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DR350 stock carb settings??


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Other than idle speed, there's only one adjustment screw on either the BST33 (street version - constant velocity) or TM33 (off road version - flat slide, pumper) carb. From the factory the idle mixture screw on the BST33 is covered by a brass plug. To change the setting this plug must be drilled out. According to the service manual, the stock setting on the TM33 is 1 1/8 turns. The manual does not provide the setting (it simply says "pre-set") for the BST33 but in my experience those are usually set around 1 turn. Also, in my experience, the bikes start and run much better with the mixture screw in the 1.75 - 2 turns range.

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ok.. ill try starting out at 1.75 turns out..

anyone know about the idle adjustment? I know that there is a sweet spot to start it..

I replaced the old petcock with one from a XT600 fuel tank I had.. Perfect fit! so no more flooding, but now I am not getting any gas... I plugged up the extra carb ports.

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hmm.. so still no gas getting to the plug...

I checked the valves to see if they were opening and they are good..

I tried opening the throttle with the choke on to see if I could flood it.. nothing...!!

so here is a pic of the plugs on the carb... the one in black was on it when I bought it... and there is a black one on the bottom in the front of the carb on the engine side that is plugged...

clear tubes are the ones i put on.. This makes 4 plugs?? is this right? or does one have to be unplugged to get air through?

http://i699.photobucket.com/albums/vv357/hollisatp/IMG_3771.jpg

http://i699.photobucket.com/albums/vv357/hollisatp/IMG_3768.jpg

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First picture, right side plug (nearest engine). This is the vacuum port for the petcock, and it should be plugged if not in use. Get a beter cap for it at the autoparts store.

First picture left side plug (nearest airbox) this is a carb vent, and must be left open. It connects to a length of tubing that normally goes up and into the frame tube (under the gas tank)

Second picture, the plug on top of the black plastic cap: This is not needed, the "port" is not drilled on the DR350's and goes nowhere. You might re-use this cap for the vacuum spigot on the side of the carb that normally goes to the petcock.

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+1 on jcalis' post.

Also, if there's really no gas coming through the carb are you sure the petcock and float needle are functioning properly? I assume when you replaced the OE petcock it was with a manual (i.e. a NON vacuum) petcock. Quick check - if you open the drain screw on the bottom left side of the float bowl does gas flow out of the drain port (bottom center of float bowl pointing straight down)? If not, there's no gasoline getting into the carb. If gas is getting into carb you can check the float level by putting a 8" piece of clear hose on the drain port and curving it upwards. With the bike vertical, open the petcock then the drain screw and gas should flow up into the clear hose roughly level with the junction of the float bowl and carb body. If so, the float level is correct and the problem is with metering of the fuel (jets, passages, spray needle, vacuum leaks, etc).

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yes.. the float level is good.. and the petcock is working....

When I get the bike started, it feels as if there is no gas getting to it on the 1/4 throttle yet if I rev it, it will respond to the 1/2 and up throttle.... nothing down low which is making it really hard to start....

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yes.. the float level is good.. and the petcock is working....

When I get the bike started, it feels as if there is no gas getting to it on the 1/4 throttle yet if I rev it, it will respond to the 1/2 and up throttle.... nothing down low which is making it really hard to start....

OK, Sounds like the pilot and/or idle passages are blocked. Those passages and jets affect performance up to around 1/3 - 1/2 throttle and are very small and easy to block. Also, very difficult to clear when clogged. You can try cleaning them with a spray straw carb cleaner but I'm guessing you're gonna have to disassemble that carb, remove all the rubber parts and soak it in a powerful cleaner.

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ok... So I think I might have found ther problem... there is a air fuel mixture screw that is on the side between the carb and the engine.. this is capped off I believe from the factory but mine has been drilled out... I removed it to clean it before, thought I put it back right but now I dont know... anyone know the number of turns out for this?? This should be the 0-1/4 mixture...

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Are you talking about the one on the bottom of the carb? It's labeled "Fuel/Air Screw" on this picture:

2471516121_e50dcdfe69.jpg

If so, try bringing it out 1.5-2 turns.

Picture taken from this thread (which you might want to check out):

http://www.advrider.com/forums/showthread.php?t=347184

That thread refers to a BST-40, but it's very close to your BST-33.

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yup.. thats it.. only 1.5 to 2 turns out? there is so much thread in there... i think it is like 14 turns all together to get it out..

ok.. by looking at this post... It seem s I am missing the spacer between the carb and the main jet... but this must be a difference from this one to mine? My main jets thread is small and would never fit thru a washer like that AND screw into the needle jet...

if I am missing the spacer and the main is wrong (which seems like a bigger step since that part was not in the carb when I opened it)... this would mean that the needle is buried in the main jet not letting ANY gas by... everyone agree??

Im gonna try to turn out the air/fule mixture screw a bit more to see what happens... Thanks all!! I'll give ya an update..

Thanks TURD!!! how is that website by the way?

edit - on the intake of the carb... there are two small jets.. on is size #.3 and the other is size #1.6... which one goes where? on mine I had the smaller one on the right.... maybe this was mixed up by the last owner....???

Edited by hollisatp
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You should probably be checking into the pilot/idle jet like someone else suggested. It's responsible for throttle response up to around 1/3 open like tn2wheeler said.

Make sure you can see light through it and hose it down good with carb cleaner. If all else fails, call or email Jesse at http://www.kientech.com/ . He's a great guy and can get you set up with what you need to get it running correctly.

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Im having similar carb problems..bike is running lean as a popcorn fart and will only start after 100 to 200 kicks...last night the bike stalled on the way home and would not start..this morning i found the spring and pilot screw laying on the motor base next to the cyc head...big luck..can anyone tell me if there are suppose to be orings or more parts to this pilot screw assembly?👍

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It seem s I am missing the spacer between the carb and the main jet... ?
The BST33 (DR350) does not have the spacer.

The BST40 (DR650) which is shown in the pictures does.

For a stock DR350 BST33 carb (or even with an opened up air box) with stock 37.5 pilot jet the fuel screw can be anywhere between 1/2 and 2 1/2 turns open. If you need to go more than 2 1/2 turns to correct hard starting or to get the idle right then you need to go up one size in the pilot jet to a .40

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ok BOB ONIT..

I think that my air screw was suposed to be fixed but the guy before me drilled out the plug... I am going to try 1.5 turns to be in the middle...

also... wouldn't the plug show signs of fouling if I open the air screw alot? say 6-10 turns?

anyone have an answer to the two jets in the front of the intake question??

which one goes where? 1.3 on the right or left? mine was on the left... the right side goes to the main jet ( I believe for starting) Im thinking maybe the PO got them backwards? Im gonna contact him ans ask if he was messing around with it..

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also... wouldn't the plug show signs of fouling if I open the air screw alot? say 6-10 turns?

Possibly, but that's only if you check the plug when the bike has been running at an idle only.

As soon as you crack open the throttle the pilot circuit is almost out of the picture. You're then pretty much on the needle.

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