Should I be worried?

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bajus22

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Dec 8, 2008
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So I went out for a ride yesterday? I came across a big puddle and figured I could cross it. Turns out the puddle was much deeper than I anticipated. I made it half way thru, when the bike got stuck and died. I have a 1987 KDX200, and the water was all the way up to the bottom of the gas tank (petcock was submerged). I managed to pull it out in about 5 minutes. Got it to dry ground, and it started right up, then died. It took about 20 more kicks with the choke on, before it started again. I rode it about 5 miles, back to my car like that. I checked the crank oil, not milky. I cleaned and dried the filter. A few specs of silt got past the filter, and the carb looked alittle wet, but other than that the bike seemed fine. Should I be worried? Or did I get lucky, and not cause any damage? Thanks.
 
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bikerman

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Sep 8, 2010
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Pull the carb and clean it good. pull the reeds and see it dirt got to them . replace if needed. change crankcase oil. use compressed air to clean out vent lines for transmission. wash airbox out ... clean filter. change plug. cross fingers.....or pull top end and make sure. good luck.
 
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bikerman

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Sep 8, 2010
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you didnt say if it quit running in the hole or you cut it off.....it does make a difference .
 
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bajus22

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Dec 8, 2008
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It ran for about 30 seconds after I really got stuck. Than it quit. Why does that make a differance and where are the vent lines for the transmission?
 
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bikerman

Member
Sep 8, 2010
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it quit running because it sucked water and dirt in the engine.not good. not because you cut it off. you would have been better to have cut it off, in deep water / mud like that, and not let it suck the dirt and water in. ill look for the vent lines on mine and respond.
 
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bajus22

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Dec 8, 2008
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Thanks. I'm about to open the carb and take out the reeds, and drain the oil. I'll let you know what I find. But hypothetically, if moisture was getting in after I started the bike (the filter was soaked), what damage would that cause. I remeber in WRC rally cars, they used to shoot water into the actual combustion chamber to keep the temperature low. It prevented pre-ignition when they were running 30 psi of boost.
 

Patman

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Umm yeah but they did it in a very metered fashion and with clean water / alcohol :laugh:
 
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bajus22

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Dec 8, 2008
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OK, so I just finished taking everything apart. No water in the oil, the reeds looked good, only one tiny spec of silt. Carb was clean, bowl looked good, spark plug looked normal (other than too much oil in the gas), and when I saw the piston, it also looked good, no dirt or water past the reeds. But I did notice two things. First, what does the crank/transmission vent line do? It was clean, but when I tried blowing into it, nothing happened. Same thing when I kicked the motor over (by hand, on the kickstart), no air came out. Is it a one way check valve? Also, one of the reed 'flaps' (sorry not sure of the technical name), was at the service limit, in terms of gap, the rest were ok. Seems like I just get extremely lucky, and didn't suck anything significant into the motor? Or is it just wishful thinking, and the damage was done in the ride back to the car?
 

Patman

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Dec 26, 1999
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I everything checks out to spec and does not appear to have any damage then you got lucky. I find it suprising that the air filter was soaked but no water showed up. Might as well at least service the top end.
 

Dirtdame

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Apr 10, 2010
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I have seen a few two stroke bikes get dunked and get going without any problems. Usually a good carb clean, check to make sure no water got in the gas tank, drain water out of the pipe and a hundred kicks on the pedal with the sparkplug out (to remove any water in the crankcase area) will get a machine running just fine again.

The vent runs up to hole at the top of the backside of your airbox. It's sole purpose is make sure that pressure doesn't build up inside the transmission and possibly cause seals or gaskets to leak transmission oil. The crank is not vented because it needs to be pressurized to work properly with the fuel/air mix flow.
 
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bajus22

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Dec 8, 2008
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Thanks for the help guys. I only have a few more weeks of riding, and then I'll do the top end. While on the topic, whats better a Wiseco piston, or OEM. Oh and nobody mentioned it, should I worry about the one reed being out of spec?
 
