RD400 - Back from the Dead

Really? I guess so. Just to get it running and riding at least. Could always fix it later if the need is there. I also did a little research sinse posting and found 86-09 Banshee pistons are a direct fit... Fast From The Past sells Wossner piston kits at 65.5mm for $99 a cylinder. Specific to the RD400.

At least I know there's options... but I'll call up wiseco and see about some new rings for now.
 
Go and check out economy cycle. Pro x, wiesco, etc. They are out there. To use banshee piston you will need to file down the skirt on the intake side but that's no big deal.

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I just bought a better bore-gauge... going to double check when that comes in. Then I can bring them to a machine shop and see what they recommend...

I found a 65.25mm Wiseco set for the Banshee for $170 shipped. And Amazon has 65.25 or .50 Pro-X for $70 a piston kit.

Not so bad after all. Hopefully I can get away with the 65.25mm overbore.
 
Gave it a legit attack tonight.... was able to borrow some better tools. Checked each cyl 9 ways, each piston 3, and re checked the rings. As you can see in the photo, the bottom of the left cyl is 65.16mm... but the top isnt too bad. This was throwing off my shim measurement with the piston 3/4 of an inch down in the bore.

BUT if you look at the top right... I tried the left rings in the right bore, and got .002" larger than the right ones... so not only are they gapped wide, but the cylinder is also large enough to double that measurement.

Maybe new rings will suffice? But 65.16 means im getting aweful close to 65.25 anyway...

Still bringing it to the machinist... but should I just bite the bullett and order pistons anyway?

My gut says yes... and so does my OCD. Lol.
 

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If your machinist is an auto machinist, he will probably have a really good bore gauge and will be able to advise what needs to be done. If teh budget will stand it, get a pair of pistons. He can tell you if it will clean up at 65.25 or if he needs to go to 65.5. Sounds like it's close to needing a rebore and hone and if the crank is getting new seals maybe a good idea to go with fresh bores that are not tapered and out of round.
 
Thats the thing. I was hoping to get the pistons before going to the shop. Then he can just match them.

I think im just going to buy the 65.25s from Pro-x because theyre cheaper. If I need to, I can return them through amazon. If he tells me he needs 65.50s, ill return them and spend the extra on wisecos.
 
JSJamboree said:
I saw RD heads in the uploaded pics feed, had to stop in and see whats going on in here

Lol, just looked through your RD build. Amazing work! You live in VT? Im in MA.
 
JSJamboree is one of the weird Indy kids, but I see how you would think he's in VT with Stowe's brewing avatar, happens to be his last name ;D
 
AimlessMoto said:
That and in his RD project it shows a VT license plate... hah.

No, its just a way to get titles for non titled bikes. Get a registration in VT (They allow out of state registration and dont issue titles), so then you can take that registration to the local BMV and get a title for it. Its backwards as shit, but gotta do what you gotta do
 
AimlessMoto said:
In MA they do that too. I can title any bike before 1989 no questions asked.

But do they let someone who doesn't have residence in the state do it? Indiana has gotten extremely strict.


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Why not just send those cylinders to bore tech in Ohio? They specialize in vintage stuff, 2 stroke stuff and vintage race stuff. They can bore and provide piston brands of your choice. I'd be weary of handing off vintage 2 stroke stuff to a machinist. I'm not saying that he isn't great at what he does but I'd like the peace of mind that it is correctly done for that particular motorcycle. It's only $65-70 a hole plus shipping and they have a very quick turn around. They won't collect dust on a shelf.

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clem said:
Why not just send those cylinders to bore tech in Ohio? They specialize in vintage stuff, 2 stroke stuff and vintage race stuff. They can bore and provide piston brands of your choice. I'd be weary of handing off vintage 2 stroke stuff to a machinist. I'm not saying that he isn't great at what he does but I'd like the peace of mind that it is correctly done for that particular motorcycle. It's only $65-70 a hole plus shipping and they have a very quick turn around. They won't collect dust on a shelf.

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Thats pricy
 
Things are getting serious...

Rolling chassis completely cleaned and degreased. Engine ready to be halved. Another go with my new bore gage found the left cyl is .16mm over from top to bottom... the right is dead-nuts 65mm. Still gonna rebore.

Gotta play with the electrical too. Lots to clean up!
 

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Great build diary, will keep an eye on this.

What's the process with boiling gunked up carbs in lemon juice, are there any don'ts when doing this? Time/temperature etc?


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