Vintage Dirt Bike Q & A

in a earlier post i asked if anyone knew the correct way to check the oil level in the crankcase on a MR175. Do i just take out the check screw and add oil until it flows out PLEASE HELP....

Yes it is full when the oil runs out the oil check bolt hole. Be sure the bike is straight up and not leaning on the sidestand.

thanks again mdlafferly. without your help, my bike wouldnt even be running

but don't forget it has to be warm and the oil has circulated otherwise you can put too much in?

cheers

Rossco

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1974 Yamaha YZ360B
1977 Suzuki RM370B
1980 Honda CR250RA

the rule of thumb with oil is that it comes to the bottom of the thread on the dip stick housing this alows for aproximatly a litre to be used in total

if you fill it right up u will have to much pressure in the bottom end and this can cause problems with blowing seals

Just trying to understand, but how would too much oil blow the seals?
Where would the pressure come from since there is no crank pressure in the gearbox and wouldn't the crankcase vent tube allow escape for any pressure build up? Just curious. thanks garry

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Garry Mainer
#33m (retired)
Honda Cr250r 1980
Honda Cr250r 1980
Yamaha TY250C 1976
Arctic Cat 650 H1 2007

Your are right, there is no pressure in the crankcase, it is vented. You could cause the seals to leak by over filling the case though, and it could run out of the vent.

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Sam Alexander

1974 Honda CR250M
1976 Honda CR250
1974 Maico MC440
1974 Maico MC250
1977 Maico AW400

Hi guys
your right in saying any pressure is released
with oil as it heats up the air space heats as well causing pressure within the bottom end most is released but dependant on how tight ur seals are wether the release tube is clear any build up ie dirt waste oils can block the vent tube i just believe to be safe as aposed to being sorry