Finally getting close to having a ridable motorcycle

[ElFuegoBlanco]

I think I'm finally on track with this rd400 project I've been working on. I had to take a few weeks off for sanity's sake.

New coils
New carb setup:
Went from 175-p2 tubes to 169-p2
Went from 5I4 needles to 5dp7 on center notch
Went from 35 pilots to 32.5
Dropped from 220 mains to 210

And what probably made the biggest difference, and I'm embarrassed to say this:
The PVC sleeve in the reproduction rd350 y-boot wasn't seated in the filter, so it was very likely blocking the air flow.

It pulls pretty nice through around 3/4 throttle, but still not 100%. 3/4 to full throttle is worse. The plugs are evenly grey.
So there's still some tuning needed. I have 200, 210, 220, 250, and 310 mains to choose from. When I get some time, I need to ride over to my FIL's garage where I can do a plug chop on flat road. Now that it will actually make it over to the other side of town.

Thanks everyone for helping me through this adventure.
Rob

[m in sc]

you should drill the airjet out to 2.0mm doing the dave f mod. (or 5/64")

[ElFuegoBlanco]

you should drill the airjet out to 2.0mm doing the dave f mod. (or 5/64")

I'll give it a try!

[ElFuegoBlanco]

Drilled the airjet to 5/64" and now there's a severe lack of power throughout the throttle. I could barely get it over ~35mph and on the hill it struggled to the point where I was worried it wouldn't make it up.

Does it sound like the two are related or it there a better chance I messed something else up? I didn't swap any jets or the needle position while I had the carbs off.

[m in sc]

the airjets at 6 o clock i hope.

on a  400 you may need a p6.

[ElFuegoBlanco]

the airjets at 6 o clock i hope.

on a  400 you may need a p6.

Haha yeah, the 6 o'clock airjets. I think I had a stuck slide, causing the performance problem on the test ride. Going to get back at it tomorrow. Hopefully the p2 will work.

[2steve]

After Chuck did update porting on mine, it is running sweet with this jetting setup, (UNI's - no red outers, boost bottle and FPP chambers):

[ElFuegoBlanco]

After Chuck did update porting on mine, it is running sweet with this jetting setup, (UNI's - no red outers, boost bottle and FPP chambers):

Aside from the different needle jet, it's a really similar setup to what I have. The p2 should work, though, right? I'm not really familiar with the difference between the p2 and p5. Can other adjustments like the needle clip and main jet take up some of that difference?

I did try to go to a 250 main as that's what SoCal250 is running, but it was way too rich.

[m in sc]

jet tube will richen or lean everything everything from 1/4 up to the main. but yes, it can work.

[ElFuegoBlanco]

jet tube will richen or lean everything everything from 1/4 up to the main. but yes, it can work.

Is that up to the main or up through the main?

[m in sc]

it will affect the main as well. that's why with stock 350 jet tubes, the main jet on a y boot chambered etc rd350 is around 240-260. dave f mod, (p series jet tube, 2.0 air jet, 5dp7 needle) , will run a 190-200 main on the exact same mechanical setup. 

[2steve]

The 169-P5's that I an running might have a lot to do with the boost bottle.

[rodneya]

The 169-P5's that I an running might have a lot to do with the boost bottle.

Take that booste bottle off and plug the holes, the bike will run the same. They do nothing for overall performance. May help a tiny bit in the midrange, but thats it, and it wont change your jetting at all.

[m in sc]

agree, they do not affect jetting at all, but can/will affect transition on some bikes. I usually tune w out one, then add it later if need be.

[ElFuegoBlanco]

I'm sure my earlier issue was a stuck slide. I don't know how that happened.

I'm now at a 200 main and it's better, for sure. The plug is a nice tan.

But it's still pretty slow. I'm going to raise the clip on the needle one notch above center (I started at center, went one notch down).

The bike won't rev over around 5-5500rpm at wot. To get the speed up, I really need to feather the throttle and it will eventually go faster, but still not over around 5500rpm.