Author Topic: What's happening on this dyno sheet?  (Read 671 times)

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Offline jjdalynh

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What's happening on this dyno sheet?
« on: September 18, 2019, 03:28:37 PM »
i happened to switch the smoothing from 5 to 1 and see some severe wiggle happening from 5000-5500rpm....  no pinging recorded, but something doesn't look right.  the AFR readings do creep up higher than what's commanded (~0.5).  The timing on front cylinder increases from 19.75 to 22.25 deg. in that rpm range.

what is this an indication of?

Offline Ohio HD

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Re: What's happening on this dyno sheet?
« Reply #1 on: September 18, 2019, 04:17:54 PM »
Could a lot of that be due to the SAE smoothing set to 1? Does it run bad, or just look bad?
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Offline jjdalynh

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Re: What's happening on this dyno sheet?
« Reply #2 on: September 18, 2019, 04:36:19 PM »
it runs fine (at least on the dyno), i'm just wondering if this means something specific.  seems like more than just a glitch.   i have a bunch of separate runs with slightly differing VEs (spark stays same) and they all have it.

Offline Jamie Long

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Re: What's happening on this dyno sheet?
« Reply #3 on: September 19, 2019, 07:14:56 AM »
i happened to switch the smoothing from 5 to 1 and see some severe wiggle happening from 5000-5500rpm....  no pinging recorded, but something doesn't look right.  the AFR readings do creep up higher than what's commanded (~0.5).  The timing on front cylinder increases from 19.75 to 22.25 deg. in that rpm range.

what is this an indication of?

Either RF interference thru the inductive spark lead or more likely a driveline harmonic; primary chain or if the bike has a chain drive conversion. 

Offline jjdalynh

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Re: What's happening on this dyno sheet?
« Reply #4 on: September 19, 2019, 02:02:05 PM »
hm.  i've gotten it on 2 different bikes.  another sheet i reviewed didint. 

Offline Herko

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Re: What's happening on this dyno sheet?
« Reply #5 on: September 20, 2019, 06:02:13 AM »
As we know, the shorter sharp teeth are typical when smoothing set to 1.
The long teeth at 5100 to 5500 are due to what Jamie said.
But,
“hm.  i've gotten it on 2 different bikes…”
If the dame Dyno was used, then there’s a high probability that the electrical noise interference (long teeth at 5100 to 5500) is coming from the Dyno. Improper grounding of the Dyno plays a big role here.

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Offline jjdalynh

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Re: What's happening on this dyno sheet?
« Reply #6 on: September 20, 2019, 12:00:45 PM »
As we know, the shorter sharp teeth are typical when smoothing set to 1.
The long teeth at 5100 to 5500 are due to what Jamie said.
But,
“hm.  i've gotten it on 2 different bikes…”
If the dame Dyno was used, then there’s a high probability that the electrical noise interference (long teeth at 5100 to 5500) is coming from the Dyno. Improper grounding of the Dyno plays a big role here.

as it is right now, i have the dyno in my garage attached to a 100A sub.  the main building is a 200A, with 2 separate ground rods and the 100A sub has it's own ground rod.  the 30A ckt for the dyno is about 24'.  then the standard length whip from the dyno itself.

is there any internal grounding in the dyno itself i should check ?  or do folks run a separate ground strap for the dyno beyond the whip?  the ground lug from the dyno to the bike is only connected with a small gauge wire with the simple spring-loaded copper clamps (like for battery tenders) to a bolt on the engines (either rocker bolt or top engine mount)  should i look to something else?

Offline harleytuner

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Re: What's happening on this dyno sheet?
« Reply #7 on: September 23, 2019, 12:35:45 PM »
As we know, the shorter sharp teeth are typical when smoothing set to 1.
The long teeth at 5100 to 5500 are due to what Jamie said.
But,
“hm.  i've gotten it on 2 different bikes…”
If the dame Dyno was used, then there’s a high probability that the electrical noise interference (long teeth at 5100 to 5500) is coming from the Dyno. Improper grounding of the Dyno plays a big role here.

as it is right now, i have the dyno in my garage attached to a 100A sub.  the main building is a 200A, with 2 separate ground rods and the 100A sub has it's own ground rod.  the 30A ckt for the dyno is about 24'.  then the standard length whip from the dyno itself.

is there any internal grounding in the dyno itself i should check ?  or do folks run a separate ground strap for the dyno beyond the whip?  the ground lug from the dyno to the bike is only connected with a small gauge wire with the simple spring-loaded copper clamps (like for battery tenders) to a bolt on the engines (either rocker bolt or top engine mount)  should i look to something else?

there's a angle tab on the front left top side of the dyno, ground that to a ground rod, then clamp a ground from that directly to the bike (motor mount works well) and if you are using the inductive pickup that goes over the plug wire clamp the ground strap from that with the one you just clamped on the frame.
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Offline jjdalynh

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Re: What's happening on this dyno sheet?
« Reply #8 on: September 24, 2019, 05:17:43 PM »
thanks chad, i'll give it a shot.  now that riding season is winding down a little, folks are starting g to come in.