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DRZ 400 Rough idle / erratic operation issues fixed

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Hello! 

 

 My membership to this website is new, but I have been using information off of it for over a few years now so I figured I would try to make a contribution. I own two DR-Z 400 bikes, one has the mikuni carb even though it's the (CA) E-model. Anyway I just picked this one up not too long ago and it was in very nice, almost showroom condition. But, I did take this for granted a little and I neglected to clean out the carb and do a couple other things I usually do when I pick up a bike. I did notice the floats stuck occasionally when the bike was off as it leaked a little gas, and the petcock would drip a little from it's outlet, even when off. I took it out to the desert the weekend after picking it up without doing much to it, and took it out for it's first ride at night. It seemed to operate fine so I continued further out with my fellow riders. On the way back however, it started to bog when I got on the throttle, and if I opened it too fast it would stall. This worsened to the point where I would start it, ride about 300 yards, and then stall and repeat. I got back to camp, frustratingly sober with a pristine bike that didn't work. I took it home to dick with it, and after many carb cleanouts (including chemdipping jets, etc and then dahmering them out until brass particles shaved off with a torch tip cleaner) it still would barely idle. The choke had no effect on the issue although I couldn't get it to run long enough to warm up anyway. It ran extremely sporadically, like it had a bad spark plug. But I had put in a new plug right after I bought it, it was the only initial maintenance I did to it. I had checked the diaphragms when I had the carb out, all good with no tears. Then, at last, I did what I should have done first. 

 

I drained the oil, and it had little viscosity. It flowed and dripped like water. Not only that, but when I was done there was about twice the amount that I usually observe in my pan. I smelled it, felt it, and tasted it and determined that somehow gas had overflowed from the carb, gone down the cylinder and filled in the crank. So I took off both drain bolts, the timing check nut and the large center stator cover nut. I took out the spark plug and even took off the head cover, and let the bike air out for about 4 or 5 days. I would get home from work and rock it back and forth to drain out any fluid still settled in there. On the fifth day of Christmas I put a new petcock on it, reinstalled all the bolts and nuts, filled it up with oil, put a cap full of 10w40 down the spark plug hole and put ANOTHER brand new plug in it,  cranked it over a few times and it worked! Just fine too, like the day I bought it. Minus the leaky floats. So pay attention to your oil when you notice your floats sticking, and make sure it doesn't smell like gas or have a noticeable increase in fluid level. Also, make sure you thoroughly inspect and clean if necessary all fuel system components and change the oil before riding a bike that has sat for a while.

 

I tried to make this as brief as possible while still covering all details! I hope this helps anyone who is having this issue. If you have any questions feel free to ask

Edited by Rumple_Stillskin
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