HELP! RD350 troubleshooting issues

TurdFurguson

TurdFurguson

Weird Indy Kid
DTT BOTM WINNER
So, this fucking RD has been the bane of my existence. Still trying to learn the nuances of these damn things. I think its almost there now. The bike will start first kick every time, and it idles like a champ. If you give it quick throttle it just dies, if you move into the throttle it boggs a bit up until about 3k PM them takes off like a fucking bat. I have lots of troubleshooting pics and videos to hopefully help.

Bike has stock airbox, stock exhuast, 140 main jets (not sure about the others unless I take them all apart, it was a sudco kit).

First i cleaned the plugs, I left it ideling and then kept it at about 1/8th throttle (3k rpm) for about a minute where it seems to have the most issue. Killed it, pulled the plugs. Attached pics of the left and right plug. Each has a decent amount of oil all over them, is this normal or excessive?

I also have a couple of videos, hopefully these links work

Right cylinder timing
http://youtu.be/XKNSoQN86dA

Left cylinder timing
http://youtu.be/0lLpjGEgsC4

Quick Throttle Issues
http://youtu.be/ACmOJ42haSA

Gradual Throttle
http://youtu.be/q2kt1zIO0h4

I have full size versions of these files if you would like to get a better look. Everything seems to be good from a timing standpoint..
 

Attachments

  • Left Plug.JPG
    Left Plug.JPG
    763.9 KB · Views: 412
  • Right Plug.JPG
    Right Plug.JPG
    735.9 KB · Views: 440
Did you completely disassemble and clean the carbs? The emulsion tubes must come out, and you have to have smooth streams of carb cleaner squirt from every passageway in the carb bodies. Make sure the assembly is correct. The slides can be installed backwards if swapped to the wrong body. The fuel bowls are not the same; The one with the drilling for the choke (enrichener) goes on the left carb body (though this does not sound like your problem.) Likely all the parts in your rebuild kits did not need replacing. Put your original needles and jets back. Condensers are ridiculously, notoriously bad, and have all manor of behavior, and the stock coils are now so old I would replace them out of hand. They were crap when new. But your issue sounds like carbs. Check for air leaks, and don't forget the little hose that connects the carbs for the enrichener.
 
The needles I didn't change, though everything else was. The carbs were completely dissembled, including the emulsion tubes. I have verified that shooting carb cleaner through the ports on the front of the carbs clears the emulsion tube chamber. Carbs were cleaned in an ultra sonic as well. Slides are correct, the flat side faces the motor while the raised side faces the airbox. Tube is connected between the two carbs. I haven't messed with the coils or condensers but would they cause issues between 2-3k rpm and at 1/8th ish throttle only? Could there be to much oil squirting? Are those plugs fowled up or do they look expected?
 
If you haven't done anything with the pilot jet/air screw then you'll need to fine tune that first since it affects idle and low speed power. Do you have a manual for the bike? That procedure should be outlined in it, somewhere in the maintenance or carb section. I know the general procedure for carbs but I don't know if it applies to the RD carb (don't have any experience with that bike) so take what I say next as a general outline as I don't want to give you any misinformation and add to the issue. Do you know what carb is on the RD?

Basic procedure is (after the bike is fully warmed up) set the air screw 1 1/2 turns out from lightly seated and then set the idle to the correct RPM (should be stated in manual). Then turn the air screw small increments (1/8 of a turn), either clockwise/anti-clockwise, to achieve the best idle. If an adjustment makes the idle increase, reset the idle to stock setting and then try another turn in same direction. Take your time with it and only make small adjustments and then wait a bit to see its affect on the RPM.

I had to tune this system on my MB5 last summer after putting on a new carb, makes a difference when its properly set.
 
I played with them a bit and made the idle slightly better but it made no difference when setting off. Still dies before 3.5k rpm, once I hit that it'll take off. I pulled my needles out to check them and it has Y30, I went through a box of old shit and I found an 5I4 needle. Mine looks fatter than the other. I don't have a match so I'm going to try moving it up a notch and see what that does
 
I jacked the needles all the way up and it drove up and down the road! there was still a little hesitation but its 100000x better than before. Time to research what needles this thing is suppose to have, obviously these kits dont have the correct ones.
 
pilot jets should be #25, and should be fine for you, but you can try #30's and see how performance is affected. #5I4 needles are the correct ones. Get FACTORY Mikuni needles, aftermarket needles are unreliable, though Sudco should be the real mcCoy. Once you get it running properly, remember that RD's can be pretty sensitive to ignition timing. Keep it at 2mm or less BTDC, (I think a lot of guys are more like 1.85 with the gas these days).
 
You must log in or register to reply here.

DTT Light or Dark

  • DTT Light

    • Spread the Love

    Back
    Top Bottom