Higher top speed!

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SansPedals

New Member
Jun 13, 2010
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brnotbrnot Hey everybody, I rarley post but read and have used this awesome forum for everything I've done to my bike.....heres my deal. I have a stinger 66cc with a new style nt carb (made a big difference) and a sick bikes expansion chamber. I have ajusted the header tube size back and forth and while it gives more or less mid power I cant get past 33mph. would a aftermarket air cleaner do andy thing for flow? Open to any ideas. I understand tuning and gearing, just seems to hit a flat spot in the powerband. Thanks I'll be watching as I always do!!
 
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maurtis

maurtis

New Member
Dec 14, 2011
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Kyle, TX
How much more top speed are you looking for? Not sure how much gain there is in a higher flowing air filter, but you can always change out your rear sprocket too. Reports are that you can get about 1 MPH per tooth you go down on the rear sprocket.

I run a 36 tooth rear since there are not many hills around here. Most stock sprockets are 44 tooth, so going with a 40 tooth or 36 tooth will gain you some top speed, but you will lose some torque.
 
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SansPedals

New Member
Jun 13, 2010
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That is an option, I live in Utah so hills are common....... Maybe I am asking to much:) I find myself addicted to this hobby:) Maybe a new project bike is in order! Thanks for the reply
 
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fonzie

Member
Nov 13, 2011
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Dillsburg, pa
One quick and dirty test would be to just take the air cleaner off for a short period of time. Should only take one run to see if it makes a difference. Be aware that you could end up running your engine lean since you are allowing more air to get in the engine by taking away the restriction. If it bogs with the air cleaner off, then your are too lean. Try a slight bit of choke to see if you can get rid of the bog. If that takes away the bog, then rejet to a bigger jet. If you think about it......the expansion chamber will help but if you are not getting an adequate amount of air to the engine, your not getting the most from the engine.
 
Venice Motor Bikes

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
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Los Angeles, CA.
I've found that the stock air filter will flow the best after you drill a large hole in the face of it (right in front of the carb throat)... I don't even bother puting those fancy air filters on my bikes anymore.
The next thing would be to re-jet the carb; They usually need a slightly smaller jet to run best. Only go one or two sizes smaller! If you go too small your engine could be too lean & burn up. The way I jet mine is where the engine sometimes still feels that slight 4-stroking feeling; Thats when I know its still a little to the fatter side but still mainly burns crisp with power.
 
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SansPedals

New Member
Jun 13, 2010
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Utah
Thanks guys, when I turn down the fuel valve I gain rpms/speed so maybe more air at wot would make the mixture a bit leaner at wot. It runs and starts so well I don't want to compromise my low and mid range. Plug color is perfect light chocolate brown.shft.brnot
 
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SansPedals

New Member
Jun 13, 2010
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Utah
Venice, that simple 1/2" hole got me nearly 2 mph and very little 4 cycle at WOT! Thanks alot!! It's tips like that that make me a fan of this forum.dance1
 
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SansPedals

New Member
Jun 13, 2010
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Utah
That sorta kills my low and mid..... might have to go down a notch on jetting? Gotta say been riding it for two years and two frames, now on 27" wheels. This is the best it's ever run:)
 
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ivan H

Member
Oct 8, 2011
622
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australia
use plug color 2 tune carb. Do a WOT run & pull clutch in & kill motor at same time. Let motor cool & check plug 4 jet size tuning. Do the same at 1/2 throttle 4 C- clip height tuning. Never remove plug when motor is hot or u may also remove the thread from the head. Ur looking 4 a "white coffee" tan color on the plug. A tiny bit of 4 stroking when the motor is unloaded is ok, it'll 2 stroke & be powerful when loaded up. Cheers
 
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ivan H

Member
Oct 8, 2011
622
1
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australia
Chocolate Tan, actually. I like a reasonably strong white coffee, so it is about the same color as"chocolate tan". Just chocolate & ur a bit rich. A well tuned 4 stroke shouldnt really color the plug much at all. Go to NGK's web page & have a look at their plug reading guide. Cheers
 
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