Yamaha TRX850 Enthusiasts Forum

Following a near death experience at Rockingham on Saturday I need a hand on a couple of 'in depth' engine questions.

1. My TRX engine is sat at Chris Applebee's awaiting re-grinding and balancing. The engine had previously been short on oil (not by me), and there is a groove worn on both sides of the lower crank case where the crank runs against it, to prevent it moving side to side. Is this normal??????? The crank moves about 0.25 mm side to side in the cases, but they are unable to tell me what is good or not. Anyone looked in their cases for this wear mark, if so how deep is normal?????

2. The top transmission plug (pictured) decided to fall out at Rockingham and ditch 1 litre of oil onto the rear tyre, and by the luck of god I managed to stay on . The book says just push it back in, but there must be something to retain it?? Any ideas Guys, thanks Nick.

Tigcraft Tdm wrote: 2. The top transmission plug (pictured) decided to fall out at Rockingham and ditch 1 litre of oil onto the rear tyre, and by the luck of god I managed to stay on . The book says just push it back in, but there must be something to retain it?? Any ideas Guys, thanks Nick.

that is the input shaft oil seal
i had a load of problems with mine after an engine rebuild
it was due to gasket sealent blockage further down the oil routing

if it has blown out then its likely you have a blockage in the gearbox fork selector rod
there are 4 pin holes that squirt oil inside the fork rod thingys

there are some pics of the oil routing on the XTZ site, i'll see if i can find em and post a linky here

ps. i've got some thicker o-rings to fit that, if you want them lemme know
i'll be in all day tomorrow so you are welcome to pop over and collect them from Wokingham
bring the part with you tho, cant remember the size you need


edit: nah cant find the pic but lots of oil routing info in my engine woe topic on the tdm site
http://www.carpe-tdm.net/ipb/index.php?showtopic=9033

for info....
there is an oil feed coming out from the crankcase and input the output shaft bearing
from there it goes through the input shaft seal and into the gearbox fork selectors, this then has 4 very small pin holes(which is assumed where the blockage was, most likely caused by gasket goo)
which puts the oil back into the main body of the motor

So am i right in thinking ther's nothing to retain this plug ?? Mine pushed in real easy - o-ring could be slightly contracted but it too easy to push home.

Tigcraft Tdm wrote:So am i right in thinking ther's nothing to retain this plug ?? Mine pushed in real easy - o-ring could be slightly contracted but it too easy to push home.

correct, it just kind slots in with a slight pop as it slots into place
although you should have an ally cover which partially covers it
this would help hold it in unless there was too much pressure behind it

trawling around trying to find a parts fiche covering the XTZ electrical system and i tripped (figuratively) over an oil routing diagram
if you have pressure in the wrong places hopefully this will help
http://www.tonydavis.co.uk/images/xtz/D ... l_flow.pdf

obviously the TRX engine is slightly different because its oil reservoir is internal
hopefully it'll be of use...

Cheers Tony, this will help come re-build time for my TRX878 engine if I EVER get my crank back from Chris Applebee!! I'm thinking the reason the plug blew out is because my crankcase pressure was too high due to high oil level in the tank.