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Post by brancher on Apr 19, 2012 18:26:14 GMT -5
what does it sound like? mine makes a knocking sound when i let of the gas a little going fast (50mph) and when i go slow (30mph) and give it a little gas. runs great. (sorry dont have a tach). plug looks good-bpr7hs I have head gasket removed and cyl. gasket removed. .68mm squish. 160psi compression. running 93 gas 03 zuma 70cc kit athena leo hm pipe 5oz weights athena var.
do i need to put the cyl gasket back in? maybe switch to a 8 plug? if so which one?
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Post by one1 on Apr 19, 2012 18:37:38 GMT -5
on a 2 stroke it sounds like a handful of quarters being jingled to the speed of the engine.
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Post by jmkjr72 on Apr 19, 2012 18:44:28 GMT -5
you need a br9hs if you are running a zuma with an athena kit
with a .68mm squish and a bpr7hs you should be glad you didnt run the piston into the spark plug
i would pull the head and check for damage to the piston
also if you want that kit to live you will need at least a 17.5mm carb and what leo hm pipe all of there pipes claim to be hand made there is the tt zx zxr and the 70 pipe that all claim to be hand made if its the true 70 pipe you need to watch the revs running above 10,500 will kill the oem zuma crank
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Post by 90GTVert on Apr 19, 2012 18:45:48 GMT -5
I usually describe it as a rattle inside the engine.
Since it's when you roll on or off the throttle you might give raising the needle (lowering the clip a notch) a shot. Might help, might not do anything. It's free and reasonably quick to try though. Not a bad idea anyway. You really don't want an aluminum kit to run lean at part throttle (or anywhere for that matter).
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Post by 2strokd on Apr 19, 2012 19:07:59 GMT -5
I agree with jmk and Brents advice. As well as running with no base will leave the port durations low. With that kit and that pipe ide be shooting for at least 175-180degrees ex. duration and around 125-130trans (at least). I really dont think you will see anywhere near these numbers without a base?
If you can degree the port duration and get it timed, i think you will be very happy!?!
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Post by brancher on Apr 19, 2012 19:10:04 GMT -5
it is the 70 hm ill get a plug tomorrow and try it i got a 21mm carb sitting here i will put on tonight.
thanks for the quick replys.
also i have the athena crank. do you think it will hold up to the higher revs?
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Post by jmkjr72 on Apr 19, 2012 19:26:13 GMT -5
yes the athena crank should be fine
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Post by brancher on Apr 19, 2012 21:07:16 GMT -5
I agree with jmk and Brents advice. As well as running with no base will leave the port durations low. With that kit and that pipe ide be shooting for at least 175-180degrees ex. duration and around 125-130trans (at least). I really dont think you will see anywhere near these numbers without a base? If you can degree the port duration and get it timed, i think you will be very happy!?! I'm still trying to figure the whole timing thing out. I printed off the wheel and the tech page. I'm still not 100% sure how to do it. Maybe I'm slow. So you shim the cylinder to get the timing right?
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Post by jmkjr72 on Apr 19, 2012 21:52:14 GMT -5
yes once set at tdc zero it out turn till the port starts to open X2 and -360 and thats your port duration heck you can even do it with a caliper www.torqsoft.net/piston-position.htmland besides squish you use the base gasket to adjust your timings to where you need to get them and once you got your timings right if the squish is too high you mill the top of the cyl
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Post by brancher on Apr 20, 2012 16:09:32 GMT -5
yes once set at tdc zero it out turn till the port starts to open X2 and -360 and thats your port duration heck you can even do it with a caliper www.torqsoft.net/piston-position.htmland besides squish you use the base gasket to adjust your timings to where you need to get them and once you got your timings right if the squish is too high you mill the top of the cyl Ok thanks Getting ready to try it.
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Post by brancher on Apr 20, 2012 17:32:15 GMT -5
dont get me wrong i love to figure things out, but this is confusing. ex-184 in-120 added 20mm shim ex-185 in-122 .88 squish 130psi so i think i need file piston or head? i think i maybe over my head
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Post by jmkjr72 on Apr 20, 2012 17:59:30 GMT -5
ill give you an idea most of the guys over on zf are running the thinest base gasket with the kit and the head gasket and running a .9 to 1.1 mm squish
so it sounds like you are in the ball park
if you file the piston in the area of intake ports you can raise that intak duration just a bit but it wont take much work on the piston
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Post by brancher on Apr 20, 2012 20:17:08 GMT -5
ill give you an idea most of the guys over on zf are running the thinest base gasket with the kit and the head gasket and running a .9 to 1.1 mm squish so it sounds like you are in the ball park if you file the piston in the area of intake ports you can raise that intak duration just a bit but it wont take much work on the piston what compression are they? if i put the head gasket on i drop down to 110? i tried my friends too while he was here and his did the same thing.
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Post by jmkjr72 on Apr 20, 2012 20:36:09 GMT -5
about 140 psi cranking warm
that is unless they own the pos comprsion gauge from harobor freight
you have been running this bore on a stock zuma carb for how many miles with a bpr7hs plug i see dates back to last aug with your posts about issues
if thats the case your proably ready for at least a new ring if not a new ring and piston and if you ever soft seized this kit they dont take well to being soft seized
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Post by brancher on Apr 20, 2012 20:43:24 GMT -5
about 140 psi cranking warm that is unless they own the pos comprsion gauge from harobor freight you have been running this bore on a stock zuma carb for how many miles with a bpr7hs plug i see dates back to last aug with your posts about issues if thats the case your proably ready for at least a new ring if not a new ring and piston and if you ever soft seized this kit they dont take well to being soft seized i had it on a sinski scooter since last summer. i but it on the zuma with a new piston/rings two weeks ago with a new athena crank.(i notice rod had play and it had 8000 on it)
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