TC90 project

I'm bringing back the '71 Suzuki TC90 project. I bought this bike in 2009, then worked on it some in late 2011 and early 2012, and hadn't touched it since. I've been wanting to do a fun and simple side project like the Z50R last year, and this is it. It is going to be a fun play bike/mini-motocrosser. The size of the bike makes it great for this; small enough for kids, but big enough for adults to ride. Here it is pulled out of project limbo and dusted off.




First I'm going to get the tank and fenders ready. When I bought the bike it had sat for years unused, and the tank had a fair amount of rust inside. The odometer shows 831 miles, so it likely hadn't been used for 30 years or more. I'm using white vinegar to clean it out. You can buy specialty products to do this, but the vinegar is about $2.50 a gallon, so only costs about $5 to do this tank. The tank is still very solid, so should clean up without any issues. If you see rust bubbling up under the paint on the outside you'll likely have pin holes in the tank after cleaning. First I pressure washed the inside of the tank to clean out any loose debris or varnish, put a handful of nuts inside, and filled it to the top with the vinegar.


Here it is soaking, the vinegar doing it's thing. I'll empty some of the vinegar so I can shake it, which lets the nuts help knock loose the rust, then put the vinegar back in. I'll do that a couple times a day for a few days. Once it looks good I'll empty it, pressure wash it, wash it out with car wash soap, rinse it with hot water and dry it, and then coat it with WD40.


It can out pretty clean.


I bought a NOS Preston Petty Mini Muder for it at the swap meet earlier this year. The Muder is a longer, more full coverage fender than the Baja. The Mini Muder is made to fit smaller diameter wheels, like many of the smaller Hodakas and similar bikes of the day. Perfect for this bike.


I'll be using the original fender mount.


Doing some mock-up here. The stock seat is kinda(very) bulky looking, but for now I'm probably not going to do anything with it. Later on I might go back and make a slimmer MX style seat, but as it is it'll work. The rear fender is a bit long and low. It isn't bad, but just looks more street than MX.


The chrome is gone on the front part of the exhaust, so it'll get painted black.


My favorite milk crate.


Back to the rear fender. I looked up a picture of Roger DeCoster's 1973 RN73. This look will be easy to do with the stock fender. I might do the green stripe on the tank also.

Here is the stock rear fender.

I'll be cutting a section from the middle, and welding the end back on kicked up.


Here it is cleaned up where I'll be welding and ready for final fitting.


Here it is fitted and tacked. I like it.