It does not matter whether there is some air mixed with the fuel before it reaches the fuel screw. It still controls the mixture by adding or subtracting fuel. Since the parts order is slide, small white spacer, clip, spring seat, and then spring, and the spring seat bottoms on the clip and not on the slide, a small washer will indeed increase the preload. To prove it, I took a .020" thick by .195" OD washer and put it under the clip, and then measured the distance from the top of the slide's spring well to the spring seat, and that distance was .020" less than without the washer installed. Regards, Derek
You may be right about the slide spring preload, but not sure how much .020" more compression makes on these 20+ year old springs. I see what you're saying about throttle rotation and slide height. Maybe thats why all these jet kits say to cut off some of the spring after shimming the needles. Still seems kind of hit or miss to me. It would take a lot of equipment to determine if those kind of changes made significant improvements. I think it's hard to beat the factory guys with their budget and testing. I wouldn't do any of it on my DR350. Mine is bone stock and runs great. ..... And just wanted to illustrate idle concerns can be connected to the idle air jet as well as the fuel jet.
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!
How old the spring is makes no difference to the fact that shimming the needle will increase the preload on the spring, and, except when the slide is at either stop, will richen the mixture by lowering the slide rather than by raising the needle. Doubtful for two reasons. One, most jet kits include an adjustable needle (otherwise, why buy one at all?). Two, while clipping the spring does reduce the preload, it also increases the rate. I use a 5-gas EGA equipped eddy current brake dynamometer for this purpose. It depends on how you define "beat". Definitely understandable. Not to say that it doesn't, and I might well agree with you, but in my experience, there seem to be varying definitions of the word "great". 10-4. Regards, Derek
Got my 350 fired for the first time today. Started pretty easy after the carb got fuel and the rings got a little oil. One thing really troubles me. I did an oil and filter change. I added one quart and a majority of the second. Fired it up and let it get warmish then checked the level. No oil on the dipstick. Added the remaining oil in the second quart. Repeated the level check proceedure and there is still nothing on the dipstick. I've got two quarts in and it's not registering anything. I never even had to wipe the dipstick. Bone dry. What am I missing? TDC
Wow, lots of great carb information here, I think I have digested most of it. With regards to the "pilot screw" I will call it that from now on since that is what its called in the service manual. The consensus seems to be to start with 2-turns out and than adjust from there once the bike is warmed up. As for the carb mods: 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: If anyone thinks otherwise than please let me know. 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. 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. Thanks again for the explanations of the BST carb mods. I think I am finally beginning to understand how all the components work together.
I think it seems pretty clear the carb you have is stock and unaltered, so now the question really is "what problem are you trying to solve"? If things are running well now then why change anything? The discussion about the spring and needle was interesting, but instead of shimming the needle why not just order a stock one with the adjustable clip and not worry about that aspect? I'd assume that the adjustable clip will eliminate any concern over spring preload..... Or use your already modded airbox and add the kit from Jesse @ Kientech (I have been happy with that mod, though it lowers fuel economy). I assume that was a typo about getting a jet kit for the TM33 since you have a BST?
Are you saying "sumps like crazy" means "it pulls the oil out of the sump and into the frame like crazy"? TDC
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.
That's a safe bet. 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. 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. 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. 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
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.
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.
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
Im looking for some lowering links if anyone has some for sale! Just bought another 350 and need it lower for the misses
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. :huh 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.
Just got this in from fleabay: http://www.ebay.com/itm/AMR-RACING-...Parts_Accessories&hash=item1e757f6deb&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.
