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Engine vent on a 650cc?????

Joined Mar 2002
437 Posts | 0+
The Netherlands
Out of curiosity, why does the 650 have two ventholes? Is it due to the bigger volume it moves around or out of safety? We are building an 04 650 engine in a quad and the second vent tube is a bit on the wrong place. Would it hurt if we closed it completely? If I recall the "older" engines didn't have two of these, or am I wrong here.
Regards
 
I think the second crank vent line was added to cut back on oil leaks. I believe the thought was relieve the crankcase pressure a little to slow the leaks and seeps down. I would think it would function fine with only one, but then I am not what you would call an expert :D
 
how about using the electric start hole as a vent? or the kcik start decomp hole?

just a thought? also what about welding one on one of the rockerbox tappet inspection covers?

regards

Taffy
 
Thanks, we probably will try only one.
The e-start will be used (if it works) and since the engine isn't ours, we can't do anything to it that requires welding and such.
 
I would venture a guess that having two holes in the head may help with the oil blowing out the breathers as the pressure would be half as much. Pre 04 models do produce a bunch of oil mist and quite possibly the single outlet and hence higher pressure may be the cause. I don't think the breather routed into the intake will change in design anytime soon as emissions overseers would frown on oil mist vented directly to the atmosphere.
 

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