This is one of the many reasons to keep an exhaust on your bike.

industrialphreak · #1 (**permalink**) 08-12-2009, 06:40 PM

Well....

Today we have a few pictures why its so very very very important you have an exhaust system on these two stroke engines. I of course had to learn the hard way by loosing out on a few days of riding and my precious 80cc engine. At first its a little exhilarating and exciting once your exhaust falls off and suddenly you have a little more umph coming from the engine, but let me stress IT IS NOT WORTH IT!

Simply for durability and practicality you not only need the back preasure but as well as some protection from road grit/ leftover salt and sand from getting into your cylinder...

Enclosed are two graphic pictures of a postmortem "autopsy" of a 80cc happy time engine.

Enjoy!

You can see were the piston was smacking against the spark plug and were mysterious grit was slowly eating away at the crown of the piston. shockingly the actual cylinder weathered nicely with no real viable signs of wear.

**2door** · #2 (**permalink**) 08-13-2009, 02:46 PM

This should be required reading for everyone who thinks its cool to run without a proper exhaust system on a 2 stroke. Thanks for the lesson.
Tom

industrialphreak · #3 (**permalink**) 08-13-2009, 03:01 PM

Quote:

Originally Posted by 2door

This should be required reading for everyone who thinks its cool to run without a proper exhaust system on a 2 stroke. Thanks for the lesson.
Tom

It was actually rather funny when it did go... i was on my way to work at the local petro station when about 15 miles into the journey my engine started making a really weird sound then rather instantly started revving down do to incomplete combustion via loss of compression. the odd part is the darn cylinder wall looks rather fine and is a smooth as a babys bottom. in the next few days i am going to try to take some shots of the cylinder. and can loosing your gasket between the crank case and cylinder have anything to contributing the the whole mess?

**Norman** · #4 (**permalink**) 08-14-2009, 12:52 PM

If your cylinder base gasket leaks it will cause a lean condition and can fry the engine. Same for the crank main seals,or the crankcase's split line gasket which has a very thin portion between the crankcase and the through shaft for the rear drive. Stock gaskets for the most part are not very well made the crankcase split line gasket if not disturbed seems to hold up but I know of some riders who have had them leak a sign is oily black poo coming out of the top back of the engine right under the carb or out of the sprocket area or under the other side where the clutch lives.
Sometimes the engine seals will not be seated in far enough and the mag rotor will eat it up or on the gear side, the small gear will eat that seal up. the seals should be flush with the case or just a little below flush something to check when you first get your engine plus you can check and clean these area as there is metal shaving under the covers that can and will wreak your seal areas or worse tear up the mag coil etc.
Norman

matt167 · #5 (**permalink**) 08-16-2009, 02:30 PM

no exhaust also runs the engine way lean

industrialphreak · #6 (**permalink**) 08-20-2009, 12:05 PM

Sure... its also a matter of having decent access to a working and well supplyed welding tools. why the bleep bleep would you go and pay around $150-250 for a prebuilt exhaust when you can get off your butt and build one yourself.

Like the pipe, could you get some samples of it running once you get the magneto installed and it operating?

**Bikeguy Joe** · #7 (**permalink**) 08-21-2009, 07:28 AM

I made it smaller, is that good enough?