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Post by kpfoten on Sept 2, 2013 10:52:28 GMT -5
My 2008 Hammerhead 2stroke starts and idles great (it was a freebie that the previous owner had problems with). When I open the throttle it increases slightly but I can only get going to about 5mph. On occasion, on the stand, I can get it to rev up high and the back tire spins accordingly. But usually on the stand, when I give it WOT it won't rev up. It only has about 240 miles on it.
Here's what I have: New Carb (tuned--the old one gives me the same result) New filter, hose, vac petcock, good vacuum, sprayed around with ether, no leaks. New CDI box New Coil, gapped plug Compression about 120 Throttle cable/mechanism inspected cvt cover removed, inspected, seems fine air in tires, rear brake seems ok Premium gas, good flow to carb Checked reed valves Muffler clear, no exhaust leak.
Frustrating because it seems like I've gone through nearly every possible scenario. What am I overlooking?
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Post by alleyoop on Sept 2, 2013 11:23:16 GMT -5
The problem is your compression, 120PSI is very low, so with a load it has no power, Time to rebuild the motor. Alleyoop
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Post by kpfoten on Sept 2, 2013 13:02:09 GMT -5
Not much previous history on it other than a missing cdi box and exhaust manifold bolts gone. With a low milage scooter I wonder how it could have lost compression? Maybe something to do w exhaust?
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Post by alleyoop on Sept 2, 2013 13:10:48 GMT -5
Not good to run 2ts without an exhaust they need some backpressure. But you can probably see how easy it is to turn the motor over just with your hand and not feel much of any resistance on the compression stroke. Alleyoop
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Post by kpfoten on Sept 2, 2013 15:19:50 GMT -5
Let me guess--it's not supposed to be easily spun with your hand? I feel a little resistance but not much...
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Post by alleyoop on Sept 2, 2013 17:41:03 GMT -5
BADA BING BADA BOOM Alleyoop
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New Rider
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Post by kpfoten on Sept 2, 2013 21:17:39 GMT -5
Thanks for the help--the piston was nasty and showed definite signs of blow-by and seizing.
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Post by skuttadawg on Sept 2, 2013 21:30:26 GMT -5
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Post by carasdad on Sept 2, 2013 21:33:28 GMT -5
Thanks for the help--the piston was nasty and showed definite signs of blow-by and seizing. Running lean can cause this too. I own one of the very same Scoots. As you know they come with top of the line Mikuni brand carbs..well except mine was a headache. Tough Carb to tune. # Jet was too lean....#87.5 was too rich. Just for fun I installed an Ebay 'cheapie' 2T Mikuni clone Carb. Problem solved!! The Mikuni caused me to soft seize 2 BBK's ..why?...no clue. All I know is that it screams now with the TK Carb.
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Post by skuttadawg on Sept 2, 2013 21:43:56 GMT -5
Wow I can use a 105 or a 120 rich with mine . With a BBK it really helped to go from a 40 IJ to a 45IJ as TK IJs are hard to find
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