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dirt bike dave

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May 3, 2000
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Patman said:
I everything checks out to spec and does not appear to have any damage then you got lucky. I find it suprising that the air filter was soaked but no water showed up. Might as well at least service the top end.
Click to expand...

If the air filter had been truly drenched, I don't think he would have been able to restart it and get it back to camp. The only time I completely submerged a bike ('90 KDX), it was not going any where until the air filter got removed and rung out.
 
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mudpack

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Nov 13, 2008
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I did the same thing on my 200; ran it into a hole that was deeper than my seat. It killed the engine, of course. After getting it out, I was able to restart it, even though the engine had sucked in water (the filter was soaked). I rode it back home.
 
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bajus22

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Dec 8, 2008
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Did you encounter any engine damage afterwards? Was there water in the crankcase? I just want to know if I should anticipate any problems coming in the near future. I have a pretty long ride planned for this week-end. My filter was completely soaked, but it seemed to ride back no problem, and like I said, everything seemed fine when I took it apart.
 

Patman

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Years ago a riding buddy rode his DT125 off a dock and in to a lake. Fished it out, kicked it forever and it finally started and off he went. No idea if there was any damage he never checked. Of course the filter was soaked since the bike spit water the first sever kicks :laugh:

The flip side is a buddy with a RX7, (another sort of 2 stroke) drove thru some water and split the case in half. Yup sucked the water right thru the intake and well.... water doesn't compress so good.

BTW anything that is out of spec should be replaced, including the reeds.
 
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bajus22

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Dec 8, 2008
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I'm buying some Boysen reeds on Thursday. The bike is stock, will the reeds make a differance? Should I change any of the jetting?
 

Joburble

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I'd say that your main problem would have been if water had got into the motor and wetted the mains and big end. They can rust in a very, very short time. The fact that you managed to start the bike probably helped in getting rid of the moisture and re-coating it all with nice premix. If not, your mains could have been a bin job. See a post by sr5bidder (I think) he sunk his bike and gave us all detailed pics and very good info.
 
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dirt bike dave

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May 3, 2000
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Yeah, bearings are the main concern, espeically if any dirt got sucked in with the water.

With a single cylinder, you are less likely to injest a bunch of water or to bend stuff. Once the fire goes out, the motor stops ASAP and stops pumping water in and out. So you don't have to worry much about it compressing the water and bending a rod or breaking a piston, head, cylinder or case.
 
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bajus22

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Dec 8, 2008
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Well, I just took it for a quick ride. It felt really good. I did the spark plug check (full throttle, than kill switch), it was bang on. As for the reeds, I kept the old ones, just unscrewed them, flipped them, and re-installed. They were all nice and flush with the reed cage, no gaps. I changed the oil one more time. Looked clean. I'll be doing some serious riding this Sunday, I'll let you guys know if it self-destructs. Thanks for all the help. But if I do decide to throw Boyesen reeds in, what should I use for the main jet (I currently have a 310), and where should I put the clip on the needle (currently on 2nd from the top). And does it really make that much of a differance.
 
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bikerman

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Sep 8, 2010
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you do not have a 310 main jet.......lmao. maybe a 155 or so... install the new reeds and try it out. with a 310 main jet .....i bet its rich.....lol.
 
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dirt bike dave

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May 3, 2000
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bikerman said:
you do not have a 310 main jet.......lmao. maybe a 155 or so... install the new reeds and try it out. with a 310 main jet .....i bet its rich.....lol.
Click to expand...

His bike is an '87 and has the old round slide carb and a completely different main jet numbering system than the later carbs.

His stock main was a #320, with a #25 pilot, a 6FL52 needle jet and an R-2 needle.
 

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sr5bidder

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Oct 27, 2008
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luky dude... mine was full of mud and if I had tried to run it it would have fried in 1 minute or less
 
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bajus22

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Dec 8, 2008
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It's definately a 310 main jet. Would the gap I encountered in the reed (prior to flipping it) have caused the plug to be black and wet (looked rich). Becuase now, the plug looks great.
 
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