Vintage Dirt Bike Q & A

I am going to go pick up my frame, handlebar, and other misc. parts from the powdercoaters later this week. However, I am flipping back and forth on what to do about the engine coating - traditional paint job or powder coating. My heart wants powder coating (more durable) as I intend to ride the bike again when the restoration is done, but my brain says traditional paint so the aluminum parts don't get baked in an oven and possibly distorted.

My biggest concern regarding powdercoating is that close tolerance parts of the engine components (ie. bearing fits and the like) will be distorted when the powder is being baked on. On top of that, I had the jug re-machined and a cast iron sleeve installed. Should I be concerned about dissmiliar metals and their different rates of expansion when being heated?

My powdercoater claims he has powdercoated CI sleeved jugs in the past, and can heat the oven slowly enough that the metals expand at the same rate. I have to dust off the portion of my brian that used to be devoted to metallurgy, but I seem to recall that this can be done, and trust this guy to do it properly. I guess I would just like to know if any of you all here have powdercoated your engines, and how it went.

Any feedback would be appreciated. I really don't want to screw this up. As you all know, one of the neatest things about this bike was the red painted engine - and all the parts are original!

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rides:
'01 Suzuki SV650 - not exactly stock.....
'79 Honda CR125 - running great, cosmetic restoration back on track!

i have a 79 cr 125 i'm about half way done, just got my excel gold rims spoked up last night. i'm going to spray my frame tank and side covers with base clear so i can cover the decals. but like you i want to powder coat the engine, its got to be a semi gloss. mines going to be a rider racer but you gota look good. go to the search and type in (engine powder coating) theirs a couple of guys on here that do awsome resto jobs dooger315 and spannerman look up some of there work its unbelievable allso search back 5 or 6 pages. good luck jay

You found someone to lace your spokes? I took mine to two different shops who looked at me like I was from Mars. I wound up finding a complete set in better shape, and just went that route.

My dream has been to get mine presentable, and do some vintage racing myself. We will see.....

You got any pictures?

I have some before shots:

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rides:
'01 Suzuki SV650 - not exactly stock.....
'79 Honda CR125 - running great, cosmetic restoration back on track!

nice picture, looks just like mine did i have my engine apart now and the frame is ready for paint. just cleaned up the forks and put new seals in. i spoked the wheels my self its not realy that hard once you get the hang of it. search the web for (bucanon spoke) they can do your wheels real nice people there. i'm allso going to use an 80 rear swingarm and shocks for now. went to a 82 cr480 front brake with a 21 in. wheel. i allso went to a 19 in. rear wheel its not realy any taller do to the lower profile tire. just got my dunlop mx51 tires these look like there going to be awsome.

Search back a few pages for dogger315's 79 250r restoration threads (there's a few over a few month period), I am 99% sure he powdercoated his engine (did it himself and specifies a mix for correct color).

Thanks, there was some good info there.

However, I am still not convinced this is a good idea with a sleeved jug. I will keep looking, maybe I missed something.

Thanks guys, and I will post some pictures moving forward.

tim

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rides:
'01 Suzuki SV650 - not exactly stock.....
'79 Honda CR125 - running great, cosmetic restoration back on track!

let us know what you find. i'm getting close to having mine powder coated. 2-3 weeks away and it has a sleeve. if you can pm dogger315 he seems very knowledgable with these. i hav'nt seen any posts from him in a long time though jay

I did some searching last night and read through some Harley and Triumph forums. Powdercoating the engine seems to be commonplace among that sect of riders - I am sure that many of those bikes will have a cast iron sleeve or some other special coating on the cylinder walls. Ours came with a chromium or nickel cladding from the factory, I think.

I still think that I will send a PM, and see where that gets me. I will post if I get a response.

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rides:
'01 Suzuki SV650 - not exactly stock.....
'79 Honda CR125 - running great, cosmetic restoration back on track!

i just had my shovel head engine case powder coated (6 months ago) and it has pressed in main brg. sleeves it seams to be ok. the powder coater did a crapy job of masking tough. he got powder were it should'nt have been and none were it should have been. (glue sniffers i think) i'm in the early stages of building my own powder coating oven then i can do my own stuff. i think alot of motorcycle engines come from the factory powder coated. you got me thinking though if the steel liner expands more than the aluminum then when it cools you would think it would get lose anyway let me know if you figure it out jay

I just spoke to someone at Wiseco (they installed the sleeve and provided the piston).....

On a side note: I love good customer service. Wiseco gets a gold star from me today.

Here is what I learned:
Our concerns are accurate. I was told that it is not uncommon for the sleeve to be pushed out of the jug both when the part is heated and cooled down in the oven. However, he told me if that were to happen you can put the jug in a press once it has cooled down and press the sleeve back in place. The interfence is 0.003".

I am going to do it! Why not?

Hopefully, I can make it to the powdercoater this weekend with the parts.

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rides:
'01 Suzuki SV650 - not exactly stock.....
'79 Honda CR125 - running great, cosmetic restoration back on track!

thats good info let us know how it turns out. thanks jay

Dupli-Color Chrysler Red DE1632 Ceramic Engine Paint is a pretty close color match. It looks and performs great. Probably not a restorer's choice, but it will fool the vast majority.

For a few bucks a can at the auto store, its worth painting some scrap metal just to compare.

Here's mine. It has a fesh top end, replated cylinder, new mikuni vm 32mm round slide carb, new oil seals and seat cover. Runs like new and is a blast to ride, a real screamer!

i got fenders from vmx and they look more red than my stock color. i'm just going to spray my frame and tank and side covers with uathane to mach the fenders. then hope to get the engine powder coated the same color only a satin finish.

If VMX have not changed their color from the Red Racer days, then RHL 3020 powder coat is a good match. Dogger did some great work on a powder coat recipe for the stock color, but the replica fenders are a darker red. So it's a question of what's more important to you - authenticity or a good match throughout.

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Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF