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High Performance Bicycle Engine Tips We all want our bicycle engines to push our bikes faster. Get exclusive engine modification tips and suggestions from us.

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  #1  
Old 06-30-2009, 01:24 PM
atvaholic atvaholic is offline
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Default Got 'er up to 28 mph today on GPS

Hehehe was quite a hoot. Is that about the best I can expect from a stock china 80cc kit? It was winding pretty high and vibrating nasty. I changed to the NGK plug as recomended on this forum..
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  #2  
Old 06-30-2009, 01:40 PM
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Default Re: Got 'er up to 28 mph today on GPS

Are you still in break-in period? Thats is about normal but it might get a little better and once it breaks in a little it is possible it can smooth out and gain a few more MPH.

My bike used to hit 30-31 but I have lost so much compression I am only hitting 23 now.
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Old 06-30-2009, 02:17 PM
atvaholic atvaholic is offline
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Default Re: Got 'er up to 28 mph today on GPS

Hi - I took it easy on the first tank of gas. This is half way through the second. Im guessing it would be the still in the break in period?
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Old 06-30-2009, 04:23 PM
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Cabinfever1977 Cabinfever1977 is offline
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Default Re: Got 'er up to 28 mph today on GPS

yes you are correct,you are still in breakin.
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Old 06-30-2009, 05:13 PM
atvaholic atvaholic is offline
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Default Re: Got 'er up to 28 mph today on GPS

Hey thanks...How will I know when its broken in? It will just start running better?
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Old 07-01-2009, 03:02 PM
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NunyaBidness NunyaBidness is offline
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Default Re: Got 'er up to 28 mph today on GPS

Usually these motors are broken in after a couple two or three tanks. Yes it will start to perform better as it is breaking in and there will have been a noticeable increase in performance when it is fully broken in.
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Old 02-01-2010, 12:06 AM
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aspireonescs aspireonescs is offline
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Default Re: Got 'er up to 28 mph today on GPS

just hit 27.4 on a stock starfrire gen 2 motor. (accroding to a handheld garmin etrex legend gps unit and NOT going downhill) trying to get it up to 30, i guess i still have some tweaking to do on the air/fuel mix? at the moment i have great hill climbing power. but just want those 2 and a half extra mph

Last edited by aspireonescs; 02-01-2010 at 12:08 AM. Reason: added how i got the speed
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Old 02-01-2010, 02:56 PM
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Default Re: Got 'er up to 28 mph today on GPS

The elusive 2mph... These stock 66/80 pull a 36T no problem, most of the time. Should get you above 30mph easy and cheaply. I have a 32T, and it cruises half throttle 35mph easy, tops at 44mph on a good day if i'm lucky, and gets to 41 mph regularly. Also required a SBP pipe, slant head, C.E. Intake, CNS carb, plug boot/wire/sparkplug upgrade, taller exhaust port, and port matching. TomTom verified mph. With real and professional porting, where data and actual math is used, These things will fly. Check pirate cycles vids out.
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Old 02-01-2010, 04:27 PM
wildemere wildemere is offline
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Default Re: Got 'er up to 28 mph today on GPS

30mph with a stock 26" / 44t setup is nearly 7,000 RPM.

Unless everything is perfect you risk breaking something or at least high wear rates running 7,000 constantly

The 50cc seems happier at these revs though.

But they are all different, some engines will pull over 8,000 others struggle to get to 6,000.

Be safer to get a 36t after break-in then try again.

Then you will be turning around 5,700 at 30mph
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Old 02-01-2010, 08:38 PM
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Cabinfever1977 Cabinfever1977 is offline
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Default Re: Got 'er up to 28 mph today on GPS

I had my 48cc Startfire gt-2 grubee engine(all stock) since march 2009 around 1 year and 1,000 miles.
I have a 26" bike with stock 44t sprocket and run WOT @ 28-30mph, i get around 180mpg.
I don't know what rpms its doing but my engine loves it, other engines may not.

I do mostly 1 mile runs to the store and 1 mile back at WOT.
Im just started on my second quart bottle of cheap 2-stroke oil too.

I might get a 36t sprocket,im not sure.

O and if you want extra mph your aircleaner and muffler need to breath, If you have a plastic aircleaner make a couple extra holes. If you have a black muffler take off cap,you see the 3 holes? Drill the 2 smaller holes a little larger,put cap back on muffler. That should give you a couple extra mph for free. And you can still get a sprocket thats smaller than a 44t.

Last edited by Cabinfever1977; 02-01-2010 at 08:48 PM.
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