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Ported the exhaust


Discussion at Motorized Bicycle Engine Kit Forum in the High Performance Bicycle Engine Tips forum. OK, another little tweak accomplished. I pulled off the exhaust, and the gasket, with a little finger-nail nudge came ...
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Old 06-21-2008, 05:41 PM
MarkTur's Avatar
Senior Motorized Bicycle Builder
 
Join Date: May 2008
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Default Ported the exhaust

OK, another little tweak accomplished.

I pulled off the exhaust, and the gasket, with a little finger-nail nudge came right off. How nice to have carbon buildup showing me exactly where to cut!

So with a round sanding block dremel tool, I modified the gasket by getting rid of the carbon. (First I used a Red Sharpie to outline it, just in case it came off in a clean chunk - which is did, so I was smart!)

After the gasket was modified to match the opening of the motor, I put it on the exhaust manifold, and again, using a red sharpie, colored in where metal was showing.

Then I stuffed paper towel into the exhaust to prevent metal flakes from going down the pipe.

Then I changed bits to the metal bit and started shaving away. I first cut outwards and left a 45 degree angle out to the edges of my red ink. Then I made sure everything was smooth and rounded and made a good transition to the pipe.

I used my shop vac to suck up all the metal shavings, and used needle-nose pliers to pull out the paper towel with the vacuum on it. Then I just tapped the manifold and kept vacumming directly to make sure it's as clean as possible.

I coated the gasket both sides with Red RTV, and then a generous amount of blue loctite on the studs (stock, and they seem just fine for now - but on the short list for replacement), and reassembled.

Of course it's freakin' raining with thunder and lightning, so I won't be able to test today....I guess it gives the RTV longer to set up.

So tomorrow I'll give you the results...but I'm sure it will only help! I am just going to get the Dax intake when it's available for the other side, but I do have a rubber o-ring for now to insure a good seal. (I hope).
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Old 06-21-2008, 07:22 PM
Motorized Bicycle Builder
 
Join Date: Jun 2008
Location: Fort Lauderdale, FL
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Default Re: Ported the exhaust

apparently porting the exhaust makes a big difference on the motors larger than 49cc, definitely let us know how it feels.
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Old 07-10-2008, 03:24 PM
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Location: arkansas
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Default Re: Ported the exhaust

by doing this, did you weaken the welding connection between the muffler pipe and the bolt-on plate?
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Old 07-10-2008, 04:28 PM
MarkTur's Avatar
Senior Motorized Bicycle Builder
 
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Default Re: Ported the exhaust

OK, quick follow up...my bike has never been better!

I ported the exhaust - that did make a noticable difference...the intake, not so much - I'm already pretty rich, so it just is letting even more fuel in..

The BIGGIE was last night - I put on a replacement Head Gasket from Dax. I also reset the gap in the plug to .022 (NGK plug). I replaced the gasket because I noticed an oil stain on the head.

Not sure which did it, but it's running GREAT! Cruised to work today doing 20 on sidewalk sections, and 30 on the straight roads. It wanted to go even faster, but I backed off.

Happy Times!
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Mark Turkel
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http://www.PalmBeachSoftware.com

HT 70cc ...lots of extras
Kulana Moon Dog Aka BLUE DOG
Like someone else said "Sticking it to the Man!"
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Old 07-10-2008, 04:38 PM
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Location: Duvall, WA PNW
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Default Re: Ported the exhaust

Just curious - prior to replacing the head gasket, had you torqued the head nuts (once or twice)?
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Old 07-10-2008, 04:55 PM
Bikeguy Joe's Avatar
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Default Re: Ported the exhaust

Nice job....these bike will make a mechanic out of a person!
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