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The Author didnt do his research very well.  They call the Suzuki TR500 a 4 stroke, and then immediately say they needed to build a 2 stroke but were beaten to the punch by Yamaha.

The TR500 was a 2 stroke that used technology they stole from MZ in the 60's.  Suzuki was making 2 strokes before Yamaha.

Everyone here should read "Stealing Speed" by Matt Oxley on kindle.  You will be delighted.  One of the most fun books for a 2 stroke lover to read.

I race with the owner of Vintage Performance in USCRA.  He's a really solid dude and a huge fanatic of 2 strokes.  His fully built Kawasaki H2 race bike is gorgeous and wickedly fast.  I've chatted with him about this project and it's really cool.  Looking forward to a set for my race RD. 

Pics of his H2 and my RD attached.

Awesome stuff!   I look forward to reading more.  Please continue to document the season!   

Quick update:  Got the replacement nut for the crank, and got it installed, went on nice and easy.  I timed the engine, got it back into the frame, and setup/adjusted the clutch.  I'll take pictures tomorrow.

Question:  While timing the ignition I discovered that TDC has a bit more of "notch" to it than I remembered previously.  I know there is supposed to be a bit of a "no mans land" at that point, but it seems more pronounced than I expected.  It also seems more subtle at TDC on Cylinder 2 than on 1.   Otherwise everything seems to turn smoothly and quietly.  Cause for concern or is this normal behavior?

Yep! I'm interested!   

Thanks!!  I ordered it up from Partzilla, should be here mid next week.  In the meantime, I just got a pile of jets in from Economy Cycle, so I can start tuning the race bike.   That's one's gonna need a name too.

Thanks guys!

The file worked well on the crank, but the threads in the nut are messed up as well, and I cant get to them with the file.  I've tried just running it on and off a few times, but it still gets really tight when it's on, so I wont be able to get an accurate torque spec when I tighten it down.   Does anyone have an extra one in their stash they could part with?   I'm also going to rummage through my parts bin later today.

I guess that depends what color you're going to paint the tank, and if you're going for an overall "dark" aesthetic. If you arent, I might leave them aluminum to brighten the bike up a bit.

Thanks guys.  I had originally thought of just filing it, but was afraid of screwing it up.  But I'll give it a shot.  I'll stop by Harbor Freight and grab some needle files and I'll go extra slow and steady on it.

I REALLY like what you're doing with this project.  I'm really eager to see how that swingarm performs and holds up, and if it's worth getting.   

So some interesting developments today.

First, the RD400 race bike shown above:  Turns out, it's not an RD400.   Upon closer inspection, it's an RD350, with RD400 wheels, swingarm, and gas tank.  This works for me.  The RD350 motor allows me to have full parts interchangeability with my street bike, and the boxes of parts I've already collected. (and I've heard the 350 likes to rev better at the track anyway).  The RD400 wheels and longer swingarm will provide more stability in corners, and the tank with its knee cutouts is easier to grip on when leaning off the bike.

Second:  I had a Eureka moment while inspecting the street bike's engine today.  I still couldnt figure out why it had stopped spinning in the bike.  Re-reading here I took quocle603's suggestion and pulled the cylinders back off to check to see if the retaining clips were still in each side of the pistons (they were).  While doing this I happened to notice this on the side of the engine.





Whatever idiot assembled this engine (yours, truly) didnt torque down the nut on the end of the crank!  Incredible.

There's a suspect circular mark at the corresponding spot on the side cover.



I think I've solved the mystery of the seized engine.

The last couple threads on the end of the crank are a little smushed now, and it's really hard to try to get the nut back on, so I'll have to go find a tap to clean it up.   In the mean time, a question for you guys.   The large washer behind the nut, that retains the primary drive gear and woodruff key is shaped.  1: is it supposed to be or is this damaged?  2: should the concave or convex side face in towards the gear?





Thanks in advance!

ZOMBIEEEEE THREADDDDD!!!!!!!   

Back from the dead and back at it!

It's been a long 2021 so far and I havent had a moment to turn a wrench on the RD since my last post in October.  My wife and I bought a house, moved, and have been very busy settling in and setting the place up.  Then this spring was all busy with me running the Honda Hawk Gt at a large variety of track days and race orgs.  I was on the track 4 weekends in a row at one point.  With other projects stabilizing it's time to pull the RD350 back up to the workbench and see what's gone wrong.



First order of business was getting the engine out of the bike and onto the bench, went much faster than expected.



I got the side covers off, and the top end off and guess what....?

Rotating assembly spins smooth as silk.

Now what?



The only anomaly I've been able to find is these 2 score marks on either side of the exhaust port that coincides with slightly flattened worn marks on the piston rings.  Pressure points of some kind.  I pulled the rings off the piston and checked the end gaps again and I have plenty.  So I've chocked this one up to installation error.  I probably didnt have the ends centered perfectly around the locating pins, so I put them back together extra carefully.



A quick annealing of the head gaskets on the stove when my wife wasnt looking.



And back together the top end goes.  Quick pic of the cool little Pro Flo mark from when the head work was done.

I'll let you know when it's back in the bike.



I'm also VERY excited to announce a new addition to the fleet.  A fully race built RD400 that I'll be racing in USCRA in 2 weeks time!  This thing is built to the nines and runs like a top, should be very interesting.  This is going to be my first time actually riding a large 2 stroke bike, and it's going to be on the race track!

Quick specs:  Fully built motor with heavy duty porting, squish/compression work, running on race gas, expansion chambers look similar to Millenniums but cant say for sure, Worx shocks and Race Tech fork internals, and a modern master cylinder, all rolling on R-compound Heidenau tires.

All bikes are track bikes.

33:1 premix :/

I passed a leakdown test before starting it.   Either I have a serious problem with carbs or ignition timing, or....

The crank shaft that I didnt rebuild and said "seemed to be in good condition", wasnt.

I talked to a buddy of mine who runs a really good vintage repair shop and he said because I only ran it for about 2 minutes under no load, it seemed unlikely that the piston would get hot enough to seize.  He thinks the crankshaft had a toasted bearing that I didnt notice.

Well bad news.   I took the bike out to an empty parking lot over the weekend and got it fired up.  I thought maybe it just needed to clear it's throat for a few minutes in order to get it to idle.



Got it fired up under about half throttle.  Wont idle but I can keep it under part throttle (not full), and give it little blips and it kept running, but was real rough.  Then, after about 2 minutes of running, instant silence.     Go to turn the engine over with the kickstarter and it's totally seized.   

I decided to put it back in the truck and take it home for the day before I decided to throw it in the river.

So, I'm sad to say this marks a significant pause in forward progress on this project.  I'm moving next week, so I'll need to focus on that for the next few weeks, getting the house and the garage setup and whatnot.  Then I'll pull the motor and inspect it.  Stay tuned!