Author Topic: dumb question about cams  (Read 1517 times)

phatboy

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dumb question about cams
« on: July 18, 2013, 05:21:40 PM »
looking at an A9 cam.

the thing is, the nuts that hold down the cam also hold down the head and cylinder so i will take the tension off the head gasket too.

so my question is, do I need to change the head gasket if I change the cam?
Agility 50 w/72cc BBK, A9 cam, stock airbox and exhaust (both drilled out), remove air tube restriction, stock head, stock carb, 105 main jet, CDI cut, smooth variator boss, stock variator w/5g rollers

reg

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Re: dumb question about cams
« Reply #1 on: July 18, 2013, 07:48:07 PM »
Hi, in the past i have got away with reusing the head gasket. If they are made of copper they can be reused after heating them up and plunging into cold water to soften them, Bearing in mind how cheap the cost of a new gasket is when added to a new A9 camshaft its got to be changed. Besides it would be good to clean inside the head. Please keep us updated as I have a gear up kit on order and if it transpires that its too high for my engine then an a9 cam will be needed !!

phatboy

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Re: dumb question about cams
« Reply #2 on: July 18, 2013, 08:03:55 PM »
thanks I will give it a shot w/o replacing the gasket and cross fingers, its a composite gasket with steel ring by cylinders

haven't ordered the cam yet, trying lighter rollers first, then placing order, probably getting cdi without rev limit too. yesterday i drilled out the air box and exhaust and it was way lean even with 95 jet, and mixture screw is now about 3.5 turns out may need a new pilot jet. installed a 105 main and its better but rpms are down.

its averaging about 7000 from 0-30 mph with 6.5g rollers, think the mods shifted the power band up in rpm, have 5g weights on order to get the revs up

i figure since the a9 is a top end cam and power band seems to be up already, the light rollers will get me a better boost

part of the reason i ask about the gasket is i can't find a 72cc head gasket by itself, just stock size or as a part of a full gasket kit or bbk so hope it seals well
Agility 50 w/72cc BBK, A9 cam, stock airbox and exhaust (both drilled out), remove air tube restriction, stock head, stock carb, 105 main jet, CDI cut, smooth variator boss, stock variator w/5g rollers

reg

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Re: dumb question about cams
« Reply #3 on: July 18, 2013, 09:48:45 PM »

phatboy

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Re: dumb question about cams
« Reply #4 on: July 19, 2013, 07:42:33 PM »
bought the a9 cam, should be here next week. will let you all know how it goes.

Agility 50 w/72cc BBK, A9 cam, stock airbox and exhaust (both drilled out), remove air tube restriction, stock head, stock carb, 105 main jet, CDI cut, smooth variator boss, stock variator w/5g rollers

phatboy

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Re: dumb question about cams
« Reply #5 on: July 20, 2013, 02:50:08 AM »
5g weights came today, installed and rpms average 8000-8500, it must be above the powerband because scoot is slower all around, but i'm keeping the weights on until the a9 cam comes, we'll see if the power band gets shifted into the new rpm range. will report back next week when it's supposed to come.

so far none of these mods are making much of a difference, i mean hill climbing is better but i'm getting like 2-3 MPH improvement. seriously thinking about going all out.

will a 52mm bbk fit on these kymcos? I'm reading that some need machining on the case, I don't care to do that.

Agility 50 w/72cc BBK, A9 cam, stock airbox and exhaust (both drilled out), remove air tube restriction, stock head, stock carb, 105 main jet, CDI cut, smooth variator boss, stock variator w/5g rollers

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