Time to Contribute! RD350 Cafe Build

[andrewlk]

Welding questions...

I've borrowed an HH25-140 flux/mig welder and am hoping to use it to weld on a seat subframe and some other items to mount ignition components/battery. From a glance, the tubing appears to be about 14 gauge, no?

My planned setup is .030 solid wire with C25 gas. What kind of filler wire should I use? Just anything for 'mild steel'? Otherwise, does this setup seem sufficient?

Yes I will practice on lots of similar tubing before touching the frame.

Thanks.

 

[jpmobius]

Hopefully some of the really expert welders will chime in, but for what it's worth: The .030 wire will be fine. I don't know what the gas you spec is, but typically 75/25 (argon/CO2) (maybe called c25 where you are?) is used for mild steel. Pure argon is ok, just needlessly expensive. MIG welding is, to a point, the easiest to make a pretty weld, but the hardest to make a good weld. (compared to other methods at least) I have had many "learning to weld" guys proudly come to show me their beautiful beads that could be "undone" with a few hammer blows. You will want pretty small welds, so my suggestion is to go too hot for running a continuous bead and instead do a series of individual puddles or "spots" cooling a few seconds between. With a bit of practice, you should be able to see a nice liquid puddle and stop before if melts away(into a hole!). Far from the optimum, but you should be able to get acceptable penetration with minimum cosmetic grinding. It is very hard to weld around tubes, and this "spot" technique lets you "take aim" a lot more easily while learning. The value of setting up your work and equipment so it is VERY easy and comfortable to do can not be overstated. Spend whatever time you need for this. If it takes 30 minutes to get organized to do 5 minutes of welding, it is still well worth it. Cutting through your practice welds with a hack saw and/or attempting break the weld with a vise and hammer can be extremely educational!! One of the great joys and frustrations of motorcycle building: By the time your done with any new task, you're just about good enough at it to do a decent job! Hope this helps. Good luck!

 

[andrewlk]

Thanks JP.

Yes C25 here in IN is 75/25 Argon/CO2. I appreciate your advice and had already contemplated doing numerous tack welds rather than a bead around the tube (partly due to skill and partly to keep the heat down). Also, I'll mostly be welding the seat hoop in behind the shock mounts which, other than joining the two top rails of the frame, won't bear much load since the solo seat will be located over and in front of the shock mounts. I take that back - I will be replacing two frame gussets as well.

I'm not going in totally blind (though it may be essentially the same as blind compared to genuinely experienced individuals). I've had about 6 hours of instruction and guided mig welding on 1/4inch aluminum, butchered some 24 gauge mild steel into a fire pit with flux core (on the machine I plan to use) and I made a welding table with tubing about the thickness of my frame. I believe I understand the difference between an ugly functional weld and a pretty nonfunctional one. Hopefully I can manage acceptably pretty and functional.

 

[bradj]

I know my own personal hell will be me stuck on a elevator with you two for all eternity. QUIT TALKING, BE A MAN AND FIGURE IT OUT!

 

[andrewlk]

And this is only 1/7 a certain thread from hell... :

 

[bradj]

Sorry. Befor you talk it to death Just try to weld the part and see what happens
i weld for a living its cake, if you just stop letting your self get bogged down overthinking every little thing

 

[andrewlk]

I will when stuff gets here but the seat isnt here yet, nor the gas regulator...its not like im sitting here paralyzed with everything I need in front of me. If a few questions while I wait can save me a headache...

 

[andrewlk]

Time to Contribute! RD350 Cafe Build: Frame cracked?

Cleaning up my frame noticed these...are they a structural concern? If so, are they repairable?

 

[SONICJK]

Are they cracks?
Weld em up

 

[andrewlk]

Those were my thoughts too...not convinced theyre cracks, but one side looks deformed a bit.

 

[jpmobius]

If you are talking about the wavy groove(s) parallel to the tubes, looks like they are undercutting from the factory welds for the stock foot peg mounts. Totally not a problem. Well done on not over grinding. (don't do any more!!! use a file from here!) I reckon you could likely cut this tube out entirely and use the engine case as structure ( better fitting engine mount bolts!) but not suggesting it. The right side has a major dent in it. It is a factory manifestation, just in case you were wondering.

 

[andrewlk]

Nothing crazy, but got engine cleaned up and some new parts. Next on the list is wheels and paint. And oh yeah, got a kid on the way so, we'll see how this progress goes...due in late August.

 

[andrewlk]

Got some cool stuff in the mail...

 

[johnu]

Very nice

 

[teazer]

Indian? How is it? The indian stuff looks good on ebay but no one seems to be willing to order a set and share the tale. It doesn't look bad in that Australian Picture (upside down).

 

[andrewlk]

...yeah I tried to post with an iphone and I gave up. fixed now

CMR Racing Products (Denis Curtis) made them to order...cost more than the Indian stuff, but this was the better route. Came with everything to mount and a damper set etc.

 

[andrewlk]

Here's a few more...

 

[andrewlk]

Rear subrframe question. Everyone seems to be tying their upper frame rails together with bent seat hoops.

1. Are there any functional reasons why I can't just make a boxed subframe from 1 inch round stock? It's not going to be visible, just need it to be structurally sound and support the seat.
2. Should I consider reinforcing my frame at all these joints with gussets, like the frame pictured? or is it overkill? If it's a genuine improvement I want to do it.

mspaint blue for subframe reference

mspaint red for frame gussets

Appreciate your advice, thanks.

 

[jpmobius]

No doubt you will get varied opinion here, but here is my 2 cents. First, unless there is a cosmetic consideration, the stock rear "hoop" is just fine for connecting the rear frame. I have had very fast RD's with no connection at all there and they drive just fine. I have a cafe seat on a customers bike and that portion of the frame is unmolested except for smoothing it out a bit, so it does not necessarily need to go (pic). Secondly, a bit of bracing is of value up at the steering head, but not so much anywhere else. If you put a much stronger, stiffer swing arm on it, some extra bracing may be useful, but if you keep the stocker, it really just adds weight for nothing. If you drive it so hard you think the frame needs to be stiffer you will find you have tweaked the swing arm and that is the real problem. The stock upper shock mounts are plenty stiff, and it is pretty hard to do much to help the rest of the frame with just some gussets. Hard, not impossible. Put tapered bearings in the steering neck, do a really careful job setting up the swing arm pivot, install decent shocks and cartridge emulators in the forks, and your RD will handle superbly - even with the stock swing arm if you are less than totally crazy driving it. Oh, and no more than 1 size up from stock on the tires, and if you are going to do that, you should consider going up 1 on the rims as well.

 

[xb33bsa]

yep as long as you have a crossmember just ahead of the shocks top mount, anything behind it is for looks or mounting points
every body is gay for a rear frame loop but unless you need it to attach stuff to it is not needed,it does nothing to strengthen for the loads put in by the suspension
on a stock bike it needs to be quite beefy to support the max load of a rider and passenger