Saturday, March 1, 2008

Classic Dirt Bike and VMX Magazine

I just got the new issue (Issue Six) of Classic Dirt Bike magazine. This relatively new quarterly publication comes from the UK, published by WH Smith. I have to say I really like this mag. It's quite different from VMX Magazine, which I wrote about back in December. Classic Dirt Bike covers the whole twin-shock market – including MX, trials, and general offroad – in the UK and to a lesser extent Europe and the US. There's plenty of historical content going all the way back to the early 1960s and beyond, as well as ongoing technical and how-to articles like the rebuilding of a TY175. But what I really like is the extensive coverage of the UK twin-shock scene, which appears to be way more active and mature than our own vintage efforts.

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Monday, January 14, 2008

Project Big Bore Lives

Got a call from old-school CZ builder Gary Davis today. A little over a year ago I visited Gary up at his home/shop in North Carolina. I left him several boxes that constituted my CZ380 motor. Back in the day Gary was known for his over-bored, reed-valved CZ motors and his inverted stinger expansion chambers.

Back in '06 I contacted Gary to see if he was interested in building such a motor for me. I drove up and we did an initial tear-down and inspection on my motor, which had cratered a transmission earlier in the year. I left there around mid-December of '06 with a list of stuff I needed to source for the rebuild. I went to work on it but weeks turned into months and before I knew it a year had passed. I have all the needed parts now. I Just need to get them together.

But as I said earlier, I think 2008 is going to be a CZ year. So over the holiday I started trying to get in touch with Gary. Finally heard from him today and we're going to get together in Feb. to start the rebuild.

The motor will cc out at about 408 cc displacement, running a Yamaha 400 piston (I think). Gary also has a dyno in his shop so when we get it together we'll dyno it and see what it does. Should be fun.

Thursday, January 10, 2008

Rebuilding the Honda SL70

The first motorcycle I ever bought with my own money was a red 1972 Honda SL70. The picture is my younger brother David jumping the bike across the football field at Moore Jr. High when we were kids. Can you imagine trying that now?

I think I sold the bike to David, but I can't really remember. I think this picture was before that because at one point I welded (well, my Dad welded) some reinforcement plates on the swingarm and we moved the lower shock mounts forward. This pic looks like the shocks are still in the stock location. But I know it was eventually sold off to someone else and disappeared. Like so many aging MXers, I'm now trying to recreate my childhood by getting my old bikes back. A few months back my long-time friend Ronnie found a bunch of SL70 and CT70 parts up in Dallas somewhere and got them for me, and my plan is to recreate my old bike.

To that end, I just got off the phone with Lyle Mirski, founder and chief bottle-washer at CHP Products. CHP is one of the top pitbike companies in the country and, even though Lyle and I never met, we graduated the same year from the same high school. Net-net, Lyle is going to rebuild my SL70 motor to kick-start my restoration project. He's pretty busy right now with the big Indy Show and racing season coming up, but by early summer the SL70 project should be well underway. Stay tuned!

Saturday, January 5, 2008

It's A Drain Hole, Dummy

Turns out the hole in the bottom of the TM motor is supposed to be there. It's a drain hole of some sort. Right there in the bottom of the motor. Whod'a thunk? Glad to hear that. Now it's off to the post office.

There's A Hole In My Bucket

I had a bit of a disappointment tonight as I was cleaning up the little Suzuki motor to ship off to the engine builder. Upon turning it upside down to clean the gunk I discovered a hole along the centerline of the engine cases. "Uh oh, this can't be good." It's an odd little hole, sort of square. It's located in a place where someone may have tried to pry the cases apart with a screw driver, but it's not broken like that would be. There's a bigger picture here. The bike wasn't leaking gear oil, and it wasn't empty because I drained several hundred CCs out of it before I pulled it from the frame. That means it must be under the crankshaft - which could explain why the engine ran so poorly, but the cylinder shows no sign of sucking dirt. It's weird. But anytime there is a hole in the motor it means my repair bill could be significantly higher. We'll just have to see.

Wednesday, January 2, 2008

Getting Un-KREEMed

I have a very nice, low-hour 1974 Yamaha TY250 trials bike. I bought it last year and it's in good shape but has two issues I need to fix – it leaks oil from the bottom of the motor somewhere, and the fuel tank is full of crap that keeps clogging the petcock. We're going to have seven trials events within a 2-hour drive of the ATL this year so I want to get it ready to ride.

The problem with the fuel tank is two-fold:

1. it's full of rust that is sluffing off
2. the rust is underneath a very bad KREEM sealer job that has detached from the metal and is actually making things way worse.

After digging around for a few weeks trying to figure what to do with it I pretty much decided to just buy a Sammy Miller fiberglass tank/seat combo, as I need to replace my trail kit seat with a trials unit anyway. But those SM units are over $400 here in the US, and you still need to coat the inside of them with POR-15 or something to keep the alcohol in our gas away from the resin. Anyway...

That spending $500 thing made me go back and look at the original tank again and I finally found a phone number for KREEM Products Inc in Somis, CA. I gave them a call and the tech there told me that if I fill the tank with acetone or MEK the KREEM sealer will go back to liquid. Of course, MEK and acetone will also eat the paint off the tank. Sadly, the tank has a very nice, resto paint job that someone paid pretty good money for. And was one of the reasons I paid a little more than I should have for the bike. And there's no way I'm going to be able to get the crap out of the tank without messing it up. I don't think.

Still, I thought I'd post the tech info here, in case someone else needs to undo a really bad KREEM job in the future.