermarket cranks at a decent price.   You can get new transmissions and clutches.  I have a source for a side cover.  What are you building?  you are welcome to PM me or E-mail me.

I am interested in getting a TZR250 3MA swingarm soda blasted, do you do it yourself or can you refer me to the shop that has done your work?  I would prefer to have someone with experience, it is not grungy and I will pull the bearings out. 

[busa1300]

I use one of these soda blasters.
It is the only thing I have bought from harbor freight that has actually worked more than a few times without falling apart or breaking.
I could do it, but the cost of shipping swingarm, might be the same as buying the blaster for yourself.

The reverse cylinders (3AK/3LC/3TC) used the same trans and clutch as the motor I pictured?
Interesting...





https://www.harborfreight.com/40-lb-portable-soda-blaster-60801.html

[Vintagetz]

Thank you for the information, and I get it,that is a reasonable cost, and I can do a LOT of parts with it!

Yes from the crank back they are basically all the same,  the 1990 TZ250A is a reverse cylinder but the cylinder design is quite different than the U and the W.  It is more like the first V-twin cylinder, again from the crank back basically the same.

The 5F7 motor had alternate ratio's for many of the gear sets, there are quite a few 5F7 gears in the V-twins, 4DP and on.