I have a lot of RZ350 spares that I’ve collected over the years, including a couple of frames without ownership, and I’ve been wondering what to do with these bits and pieces.
There are a couple of local race series here that have classes for the RZ350 so I thought I’d build one up as a track/race bike that I could run in at least one of these series. It's better than letting them sit out in the garage rotting away.
The rules state that the bike can’t be 5% more displacement over what was shipped from the manufacturer and must run the original cylinder blocks so for the RZ that 367cc so it will probably get a nice tune, carbs and pipes.
I’m allowed to run modern right way up cartridge forks so I’m looking for a set of 41 or 43mm and a FZ600 swingarm. I’m also allowed to run 17” wheels so I’ll probably run 110 front and 140 rear Pirelli race tires as they can be bought at the track. I know I could probably go 120/160 but I want to keep it somewhat nimble
I wanted to post the progress here to give me some incentive, because if I work at my usual pace it will be 2025 before its done.
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Good. Denis has the chassis at the moment to make some small bits and pieces. I'll post some pictures when I get it back. I finished the motor at the weekend. I'm going to try and make it look like a Pro-Am bike from back in the day. I just bought a fairing and screen from Norbo today.
Denis is great. I have a little CB350 for Period 1 one and both bottom frame rails were completely rotten. He was able to replace both and did a lot of bracing to really stiffen it up. I think you will be pleased.
The LC is actually quite competitive in that class. It runs against 4 cylinder 750's and last year a LC won the P3 middle series and was 7th in the P3 Heavy series against 1000/1100 cc 4 cylinder bikes.
I have not been able to get much work done on this because of COVID. Not because everyone is closed, but because the machine shops are so busy. I think people are just sitting in the garage looking for something to spend their emergency response benefit on… LOL
The rolling chassis is basically complete.
1989 Suzuki GSXR 750 forks - they are cartridge forks but are vintage legal as they are from the correct time period, and I already had them in the shed
1st Gen Yamaha R6 clamps – the trail is around 100mm now which is much better than the original GSXR at 112mm and they fitted nicely with a couple of spacers and a bearing swap The center to center fork spacing is exactly the same as the Suzuki so I was able to use the same axle and fork brace
FZR600 front wheel – had to make a 20mm ID spacer for between the bearings
FZR1000 320mm disk
FZ1 silver spot caliper
400 Bandit Rear wheel
GS500 rear caliper
GS500 sprocket carrier
GSXR 600 Steering Damper
Pirelli Diablo 110/140 tires
Once the wheel was centered in the swingarm the GS500 sprocket carrier and sprocket lined up exactly with the standard drive sprocket on the motor. It also provides more than enough clearance for the 140 tire, but it may be tight for a 160. I guess you have to get lucky some time
I had him check the frame for straightness and it was spot on, but with the big forks he recommended some additional bracing around the head stock. He did a lovely job. It’s a shame to paint it.
Next step is to detab the frame and then its on to the forks and swingarm
I've heard this before when people have fitted beefier forks and been advised to brace the frame. Is this because the original forks flex whereas thicker forks transfer to the frame?
If this is the reason is it only under breaking?
Also heard if a frame is too stiff it lacks 'feel' ?
Bloody confusing because I can never get my head round is it best to have flex or not? I guess it's a fine balance a bit akin to setting up your carbs except a Dyno or plug chop won't help?
Great thread btw. I have always wanted to do a track bike but never got anywhere with my 'road' bike.
Looking great so far. Looking forward to seeing how this turns out.
Thanks Flames. The gent who did the bracing builds race frames. He said the the RZ was not a bad frame considering when it was built but the head stock is the weak point as it can load and unload under braking and cornering causing some strange behaviour so he recommends having that extra 2 tubes making a total of 6 tying it into the frame.
I just wanted to share some pictures of the final build.
We had our one and only vintage racing day for this year at the weekend so I was able to get the the bike out to the track and I'm really pleased.
The motor is a ported 350 and pulls really nicely from between 6000-7000 all the way up to 10,500.
The chassis turned out really nice. I don't know if its the bracing, wheels, suspension or tires - probably a combination of everything - but it just handles so well. It's planted right through every corner and soaks up the bumps on that track like a champ - and its really bumpy in places. The chassis never seems to get too loaded
I think it was a good decision to stick with the 110/140 tire combination. I had been thinking about going larger but the smaller tires still keep the bike very nimble, it almost falls into the corners and they have more than enough grip for 60-70 hp
Had a lot of very nice comments and have started a few people thinking about getting out that old RZ that has been gathering dust in their shed for years
One small issue I did have was on the Sunday where I lost the spark completely. I'll post in the Advice and Help page about this. Quite a frustrating end to the weekend but overall I'm really pleased and looking forward to a full season next year.
The bike looks great, simple and clean. I also like the fact you have used one disc, i have two discs on my bike and keep thinking about dropping to one. How we does it brake with one disc? I like the 140 size tyre best as well, shame about the ignition problem.