1971 R5 350 Scrambler

[MaryPoppins]

Good afternoon,

Its been a while since I've joined a new forum. Glad to be here.

Previously I've fixed a 73 Yamaha 650XS Twin that I learned to ride on. Recently got bored and decided to pickup a 2 stroke. This will be the most intense build I've done so far so I may be a little outside my depth.

1971 R5 350. 6500k miles. I was told its history was mostly as an abused shop bike for a group in metro Detroit.

From my research I have decided to replace the top end with 350RD specs.
Ebay Cylinders
Wossner Pistons
Vintage Performance Head
JL Exhaust
Reedvalves/Intake boots
Complete gasket set.

Motocross handlebars

I ordered 14in shocks that I'm hoping I can fit under it without too much modification.


I have a few questions.

Am I overlooking something glaring?

I know I'll need to completely rejet the Carbs and am open to suggestions.

Oil feed is going to be my other issue that I will have to overcome.

Pics from the original post and pics since pickup attached.

Open to any and all feedback.

[m in sc]

welcome to the forum. 
are you going to run an oil tank?

plan on crank seals, they will need to be done, no doubt. they can be done w out splitting the cases. plan on a new clutch, at least frictions. there's a posting on here about using fz600 discs, john at economy cycle sells them as well i think. get this out of the way now.

stock r5 carbs are good, they basically are 'factory' dave f modded carbs. the engine side, my 72 is set up pretty much like you have, i did a thread on it, but also run a cdi and chambers.

[MaryPoppins]

I'm torn between removing the oil tank and running premix (its not nor ever will be a daily) and maintaining the oil injection.

I will look into your thread. I did get the expansion chamber exhaust. Economy and HVC both got several orders from me over the weekend :D

I'm in my 30's just really getting my feetwet with moto-building. 

[SoCal250]

Welcome Sounds like you're going to have some nice bits in your build

You mentioned oil feed. If you keep the oil tank and pump (which I recommend) it should be fairly straight forward, you'll just run new lines from the pump to the carbs since you'll lose the banjo fittings on the cylinders when you switch out to the RD pieces. The OEM hose (Yamaha 90445-05M07-00 HOSE) is enough to do both sides. You'll have to drill the carbs for oil nozzles (either OEM Yamaha type or standard brass barbs). I believe there may be a boss on the R5 carbs that can be drilled. Mark will know.

Those 14" shocks are going to be a bit long and raise the rear of the bike. Standard length is about 12.75".

[MaryPoppins]

Thank you for the reply.

When I get to the point of Drilling the carbs I will reach back out.

Will it cause a major issue if I raise the rear a bit over an inch? Will swapping out RD400 swingarm extend it an extra inch to make up for the geometry change?

6'1'' on a bike from the 70's is always a good show.

[m in sc]

nah it'll be fine. just watch chain to chamber clearance. also, look into sidestand to chamber clearance. mock it up now

[MaryPoppins]

No side stand, Just a center stand.

[m in sc]

what pipes are you running to clear chambers? most don't allow use of a cenerstand

[MaryPoppins]

Well, Now that I'm looking into it. The Center stand will probably need to be removed once I put in the new pipes.

It had the (I assume) OEM pipes on it.

I ordered the JL retro polished exhaust. Should I cancel and pickup something else?

[m in sc]

the retros may clear a center stand

[MaryPoppins]

Well,

Replacement wiring harness, ignition conversion, battery eliminator and clutch discs ordered.

Pulling the wheels off today. New rubber already showed up.

Pretty sure I've decided to mix the yamaha colors together, The frame and such will go orange and the tank and side covers will get painted blue. A bit like the KTM's out there.

[m in sc]

you're going to run an MZB/ Vape cdi? no reason for a stock replacement harness then. easier to make your own vs rewiring everything IMHO.

[MaryPoppins]

Dyna S?

Well, I suppose its a bit too late to change the order now

[m in sc]

you need a battery to run a dyna s. no way around it w out a cdi.  its not like an xs where you can run a pma. ;)

[RD4140]

I actually put (Triumph) scrambler shocks on my R5, and it raised it up so much that the puny little kick stand now lets the bike lean over like an old chopper. It's weird and I like it.