bad crank seals?

[69zandar]

how can a person tell if the crankshaft seals are bad in my 250r?

[hondamancbr03]

I will assume you do not have the tools for a leak down test...... If not then things to listen or look for is a hanging idle from the flywheel side and bogging or fouled plugs with excessive oil from the clutch side..... Easy to change out and and good for a motor with a couple seasons on it.

[69zandar]

Yea I don't have a leak down tester,(i may try and borrow one) I rebuilt my quad about 2 years ago and I have a wicked bog at about 1/4 to 1/2 throttle and wont rev any more.The plug is wet as well as black spots (kinda oily?). As well as what seems to be alot of smoke but hard to judge with a 2 stroke. Ive gone through carb,coil,cdi,compression,plugs,and tested stator and pick up. Not sure what else it could be? Does that sound like a seal thing? I like what you said about a couple seasons, gives some hope to look there next. Thanks

[atvmxr]

i think I know the answer, but to confirm. if you change the trans oil and it smells like race fuel then the seal is probably leaking?

[addictedtomud]

Bad crank seals can cause:
-sucking air, lean running condition, high revving without touching the throttle
- fuel/oil inside stator cover
- sucking tranny gear oil into crank area

[fearlessfred]

I have had mostly the tranny side seals go bad and could always tell by the smell of tranny fluid in the exhaust and the tranny fluid being low . if u need to change it out,make sure u ck. the collar that the seal lip sits on because it can groved and the new seal will not last very long or not work at all. if it is groved,u can set the seal in at a diff.depth so the seal doent ride in the same grove or replace collar with seal . i use a self tapping teck srcew and small dent puller to pop seal out

[69zandar]

Thanks everyone for the replies , I'm going to replace the seal today, hopefully thats the problem. I was wondering if that collar could be an issue, I will try and alter the depth if it looks bad. Thats a good tip! I did try and smell the plug, ect. but it all smells like race gas and I never tried the gear oil after i changed it the other day.:rolleyes: I'll try the tek screw trick to remove the thing another good tip ! Love this forum

[69zandar]

o.k. i replaced the seal on the tranny side and still have the problem? It seems when i tap into the power band the quad noses over. Really frustrating!!:grr: any other ideas? Thanks guys Jetting is the same as before when it ran great,

[J.B.]

How are your reeds?

[69zandar]

The reeds are 2 year old v force 3's, when i pulled them out to take a look a couple of the petals were not 100% closed, I took a look at the web site and it sounded as if that is normal(?). Also when i had the air cleaner boot off after cleaning the carb. I fired up the quad and it seemed to be a lot of fuel blowing out of the carb at idle or so. but after i accelerated to 3/8 throttle it went away. That seems weird to me with reeds. I hate to just throw money at the thing but does that sound like it could be causing the problem? Thanks everyone for the help!

[RyanWsly]

Did you check the wear on the main bearings when you replaced your seals? the spec. is very tight, same as if it moves they are junk. I had this on one of my friends not long ago, previous owner had installed new seals, it would hold a pressure test. We almost had the symptoms jetted out of it with some very lean settings, but could not make them leave totally, very difficult to find when you assume the seals are good and someone has checked that when it has a fairly new set of seals in it.

[69zandar]

I couldnt actually measure the bearings, but the flywheel side did wiggle up and down a little bit, very slight. they were replaced 2 yrs ago but........?