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Post by stretchedscoot on Jun 13, 2012 23:23:42 GMT -5
having a problem whit what i think is detonation on my scooter
stock 1e50qmf 90cc engine 70cc hoca head hoca reed cage w/ carbon reeds 21mm oko carb (90 main) stock exhaust premix ngk br8hs plug
running around 160-165 psi compression
im getting a kinda rattling noice when i'm getting past 1/2 throttle so i had some leftover 110 vp race gas i put in and the noise went away.
also running stock ignition never touched or moved.
should i be having these problems with my compression or do u think something else maybe cause the problems?
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katastroff
Scoot Member
Dont F*%$ With Me, I'm a Dad!!!
Posts: 67
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Post by katastroff on Jun 14, 2012 4:36:36 GMT -5
You gas it up with super?
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Post by 90GTVert on Jun 14, 2012 6:31:38 GMT -5
I usually push up to 175-180psi cranking compression max on the street with 91-93 octane fuel. Even then I may hear some spark knock. Are you sure the compression number is correct? I know some will use only electric start. Sometimes that'll give you a proper reading, but often you need to kickstart to get the right number, throttle wide open.
If you aren't running premium, you should. If you are jetted lean or have the needle set too lean it will heat up and you'll get detonation. If you run a small cooling fan it's more likely to run hot and have detonation as well.
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Post by 2strokd on Jun 14, 2012 8:40:07 GMT -5
Maybe the smaller head is holding in heat?
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Post by stretchedscoot on Jun 14, 2012 10:44:08 GMT -5
i do use the electric start to get the compression up then give it a few kicks to get the highest compression reading.
i always run shell 93 octane usually 5-gal premixed 40:1
i'm going to do more plug chops once all the 110 runs out to find out if my jetting is wrong
currently running 90main jet with needle in center position
my stock engine came with the large cooling fan
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Post by stretchedscoot on Jun 14, 2012 10:45:54 GMT -5
not sure if the smaller head is holding in the heat. i switched it out because my stock 90cc head is a non-squish type.
maybe i will throw the stock head back on and get some compression readings
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byte
Scoot Member
Posts: 51
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Post by byte on Jun 14, 2012 11:44:47 GMT -5
maybe your piston is hitting something...
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Post by reveeen on Jun 14, 2012 13:05:45 GMT -5
Maybe the smaller head is holding in heat? If anything is "holding in the heat" it is likely the stock exhaust
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Post by stretchedscoot on Jun 15, 2012 16:31:29 GMT -5
im trying to get a performance pipe but no luck so far besides a local dealer trying to charge $400 for a leo for an areox 100
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Post by lshigham on Jun 15, 2012 16:35:11 GMT -5
Maybe the smaller head is holding in heat? If anything is "holding in the heat" it is likely the stock exhaustYes, restrictive exhausts are a quick path to high piston crown temperatures. However, that said, Brent has not had the same problem with stock exhausts, though they aren't created equal.
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Post by 90GTVert on Jun 15, 2012 17:34:34 GMT -5
I've ran 2 diff styles of 49cc pipes on a 96cc stroker and it ran well with similar temps to performance pipes (although the really hard running pipes that upped the revs increased CHT vs the mild and stock pipes). My biggest problem with heat was a tuned pipe with a small stinger. That got so hot that it started melting away the crown of the piston starting from the exhaust port opening into the cylinder.
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