DR350 Thread

[TopDeadCenter]

Originally Posted by plugeye

you need to ride it with some rpms for a bit.
in my exp, this motor sumps like crazy

Are you saying "sumps like crazy" means "it pulls the oil out of the sump and into the frame like crazy"?

TDC

[plugeye]

Originally Posted by TopDeadCenter

Are you saying "sumps like crazy" means "it pulls the oil out of the sump and into the frame like crazy"?

TDC

no, the motor sumps it out of the frame unless ridden daily

[slartidbartfast]

Originally Posted by markk900

... I'd assume that the adjustable clip will eliminate any concern over spring preload.....

Yes, it will - but I think the person who brought that up is being overly pedantic. You will NEVER be able to tell the difference in where the slide lifts from shimming the spring .020". However, the difference in fueling from having the needle .020" higher will be marked.

[tntmo]

If anyone needs any bits and pieces, I have an entire 91 DR350S that I'm parting out.

[motolab]

Originally Posted by visovm

With regards to the "pilot screw" I will call it that from now on since that is what its called in the service manual.

That's a safe bet.

The consensus seems to be to start with 2-turns out and than adjust from there once the bike is warmed up.

Procedure for adjusting the idle mixture:

Warm the engine up. Set the CO to between 3 and 5%. Check and or reset the idle speed. Recheck the CO%. If you do not have access to a gas analyzer, lower the idle speed a little bit (this increases the sensitivity, so you can more easily notice the effects of your adjustment). Adjust the fuel screw in until you notice it is running worse, then adjust out to the point where the idle is the strongest, and then no more than 1/8-1/4 turn further. Adjust the idle speed back to normal.

If you look back at my previous pictures you can see that the slide is already drilled with one hole on either side of the needle. I believe this is how the carb came stock, but for reference the top of the slide looks like this:

Two holes are stock, but you can check to see if they have been enlarged by having a look down inside the bores. The walls should be smooth (as molded), with no drill marks.

As far as I can tell it does not look like the needle was ever shimmed with washers and the spring does not appear to be trimmed. Judging from the responses I should leave it this way.

I would not clip the spring or shim the needle, but I might install an adjustable needle with a suitable profile. Aluminum would be preferred as a material, as stainless steel and titanium can accelerate emulsion tube wear. Machining extra clip grooves into the existing needle would probably work well.

Likewise, the best way to improve performance and throttle response would be to get a jet kit or spring for the TM33 carb, instead of fiddling with shims, and trimming of the spring.

The Factory Pro jet kit is likely to contain a needle with a suitable profile, but it is made of titanium. The DynoJet kit is not as likely to contain a needle with a suitable profile, and I'm not sure if it's stainless or aluminum.

Regards,

Derek

[brianjonesphoto]

Originally Posted by plugeye

you need to ride it with some rpms for a bit.
in my exp, this motor sumps like crazy

Mine doesn't sump too badly but you must get this motor nice and hot to check the oil level. If you've got 2qt in it you are fine. Take it for reasonable
Ride for 15 minutes then check it and it will read normally if not a bit high.


Typos and nonsensical words courtesy of fat fingers on a make believe keyboard.

[visovm]

markk900: yes we have determined the carb is stock. I also believe we have come to the conclusion that trimming the spring and fiddling with the stock needle is not necessary. The bike is running well. What I am trying to accomplish (and seem to be close) is to get feedback from others who have tried mods to this carb to see what works. Or feedback from people who are way more knowledgeable than I but do not necessarily have this carb. A good running bike is subjective to the user (to a certain point where there is an obvious problem) and what works for someone may not for another. Lastly, my wording was incorrect i meant to say "spring for the TM33 carb" as is in take the plunge and shell out the money for that carb. But it does sound like making spring changes to the TM33 carb as if that was the one in question.

With regards to the other comments:
I believe that making no changes to the BST33 that I have will be the best solution at this point.

Thank you for motolab for the pilot screw adjustment procedure. Once I fiddle with that I hope to have this carb running a bit better than before. I have access to a gas meter, but its not intended to read exhaust gas (it does read CO among 4 other gases) If i can get away with your "by touch" method I will stick with that. I will also check the holes more closely to see what is going on in there. Adjustable needle is a viable option and I will seriously consider it after testing the stock settings with the pilot screw properly adjusted.

Thanks again to all who weighed in If there are more comments I will love to hear them. I will report back when I receive the parts and get the intake/fuel system back together and the bike running.

[motolab]

Originally Posted by visovm

Adjustable needle is a viable option and I will seriously consider it after testing the stock settings with the pilot screw properly adjusted.

If there are any misbehaviors, put some tape on the throttle housing and the edge of the grip. Mark zero throttle with a sharpie. This is best done with the engine idling, so you can tell when the slack in the cable has just been taken up. Turn off the engine and mark wide open. Now take a tape measure (metric works best in my opinion) and measure the length of the arc. Put a mark at the mid point. Duplicate this procedure to mark the mid-point between here and zero throttle opening to get 1/4 open. Repeat for 1/8 and 1/16 openings. With the help of the marks, determine precisely during what throttle opening(s) it misbehaves. Don't have an accident trying to look at the marks while riding. If you do, I'm not responsible!

Regards,

Derek

[Noah M]

Im looking for some lowering links if anyone has some for sale!
Just bought another 350 and need it lower for the misses

[visovm]

motolab, thank you very much for the detailed description. I hope that method will get me close enough to enjoy riding the bike again after this little winter refresh. I will be extra careful when testing the throttle at different positions, and of course I would not hold anyone responsible for something I am choosing to try myself.

Thanks again to all the DR350 folks for all your help! This forum is my absolute favorite, too bad I would never have enough time to read through all there is on here, but Google search is my friend.

[RuggedExposure]

Just got this in from fleabay:
http://www.ebay.com/itm/AMR-RACING-C...7f6deb&vxp=mtr

Maybe tomorrow I'll have time to swap it out with the stock one to see if that helps with the backfiring.
I got the bike fired up two days ago (it was 19*F) and it seemed to idle alright, but still backfired like a SOB when you gave it throttle. I did determine that the backfiring is coming from the tail pipe, and having the choke on seemed to help.

Who knows if this new coil will help, if it doesn't at least I have a spare coil now.

[MiteyF]

Backfiring, and choke helps? Sounds like she's running lean

[dbarale]

Originally Posted by MiteyF

Backfiring, and choke helps? Sounds like she's running lean

And the colder, the leaner. Cold air is more dense which means more oxygen to the carb = leaner.

[Greg Bender]

Originally Posted by jmderyke

Didnt know anyone could be so picky about idle mixture screws names

I actually appreciated motolab's post because I now have a better understanding of the functionality. IMHO, using accurate and proper terminology is important because we all (me especially) struggle from time to time trying to figure out what we are trying to figure out :> :> :>

The old Guzzis I work on use a Dell'Orto carburetor (VHB 29) that has a choke. Only, it isn't a choke at all. A choke richens the mixture by reducing the air intake. The Dell'Orto system acts as an enricher, adding fuel instead of reducing air. The end result is the same, but it is very helpful to know what is happening in case something starts to act funny.

Regards,

Gregory Bender

[Greg Bender]

Originally Posted by mustangwagz

Got them there DR350 Crash bars i ordered via ebay, Imma see if my buddy can replicate them just for the heck of it. Ill let yinz know. THEN ill get pictures n stuff! man they look awesome, and will fit flawlessly! Someone put some time into them!

The Germans don't mess around when it comes to putting stuff together ;> I can't wait to see the pictures!

Regards,

Gregory Bender