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So i was out cruising the web and happened upon a " looking for the best pipes for my RD400" Thread.

Not going to mention any names here, but there is a certain cat out there claiming that his pipes will push 75 hp out of an RD 400 with 34mm carbs and porting, which he stated the porting changes some power output but his pipes make the biggest improvement-bar none.

Have I missed something?

Im not on here as much as i was in past years do to a shift in hobbies, buildings and having kids, but what the hell.

I know Chuck was making some pretty sick power out of his 400, but I just dont recall exactly how much. And if anybody is going to make big power it would be chuck.

Just the fact that the guy claimed his pipes made up the biggest difference and the porting was minor has me really second guessing things?

Just wanted to check in and see if there is any truth to this.

Ive got a piped DT 400 with a 38mm carb and some other "tricks" done to it aswell, revs out excellently now, lol....

In stock form they are scary slow for a 400 cc single but they have TONS of potential. Yamaha did a lot to choke them down. ditch that crap cdi for a points set up, do some port work, yada yada yada....

But after a pipe and a carb they are stupid fun, just like a 400 single should be. I often thought of adding an 18" front wheel and a disk on mine, but just havent done it yet.

Ive piped the DT 250s and the 400s aswell. GYT spec pipes in both cases that Ive built myself. For 370$ id go for it.
The only other mod you might want to do to take full advantage of the pipe to its fullest is a bigger carb. I run the 38mm Mikuni roundslide, which delivers very, very good results with some pretty straight forward tuning.
My opinion is if you do the pipe, do the carb aswell.

You dont need to swap an aircooled engine for another aircooled, you just need to learn as much about the one you have and go from there.

If your going to swap out engines you should just go for a 2004+ Yz250 and have 50hp out of the box and be done.....

https://www.denniskirk.com/drag-specialties/baffle-w-fiberglass-wrap-for-2-in-od-exhaust-1861-0913.p4407406.prd/4407406.sku?fbclid=IwAR3VBl9nBmSzznh6UC5yWOMuSwcnxQk-XsYGRSeiGSRx9X2Yl0laZED4QTw

Look at these for silencers, cheap and built pretty decent.

just as others have stated, keep the silencer larger than the stinger or you will have just created a longer stinger.

Have fun experimenting, you can really change the characteristics of the bike with a different taper on the end cone and the ID of that stinger. Just make sure you jet down and not up.....

my RD like to mark it's territory

PTFE tape on drain plug threads

Atctually thumbs down.

Those are straight threads. YAMAHA put a fiber washer on it for  reason. your just asking to strip the case out by over torquing it.

I seconf Belray Gear saver. Good stuff.

To be honest ATF isnt really ideal for this application. Furthermore, if you know anyone that does any serious drag racing with more than 7-800 hp atf even type F is not used.....

Thats not really that high considering its well sorted and ready to ride.

Tasteful mods and original paint. I wouldnt move much on that price.

GLWS

Did the 92 SPs come factory with white wheels?

Given the fact that there appears to be mud? packed on the backside of the cylinder, is the guy offroading with the bike? Lots of gravel roads?

Has he sent you any manifolds back?

What do the insides look like?

Is he steam cleaning the bike, using a pressure washer at a carwash perhaps?

I know guys in the sled world that run some alternative fuels, maybe he is using a special blend thats killing them?

I always heat the aluminum up to 100-150* just before painting,

I would not do this, IMO the paint dries too fast as it is going on and does not flow properly as you apply it. I paint them at room temp, let them dry to the touch or even longer and then bake them at about 200 to cure the paint.

You have a point. You must be more consistant when applying the paint.

Either works.
But I find metal, especially aluminum  holds so much moisture that it can negatively effect the durability of the paint/ product applied.

Would aluminum oxide work? I found a blast cabinet I can borrow

Absolutely,  but it will be very aggressive. Dust, if you will, lightly very the cases and it will remove the shine very fast. Just don't sit in one spot or you will see the removed material after paint is on.

You will need to clean them with acetone, blast with glass bead and then acetone again.

I always heat the aluminum up to 100-150* just before painting, put 2-3 coats on and let it dry for 48 hours before installing.

My paint of choice is VHT gm satin black for engine cases for RDs. But i recently did a Harley engine for a friend and used VHT wrinkle black and it turned out very nice for rattle can paint.

Take your time on the prep and cleanliness is key.

BTW: the VHT is fuel proof, ive spilled fuel/premix on my cases and have never had issues.

When I did this it was between 1.5 and 2mm.

I believe it's 2mm for a 400.

Hopefully supertune can verify

For anyone in Wisconsin I can confirm it 100% works.
You will need to coach the Dmv employee on the transfer to a WI title. They will need to get their big book out and learn that they can actually make you a title right there on the spot.

I've gotten 4 bikes title without issue this way.

How far back does your data go?
I have a '63 YD3 and a '68 YG5T, I'd be interested in seeing produnction numbers of.

Definitely a bitsa bike.

Look at image 18 of 22. It shows the mounting tabs for the oil injection fill cap/ battery box.

I wonder if he'd sell the tz water pump separate?