Rd400 carb assembly

[Membername]

My first time assembling the carbs.  Does it look correct?  Any suggestions?

http://www.youtube.com/watch?v=sMBHubJK8Wg

Thanks,
Karen

[LexPaul]

That looks correct to me, except, that I couldn't read the float measurement, which I'm going to assume you got correctly. The only think I would make sure of is that that channel from the air box nipple into the carb is clean, and I would, and I'm sure you have, checked to make sure the jets, needle, etc are the correct OEM part numbers.

Non Standard parts will kill what would otherwise be good performance from a carb. I had two bikes that the PO had used non standard carb kits on and neither bike had the right needles. When I changed the needle back to OEM, the bike ran just perfect.

Have fun. LP

[Membername]

Thanks LP for taking a look.  The bike is completely stock.  The needle jet (175P2), needle (5L1 3rd position), main (115) and pilot air jets (27.5) are all Mikuni.  The air screw and seat assy are from a kit.  All the channels are clean, except I didn't remove the brass ball.  I know this could be trouble however when I close off the needle jet channel with my thumb and forefinger and blow canned air through the intake from the air box, I can tell air is getting through.  Hopefully this will be enough otherwise I will be disassembling it again and removing the brass ball to clean the jet behind it. 

K.

[SUPERTUNE]

Another tip from me is I reuse the old red fiber washer under the needle and seat valve and not use the aluminum aftermarket washer seal as they tend to leak and should use a 10mm deep 1/4 socket and ratchet to tighten it up a bit more other than a nut driver hand tool. Use oil on the threads as well, not dry. The red fiber washers are still available new from Yamaha.
I couldn't see if you put the main jet washer in correct? Rounded side of the washer faces the main jet, in other words as the carb is mounted on the engine the sharp edge goes up.
Use a smaller screwdriver and set the air mixture screw to 1 1/4 turn out from seated for a start up point.
Hope this helps.
Chuck

[SUPERTUNE]

What air filter do you have in the airbox? Stock paper OEM or a UNI replacement?
I also would jet up to at least a 120 or 125 main jet for todays pump fuels. stock jetting was for leaded fuels back in the day.
Pilot should be fine @ a 27.5
Chuck

[Membername]

Chuck, thanks for checking it out.  I will swap out the washer on the seat valve and use the old fiber one, it's in pretty good shape.  Also I will put a bit of 3-1 oil on the seat threads and torque it to 2.9 ft-lb per the manual.  I was being lazy and didn't want to get the torque wrench from the garage. 

For the main jet washer, it is domed out facing the main jet (the bottom of the carb when on the bike).  So only the edges are touching the needle jet, hopefully this is what you mean. 

I'll also look into getting 120 needles.  The air filter is stock paper. 

K.

[SUPERTUNE]

Chuck, thanks for checking it out.  I will swap out the washer on the seat valve and use the old fiber one, it's in pretty good shape.  Also I will put a bit of 3-1 oil on the seat threads and torque it to 2.9 ft-lb per the manual.  I was being lazy and didn't want to get the torque wrench from the garage. 

For the main jet washer, it is domed out facing the main jet (the bottom of the carb when on the bike).  So only the edges are touching the needle jet, hopefully this is what you mean. YES

I'll also look into getting 120 needles. MAINS The air filter is stock paper. 

K.

Sounds like your on the right track now!
Let us know how you make out!
C

[Membername]

I just got the 120 mains in the mail today, and I also ordered Mikuni rubber tipped needle valves (HVCcycle) so I don't have to use the ones from the kit.  Are these ok to use and if so, what's the deal with the little clip?  Keep it on or off?

Thanks,
Karen

[SUPERTUNE]

I just got the 120 mains in the mail today, and I also ordered Mikuni rubber tipped needle valves (HVCcycle) so I don't have to use the ones from the kit.  Are these ok to use and if so, what's the deal with the little clip?  Keep it on or off?
Thanks,
Karen

Hi Karen, These are the higher end Viton mikuni needle and seat valves.
Yes, leave them on. these Vitons are all I use if I purchase for the customer.
Chuck