Posts
182
Joined
2/13/2015
Location
Austin, TX, USA
Hi Everyone,
Probably a stupid question but can you ride without a counter shaft seal? I know it’s not ideal but is it possible without issue or would I have a heavy oil leak or something else? Have a race on Saturday but can’t get the part in time.
Bike is an 02 YZ125.
thanks!
no you cannot. You will lose oil immediately
On a 2 strk. you will lose transmission fluid, will damage gears, bearings and most likely clutch plates. On a 4 strk., you will lose motor oil and damage all of the above including main brgs., rod brgs. in addition to valve and camshaft components. You should have known!
You are correct, it is a stupid question!
A YZ125 cannot run without a counter shaft seal, if you remove the seal, there will be no crankcase compression, it's unlikely the bike will even start, if it does start, there will be a significant amount of smoke out the exhaust, the spark plug will foul, and gearbox oil will be blown out the gearbox breather.
Have you rung all the dealers in your area?
Actually you are wrong. The countershaft seal has nothing to do with crankcase pressure.
The engine will still run fine. The transmission however will be loosing oil quickly. Plus if it was ridden dirt would quickly damage the output shaft bearing and possibly others.
The Shop
Luxon 4-Post Bar Mounts
$189.95 - $239.95
DeCal Works Huge Plastic Inventory of UFO and Polisport kits.
Wow, very wrong info. You should brush up on your 2 stroke engine technology, especially given your user name.
@Layton, @38special I'll screen grab your comments before you edit them...
Engine tuners commonly use engine stuffers to decrease crankcase volume, increasing the crankcase compression ratio.
If you remove the countershaft seal, the total crankcase volume increases, because it then includes the clutch cavity and transmission cavity, reducing the crankcase compression ratio and crankcase pressure.
The other guys are right. On two strokes the crankcase is seperated from the clutch and transmission by the crank seals, no crankcase pressure in the transmission (they are even vented to atmosphere by a hose).
Back on topic, dont run the bike without a countershaft seal. The transmission bearings will be shot best case, worst case you'll need a new transmission because the gears will "weld" themselves to the shafts without lubrication.
You didn't read my post, the OP was talking about running the bike with no countershaft seal, the crankcase, clutch cavity and transmission cavity are then connected.
You need to take a lesson in BASIC 2 strk. engine principles and design. You've got it ass backwards. Change the word countershaft to crankshaft and you'll be close. Sort of.
The countershaft seal is between the countershaft sprocket and the transmission bearings, nowhere near the crank.
LOL, this thread has gotten funny. Not sure how you haven't grasped what people have written. The countershaft seal is behind the front (countershaft) sprocket. It seals the inside of the countershaft from the outside elements. This shaft is part of the transmission, a separate cavity from the crank. It has zero to do with crankcase volume and luckily also has nothing to do with fuel and premix oil.
Mind boggling!
LMAO. Wow, he doubled down.
Unbelievable.
You beat me to it 😊
I was going to grab a screenshot of his post.
We'll chalk all that up to Friday night posting possibly including a few drinks? hahaa
Back to the OP...... did you already remove the old leaky seal??? Because you can just let the leaky one in and ride like that until the new parts come. You've probably been riding it how long like that anyway? A seal with a leak is better than no seal at all, for sure. Just keep an eye on the trans oil level and maybe keep adding a little to keep it at the right level as it leaks a little.
If you have the old seal take it to a local bearing supply house and they can get you something that works.
Thanks for all the education guys! Except that one dude…😂 I figured it wasn’t possible to ride without it but thought I would ask.
I was actually told the countershaft seal was a little torn from the guy that put the motor back together but I pulled it out myself and looked at it and everything looked good. Filled it with oil and checked for leaks then started it and checked again. No leaks after riding either so I think it’s good to go but I have a fresh one coming just for insurance!
Post a reply to: Countershaft Seal Question