Yamagama 100

[Mrs Busa Pete]

After endles reserch i found that an rg400 piston was the perfict size to use in the sleeveing down of the tzr 125 motor that i got of trade me .I found a listing in for 2nd hand barrels and pistons and went and checked out the diference in the pistons both pistons have a 26mm pin to crown hight only the rg 400 has a 14mm pin and the tzr125 has a 16mm pin this will be sorted by a 14/20/17 cage roller bearing for the conrod and taking 1mm of the bottem of the tzr125 barrel so the new piston is at the same zero point for ports.
After shit loads of phone calls to all sorts of outfits i went with colliers in levin sent the tzr125 barrel and the rg400 piston plus the tzrs power valve down today they should get it in the morning and i should get it back in 7 to 10 days including weekends,no turning back now.

yamaha tzr 125
bore 56.4
stroke50.7
pin 16mm


rg 400
bore 50mm
stroke 50.6mm
pin 14mm

[Mrs Busa Pete]

was thinking of fiting it to my fxr 150 frame that runs ns400r rims front and back that way i can change out the motor track side if the 2 stroke stops

[Mrs Busa Pete]

i have a nice wobble 125 chamber just waiting for the motor plus alot more bits

[Slingshot]

So do you have a spare RG400 barrel?

[Mrs Busa Pete]

try 021552488 ask for eric he had 12 sets of them $100 od for piston and barrel he is located in wiuku near glen brock. i cut the barrel up to try and save money on a sleeve didnt work it was to small for the job.

[Mrs Busa Pete]

So do you have a spare RG400 barrel?

what for read new post

[Slingshot]

what for read new post

I'm thinking I might try sticking one on a GP100.

[Mrs Busa Pete]

I'm thinking I might try sticking one on a GP100.

and do what cut the waterjacket of and tig some fins on it just remember the rg has a twin head

[Yow Ling]

and do what cut the waterjacket of and tig some fins on it just remember the rg has a twin head

You need to cut the head in half. Diesel pig had a rg400 barrel on his GP125 bottom end with rear facing pipe. Bren Chchc has a rg400 barrel on his bike called Joe water cooled half a head , very very fast

[Mrs Busa Pete]

You need to cut the head in half. Diesel pig had a rg400 barrel on his GP125 bottom end with rear facing pipe. Bren Chchc has a rg400 barrel on his bike called Joe water cooled half a head , very very fast

there you go eric has 10 sets left 4 fronts 6 rears

[F5 Dave]

Slingy will have seen Bren's bike when I had it.

Word of caution about sm.e brgs.

One check that the different piston doesn't have too much latitude that the brg moves sideways. Don't RGs run with side piston washers? No drama, but a piston that allows the brg to move to the side will run just fine. . . For a while, & then untold damage as it gets out & cocks a bit, grabbing the pin in a death embrace & shoves it out the side of the piston. Don't ask me how I know. I was younger.

Also be careful with alternative brgs. My 150 I resleeved (by Colliers) to 125 aircooled, but I had to run a bigger sme brg. It didn't have as many rollers so wasn't up for the job of high revs. I'd ask Wobbly to look at it if he has done some work for you.

You know, I wonder if you did carefully weld some fins on your stripped TZR barrel & then rebored it if that would be effective cooling. That would be a great starting point for a 125. Don't think anyone has tried that yet.

[k14]

Can you not machine up some inserts to press into the sides of the piston and then run the standard little end? Although may get some issues with different expansion rates?

[F5 Dave]

I think his pin size is the same, but the Rod is for a bigger bearing. Bearing will need to run on a plated surface.

Hmm I wonder if you got a 1mm precision sleeve if you could run that over the pin (ie inside the Bearing ID) & use the std TZR bearing? Would have to be a tight fit on the pin & would be a pig to insert/remove the pin.


You couldn't fit it outside ie: sleeve the rod, as it wouldn't oil well, . . . unless you cut some slots & likely that would hook up on the bearing.

[TZ350]

Can you not machine up some inserts to press into the sides of the piston and then run the standard little end? Although may get some issues with different expansion rates?

I have seen this done with different 2-stroke pistons, also Speedpro has had some success with this in a 4-stroke.

.

[F5 Dave]

I'm not sure I understand. care to elaborate?


Perhaps machine the piston to a larger pin & make some end caps, I think that is what Mike did with his old CB360 erm back in the day & is commonplace in drag cars I understand, but still not sure exactly what is entailed.

Bugger! that would have helped with my 125.

So what did you think of my weld fins on idea TZ? Got you thinking yet?