Rd400 more low / mid?

[quocle603]

change your gearing and chain (520). Thats a simple easy change that you can do to give your bike more torque

[pdxjim]

OP is right, tho.

Yamaha R&D knew what they were doing.  For an around town grocery getter, there's no beating the stock setup.

They didn't call it TORQUE INDUCTION for nothin'   

Too bad I've been 100% unsuccessful at keeping my bikes stock.

[Organicjedi]

Is the 520 chain conversion so that they can run o-ring chains?

520 chain is lighter than the stock 530.  In theory, the heavy overkill 530 stock chain robs some power.

More hp to the wheel has been proven with a 520 chain vs 530. Simple mod for more power.

[quocle603]

Is the 520 chain conversion so that they can run o-ring chains?

Do not run o-ring or x-ring chains. Run the simple DID Roller chain.

[pdxjim]

Is the 520 chain conversion so that they can run o-ring chains?

Do not run o-ring or x-ring chains. Run the simple DID Roller chain.

Yes, it's assumed the o/x-ring seals rob some power too, but for a streetbike ridden in all weather IMHO it's totally worth the .5hp loss for the ease of maintenance, etc.

I like the DID 520VT2.  Lighter than the rest and the size of a standard 520 with the ease of use of an o/x ring.

https://www.powersportsuperstore.com/products/d-i-d-520vt2-112-520-vt2-enduro-racing-t-ring-chain-112-links-gold?CAWELAID=120009580000067813&gclid=CjwKCAjwxt_tBRAXEiwAENY8hdNMowK0Lo1vl07APt4_Z8evPnm7loyB3tKoVmP85X2IsxG6dYjeohoCkgwQAvD_BwE


On a racebike or landspeed bike, absolutely run the lightest/strongest plain roller chain you can afford.

[Brad-Man]

Put an ignition with timing curve in and have better low AND top end.

Stock is a compromise.

[rd400canuck]

ok... I didnt know about the 520 conversion thing... thanks guys. I'll prolly run whats on it... I suspect it's a 530 because I remember thinking that is a chunky looking chain. When it's time I'll do the conversion and prolly do the x-ring chain just for the ease of use and longevity.

Funny you mention ignition, Brad-man. It occurred to me today that since it's a points ignition there is no ignition curve. From what I've learned over the years about engines is there is a lot to be gained from a good curve. So much power must be left behind with no curve.

I like the Vape because it has a 150 watt accessory coil plus it will add a little flywheel effect which I dont mind at all. I dont like that they arent keyed to the crank...  I'm hoping they never slip. The other thing I dont like about the Vape is you dont get an ignition module for that money... if you want a curve and control over it you need to drop hundreds more on the module and its handheld programmer. That's a lot of damn money.. by the time it gets to me in canuckistan it'll be $1000.

However, I do relish the opportunity to tune in a curve to get all the power I can so.... maybe it'll be a treat to myself and something I can do over the summer after I got everything running good.

[Frank B]

If you get your Vape system from HVC they offer a key service for $75, it'll never slip but you can't adjust your timing without a ZEEL box and programmer. I have the keyed Vape on my 400 and it's awesome. There's a few spots on the case and cover that need to be "massaged" but it's really easy to install.

I used the same VT2 chain, it's a thinner, lighter, stronger chain for moto cross, aluminum rear sprocket and 16/39 gearing and it's great!

[SUPERTUNE]

Pull out the stock pipe baffles and burn them clean.
Rebuild engine with a fresh crank and a proper bore and hone.
Rebuild the stock reed cages so the reeds seal 100%
Stay with stock airbox, uni filter is fine just jet up for today's modern fuels.
30 pilot 1  3/4 out, 120-125 main jet, 120 for summer and 125 for winter.
Remove the ball in the carbs to clean the .5mm air jet, then tap hole with 5 x .8 tap, do only 2 threads!
Then replug with 5mm x 10mm length set screw.
Make sure you keep the airjet hoses connected from the floatbowls to the plenum of the airbox.
Set timing to 2.00mm
I would even add 1 tooth to the rear only.
17/39
If you use aftermarket .020 base gaskets and bore to 65.00 mm you don't need to
'SET THE SQUISH'.  400's are fine in that area. The aftermarket basegaskets are .004 thinner than OEM Yamaha gaskets. Torque heads to 24 ft lbs also.
Chuck

[Yamaha 179]

Chuck is absolutely correct.  The changes you need to make to a RD 400 to make it an ideal street bike are minimal.  You know from experience what you get when you "tune" an RD engine, they are great on a twisty road but a bear in town.  My last 400 was stock except for the filter in the air box, the carb changes Chuck mentioned, and the handle bars.  I left the ignition stock and it was no problem at all (but I've been messing with RDs since 1974).  You will probably want to spend some time rebuilding the brakes also. BTW
I sell base gaskets in varying sizes if you decide you need different thicknesses. 
Lyn Garland

[m in sc]

this is what i was driving at w the carb comments. set the stock base tune with everything serviced correctly, 400's are tractors stock. (and i mean that in a good way).

[hayduke]

Do what Chuck said, I did it to mine and I love it. Basically I was never happy with how my RD400 ran, because about all I do is tool around town in traffic.

I sent him my carbs and heads, he did his magic, I followed his instructions on the pipes and coil wiring relay, when I installed the carbs it fired on the second kick, and idled perfectly. The bike starts and idles clean and 'drives' like a modern(er) bike, lots more torque, or at least it pulls clean from low rpms.

[rd400canuck]

wow, thanks everyone for all the great info :)

I went and pulled a baffle out... omfg it's like someone dipped it into thick grease. Ive ordered some baffle packing and I will take a torch to them. I ordered some different sizes of pilot jets, too. I didnt know I could clean the air jet either... thanks for that tip!

There seems to be a middle piece in this baffle and it can slide up and down about 1/4 inch. Is that normal?

Thanks Lyn.. I will most probably come looking for thinner base gaskets once I get everything back and see what kind of clearance I have.

Btw here is what I am planning on having the bike look like. Not what the bike looked like originally but I love this look. It's not the stock blue either, it's the same blue on the R1 and R6's.

I guess I'll start build thread

[SUPERTUNE]

Do what Chuck said, I did it to mine and I love it. Basically I was never happy with how my RD400 ran, because about all I do is tool around town in traffic.

I sent him my carbs and heads, he did his magic, I followed his instructions on the pipes and coil wiring relay, when I installed the carbs it fired on the second kick, and idled perfectly. The bike starts and idles clean and 'drives' like a modern(er) bike, lots more torque, or at least it pulls clean from low rpms.

Wow,
Time flies!
It will be 3 years ago in 2 weeks that I did your carb rebuild  and rejet!

I looked at your notes and I did have you drill your baffles and run no packing on them.
I did re-drill to tap for removable air jets and used a .7 air jet with a 135 main jet
I set the air screw at 1 3/8 at the time for 1st fireup.
Chuck