Talk about Dejavu ...
I had a geek on PM to see if I could find the post that the mountain was referring to and found this ...
Pumping a lot of oil out of the breather GPX165 - Planet Minis
I had already typed out a long winded reply but our computer messed up just as I was about to post it ... I can get on here no probs from internet explorer but I keep getting cut off when using Mozilla Firefox ... The only trouble with that is IE is dog assed slow on other sites and stuffs up on hotmail (freezes and won't open emails) whereas Firefox is faster on all other sites and hotmail works spot on with it ...
Here's what I was going to post ... the yanks have already said some of the same things ... Man it took a bit of friggin' around to retrieve this info out of hotmail ... IExplorer sucks ass ...
MR WINDAGE POST ...
From: Cactus Jack (
[email protected])
Sent: Monday, 17 November 2008 4:55:42 AM
To: Cactus Jack (
[email protected])
It's to be expected and is caused by windage ... which any laid over cylinder would suffer from ... Basically , if you were going to build a racing engine from scratch , you'd use a vertical cylinder to get the piston up high so that it doesn't lose power due to having to push oil out of the way all the time ... Obviously the oil gets tornadoed around too much in the crank case so oil mist gets blown out thru the breather ... especially under heavy braking ... For TRUE racing engines the builders go one step further and go to a dry sump oiling system with a supply and scavenging pump where the oil is kept in either an external tank or inside the frame tube to get around all of the problems of windage , roping , and oil control ... Where a dry sump system can't be used , the sump/oil pan is deepened to get the oil level as far away from the spinning crank as possible and crank scrapers and louvred baffles are fitted on the upwards rotating side ... the crank and rod are also "knife edged" to reduce their fanning effect ... Chev engines are known to pick up 50 HP just from windage control ... Honda obviously went to a vertical cylinder to get more power out of the same 72 cc and avoid the oil spewing problems when they stepped up from the horizontal cylindered SL70's (72 cc) to the vertical cylindered XR75's (72 c) ... Verticals have zero OIL loss problems using only the stock breather at the rear .. no matter how big they're bored or how hard they're revved ... even when wheel standing ... The chinese have copied everything with their horizontals ... including the faults ...
You'll need to add as many breathers as you can to reduce crank case pressure ... a catch tank on the rear breather , a dipstick breather , and a top valve cover breather and hoses routed up high ...
Another factor you could be encountering is blowby past the rings ... It's doubtful that they'd be seated and sealing as good as possible after only 45 minutes from new ... There's no way you should be caning the engine yet unless you've used moly rings , had the cylinder precision torque plate honed and the piston to bore clearance increased to compensate ... YOU should already know all this dude ...
I've just had a look at my YX150 and there is f'ck all oil depth below the crank counterweight line ... no wonder they eject their oil ... IF the cases were deeper it wouldn't happen ...
