92 DR 350, choke works like a kill switch

[jvorpagel]

I have a dr 350 i got from somebody.The carburator had been taken apart before. Bike runs with choke on, but dies as soon as its off. Im not familar with the diapham style choke. I was wondering if anyone else had any problems

[bills442]

not familiar with that exact carb, but as a general rule which you've probably already deduced ... the bike is running way too lean, so lean it now needs the choke to run at all. Make sure that the pilot jet is still actually in the carb, check the float level, etc.

[jvorpagel]

I did a little more research and found that the carb has a vacuum vent for the petcock, that has long since been changed out. I now have a petcock with no second outlet and plugged the associated vent from my carb. Still no luck. It runs so well with the choke on, Ive got to have something simple wrong but cant seem to figure out what. When I turn the choke off it kills instantly, like I hit the kill switch. If I keep the RPMs up, and turn the choke off, the bike backfires, runs like crap and eventually dies. My pilot screw is set out about 1.5 turns. It seems too drastic a change to be a little off on my mixture.

[jcalis]

Remove the bowl and take out the pilot jet. Check the markings to verify it is a 37.5 (stock). Clean it good, blast carb cleaner into the pilot jet mounting hole and remove the idle mix screw and shoot cleaner in there as well. Make sure you have no vacuum leaks on the intake manifold boot when you reassemble.

[jvorpagel]

I pulled the carb off, and attemted to remove the pilot jet but the head is damaged. Looks like most likely that is the problem since that is where fuel comes from if the choke is off. I will look into extracting it but am a little nervous. Would a plugged pilot jet also affect the mid to high RPM range? I thought it only applied to lower RPMs and am having trouble keeping it running even if I raise the RPMS before I kill the choke.

[jcalis]

You may have a vacuum leak causing the poor running. Get the pilot jet replaced first and clean everything. Order a new jet from a Suzuki dealer, some pilot jets have 4 holes drilled in the sides, some do not. Bring in the old jet when you order to make sure you get the correct one.

See page 8-19 for carb diagram: http://www.suzukidr350.com/suzukidr350/majorrepairs/majorrepairsphotos/copyofCh%2008%20-%201990%20DR350S.pdf

[mxracernumber1]

Sounds like your pilot jet has been damaged when installed. I would vote with these guys & say that it's probably ruined. If it's chewed up like you're describing, it probably had some shaving come off of it after it was put back togther or is deformed to the point that the passage through it is probably blocked. This is where to start. Don't attempt to remove it yourself. This is something that you will only make worse with a hand-drill & a bench vise. Take it to a local machine shop. They can set it up & indicate it in to perpendicular and get dead-centered over the jet to drill it out. They will most likely have a left-hand drill that will actually begin to back the jet out before it cuts into it much. It might cost you $50 or $60, but that beats the heck out of buying a new carb. Once you wally-gallop the hole, there will be nothing you can do to fix it. Take it to a machine shop & let them do it on a precision machine tool. I was the production manager at a small shop where we built robotic laboratroy equipment. Since the owner was a home-town guy, he still insisted that we take simple walk-in work from the public (which he's done away with now). Since I was the manager, I would regularly find myself at work after everyone else had gone home for the day. I cannot count on all my fingers & toes the number of times someone would come in with a carb. (usually for an old pickup or car) after they had already been fiddling with it all day & wanted me to remove a stripped screw or jet. By the time they decided to do the smart thing & bring it to me, it was usually too late. They had already ruined or busted the hole & it was almost always in a place that could not be legitimately repaired. Of all these instances, I was able to save only a handful that had not already been "worked on":bonk: . Carbs are usually cast magnesium, or a zinc-magnesium alloy. They are very soft & one slip of a drill can destroy the entire carb. Take it to a GOOD machine shop that can set it up squarely & remove the jet precisely without causing damage to the rest of the carb. You'll be wishing you'd taken my advice if you don't. I know a couple dozen who wish they had.

[Fariborz]

I had a similar problem on my DR350S after I switched to the pumper carb. The bike would run well with the choke on but pushing the choke in would kill the engine.

In my case the fuel-mixture screw was tuned it too far. I backed it out an additional 1 turn from where it was richening the fuel mixture and the bike runs and idles perfectly.

-Fariborz

[dirtnsnoryder700]

I could be wrong but I think the mixture screw is supposed to be at 2 1/2 turns. I have mine closer to 3 actually.

[Fariborz]

I modified my post to indicate that I backed out the fuel mixture screw one turn from where it was. I think all together I have slightly more than 2 turns out.

-Fariborz

[jvorpagel]

I am working on getting that pilot replaced, I have to order a new one, will let you guys know how it turns out. Thanks for all the info.