ive had my mc21 for just over a month now
i was fully aware of the maintenance 2 strokes need
but just recently my bike has been starting to leek everywhere.
its not petrol and i dont know where its comming from beacuse everything is covered.
my bike didnt start one day beacuse the plugs were just covered in muck
i took it to the mechanic with the fairing open and he said it needs a bottom end rebuild beacuse its leaking from there and that its burning my gear oil.
could it be that im due for a bottom end rebuild and could oil leak from there and could that ever be a result of using poor quality 2 stroke oil which isnt burning up well.
also how do i check to see if my bike is running to lean
beacuse one exhaust is starting to squirt a bit
sorry bout the noob questions

Noob questions are ok. That's why we're here!

"but just recently my bike has been starting to leek everywhere.
its not petrol and i dont know where its comming from beacuse everything is covered."

Wash it, and find where it's coming from.

"my bike didnt start one day beacuse the plugs were just covered in muck"

They need to be clean or the spark will not jump across the gap, it will simply run down the muck.

"i took it to the mechanic with the fairing open and he said it needs a bottom end rebuild beacuse its leaking from there and that its burning my gear oil. "

Does he know what he's doing?

"could it be that im due for a bottom end rebuild"

Deopends what you / he mean by that. If he is saying you need a new crank, I'd be suspicious...

"and could oil leak from there and could that ever be a result of using poor quality 2 stroke oil which isnt burning up well."

Poor two stroke oil will ruin your crank yes, but that won't make it leak.

"also how do i check to see if my bike is running to lean beacuse one exhaust is starting to squirt a bit"

Thought you said it wasn't running? Do you know what running lean means? I'm not taking the P here, you do sound a little out of your depth, so I'm trying to establish what you do and don't know.
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Triumph 9551 Daytona Big boys toy
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GTS1000 oddball

Dave's right, clean the bike to establish where the oil leak is coming from.

My first thoughts are that it could be the two stroke oil leaking in to the crankcases. This then mixes with the gearbox oil and will eventually work it's way outta the overflow pipe.

Sounds serious I know, but is a fairly common NSR fault and a fairly simple fix.

What happens is the 'O' ring on the 2-stroke oil pump slips down it's shaft and allows the oil to pass into the cases. What you need to do is remove the oil pump from the cases. Watch out for the small washer at the bottom of the shaft.....it'll most likely fall off when you remove the shaft or might remain in the cases.

You sould now see the 'O' ring has slipped down. Clean it and the shaft up, removing all the oil. Then using a bit of sealent, 'stick' the 'O' ring back up in to the housing at the top of the shaft.

Put it all back together and it should be OK.

One way to quickly check if it is the 2-stroke leaking into the cases is to open the gearbox oil dipstick whilst the bike is on it's sidestand. If over full, oil will gush out, so get something to catch it in before doing it.

Hope this all helps and good luck.

Lets all just hope its just 2-stroke leaking from the reservoir bottles that have leaked over the spark plugs. That way cleaning everything may be all it needs (aprt from obviously fixing the leaky bottles). It would seem strange to me that it was running and then it wont when it started leaking.

As mentioned, cleaning the bike is the first thing that needs doing to establish what and where it is leaking!

My MC21 started leaking as I was riding it. So it can leak and still run. Then again the crank was also spinning in the cases and it still ran.


Miracle bike that one.

If you are leaking engine oil, heres a guide that really helped me out. I had 2 leaks, clutch cover gasket needed replacement, and the drive shaft seal..

http://www.nsr250.net/forums/viewtopic.php?t=7816
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i will do a thourough clean of it very soon to see where its leaking.
i just did a quick clean of the plugs and my bike started after a couple kicks. its only leaking randomly. its not consistant. like in between rides it leaks like mad and inbetween some rides it doesnt leak at all.
which is puddling up in the middle of the belly of the bike and dripping through the gap onto the ground
but what started to worry me is when i last took it out for a ride the right exhaust was squairting out like mad when warming it up and in the first 10 or so minutes of riding consistent white smoke was comming out of the right exhaust tip
but while riding the bike nothing felt unusual or out of the ordinary.

I would agree with racer 38 sounds like it could be the oil pump seal, although you havent mentioned if you are running autolube or premix. Obviously if its premix it wont be this.
If its not this it could be one of the gearbox seals or clutch cover gasket which are pretty easy fixes as well.
Badly sealed exhausts can coat the engine and inside of the fairing with an alarming amount of oil.
If the oil pump is set incorrectly it could be over oiling which would cause the problem with oil "squirting"out of the exhausts, likewise if your running premix with the incorrect ratio.
The exhausts could need a de coke as well if its spitting sh*t out
I would do as the others say, get the bodywork off, give it a proper clean, take the exhausts off and re seal the manifolds (de coke the pipes if it needs it),check the gear oil level, pull the pump out and check that seal and check the pump adjustment is correct. I would also pull the power valves out, clean and check they are set correctly while you are at it.

I have the EXACT same problem except for running/smoking issues. Just have a bunch of oil dripping out the crack at the bottom of the fairing. I see oil on the lower chamber and coming down from above too. On the front cylinder it appears to be coming from the exhaust port.

This bike has no oil pump (using HRC plugs in the engine) and I mixed it around 40 or 44:1 with Castor oil (can't remember the exact name but the previous owner used it so I bought the same thing). He told me to run 50:1 but I was concerned that wasn't enough oil. It smoked a lot more when I put my first tank of premix in it so maybe I have a combination of too much oil and leaking exhausts.

What parts are needed to seal the exhausts and where can they be sourced?

Thanks guys.

craigsutton wrote:I have the EXACT same problem except for running/smoking issues. Just have a bunch of oil dripping out the crack at the bottom of the fairing. I see oil on the lower chamber and coming down from above too. On the front cylinder it appears to be coming from the exhaust port.

This bike has no oil pump (using HRC plugs in the engine) and I mixed it around 40 or 44:1 with Castor oil (can't remember the exact name but the previous owner used it so I bought the same thing). He told me to run 50:1 but I was concerned that wasn't enough oil. It smoked a lot more when I put my first tank of premix in it so maybe I have a combination of too much oil and leaking exhausts.

What parts are needed to seal the exhausts and where can they be sourced?

Thanks guys.

I use a high temp (red) rtv silicone sealant. Presuming you have race type exhausts seal the manifold to the cylinder using plenty of rtv on the sealing faces and gasket, apply the rtv all around the manifold on the part that slides into the pipe. You should get a good amount of sealant squeeze out around the edge of the pipe.
I dont run premix but I think most people on here run richer than 40:1 but I'm not sure about the castor oil though! I heard it can gum up the rings and stuff, most people use fully synthetic.
Also expect to be told to start a new thread by Andy anytime soon

craigsutton wrote:What parts are needed to seal the exhausts and where can they be sourced?

You can order genuine Honda items, I bought some last month - £14 each. The part number is in the parts catalogue on this site.

Yes they're a bit pricey, but the seal the exhaust completely, so no spooge and no loss of power through leakage. And they won't degrade over time like silicon will...
_________________
MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball