Rd400 — Leaving Barrels unpainted??

[Joshua]

So has anyone left your barrels unpainted. I picked up a vapor honing machine and am working through my rd400 build. Cleaned up some casting flaws and flattened the fins a bit. Vapor honing seems to get aluminum super smooth so I think cleaning won't be a huge problem. Obviously vapor honing was just the last step. For some reason I really making parts look new!!

Chuck, I know it's been a long process, but I'll swing up there with everything when I get my feet under me with all the important parts. By the way, Chuck you have been a huge help/encouragement for tackling this rebuild on my own. Thanks!

[SUPERTUNE]

Absolutely leave them with Vapor blasting!
I did a racebike RD400 engine with all vapor blast, no paint at all for the chrome bike build...have to find pics off my phone of the completed bike.
Chuck

[~JM~]

Is there any cooling benefit to leaving the aluminum raw?

Does the aluminum begin to corrode or become stained/discolored over time, or after being exposed to moisture?

[m in sc]

all kawi triple sare raw, you can look at them for staining or discoloration. in my experience, its liveable as long as you dont leave it outside, uncovered, or do a lot of road riding. I think any heat shedding benefit is minimal leaving it on or off, except when people powdercoat, that to me is too thick.

[pdxjim]

[Joshua]

Thanks guys, looks like I'm on the right track!

[Brad-Man]

Tests have shown that when moving, black painted intercoolers cool air more than unpainted ones.  They do heat up more when standing still than unpainted.

I would suspect that air cooled engines would behave the same way - so unless you idle a LOT I'd say paint 'em.

[Yamaha 179]

The Yamaha factory air cooled race cylinders and heads were left unpainted.  When they went to water cooling they coated them black.  Maybe the reason they left the air cooled parts natural was to save money but I don't think so.  I like the natural color of the alloy cylinders and heads.
Lyn Garland

[SUPERTUNE]

Guillermo's STG II  RD400...
Chuck

[tony27]

I raced a YZ465H for a few years with vapour blasted top end & found that there was no staining or corrosion even when I sold it. I definitely prefer it to the original painted surface & did the same thing to my TY250C, makes it bike look a bit more worksy to mind as well

[SUPERTUNE]

I like cylinders painted satin black w/highlighted fins and bare heads with polished side fins.





Chuck

[AAAltered]

Just to chime in, here are some pics of a top end I did some years back...
1) bead blast
2) lots of polishing
3) masking
4) paint with PJ1 satin
5) repolish the edges

Fresh polish and paint really looks eye popping.

[paul1478]

For me I love the painted with polished edges and the polished end of the heads just like the above.
they say RD to me.

[teazer]

I love that black and polished look on a stock(ish) RD350. I just did that on one I rebuilt.  The last 400 I had was painted satin black as were all my TZs.

On the other hand, my TD3 and client TD/TR's were all blasted and no paint, just as nature (Yamaha) intended.

In theory, black surfaces emit more heat than sliver ones.  The flip side of that is that paint tends to act as an insulating layer, so it really doesn't make much difference either way.  It's more of an aesthetic issue than anything else.

[Joshua]

I really like the painted look with the polished touches. Thanks for sharing everyone. I'm really into the raw look personally, have no clue why though. For my minimal build I'm going to go for as much unpainted surface as I can possibly do. Frame may stay black but I'm undecided. I've got so much work to do, just happy I've got my vapor honing machine. Carbs before and after although I'm going to upgrade to flatsides I think. Still have to talk with Chuck about how far I want to go for the motor work.

When I get done the case work I'll post more pics. Rims are well on their way as well. Rims look sick vapor honed.