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Old 05-16-2010, 03:04 PM   #1
adonets
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Question 4-stroke exhaust

How dangerous is it to be running a 4-stroke without an exhaust?

My exhaust is there, it's even intact, but where it connects to the exhaust part of the engine, it is detached and half of the exhaust comes out from the bottom, not from the muffler.

I am going to reattach it as soon as my double threaded studs arrive, but as for now, should I be worried about damaging the engine from cold air getting in and deforming hot parts? Or is this jibber-jabber nonsense?

Does have a nice purr to it now though...
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Old 05-16-2010, 04:19 PM   #2
mscuddy
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? So it's got a major exhaust leak where the headpipe meets the muffler (down around the motor)?

Nothing will happen to the exhaust valve(s) most likely, because of the hot headpipe that keeps the air on the warm side when you shut the motor off.

What you're thinking of is when there is a MAJOR exhaust leak at the exhaust port, where cold air can enter after you shut the motor off, and warp the red-hot exhaust valve, or seat.

What kind of motorcycle? That would help.
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Old 05-16-2010, 10:25 PM   #3
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? So it's got a major exhaust leak where the headpipe meets the muffler (down around the motor)?
I'd consider this a "major exhaust leak". But let me explain myself better. Where the exhaust pipe begins - at the motor itself - is where it is disconnected, or not disconnected but rather, one of the stud bolts holding the exhaust is missing, and one is still intact. Both the nuts holding a little plate are missing so the little plate is dangling on the pipe itself. The exhaust pipe still goes into the engine because it is held by bolt points throughout the frame. It IS shaky though. Evidently, approximately half of the exhaust manages to go through the muffler and half of it through the bottom, or where the exhaust connects to the engine.

Is that a better explanation?

It's a small 88cc engine. 1 cylinder, 4 stroke.

Let me know if I can run it until my studs arrive. Thanks.
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Old 05-17-2010, 05:59 AM   #4
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Quote:
Originally Posted by adonets View Post
I'd consider this a "major exhaust leak". But let me explain myself better. Where the exhaust pipe begins - at the motor itself - is where it is disconnected, or not disconnected but rather, one of the stud bolts holding the exhaust is missing, and one is still intact. Both the nuts holding a little plate are missing so the little plate is dangling on the pipe itself. The exhaust pipe still goes into the engine because it is held by bolt points throughout the frame. It IS shaky though. Evidently, approximately half of the exhaust manages to go through the muffler and half of it through the bottom, or where the exhaust connects to the engine.

Is that a better explanation?

It's a small 88cc engine. 1 cylinder, 4 stroke.

Let me know if I can run it until my studs arrive. Thanks.
Don't run an engine without the head pipe being securely attached to the cylinderhead. You'll need to get a new stud and the plate and a gasket.
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Old 05-17-2010, 08:01 AM   #5
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The exhaust lead at the header to head gasket will result in burned exhaust valves. My Shovelhead had one stud to hold the header, and it frequently worked loose or broke. It broke on the way back from Daytona (about 250 miles) and by the time I got home, the valve was toast.

Fix it before you ride again.
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Old 05-17-2010, 09:18 AM   #6
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Doona Ride The Bike Laddie! She's Gonna Blow!
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Old 05-17-2010, 11:17 AM   #7
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Make sure you get the ABS workin' on that thing before you take it on the road.
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Old 05-17-2010, 12:45 PM   #8
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Thanks to everyone who commented!
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