RM400N Oil in Crank...Help!!!

[Toolboy]

Thanks for your input guys, i will try to answer the questions:
Smed.. i use Mobil 2T Racing oil, 32:1 mix
PMC..The crank seal is fitted the right way around, as per workshop manual
Lozza..The piston is Weiseco
Doc..I sanded the cases with wet/dry 800 used a smear of aviation sealant. I was thinking of not using any but did so lightly and only on the cases. No other gaskets.. The oil matches the colour of the gearbox oil i drained.. and to answer your earlier question the pics taken were as i pulled the barrel of the piston so there is a pool of oil in crank. When i have checked this before i had the same situation, with a gheavy amount of gearbox oil in the crank.
Mike..I fouled a plug on the test run after the rebuild but before Connondale and switched to a B7ES plug...it was a bit of a gamble not too burn a hole in the piston.
Hardo.. As per the answer to Doc
Slawsley... I use 96 Octane with Mobil 2T Racing oil 32:1

What is a big give away is the blackness on top off the piston, i have never had this before

Thanks guys...looks like i need to split again???

Tim

[Mike52]

Ahhhhhh.
Check the left side seal " again ".

[Toolboy]

Yeah Mike i will do that...I have the engine out of the frame and in the next few days i will look at the seal and oring,,, i did clean and lightly sand the surfaces of the crank and used rubber grease so as not to damage the lip of the seals... I will add pic's

Tim

[Toolboy]

Just to add that the bike did run fine and that i reved it pretty hard at Connondale, so much so that the pipe split from vibration. I was going to pull the engine out to fix the mounting bolt holes being out of shape causing the bad vibration and checked out the barrel to see if i had fixed the leak..

Tim

[LWC82PE]

32 to 1 errrr, get some more oil in there. 20 to 1 will improve things. I would go to a 8 or 9 on the plug (400T uses 9EGV as std) and also swap the ES for the original spec EV or EGV or iridium. ES are the most bottom grade basic plug you can get. I can easily see why things look hot and skuffed now. Very close to seizure thats for sure. Remember, the original specs by suzuki for 20 to 1 are to provide good cooling and lubrication and the bikes were designed to be ridden and reved hard. Try and use the highest octane fuel you can get/afford but you may still find you need lean off the needle and mixture screw (new fuels/lower octane dont burn as well at lower temps to get complete combustion and the fuel companies have admitted this) but it will depend on how you ride it. A lot of people ride like grampas in fear of breaking their bike but all this does is cause fouling problems requiring jetting tweeks or just simply changing riding style and giving it some more revs (eg rev it right out through the gears and dont labour it) I do understand this can be hard to do for road use with all the 50km zones we have though

[Billet YZ]

G`day Toolboy,
                       just adding my 2 cents worth. I would have a close look at the length of the bolts that hold the cases together and make sure you haven`t got too much thread length going into the other crankcase half, they may feel like they have tightened up but may be bottoming out in the case first.

It would only take 1 or 2 of the screws to not clamp the cases together and you will have a small leak, if this isn`t the problem you may need to look for a small fracture somewhere in the cases. Hope you solve it.   Peter.

[Mike52]

I'me trying to remember a discussion somewhere , PE forum I think , where the guy had the bearings loose in the c/case letting the shaft wobble and the seal leak.
Sounded like a rare sort of problem.
He ended up putting a sleeve in it.
Might pay to check.

[holeshot buddy]

looks normal docs right and some of the residue is from
sealer
b7es is not a problem if jetting is ok
looks lean like lozza said

20 to 1 is ok for original standard jetting
32 to 1 is fine but you would have to rejet
also a fouled plug can be as simple as a oversize pilot by 5

[Bikeaholic]

My RM250X had a vaccum at the gearbox vent tube. It kept fouling plugs. Thought it was crank seals or centre gasket too. However when I pulled it down it was the inserts in the cases for the main bearings that were loose causing it to suck gearbox oil. I had a look at another set of engine cases from another engine I had and it had new inserts that had been machined up which suggests it may be a common problem. The original inserts are dowled but they had come loose just enough to cause the problem. Might be worth checking

[Toolboy]

Bikeaholic... Yes i have considered this, and will look into it more
Holeshot.. My fuel mixture and carby settings have never changed since first rebuilt, the problem with the fouling plug is only recent.
Mike..I did consider putting speedy sleeves on the crank to ensure a perfect seal. Maybe i need to do this??
Billet...Yes i will check this for sure when i pull the covers off...but when i did split the bike i could not see no sign of where the oil was getting past the gasket..
LWC...When i had the cylinder rebored i was told by the Serco/Wieseco machinist that 20:1 is old school oil and with the advances in technology of oils 32:1 was fine. I have had this discussion with people before who say the same thing that you dont need 20:1 and others that say you do???.

Thanks guys

Tim

[Doc]

Start playing with fuel oil ratios and you'll need to start looking at plug chops and jetting changes. 20:1 isn't old school if you use regular oil like Castrol SuperTT, it's been around just as long as the RM and besides, while the new oils now may not be oldschool the engine still is. You'll find the more oil in the mix the cooler it will run

[Lozza]

LWC...When i had the cylinder rebored i was told by the Serco/Wieseco machinist that 20:1 is old school oil and with the advances in technology of oils 32:1 was fine. I have had this discussion with people before who say the same thing that you dont need 20:1 and others that say you do???.

Thanks guys

Tim

With advice like that i would be seeking another reborer.There has been no advances in oils.

Tim it's running lean and a cold day will have that seizing solid. The piston does not lie.

[jimg1au]

the best way to check if you are sucking gearbox oil into the engine is to use castrol r30 in the gearbox take it for a good run then get behind the bike with some one giving it a rev.your nose will tell you due to the smell of the r30.if you can smell the r30 its sucking oil.
jim

[D project]

Have the same problems with my RM125X. Thought it may be the crank seals,but have left well enough alone for the moment. Running motul 800 at 32:1 and have had no problems and piston crown looks great. Plug is a little dirty. It could not leak that much past the seal while the motor is stationary could it

[Mike52]

Toolboy I was talking about the same thing as Bikeaholic not speedy sleeves.
Bearings or bearing housing loose in c/case.


Ps. Talking about oils , didn't Maico invent or at least promote the first use of synthetic oils ?
My memory is shyte but the figures 50/1 and 100/1 ring a bell.