02 Dr650 suddenly started running like crap... FIXED! - THANKS ALL !!!!

OK, So, I decide to go for a ride after dinner tonight to a friends place. The bike starts and runs great (with the exception of the typical 'flat spot' off idle) on the way over.

It's a bone stock 2002 DR650 with about 21xx miles.

I park the bike for maybe 30 min for a short visit.... OK, time to leave, the bike starts right up, idles great! I pull out of his driveway and give it some throttle.... It falls on its face and is backfiring like crazy!!!! :smirk:

I nurse the throttle and give it a bit of choke. I can keep it running, but can barely.

So, I switch the fuel (that is only maybe 10days old) selector to Reserve, I'm thinking that there isn't much else I can try that's as fast and easy as that. No Change. :lol:

So, I keep nursing the bike and can only go about 3-5 mph.... If I try to add throttle, just off idle the bike falls on its face and backfires like crazy...... I get about a mile down the road to a gas station, thinking, let me add some more fuel, Hey why the heck not... I was able to get just under a gallon in... So, now the tank is full... I switch back to normal on the fuel tank selector and try heading for home --- Yeh, that's about 15 miles away. (insert 'Blue's Brothers' reference here) :smirk:

So, in short, it takes me forever to get home nursing the choke and throttle. The bike idles like a champ, but add throttle and it's a PIG. It wants to die and starts to backfire....

OK, So, the bike is now back in the garage, it's far to hot to try to mess with, but I'm thinking carb all the way. It idles, the oil is full (just changed it about 200 miles ago). It starts right up, idles and shuts off like nothing is wrong.

So, oh great DR guys... Am I nuts thinking carb?? Anyone have any ideas?

Thanks ahead for the assistance... I want to get this thing back into service for the upcoming weekend :prof:

BTW- I did lube the chain the other day (I kinda soaked it pretty good) not sure if that makes any difference in the world, but figured it's worth a mention....

Edited by K2DR650SE

Clogged main jet.

Clogged main jet.

Thanks! :smirk:

I was thinking Trash in the carb while I was limping my way home...... Well, I wanted to get in there anyway, now I dont have any other option.

Thinking my weekend might be :smirk::lol::prof::lol::lol::lol::lol:

I had a DRZ400 that did that exact same thing at about 11,000 miles. It would idle fine and start perfectly. But every time I gave her some throttle she started missing and backfiring badly. Thankfully it happened after a good ride, and I was just a quarter mile from my house. I went through my carb three times to no avail. I cleaned that carb so much that it looked like a factory unit inside and out. Well it turned out to be my stator. It was fried. I ebayed a used one, put her in, and she ran like new again. But what a pain trying to diagnose that fix! Hopefully your is as simple as a clogged main jet or something simple.

Clogged main jet.

Nah. He's not getting the throttle open far enough for the main jet to have any effect - clogged or not.

I say it's the tiny filter that Suzuki inserts into the fuel inlet tube on the carb. This is a common problem and the description matches perfectly what happens when the little filter gets plugged up. Most riders that have this problem remove the factory fuel filter and add an inline filter to the fuel hose.

Sounds good. I'd say Pilot jet but could also be the little filter too. This filter can clog up over time. Best replaced every 10,000 miles or so ... or just run an inline filter as suggested. It is located in the metal fuel inlet tube. It's white, bit hard to see, but it's there. Carefully pry out. I recommend replacing it.

But the symptoms also fit with the Pilot jet being clogged. It's a very tiny orifice, does not take much to clog it up. Buy a new one from Suzuki and put it in. It's right next to the Main jet. Check that one too as long as you're in there, but the main is not your problem.

When you pull the float bowl off to gain access to the Pilot jet, have a look for crud and debris in the bowl. Clean. Handle with care, do not bump float or its mechanism.

