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Old 08-19-2009, 07:49 PM   #1
oo7alfa OP
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Anatomy of a DR350 carb. Video added page 2

I just got done tearing my carb apart on my DR350 to clean it and took pictures all the way along so I would remember how to put it back together. I got to thinking that maybe these might come in handy for someone else thinking about doing the same thing. I have taken apart a few small carbs before, a weedeater, my Honda lawnmower, but I am not very experienced so I was a bit worried taking it apart in the first place.

The reason I took it apart in the first place was I am having a bit of a problem. I can run for about 5 minutes at not quite full throttle, then it decides it wants to die on me. I pull over and wait about 30 seconds and kick it again, it restarts perfectly and I go about another 4 or 5 minutes and it does the same thing again...rinse and repeat...

If I am just running at lower rpms I don't stall out. So, it seems to me that maybe my Float bowl is emptying and not filling up quickly enough, then when it dies, it refills and starts up again. Good guess?

Anyways, I was hoping, before I go into all the pictures, for some help naming a few of the jets and such.

Can someone tell me what this screw is?:


Which jet screw is this and how do I tell the size?:


The float needle? Again, are there different sizes?:


This is the Slide?


And what is this called?

oo7alfa screwed with this post 08-22-2009 at 03:32 PM
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Old 08-19-2009, 07:58 PM   #2
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Old 08-20-2009, 06:31 AM   #3
mudmantra
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carburetor

Check your fuel flow from you tank too. The stock tank fuel valves go bad a lot. Look up your carburetor on bikebandit under OME parts, and it well give you a brake down of each item. Replace all your O rings too. 1. drain screw 2. idle mixture screw, adjustable for mixture. 3. float valve, 1 size, has an o-ring under the seat. 4. slide. 5. drain/ main jet access cover. And it looks like you've already removed your main jet. I'd replace that carburetor float bowl gasket too. have fun!
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Old 08-20-2009, 07:15 AM   #4
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Quote:
Originally Posted by oo7alfa

Can someone tell me what this screw is?:

It drains the bowl.



Which jet screw is this and how do I tell the size?:

This is the fuel mixture screw. If you have a manual it will tell you what the stock setting is. Possibly somewhere around 2-2 1/2 turns OUT from the seated position.



The float needle? Again, are there different sizes?:

NO, there are no different sizes for the float needle. All it does is once the float bowl has sufficient fuel in it, it stops the flow so it doesn't overfill.


This is the Slide?
YES.


And what is this called?

Taking off that bolt should give you access to the Main jet. At least on my bikes that's how it's set up. I'm not sure what i'm looking at in the picture there though.
Clean your carb out thoroughly with chemicals and compressed air thought ALL of the small orifices and you should be good to go. GET A SERVICE MANUAL.
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Old 08-20-2009, 08:28 AM   #5
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If you have to ask what everything is I'd advise you to STOP. Get a manual or turn it over to a qualified mechanic before you lose something and render it useless and expensive to replace.
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Old 08-20-2009, 01:41 PM   #6
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Originally Posted by matey peeps
If you have to ask what everything is I'd advise you to STOP. Get a manual or turn it over to a qualified mechanic before you lose something and render it useless and expensive to replace.
Thank you for the concern. I may have overstated my inexperience. As I said, I have taken apart a few carbs and was able to get them clean and back together and running, with no manual at all. Also, this is why I have taken good pictures and laid out everything the way it came out of the carb as well as a couple of drawings with the number of turns on the screws in before taking them out. I am not concerned with getting it back together correctly, I am more interested in what items are adjustable in size to see if a PO had messed with the jets at all. People are always talking about oversized jets and things and I am trying to figure out how to determine what size is in mine.
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Old 08-20-2009, 01:54 PM   #7
oo7alfa OP
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Quote:
Originally Posted by mudmantra
Check your fuel flow from you tank too. The stock tank fuel valves go bad a lot. Look up your carburetor on bikebandit under OME parts, and it well give you a brake down of each item. Replace all your O rings too. 1. drain screw 2. idle mixture screw, adjustable for mixture. 3. float valve, 1 size, has an o-ring under the seat. 4. slide. 5. drain/ main jet access cover. And it looks like you've already removed your main jet. I'd replace that carburetor float bowl gasket too. have fun!
Thank you. I actually have already replaced my Petcock with a brand new one from a Yamaha Raptor and it has been working perfectly, at least for a few hundred miles. I was thinking about possible rust in the OEM tank clogging up the petcock.
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Old 08-20-2009, 10:06 PM   #8
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yeah rust and dirt in the tank could be slowing or stopping the flow. Most petcocks have screens that can get clogged. Try this, unhook your gas line from the carburetor, then turn on the gas and have it flow into a container. It should flow real good and long. Fill about a cup up to see if anything strange is going on in your tank. I just checked a tank that had a vent check valve installed backwards. The engine would start, run, then starve for gas after a while. Check your vent if you have one too. Be careful and put the gas back in the tank when your done. good luck!
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Old 08-21-2009, 06:09 AM   #9
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Quote:
Originally Posted by mudmantra
yeah rust and dirt in the tank could be slowing or stopping the flow. Most petcocks have screens that can get clogged. Try this, unhook your gas line from the carburetor, then turn on the gas and have it flow into a container. It should flow real good and long. Fill about a cup up to see if anything strange is going on in your tank. I just checked a tank that had a vent check valve installed backwards. The engine would start, run, then starve for gas after a while. Check your vent if you have one too. Be careful and put the gas back in the tank when your done. good luck!
Well, I did what you suggest last night, and the flow is very good and nothing unusual in the fuel. I cleaned out the carb and put everything back together. It starts easily right away and runs at quarter throttle and higher just fine, but it is dying when it goes down to idle. The only thing that I did differently was the fuel mixture screw, it was at 3 full turns out originally, I figured I would go with the manual and set it at 2 1/2 turns out. Once I realized it was not idling at all I turned it out another 1/2 turn, but that didn't help at all. Once it drops below about 3000 rpms it dies immediately. Suggestions?

