Messages

Jspooner,
You nailed it!
Disassembled the forks today, and found the top out valve had been reassembled incorrectly by the previous owner.
The oil flow ring that contains the spring was upside down, easy to see how that could happen.
No more clunk at extension, hard to believe that little spring and ring make such a big difference.
Many thanks!
Hemi

Glad you figured it out. I remember thinking the same thing when I figured it out.

Thanks Dvsrd,
I've tried more fork oil, thicker oil, less oil.
With more oil, the forks seemed a bit more extended at rest, felt stiffer, less sag, still had the clunk.
I'll check the other things you mentioned.
Hemi

I'm still going to say its the "top out valve" as 1976RD400C calls it. As I said, you can assemble the parts MORE than one way, but it only works ONE way.

It's not the dampening rod. Can't really do anything wrong there. What I'm talking about are actually at the bottom of the tube on the inside. If you pull it all apart and remove the dampening rod and look at the bottom of the tube you'll see s9me stuff held in with come c-clips. That's what I'm talking about. Normally you leave that stuff in tact when working on the forks but when you replace tubes you have to remove then and reinstall them in the new tubes.

I think it's called the top out valve. It causes real strong damping the last 1/4" of topping out. Remove the snap ring on the inside of the fork tube and pull the piston/bushing out and it should be in there, aluminum valve and spring.
<a href="https://ibb.co/BsT7108"><img src="https://i.ibb.co/9YyfMQR/20240414-074827-1.jpg" alt="20240414-074827-1" border="0"></a>

Thats what I'm talking about.

In all honesty, I thought it was all of the obvious stuff too. Before you remove that stuff see if you can fine a diagram that shows it. If I remember right it can go together a few different ways as far as the actual order of the parts and which way they are flipped, but only one way is correct.

It's not the dampening rod. Can't really do anything wrong there. What I'm talking about are actually at the bottom of the tube on the inside. If you pull it all apart and remove the dampening rod and look at the bottom of the tube you'll see s9me stuff held in with come c-clips. That's what I'm talking about. Normally you leave that stuff in tact when working on the forks but when you replace tubes you have to remove then and reinstall them in the new tubes.

I don't think it's any of the above. I ran into the same problem. There's some hardware at the bottom of the fork tubes that you needed to swap, correct? It's very important that you get that back in the right way. It will go together either way but I'm pretty sure it has something to do with dampening control in that direction. I couldn't tell you which way is right or wrong because I just figured it out by trial and error. It wasn't my bike so someone else did the swap, I noticed the "top out" problem and just started swapping and flipping parts. I would bet that's the problem. Maybe one side is right and the other is wrong or maybe both are wrong.

Anybody want to guess who made these? They came off a 1975 RD350 and they have been on the bike since the late 70's.

I think they are DGs.

I have dealt with him. He will get back to you, sometimes it takes a while.

Wow! I wonder what part of complete that 80-90% is?

I would keep the oil pump. They're reliable and it will simplify your life.
Rebuild it with new seals if needed. Easy to do and the rebuild kit is available from Economy Cycle.

I second the motion. HVC sells the kits too. It's a good chance to make sure everything is set up correctly, so that your ratio is good.

I third that, keep the pump. No reason to get rid of it in my opinion. I even run one on my TZ/LC motored TZ replica. On a street bike you will never notice the performance gain or loss, but you will really appreciate the pump when you're at the pump.

I've seen this motorcycle. When Warren lived in Arkansas and I went to visit and meet him for the first time. This is/was just one of the many very cool motorcycles he had at the time.

That's pretty cool.

I put grease on then, in the hope they come apart cleaner

I do this as well, but no sealant.

I know this has been addressed, but do you use any sealant on RD 400 base gaskets?

I don't

Hello All,

I have an early rd350 motor and I am going to upgrade to 7 plate clutch.  The thrust washer shows 2 different part numbers on the breakout manual.  Is ok to go with either or?  It looks like the 278 part number is the washer with the bevel.  I was able to source a clutch hub and basket and all the steel plates.  I have new friction plates and springs.  Has anybody used the 278 part in a 7 plate clutch upgrade?

thanks

Do you have the pressure plate and bolts for a 7 plate? Pretty sure you will need those as well.