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Post by ital on Apr 27, 2015 22:21:29 GMT -5
Hi All, bought a digital tachometer with a battery so it only needs spark plug signal. Had a quick questions to set this up. Do our engines fire 1 spark per 2 revolutions?
Thank you
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Post by lain on Apr 27, 2015 22:31:01 GMT -5
en.wikipedia.org/wiki/Four-stroke_engineDepending on what your definition of revolution is. Yes the crank revolves and move the piston in and out twice per spark, but some might argue that the full cycle for the 4 stroke even though it spins twice is one revolution.
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Post by geh3333 on Apr 27, 2015 22:40:58 GMT -5
Hi All, bought a digital tachometer with a battery so it only needs spark plug signal. Had a quick questions to set this up. Do our engines fire 1 spark per 2 revolutions? Thank you Some of the TACHS have different settings . |
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Post by ital on Apr 27, 2015 23:55:00 GMT -5
well, I installed it. Did not touch it and it seemed accurate out of the box so I am not messing with it. Tested idle only, but on idle i was around 2k RPM on start up while it was worming up and then it dropped all the way down to about 1300 RPM for a second or two and then settled around 1700RPM when fully warmed... sounds ok to me...
I will post some picks of it and let you know the rpm while driving...
Thank you - Luigi
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Post by ital on Apr 28, 2015 0:07:04 GMT -5
Here are some pics. Had to mount it below steering as wire was a bit too short. It is also water proof not that I leave it outside or drive in the rain but its a good option to have. URL=http://s33.photobucket.com/user/dicostal/media/Mobile%20Uploads/20150428_004307.jpg.html]  [/URL] |
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Post by ital on Apr 28, 2015 0:08:34 GMT -5
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Post by geh3333 on Apr 28, 2015 0:09:35 GMT -5
well, I installed it. Did not touch it and it seemed accurate out of the box so I am not messing with it. Tested idle only, but on idle i was around 2k RPM on start up while it was worming up and then it dropped all the way down to about 1300 RPM for a second or two and then settled around 1700RPM when fully warmed... sounds ok to me... I will post some picks of it and let you know the rpm while driving... Thank you - Luigi I suggest tuning the carb and seeing how far down the idle will drop before it shuts down . 2000 rpms at at warm up is a little low , at least in my experience. If your scoot idles near 1000 rpms or below and doesn't stall , then the gauge is set wrong . |
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Post by geh3333 on Apr 28, 2015 0:11:47 GMT -5
TBA , if you can post a video of he scoot warming up and idling , I can usually tell about what rpm its at . let's say the rpms gauge says 1700 , if I hear the scoot in the video ,I can more then likely tell you if the tack is right.
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Post by geh3333 on Apr 28, 2015 0:15:07 GMT -5
Not that long ago , a member had an issue and ordered an rpm tach. He posted a few videos and his tach was reading between 2-3k rpms . everyone was trying to help him out, but once I heard the scoot idle in the video , I told him that there was no way his scoot was Idling that high. It sounded much lower. Turned out he had it on the wrong setting.
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Post by ital on Apr 28, 2015 0:18:35 GMT -5
Not that long ago , a member had an issue and ordered an rpm tach. He posted a few videos and his tach was reading between 2-3k rpms . everyone was trying to help him out, but once I heard the scoot idle in the video , I told him that there was no way his scoot was Idling that high. It sounded much lower. Turned out he had it on the wrong setting. OK I will get a video of it. Perhaps tomorrow. It did go as high as 2400 rpm but just for a few seconds... Thanks |
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Post by ital on Apr 28, 2015 0:19:56 GMT -5
Also at 1300 rpm my scoot is about to stall any lower it will shut off...
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Post by geh3333 on Apr 28, 2015 0:34:00 GMT -5
Also at 1300 rpm my scoot is about to stall any lower it will shut off... That sounds about right. That's actually pretty good , not many can get their scoots to idle that low without stalling. When mine is tuned just right it stalls about the same rpm between 1300-1500 rpms. |
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Post by ital on Apr 28, 2015 9:37:21 GMT -5
geh3333, I took a video but I am not on wifi right now and I cannot upload it, but I will as soon as I can. Anyway Played with the settings and the best one was 1 spark per Revolution even though according to the instruction for 4 cycle one cylinder it should be 1 spark 2 revs but my scoot did not like that setting as it stated it was idling @ 4k rpm.. :-) went for a quick spin to check RPM and I am a bit disappointed that RPM seemed to be perfect... I was hoping to be able to lower roller weights a bit but I am not sure it is possible.... On take off I was just @7k RPM and then RPM would stay at around 6500 RPM all the way up to 55MPH and then peak about 7200 RPM at 60 MPH. I am on 12 Grams Rollers, wanted to try perhaps 11 Grams DR pulley sliders but I think I would reving to high... Opinions? those are not GPS speeds... so take that with a grain on salt.. MPH are a bit off. Thank you
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Post by geh3333 on Apr 28, 2015 10:59:16 GMT -5
You have enough room to go with 11.5 grams rollers. That should get you up around 7500 7700 RpmS . you have to stagger 12 and 11 grams weights.
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Post by geh3333 on Apr 28, 2015 11:02:13 GMT -5
You have enough room to go with 11.5 grams rollers. That should get you up around 7500 7700 RpmS . you have to stagger 12 and 11 grams weights. Your powerband is around 7500 rpms . that's where your pulling your top horse power. Its nice to be able to reach it on straight runs. |
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