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 RPMs 
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MMT Pro Member

Joined: Mon Dec 05, 2016 11:59 am
Posts: 219
Location: Panhandle of Florida
Post RPMs
Don't know if I have a bad BPS Tach on my brand new MB 440 HDR or what. I've asked and googled everything on this motor. It idles high (well I think anyhow) and the WOT RPMs are in the 8Ks ..... I have it set to 1spk to 1, It seems to idle fast,,, 1150-1300 at WOT it is 7000-8300,,, is there something wrong with this thing or way... I have 8hrs on the motor

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1754 Gator Trax Hybrid, Hunt Deck ,with MB 4400 Black Death HDR, Duck Slaying, Mud Slingin Machine!!!


Mon Feb 27, 2017 7:45 am
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Joined: Mon Dec 31, 2012 11:07 pm
Posts: 4820
Location: West Monroe, LA
Post Re: RPMs
Idle should be somewhere between 1100-1500. Max rpms should be around 4300 or 4750 depending on coils. Should be set on 1 and 2, I think. This aftermarket tach I have is set on that and reports correctly.


Mon Feb 27, 2017 7:55 am
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MMT F.E.
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Joined: Tue Aug 26, 2014 10:36 am
Posts: 822
Location: Jefferson TX
Post Re: RPMs
Must not be a Tiny Tach? Mine is set at 360 which is 1 spark per revolution. Also look at the number of wraps on plug wire, 3-4 is all that is needed, I have 3 and my cable is 12 ft long and works.

you should, with a mikuni, be able to adjust idle lower(750 for me in neutral), make sure that your throttle cable is letting the carb come back to a idle position. I made sure that when throttling all the way down there is cable slack at the carb.

8k rpms, is really high on rpms.

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Mon Feb 27, 2017 8:38 am
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Joined: Mon Dec 31, 2012 11:07 pm
Posts: 4820
Location: West Monroe, LA
Post Re: RPMs


Mon Feb 27, 2017 9:16 am
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MMT F.E.
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Joined: Tue Aug 26, 2014 10:36 am
Posts: 822
Location: Jefferson TX
Post Re: RPMs

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SEAARK FX 2472 CC Merc 150HP 4Stroke(CypressCadillac)
Uncle J Custom - 19x54 CC Skiff w/40XD GTR


Mon Feb 27, 2017 10:27 am
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MMT Pro Member

Joined: Mon Dec 05, 2016 11:59 am
Posts: 219
Location: Panhandle of Florida
Post Re: RPMs
Thanks, guys,,, I have 4 turns on now,,, I will take a wrap off and see what that does... Any no it's not a Tiny Tach its the BPS that comes on the 4400... At 10hrs. I will check the valves lash and also change out the break in oil and put my Mobil 1 syn. oil in her....

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Lead, Follow or Get The Hell Out Of The Way!!!!
1754 Gator Trax Hybrid, Hunt Deck ,with MB 4400 Black Death HDR, Duck Slaying, Mud Slingin Machine!!!


Mon Feb 27, 2017 10:33 am
Profile YIM
MMT Pro Member

Joined: Mon Dec 05, 2016 11:59 am
Posts: 219
Location: Panhandle of Florida
Post Re: RPMs
wound up having to take ALL the wraps off with the exception of 1. Now for the first time, I'm reading the REAL RPMs... Thanks guys...

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Lead, Follow or Get The Hell Out Of The Way!!!!
1754 Gator Trax Hybrid, Hunt Deck ,with MB 4400 Black Death HDR, Duck Slaying, Mud Slingin Machine!!!


Tue Feb 28, 2017 8:43 pm
Profile YIM
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Joined: Mon Dec 05, 2016 11:59 am
Posts: 219
Location: Panhandle of Florida
Post Re: RPMs
Well,, I reached the 10hrs on this MB4400 and set the valves at .005 drained the break in oil out, changed the oil filter, put new oil in, and just came back from a test run.

She runs smoother then before, and I increased my speed from 29 mph to 31 mph. and my RPMs at WOT was 4110 and now it's 4300,,,, I can't believe it, but she runs even better now....

Thanks again for every bodies advice, greatly appreciate it!!!!!!

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Lead, Follow or Get The Hell Out Of The Way!!!!
1754 Gator Trax Hybrid, Hunt Deck ,with MB 4400 Black Death HDR, Duck Slaying, Mud Slingin Machine!!!


Sat Mar 04, 2017 3:41 pm
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