RZ350 Super Motard

[Smoker]

Thanks, guys. I'm definitely trying to do some interesting stuff, but perhaps my tactics are bad, or it's still inexperience.

Bad day at the welding lab. I think the main mistake was trying to clamp parts for tacking. I just put too much pressure on the clamp, and probably my tacks were of insufficient quality and number. Tacks popped, and I'm not able to squeeze them back to close the joint.

So, I'm learning about sheet aluminum. Overall, I like it.

I'll post pics of my mistakes after a couple of cold ones.
Thanks to RGVSteve who talked me down.

[JonW]

Welding is a funny business, it sucks you in to thinking youve got it early on and just when you think youve got it licked it then doesnt seem to work how you wanted due to a billion reasons that you have since learnt about.

I often look at stuff experts do now and realise that I am less confident about the welds I do than ever lol. I should have welded everything I needed when I was in my teens/20s as I was a super welder back then... er... or at least i thought i was... I didnt know so many of the pitfalls and issues lol

[Smoker]

Popped these 2 tacks.



Made a rookie mistake (besides maybe over-clamping). I was dressing the tacks as I went. This weakened the tacks for no reason. I could have left the extra material on the tacks and they would have been stronger until time to weld.

If I can clamp the joint before re-tacking, this one should be okay.



Other side is like this. Only after the last tack.



Maybe not a big deal to a real welder (not me), but we'll see. Good thing I'm using 1/8 inch aluminum. I'm prepared for bigger problems to arise, but I'll do my best.

[Smoker]

Wish I had pics of all the jigs and rigs I've made over the years.

[JonW]

Ahh yes... no need to dress til the end.

I'd think you could clamp those? but... I am not a welder of alloy :/

[brrrappp]

I am still here also. Keep posting Pete. I do even though there is not much response.

Ditto
Enjoy seeing the progress-

[MK]

That gap will easily weld up.
Don't worry and get the torch out.

[Smoker]

Not much progress on the tank to show. Also, I don't think I ever posted about this mod I want.

If anyone can help fabricate these little cups, please let me know. I can pay or trade. I'll try to make a pencil drawing and see if that's good enough.

Also need someone to machine the aluminum cups, and someone to do the welding. I could probably weld them, but thin cast aluminum may be tricky.

[JonW]

Someone (Roger?) was doing bigger CNC carb bowls, I wonder if he would have one to fit this application or make these for you?

[Smoker]

Someone (Roger?) was doing bigger CNC carb bowls, I wonder if he would have one to fit this application or make these for you?

Roger showed me the drag bowls he makes. To use them, his special intake manifold is needed- to angle the carbs forward, providing clearance for the clutch arm.

I'd rather not change the angle of the carbs, and the special manifold is longer, which may push the air filters into the rear shock. Not much extra space there.

I don't think Roger, or anyone, make drag bowls for the PWK28. Only for the larger body PWK33-35. Okay with me. I think drag race bowls would look out of place on this bike. With this weld-on mod, the carpet would match the drapes (fuel tank and carbs).

[JanBros]

why would you need bigger bowls ?

[Smoker]

why would you need bigger bowls ?

Bigger bowls es mas macho!

Thank you JB, for checking on me.

I believe most of the mods and parts I've designed are over-engineered. Because my background is not in engineering or mechanics, it's sometimes difficult to titrate the level of modification that's really necessary.

I remember asking- "What are these?" The answer- "Oversize float bowls. Sometimes these drag engines burn so much fuel they can suck the carbs dry. We also use a fuel pump on some of these bikes, for the same reason." Okay, well I'm not building a drag bike, but....

Most of the 350+4mm engines I've seen use larger carbs than 28mm. I've read about one, or more, that have made good power with 28mm carbs. I had 33mm carbs for this engine, and I changed to 28mm. I thought it would be a better choice for street riding, but the 28s have smaller float bowls than the 33-35s.

The engine and pipes are well-engineered and modified for power (not by me). So, how much fuel do I need to flow? I don't know. Enough flow for sustained wide-open throttle of 2 gallons of fuel.

I think this mod would fit without interference, and adjustment of the float levels would remain the same. I don't anticipate any bad effects of this mod, if done properly.

Not sure if I can get this done. Please let me know if you see anything potentially bad about this mod.

[MK]

Well at least you know you're overengineering

First of all I wouldn't count on the carbs being Aluminum. Could also be a Zinc based alloy.
And "welding" such small, thin walled exotic material will be the nightmare of any welder. Especially when already in contact with fuel/oil.
If I were to do such a mod at all, I'd rather solder it.

That brings me to the last point as I don't think you will need that at all.
Worldwide people run RD setups with different carb sizes and large float bowls are very rarely used and even more rarely needed.
They compensate a sinking fuel level when the bike is under WOT and high rpm resulting in full acceleration. And for engines that are tuned on the verge of disaster.
On road bikes you're on the rich side and you don't always accelerate that hard. Especially in a country with a 55mph speed limit and living in the most overpopulated region...
So you're not in the range where the engine would "require" this modification.

[JanBros]

using bigger bowls will only mean you run out of fuel a bit later, but you can still run out of fuel. better is to improve fuel flow so you can not run out of fuel.
Frits Overmars says a race engine needs about 7cc's of fuel per HP per minute, so take of the bowl and let the floater hang so the needle is open, open your fuel tap and measure how much fuel can run through the float valve for a minute.

[Questo vecchio rz]

Good fun stuff as usual for the hobby

You made the right choice on the carburetors 28 mm in my opinion is The Sweet spot. Even stock 26s you will achieve 70 horsepower. The float bowls just look cool on a street machine we will never have to worry about running out of fuel ....ever. I have probably seen just about every kind of rz350 at Willow Springs since 19 84 and I don't believe any of them I've ever run out of fuel even on the one of the longest straits in America.
BUT THEY LOOK COOL! AND WHEN THINGS LOOK COOL UNDER THE RIGHT COLOR... DAMN STRAIGHT THEY'RE FASTER