Advice for a dunked yz400

[Dangousity]

So yeah, My 1999 yz400f went swimming in a large mud puddle ( I swear showing off sucks) As soon as I got it out of the swim, I took it to my trailer and pumped the water outta the exhaust, realized the air box was full too and trailered it home. That night I rinsed out the engine with some clean water, removed the exhaust, air cleaner and carb and cleaned them. I drained the oil and re serviced. I reinstalled everything and the bike fired right up and ran decent. To make a long story short 4 days later I got it out of the garage and took it out to ride, it ran but not decent, and the bike degraded to the point where it would idle but would backfire and bog down with the throttle, to where it would fire with hot start but would not run. The kickstarter almost is easy enuf to kick over that its more like a xr250 instead of the nightmare yz400 compression it used to have. What did I do? Is my top end needing replaced?
Anyone with any advice or thoughts would be kindly regarded.

 

[BBking25]

can't help, take it to the shop though... they can probably figure it out better than any of us who can't see the bike

but i'm not very good tech wise with bikes ( i'm gonna try and get better )

 

[mrliquid]

unless you are an experienced Motor Man I'd take BBKing25's advice. I sunk a new 4wheeler back in the day and tried to fix it myself. I ended up blowing up the engine.

 

[Dangousity]

unless you are an experienced Motor Man I'd take BBKing25's advice. I sunk a new 4wheeler back in the day and tried to fix it myself. I ended up blowing up the engine.

I consider myself a experienced engine rebuilder, but atlas I'm not perfect and never will be :nod: , and I just spent all week with it torn apart and really hate to take the engine completely apart ( head, cams, ) to find out I overlooked something stupid. I dont exactly know how a leakdown test of the yz400f is done, But i do know that blowby on the compression stroke through the kickstart is 10X's more then it was last week when it ran fine.

But I think I will take the advice and pay someone in a shop for their advice, cant hurt more then paying 300$ for a top end kit i dont need! heh

 

[dezryder]

Do you have some kind of compression release that my have hung open a little? Not familiar with any of the newer rice 4 t's...just a thought.

 

[Dangousity]

possible, I was trying to get it started for like 10 minutes ( kickin it stright for 10 minutes) and I noticed by the end of that time my compression had changed .... so maybe the compression release is messed up. The bike would run last only with hot start valve opened, even thou the engine was not hard. It would not run with choke, or hot start off, it died instantly if i pushed the hot start valve in.

 

[dezryder]

I've drowned my 2t bikes a couple times. Just pulled the plug pumped all the water out, plug back in and fire it up.

I was riding from gravel bar to gravel bar in a near by river gathering fishing lures off snags in the early seventies on my XL 250 Honda. Dropped right into a huge hole that literally swallowed the bike up to the bottom of the tank and seat. Rode about a bike length before climbing out of it. That bike never missed a beat! (All occasions were clean water)

You said you familiar with engine work. (Trust your own abilities. You can justify buying some really cool specialty tools and probably have money left over if you fix it yourself!) I'd check engine compression, compression release operation. Also go through the carb blowing out all the jets, etc. Still not back to it's old self, I'd be looking at ignition/electrical.

Good luck!

 

[Dangousity]

Yup, Figured I am going to take my time and slowly tear down and inspect the bike and then rebuild it. This water was soo muddy ... Ky muddy a day after a rainstorm. Well I will go out and buy the tools i need to do the work properly due to the fact that I convinced the wife to allow me to buy another bike to ride (yz400 or 426) for the time being. She will prob take over ridding it after I get done rebuilding mine. Or it will be used as a buddy ride spare :)

 

[dezryder]

Good call. Make sure a shop manual is one of the tools you get! Good luck. :)

 

[Dangousity]

Good call. Make sure a shop manual is one of the tools you get! Good luck. :)

Yup bought it day 1 :)

 

[MX86]

you could have pitted the cylinder wall causing compression loss. pull the head off and have it mic'd