RD350 Dirt Tracker

[yamaico]

With Firko and Jim's twins on the way, and the concept of the forthcoming twin class gaining interest, I've made a start on a budget (surprise, surprise) twin racer. I picked up an RD350 for free a couple of months ago.



It had been sitting in a shed on the south coast of NSW close to the ocean, so it's a bit rusty, but quite original and not butchered (well not until I got to it anyway). The pistons were stuck in the bore but a soak with acetone/ATF and it freed up nicely.

Stripped it down and fitted up a back wheel that was a spare rear wheel for my Yamaico that had a K180 on it.The front wheel is off a CR450 that I bought and fitted it up with a new K180. It'll be laced up to an MX250 hub later.



The frame will be hacked up with virtually just the cradle remaining, with a DT top bar and seat rails to be grafted on, but to keep it all straight while I de-rake it I've just cut out the top bar so that I can pull the steering head back to 25 degrees.





This will be a fun project...

[firko]

What's the estimated finish date Pete? I've got a warm and fuzzy feeling that this one will top 'em all . I'll have to put some effort in on the el Cheapo TM250 for the 'Cheapo Challenge 2013' The answer re your crank question was a resounding yes, it would require balancing, from Frank btw. Jonesy and I went over to his place today to help him get his Matchy going....Blair Harley was there too.

If it's not finished and you're not in Vietnam, Uzbekistan or Costa Rica around at DT Nats time you're on the OW72 if we can get it together in time. Failing that youre welcome to throw a leg over 'Little Red' the mystery framed 360 Yammy tracker.

[oldyzman]

Looks interesting, i saw a yamaha RZ350 on ebay and was pondering it as a DT.
Whats this about the el cheepo challenge, i am trying to build a bike right now for sub $2k, is this a contender in the el cheepo 2013. All of the costs seem to add up just to make it reasonable and replace all the bearings incl swing arm ones etc....
Brett

[matcho mick]

crank rebalance?,ah,i detect a hint of twingle approaching  ,

[yamaico]

What's the estimated finish date Pete? I've got a warm and fuzzy feeling that this one will top 'em all . I'll have to put some effort in on the el Cheapo TM250 for the 'Cheapo Challenge 2013' The answer re your crank question was a resounding yes, it would require balancing, from Frank btw. Jonesy and I went over to his place today to help him get his Matchy going....Blair Harley was there too.

If it's not finished and you're not in Vietnam, Uzbekistan or Costa Rica around at DT Nats time you're on the OW72 if we can get it together in time. Failing that youre welcome to throw a leg over 'Little Red' the mystery framed 360 Yammy tracker.

Hope to get this one finished before the Nats Mark, but I've got a lot on my plate at the moment. If not having it finished means I can ride your OW, then I don't think it will be 
I pretty much new that the crank would need balancing. I'll do that when I pull the motor down.

Looks interesting, i saw a yamaha RZ350 on ebay and was pondering it as a DT.
Whats this about the el cheepo challenge, i am trying to build a bike right now for sub $2k, is this a contender in the el cheepo 2013. All of the costs seem to add up just to make it reasonable and replace all the bearings incl swing arm ones etc....
Brett

The more the merrier Brett. Under $2K is definitely a contender.

crank rebalance?,ah,i detect a hint of twingle approaching  ,

You're almost on to me Mick. I was thinking about trying a 90 degree offset and eliminate that deadspot at TDC/BDC that 180/360 twins have. Might be right off the mark, but it's an easy experiment.

[Curly3]

 

[firko]

Whats this about the el cheepo challenge, i am trying to build a bike right now for sub $2k

2K is a positive kings ransom for Yamaico Pete. I think he's aiming to bring this in at $800 or less. The challenge involves the TM/TS250 Suzuki I built using the old mate network and skip bin parts and my stored away stash for $100 that we covered in a couple of early VMX editions. The bikes sat doing nothing since not long after it was completed so I'm very slowly converting it into a flat tracker to give to a mate who's doing it tough for Christmas this year. The same el Cheapo concept that I used to originally build the bike and that Pete has taken to new levels is being used. Once I get a bit further into it I'll post some progress shots.      Below, the $100 TS250 powered TM250 that'll soon be a flat tracker.                              
                                                                                          

[firko]

Here's one that was on vft.org recently.............................
                                                                             

[matcho mick]

geezas 90 deg,thats doing me head in ,won't sleep now ,

[oldyzman]

The bike cost me 1000 to start with, So the sub 2k is about as low as i can go as i dont have a stack of new parts, also i really dont want to put in all the time and try to skint too much on the rebuild.
Brett 

[Lozza]

The is no 'dead spot' in 0-180 firing and 90 deg will need a balance shaft and an ignition to make it run. RD crank will be up to the job though. 90deg will produce unusual and annoying vibes.

[firko]

                                           http://www.bikeboneyard.com/yamaha%20rd-350%20flattracker.html

[yamaico]

The is no 'dead spot' in 0-180 firing and 90 deg will need a balance shaft and an ignition to make it run. RD crank will be up to the job though. 90deg will produce unusual and annoying vibes.

From my perspective there is a flat spot as each piston reaches a point of zero speed at the same time. The 90 degree crank was just an idea to reduce the inertia torque period. It could just as well be 10 degrees. "Big bang" is a bit of a black art anyway - Hope you got some sleep last night Mick
The ignition is no problem and I will discuss the difficulties of balancing it with Frank from "Frank's Cranks", even exploring the twingle option.
It's no big deal either way, and it would probably be hard to even detect the difference, but it's something different.

I've had the cylinders off my motor and the crank is perfect, so if I leave it at 180 degrees it will just need to be trued up and put back in.
The motor is filthy but from all indications has never been apart. It doesn't even look like the countershaft tab washer has ever been turned down. The bore is original and measures to well within tolerance. Even the ring end gaps are good, but I'll replace them as standard rings are cheap as chips, as well as the little ends and gudgeons. Looks like all this will need in addition to that is a set of seals and gaskets. The whole bottom end turns over very smoothly, so the bearings will probably be OK.

[SON]

I suggest you replace the mains, external crank seals and big end rollers,
Consider a 2 into 1 exhaust.

[Curly3]

Pete know's what he's doing, he's been there and done that and sometimes, done it twice.
It'll be a decent thing for sure and brought in on a budget.
This is along the lines of my T20 Suzuki weapon that Pete was keen to help me with, injury and financial's put a stop to that.
I just wish I had the same motivation.
Love your work Pete.