Thanks again for all the help, it's appreciated!
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Old 08-21-2009, 06:47 AM   #10
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Tried adjusting the IDLE SPEED SCREW (if any), in contrast to the PILOT SCREW (called by some, the "idle mixture screw")?
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Old 08-21-2009, 07:45 AM   #11
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Quote:
Originally Posted by oo7alfa
Well, I did what you suggest last night, and the flow is very good and nothing unusual in the fuel. I cleaned out the carb and put everything back together. It starts easily right away and runs at quarter throttle and higher just fine, but it is dying when it goes down to idle. The only thing that I did differently was the fuel mixture screw, it was at 3 full turns out originally, I figured I would go with the manual and set it at 2 1/2 turns out. Once I realized it was not idling at all I turned it out another 1/2 turn, but that didn't help at all. Once it drops below about 3000 rpms it dies immediately. Suggestions?

Thanks again for all the help, it's appreciated!
Did you remove and clean the pilot jet? It's a brass jet. kind of near the main jet. If it's plugged, no idle.
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Old 08-21-2009, 08:13 AM   #12
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Quote:
Originally Posted by mudmantra
Did you remove and clean the pilot jet? It's a brass jet. kind of near the main jet. If it's plugged, no idle.
Is it the one pictured just below and to the right of the Main Jet, still in place? If so, yes, I did remove and clean it.
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Old 08-21-2009, 05:07 PM   #13
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OK, so I figured out that someone put i a 140 main jet, stock is 132.5, but the airbox has not been opened and it has a stock exhaust. Do I need to replace it with a 132.5 to get it to run consistantly, or is it possible to work with this one?
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Old 08-21-2009, 09:15 PM   #14
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carb stuff

OK na href="http://s797.photobucket.com/albums/yy255/shopdog/?action=view&current=14e3.jpg" target="_blank"> I'd check your pilot jet again. Make sure it's completely.. 100 percent clear and check the numbers on it. Also when you installed the raptor petcock, did you cap off the vacuum lines? I believe the 2 lines above need to be capped off, or it well have a vacuum leak and a fast or no idle speed. I had a DJ138 in my carburetor.. but also a supertrapp exhaust and airbox mod. I'd run a smaller main jet with a stock exhaust. let me know if this pic worked.

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Old 08-22-2009, 05:52 AM   #15
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I'll second the above statement...........

.........in regards to the pilot jet AND not just capping off any unused vaccuum ports but also checking the condition of any vaccuum hoses (look for cracking and dry rot)
In regards to the pilot jet. That sucker (and it's circuits within the carb) are soooo small, you could have very easily gotten dirt into it while cleaning the rest of the carb. I'd clean it again and force gumout and then air through the circuit passages.
What's the plug color?
If it's black, the bike could be getting too much fuel at sustained speeds and simply fouling out and dieing when you return to low idle speeds.

Also, before trouble shooting any carb issues; it's always best to make sure everything else is good like =
air-filter, valves in adjustment, muffler not restricted with crap etc.
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