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Author Topic: Front end ringing sound at top of the RPMs  (Read 707 times)

chumma7

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Re: Front end ringing sound at top of the RPMs
« Reply #15 on: May 09, 2014, 01:55:47 PM »
Hey man,
As long as your bike was dead on TDC when you installed that powerarc disc (and the disc didnt move when you tightened down the allen bolt) than there's no need to try to manually retard it right now.
The first priority would be to get that exhaust sealed. I make my own exhaust gaskets out of .005" sheets of copper which I purchase in bulk. You could make something similar out of aluminum foil. Wrap the end of the pipe in the foil till it fits snug into the cylinder. For larger gaps, a chopped up beer can do the job.
After sealing the head, take a few test rides. Get the bike to full operating temps and give it the guns, if it still pings than start bumping up the main jet till it smooths out. Sort out the main jet first before dialing in the other circuits. I'm not familiar with jetting on a 30mm flat slide so I cant give you numbers. Is it a mikuni tm30? or keihen variant?  The 38 pilot does seem like a large number for a pilot but I know from experience the powerarc has a tendency to require rich pilot jetting in order to maintain easy starting. If the bike doesn't feel squiggly (searches and surges) while maintaining 1/3 to 2/3 throttle and throttle response is good than your needle and needle jet are good.
Also forgot to mention, you should be running a ngk br8es plug with that powerarc and not a b8es(non resistor) or a br7es/b7es(too hot) or a bpr8es (projected tip plug). The br8eix (iridium) plug does well with powerarcs.
« Last Edit: May 09, 2014, 01:58:48 PM by chumma7 »
ACE Fireball 001

Nixie

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Re: Front end ringing sound at top of the RPMs
« Reply #16 on: May 09, 2014, 04:16:26 PM »
Sorry to thread - jack but is there anything particularly bad with using a bpr7es plug on my fireball? I haven't fully tuned it up yet and I'm not using a power arc, but a trispark. Everything seems good but I don't want to damage anything! Pardon my ignorance..


chumma7

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Re: Front end ringing sound at top of the RPMs
« Reply #17 on: May 09, 2014, 05:50:03 PM »
Sorry to thread - jack but is there anything particularly bad with using a bpr7es plug on my fireball? I haven't fully tuned it up yet and I'm not using a power arc, but a trispark. Everything seems good but I don't want to damage anything! Pardon my ignorance..



Using a bpr7es plug would be potentially fatal for a fireball for 2 reasons.
The first reason being that the 7 heat range is too hot a plug for a stock bike let alone a high compression setup like the fireball. The flame front on a high compression bike burns hotter already so introducing the hotter plug creates the perfect situation for preignition and/or detonation.
The second reason being the p designation which stands for 'projected tip'. A projected tip sparks deeper into the combustion chamber, essentially advancing the flame front. It ignites the mixture sooner in the combustion chamber during the compression stroke. This alone is not desirable on a fireball setup but combined with a 7 heat range plug, it's a double whammy.
The projected bp8es/brp8es is sometimes beneficial on stock setups that arent driven at higher rpms because it allows the need for less advance creating easier starting as well as giving a low rpm boost in torque at the tradeoff of ragged higher rpm running. A br8es is better on stock setups where the entire revrange is used.
 A high compression motor naturally needs less advance to efficiently burn it's mixture so the projected tip does no good and can only do harm.
Now, I am sure you havent done any damage to your motor. You're probably still running it, doing short runs which should include short acceleration and deceleration bursts, while not holding the throttle wide open or keeping it pegged in one rpm for long. Also your rings probably haven't yet built up enough cylinder compression yet to really force a catastrophe but do swap those plugs asap before they do.
The trispark is a digital electronic ignition which requires a resister plug to function so the br8es or br8eix is what would be best.
The powerarc and the boyer micro digital are also digital setups which require resister equipped plugs. The boyer mk3 and mk4 are analog/solid state units which do well without suppressed plugs. As do points of course.
« Last Edit: May 09, 2014, 06:11:01 PM by chumma7 »
ACE Fireball 001

Nixie

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Re: Front end ringing sound at top of the RPMs
« Reply #18 on: May 10, 2014, 05:38:03 AM »
Thx dude, my bike was run with bp7es before I git it by PO,  so I just got a resistive version to go with the trispark, I will sort it out!

Thanks  :-[

ace.cafe

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Re: Front end ringing sound at top of the RPMs
« Reply #19 on: May 10, 2014, 05:59:21 AM »
Thx dude, my bike was run with bp7es before I git it by PO,  so I just got a resistive version to go with the trispark, I will sort it out!

Thanks  :-[
Yes, please do.
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