Got The Holeshot
Arm chair racerJust too addicted
I'm working on a 125 dirtbike and the pipe has a hole drilled in the bottom at the lowest point after it comes out of the cylinder (see picture). Why would someone do this (maybe to drain water/condensation???) and is it bad, could it cause harm to the motor?
86 350X ::: 85 250R
Projects
350x
Come and Gone
86 350x : 84 250r X2
85 350x X2 : 84 200es X3
83 200e : 78 ATC90
Power User
Catch me if you can
You're probably right about the drain, but it may also have been used to pull a dent out.
A small leak, like a pin hole is no big deal on a dirt bike, but if the hole is larger than that I'd plug it with a brazing rod for a number of reasons.
One being that when you trailer a bike there can be a lot of air flow caused by a vacuum being created at speed. It can draw air through the carb (no big deal) but it can also cause unfiltered air to come in through the pipe and into the engine (very bad). A hole of a decent size may let that happen if the piston wasn't at the top of the stroke. For this reason I always turn my engine by hand till I feel compression and use a plug in my pipe when I trailer.
The other reason would be that if you happen to stall out in a water crossing your pipe may fill with water.
If you do weld it up, make 100% sure that there are no loose blobs of weld in the pipe. Best take it off to weld anyway.
It sucks to get old
Roostin' Away
Arm chair racerRoostin Away
Thinking it maybe a port hole to take a EGT. (Exhaust Gas Temperature) for tuning/ jetting. I know my friend had one on his 125 shifter kart. Mind you this was back in 1996...
Is the hole threaded or just a hole?
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'83 200X
Chicks love guys that ride trikes
Got The Holeshot
Arm chair racerJust too addicted
Thanks for the reply guys. The hole is not threaded and about 1/8" so definitely bigger than a pin hole. My biggest worry was if it was going to act like an air leak and lean it out while running.
86 350X ::: 85 250R
Projects
350x
Come and Gone
86 350x : 84 250r X2
85 350x X2 : 84 200es X3
83 200e : 78 ATC90
Power User
Catch me if you can
Maybe you can just screw a 5/32” sheet metal screw into it with a dab of JB Weld to hold it.
It sucks to get old
At The Back Of The Pack
Arm chair racerFirst time rider
Somebody may have flooded it really bad at one time and filled the pipe with fuel. Instead of pulling the pipe they drilled a drain hole. The old YZ465 I used to have got a good bit of fuel in the pipe when I first got it. It was a mess that someone had been screwing with for a while. I pulled the pipe and fuel flowed out of it and kicked the engine over until fuel didn't blow out of the cylinder anymore. Things happen, ya never know.
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