Bad crank seal after only four rides.

[Purpletj]

I did a complete engine rebuild a couple months ago. I had her running great and now she is puffing like a train and fouling plugs. I know the culprit is the clutch side crank seal.  I have never heard of them going bad so soon. Anyone have and suggestions when I pull this beast apart again.?

[Goat]

I would make sure the crank isn't beat up or gouged where it goes through the seal. Could have even been the smallest grain of dirt. Wouldn't take long to tear a seal apart. May have not been seated right behind the bearing all the way, Slightly crooked will wear it out. Check for any debris when you drain the oil as well. Hope this helps.

[no sub for cubes]

i had similar story,when i bought my 500 it was supposed to of been rebuilt,ran fine a few rides then same issues,when i rebuilt it myself i used case sealant on the crank seals,just a suggestion when you put your new seals in might just help seal them properly in the cases.

[dave916]

check the crankbearing houses in crankcases, at the moment i have 3 set of cases with them worn
if you cases come apart to easy and bearing stay on crank could be a sign , i usual check engines with the topend removed i try and move the crank left/right with a flat screwdriver
 can be hard to see with engine fully striped as bearing may only be  loose when fully pressed into cases
also check the cases to make sure they are not warped or have any cracks  where tranny oil could also enter the motor
dont forget to put suitable grease on lip of seal  
good luck with the build

[Purpletj]

Here is a little more info. I have the engine out now and pulled the jug off. There is atleast 2 ounces of oil in the bottom of the crank case. I am beginning to think when I did the full engine build I may have run the case sealant thin behind the crank. I'm second guessing myself on the crank seals and think this is not my issue,. As I tear more into it tomorrow I will keep everyone informed.

[dave916]

dont forget check for side play on crank before you strip engine
try move with big flat screwdriver between crank  and cases

[Purpletj]

dont forget check for side play on crank before you strip engine
try move with big flat screwdriver between crank  and cases

ok. i have found slop in the crank, whats the fix? crank rebuild with new bearings?

[dave916]

  if your bearings stay on crankshaft when seprating the cases it is  the cases, if the bearing stay in cases you may want to check your crank for wear
     , $461 for a new set  of cases is problably your best bet, will also need to buy new crankbearings as your new ones could be sightly worn if they spun  in cases,
also u will probably need a few of your gearbox bearings that could be hard to change ie;clutch arm bearings

maybe a good machine shop could repair ur old cases ,
someone on here could probably recommended where to get it done,[ not sure how good a job it is]

[Purpletj]

When I had the engine apart the first time a replaced several bearings for peace of mind. I didn't however replace the crank bearing cause the were in excellent condition. I do remember the bearings staying on the crank when I split the cases. Dang I really didn't want to buy new cases.

[Roostmad1]

dont forget check for side play on crank before you strip engine
try move with big flat screwdriver between crank  and cases

ok. i have found slop in the crank, whats the fix? crank rebuild with new bearings?

if the crank is moving side to side its not worn cases but a worn crank,its worn where it runs on the main bearings,had the same problem when i got my KX250,unless the cases are worn out where the main bearings go,but all i did was put a hot rods crank in it and now its all tight,goodluck

[dave916]

dont forget check for side play on crank before you strip engine
try move with big flat screwdriver between crank  and cases

ok. i have found slop in the crank, whats the fix? crank rebuild with new bearings?

the slop you are taking about is crank side play??? ie flywheel moving in out

[Purpletj]

ok guys. I discovered the crank seals are loose and spinning when I turn the crank. I also noticed the crank bearings had slop. So now i'm looking at rebuilding the crank and possible replacing the cases. Does any know if a machinist can replace just the crank bearing journals?

[DoldGuy]

Larry Wiechman

[Purpletj]

Larry Wiechman

LOL. I sent him a messege lastnight,

[kaw rider]

See what Larry has to say.