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DT175MX Crankcase Breather


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Evening all, I recently purchased a 175Mx - 1978, engine had apparently had both top & bottom end rebuild but the issue I have is 2 stroke oil coming from the crankcase breather pipe. I've checked the oil pump clearance which was 0.014", removed shims to take clearance back to 0.008" but I still have the problem ? Any help would be appreciated - Dave.

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Evening all, I recently purchased a 175Mx - 1978, engine had apparently had both top & bottom end rebuild but the issue I have is 2 stroke oil coming from the crankcase breather pipe. I've checked the oil pump clearance which was 0.014", removed shims to take clearance back to 0.008" but I still have the problem ? Any help would be appreciated - Dave.

bit of a misnoma that, in reality it's a gearbox (transmission) breather pipe . Whats the dipstick saying then?

As you're new here Dave, how about an intro in new members?

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10 out of 10 airhead, checked this morning & the gearbox is full to the neck with what appears to be 2 stroke oil ! I'll drain, flush & refill with gear oil.

I'll post an intro shortly, I was in too much of a hurry to post my question - sorry.....

Thanks again.

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I had a quick check but couldn't see the seal after removal of the pump, will I have to remove the entire right hand casing ? I've drained & replaced the oil to the correct level so I'll be able to check the level after a few days of running. Appreciate the advice.

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I had a quick check but couldn't see the seal after removal of the pump, will I have to remove the entire right hand casing ? I've drained & replaced the oil to the correct level so I'll be able to check the level after a few days of running. Appreciate the advice.

no you wont see it by removing the pump you have to remove the RH casing, be careful of the shim washer that always falls off the peg at the front

a few tips

Drain the oil, if its good oil clean around the drain plug first and drain it into something clean...and then you can re-use it (your choice)

undo the rear brake rod adjuster and use some string / cable tie around the arm and footrest brkt to hold the lever down out of the way

disconnect the pipe to the oil tank and jam it in the cylinder head fins, if the bike is on it's side stand no oil will come through (but check)

you may get away without disconnecting the awkward to remove pipe from the pump to the carb if you pull off the case and invert it and tie it up...see pic

dont forget the hidden case screw behind the pump cover

dont forget to replace the shim as mentioned earlier on re-assembly

how about drawing a line on some masking tape that indicates the 2 stroke oil level and monitoring that?

The seal in question is behind the plastic drive gear, heres the case tied up to save work :thumb:

If your case gasket is in good nick like the one in the picture...hey you can even re-use that...another scotsman showed me :lol:...If not.'Wemoto' sell them individually, or at least they did do

102_2568.jpg

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