building pressure in transmission

[banshee_phil]

hi there,

 

just so you know my motor is currently torn down.

 

however, before i tore it down, whenever i rode it and i let off of a full throttle, trans fluid would spew out of the vent tube.

i had a guy tell me that the right side crank seal was out??? so i replaced it and nothing changed.

 

my question is what would cause this and what can i do about it before i assemble a newly built motor?

 

i would go through about a half quart of trans fluid per ride (several hours)

[FATBANSHEE]

Sounds like you have a clogged or pinched vent hose. check to see if the crankcase and gearcase vent hoses are free flowing.

[RadarRacing]

I would say crank seal as well but if you don't have the vent line on the clutch cover up high and not hanging down low they will leak like mad and even siphon and it seems like they do it once the bike is stopped and it will just pour out of the vent tube. If you think that's a possibility rout the line up higher on the bike. I have mine blocked off.

[banshee_phil]

i will check to see if the vent tubes are clogged or not.

 

if i remember right, the tub sat right on top of the motor case...maybe i need a longer tube and hang it higher up...i will try that.

 

i put a screw in the tube for a while to slow the spewing...but i was afraid it would hurt it somehow so i took it out.

[sheefreak]

I have seen two things cause this. As mentioned above, either a crank seal or leak between your crank area and tranny area in the cases.

 

I have also seen slipping clutches cause this by getting the tranny fluid hot enough to "boil over" persay.

[J-Madd]

I wouldn't think stock cases should do that if the vent lines are free flowing. My billet cases lose about half a quart every 2 passes. Like mentioned, it just sits there and siphons even with the engine off, and the fluid won't even be hot.

 

Radar, what do you have blocked off? Just the clutch cover vent or both?