Messages

Yes , RD painted cylinders are painted black with sanded edges on the fins as stock as Mark posted.
They do fade off the original paint after 40 years old!
Chuck

Here's a good baseline for VM30's:


3.0 cut slide
6DH3 needle
159-P2 needle jets
2.0 air jet
45 pilot
280 main
40:1 premix

This is a great baseline I use for 30mm carbs.
Chuck

Skinny lift...
My handy is way wider...
Chuck

No clamps other than some rubber wrap bushings on the hose along the stock swingarm tabs.
Chuck

No good machine shops around? Maybe all closed up there?
That cylinder hone just burned my eyes out...
Not a very good one for doing this kind of work. That hone is just for breaking a glaze off a wall, not stock removal.

I guess it's time I get some new honing stuff up...
Pic's of what I use.







Chuck

[The oil line is off the carb and the fitting is stuck on the oil line and I don't want to remove the fitting off the line because they're so fragile I'm afraid it will get damaged]

It won't be a cap it will have to be a PLUG  and running the line from side to the other won't work because there's no fitting for the line to go to

The oil line is off the carb and the fitting is stuck on the oil line and I don't want to remove the fitting off the line because they're so fragile I'm afraid it will get damaged

Also I'm aware of the idle screw hitting the slide if it's in too far maybe i'll run mine all the way out like you suggest and then adjust as necessary.

Just wondered what the most common method / setting you guys use when you set your carbs up for ther 1st run after they've been rebuilt. How do you set your idle screws?

Thanks

Stupid to get in a hurry!! I stock brand new oil lines...fix it right!
You should be using red or green loctite the fittings in the carbs as RD are known for them falling out ALL the time...

Screw out the idle screws all the way out. with the airbox tubes off, and screws turned all the way out, synk the cables first, then stick your finger in the inlet and feel the slide, turn idle screw in until screw just hits the slide, mark a line on the screw then go in 1 1/2 turns for each. put the carb tubes back on and your ready for your 1st start.
Idle will be a too low but is a great place too start if you have outer issues like an air leak...
Chuck

You could just use a length of hose from one carb oil fitting to the other.

I usually screw the idle screws all the way out so that the slides bottom out and set them after the bike  is running.
If they are too far in you might start revving, or not start at all as the gap under the slide lets too much air in for the choke circuit to work properly.

Bingo a winner!!
Chuck

The Wiseco's will go away in 5 or 6 race double header weekends. When they get to about .007-.008 they're done for.
C

Hi Chuck!  Thanks for all the tech tips you post here, they're hugely helpful to me!

I'm building an aircooled RD350 for road racing in USCRA.  The cylinders are heavily ported, and heads have had some squish band work done.  I have Wiseco pistons measuring about 65.44mm (2.5760" to be a little more exact). 

What do you recommend for a clearance for this type of application?  How much clearance is excessive? 

I'm measuring about 0.05mm  (0.002") Clearance, and I'm worried that's far too much.  I also admit my measurement skills are rudimentary, and I may need more practice to get a better reading.

No .002 is way too tight!!
Can you tell me if your using 393 RD pistons or the Banshee 513 pistons?
No less than .0032. with a break in. I run Wossners @ .0035.
I have gone as little as .0027 with ceramic coated Wiseco pistons @ 20:1 premix and always use at least 110* octane race fuel.
Chuck

Fuel flow seems good.  I think I'll try a bigger main, but I'm already at 290.

I rode it a bit yesterday.  It starts right up and runs along fine in midrange.  Crack the throttle and it goes flat or maybe just running on one.  If I ease into the throttle it will take it.  Winds out until about 8500 then pinging starts on the left side.  It just doesn't seem consistent.  Except the pinging.  Get the revs up there and it always pings but just on the left.

290 main jets means your still on stock bleed needle jets?
You should go to the primary needle jet conversion (dave f mod)
I would be using RZ manifolds and crossover tube (or my TSR/Barlow boost bottle) (no way are you using stock airbox with that big of jets)
Then you would be in the 200 main jet range.

Ignition/charging system has to be right first.
Chuck

Not much choices anymore for carbs. Go used off ebay and use your new jetting parts.

https://www.ebay.com/itm/Yamaha-RD400-RD-400-1977-Carbs-Carburetors-MIKUNI-Restoration-GREAT-SHAPE-cables/143608049602?hash=item216fb4efc2:g:ExMAAOSwg~lewVGi

Or go new and have to make throttle cables.

https://www.ebay.com/itm/MIKUNI-VM-ROUND-SLIDE-CARBURETOR-28MM-VM28-49-1002-0052-13-5007/231584793243?epid=202940934&hash=item35eb87829b:g:6u8AAOSwPoZaq6eu

Chuck

Are the needle jets new?
I always preach...never reuse any of the old brass, only the needle unless bent or the anodizing worn off.
The needle jets are a high wear item...
Chuck

You never did say what model you have...
Chuck

Wow...some nice advice! I like most of them!!
Now Paul has a big choice.
The marker running lights that Mark got are sweet too. I think the more visibility the better nowadays is always a good thing!
Reminds me of good old Honda 750's!
Chuck

Ok it's time to replace the stock oem turn signals on Paul's RD400.
What have you guys done for descent conversion without the big $$ stuff?
I just took them off on my Yellow Screamer 20 years ago...
Don't care if we lose the self cancelling.
Thanks
Chuck