I have had a 4 stroke viper 90R for a few years. My daughter rides it around the acreage randomly with no real issues. It does bog down when you open the throttle but still goes so I'm not terribly concerned.

Yesterday an issue showed up. She rode for about 30 minutes and came back. I noticed oil dipping from the bottom of the cover below her left foot rest. I took it off and dug in and on the front output the seal was pushed clear out of seat. I cleaned it all up, drove seal back, filled oil and started it. No issue. Drive one short lap around yard and oil started coming out again. Tore apart and seal was pushed out again.... what would cause the seal to push out? I mean like an inch clear to the gear...

I am no mechanic but can do simple teardowns and rebuilds of seals and such if I have the tools. Any help would be great.
I'm in Nebraska by the way and only dealer that will touch the eton is about 2 hours away.

Thanks in advance!

 

Possibly a blocked breather. A single cylinder 90cc bike has to shove 90cc of air out of the crankcase every time the piston goes down, then suck 90cc of air back in as it rises, any breather restriction can cause pressure to rise in crankcase. Alternatively the seal could just have got worn on it's outer diameter.

 

Thanks! I will dig into it again this weekend when the new seal comes. I pulled the dual air filters off and they are disintegrated so I have new coming.

What exactly are you referring to with breather? Is this an internal chase in the motor? I see no breather tube in the crank case like there is on the rear gear case unless in completely missing it. I don't see one in the service manual either.

When i ran the engine i pulled the oil dip stick and oil splashes out when it's running..... it's this normal or showing me something is wrong?
Thanks again for the help!

 

I finally got this fixed. There is a little tube that goes up from the head to an inline black filter then back into the intake. It was clogged. I belive its for unburned fuel for emissions. I eliminated it since i can't locate the part and it's been discontinued. Runs like never before and tops out about 32 mph.
Hopefully this helps someone along the way!

 

Sorry I didn't reply to your previous post, I run an on-line shop as well as mending ATVs and the lockdown increased my on-line sales exponentially, so I gave up posting regularly here from April to June.

Anyway, there is usually a breather tube running from crankcase to the filter as well, but if it now breathes OK that is fine, and yes it will spit oil from the filler hole when running, as I wrote above 90cc of air has to escape as the piston falls, so it tries to blow some of this out the filler hole, if open.

 

Anyone got a pic of where that hose is that goes to the air filter? I have an orange breather hose on mine that goes up and just lays there by the frame under the seat, I'd like to know where it exactly goes