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Modified 72 R5 at sunrise

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1972 R5 with Rd350 motor and forks

Started by Scooterror, August 04, 2025, 05:38:48 PM

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Scooterror

Bought this 1972 R5 in 2014. Just now getting around to it. Previous owner was a hack. Really started to look into it and found it's easier and safer to do everything the right way. Ill update as I move along.
You can check out my other builds and events/rides on insta @lancasterlambretta

Scooterror

I have two sets of cylinders to work with. One has an old conversion to what I think is a tz reed cage? Cutting that and converting it to fit the v force. Bottom picture is comparing what I think is a stock rd350 cylinder to the weird conversion cylinder. You can see the standard boost port is wider in the stock cylinder than the weird reed cage conversion. Have to measure the port timings

Scooterror

Started teardown. Rear swing arm went to the powder coater. Rear wheel and hub went to local shop Service Pavilion to get relaced with ss spokes

Scooterror

Back from the shop and then I put it back together

m in sc

nice. yeah, that tz reed cage thing was a big deal back in the day. i had a set of cyls like that, still have a set of rock hard tz manifolds from it i saved for .. no particular reason.  i alwasy found it funny that you could actually do th same thing as a bolt on w flat head cap screws & an adapter..., but, i digress. the past is the past.  you going to run those cyls? i also find it hilarious they ran the tz sized cage but chocked it down with the dual stage boysen reeds. lol. man those are a bottle neck. 








Scooterror

Yeah, if everything turns out ok, I'd like to use them. They do have a tune on them. Also have a nice set of unused (as far as i can tell) old dg 350 heads to go with them. From what I've read, I'd have to have the combustion bowls reshaped for modern pump gas? True?

dgorms

Yeah, do the combustion chambers. You have a nice start there.
rz,r5,ds7,srx,fzr400rr,vfr,cl77,s90, F-7,CL 77, CA-77,ad infinitum

Scooterror

Frame is back from the painter. Im happy with it. Have a solid plan for the motor and I got the DG heads back from being recut. Bought a new vitos crank. The old one was questionable. Using an rd 6 speed, tuned rd350 cylinders with the tz750 reed blocks, custom made intake manifolds (cant find tz ones that aren't hard as a rock), mikuni tm flatslides, weisco banshee pistons, DG heads, dyna s electronic ignition.  Hoping to have a rolling frame by the time it gets cold..

Scooterror

R5 frame from painter

SoCal250

Nice! Looking good. :clap:
Who did you end up using for recutting the heads, Toomey?
75 Yamaha RD125B   75 Yamaha RD125B (project)
75 Yamaha RD250B   75 Yamaha RD200B (project)
73 Yamaha RD350     77 Yamaha RD400D   79 Yamaha RD400F  
91 Yamaha TZR250R  89 Yamaha FZR400   05 Yamaha FZ6   
05 Yamaha XT225TC  82 Honda MB5  02 Aprilia RS250 Cup (sold)

Scooterror

 I ended up using Economy cycle to recut the heads and o ring them. Really happy with the work, reasonable price and quick turn around. Good communication.