Good luck.:smirk:

Thanks guys! I'd like to add, I wish Suzuki (or aftermarket) made a "kit" for stock carbs... Ya know, a "kit" with all the gaskets, o-rings, filters, etc. It sure would be nice.

also check the condition of the 2 o-rings in the float bowl. if they are looking haggard, replace them with factory o-rings, not o-rings that you can get from a parts store, the ethanol and gasoline these days will eat them up in a matter of weeks.

Thanks guys! I'd like to add, I wish Suzuki (or aftermarket) made a "kit" for stock carbs... Ya know, a "kit" with all the gaskets, o-rings, filters, etc. It sure would be nice.

Yep, that would be a great idea. Pro Cycle sell some O ring kits I believe but not a complete kit, AFAIK.

There are KNOWN parts in the carb that wear out on the BST40 Mikuni carb. The main one is the Jet Needle. (Not the needle itself, but the piece the needle drops into) If you price all the individual parts it gets expensive. Most hold up well but the Jet Needle gets wear and cause hesitation off idle.

Want to know what I did? In '10 I bought a used carb off a guy here. It was off an '09 and had only done 2000 miles. Many DR owners go to different carbs, so there are quite a few DR650 stock carbs for sale. Get one with very low mileage and just swap it out with yours. Easy. They are all the same.

My DR is a '06 and at around 30,000 miles I could see and "feel" that the needle jet was worn. I just bought a whole new carb and am saving the original for parts. Cost? $75 shipped. Most are under $100. Get one off a low mileage bike.

There are KNOWN parts in the carb that wear out on the BST40 Mikuni carb. The main one is the Jet Needle. (Not the needle itself, but the piece the needle drops into)

Actually the part the needle "drops into" is the needle jet.

The "jet needle" is the needle itself

The parts fiche's use the comma in an odd way.

The needle jet has the bleed holes in it :smirk:

Actually the part the needle "drops into" is the needle jet.

The "jet needle" is the needle itself

The parts fiche's use the comma in an odd way.

The needle jet has the bleed holes in it :smirk:

Sorry about that Bob ... I always get those buggers mixed up. :smirk:

Sorry about that Bob ... I always get those buggers mixed up. :smirk:

Well they dont make none too easy on the parts fiches.

If you look at the pilot jet on Ron Ayers.com it reads jet, pilot :smirk:

Check out what I found today when I opened up the carb :prof: .... Thanks to all for the assist :smirk::smirk:

I cleaned it and it's back running better than ever before!!!!!!!!!!!!!!!!!!!!!! :lol:

I could not even see daylight through the main jet.... It was packed SOLID!!

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Yuky! Glad she's up and running.... :smirk: Try buying gas next time instead of whatever that crap was. :smirk::prof:

Yuky! Glad she's up and running.... :smirk: Try buying gas next time instead of whatever that crap was. :prof::lol:
:lol::smirk::lol:

Also add Sea Foam to the fuel for winter storage

One ounce per gallon :smirk:

I just got the bike back on 4/17, it had 1923 miles (remember, it's a 2002) and it had not been out on the road in some time... I somewhat expected trash in the tank, so I installed a small filter between the tank and carb before I ran some premium and SeaFoam. It was running great, but after looking at what I found, I'm amazed it went this far without any issues.

Today when I had the tank off to clean the carb, fuel selector, I flushed the tank in the parts washer. I also installed a new filter between the tank and carb just to be sure.

Oh yeh, there is fresh premium fuel and SeaFoam in the tank!!

Good work! I've never seen a main jet that bad before ... unless the carb came out of a junkyard bike! I hope you cleaned up the pilot jet too ... inset next to main. Keep in mind most USA gas these days just does NOT LAST. 6 months is about it. Good call adding a bit of Sea Foam to fuel. For storage add some Stabil and a bit of Marvel Mystery Oil as well. That will keep carb orifices cleaner and with your inline filters you should never have this problem again. oh ... and clean out fuel tank and pet cocks at some point as long you're doing it all.

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