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| How many rpms are a safe number to be turning? http://mudmotortalk.com/mmt_v2/viewtopic.php?f=3&t=10712 |
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| Author: | bbb [ Wed Jul 07, 2010 6:14 am ] |
| Post subject: | How many rpms are a safe number to be turning? |
I got my rpm issue fixed by changing to a 2 blade. Now I can trim the motor up without the prop blowing out and can actually see 3850-3950rpms. Question is, I'm not use to "hearing" this many rpms and I'm kinda cautious about running it like that. I have the CDI motor with the built in Rev limiter and to my knowledge have not hit the limiter yet. But I've also been watching the tach trying to stay off 4000 rpms. Lets say the sweet spot on a stock motor was 4000rpms. Is it really safe running these rpms for 10-20 minutes straight? Should I keep it down in the 3850 range and only use higher rpms sparingly. I guess with a 2 year warranty I should run it like I stole it. |
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| Author: | MaXXis85 [ Wed Jul 07, 2010 6:53 am ] |
| Post subject: | Re: How many rpms are a safe number to be turning? |
dont go above the 4200 mark and run that engine wfo. With a stock motor doubtful you will see over 4k with a load on the prop. Seriously man theres enough info on here to tell you that. |
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| Author: | UNCLE-J [ Wed Jul 07, 2010 7:04 am ] |
| Post subject: | Re: How many rpms are a safe number to be turning? |
I turned 4600-5k. Never blew anything, but think I just had baby Jesus on my side. God Bless, Uncle J |
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| Author: | OwenDickeson [ Wed Jul 07, 2010 2:47 pm ] |
| Post subject: | Re: How many rpms are a safe number to be turning? |
turnin 4k rpms is just fine...The rev limiter is set just a hair above 4300. Run it WFO. |
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| Author: | DeuceChunker [ Wed Jul 07, 2010 3:17 pm ] |
| Post subject: | Re: How many rpms are a safe number to be turning? |
I stay around 4100 RPMs and haven't had a lick of trouble. KP said they generally run between 4000 and 4100, so I'd say you're good to go. |
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| Author: | dog walker [ Wed Jul 07, 2010 3:28 pm ] |
| Post subject: | Re: How many rpms are a safe number to be turning? |
Survey says,4000-4150 |
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| Author: | bbb [ Wed Jul 07, 2010 4:08 pm ] |
| Post subject: | Re: How many rpms are a safe number to be turning? |
Thanks, sorry for the dumb question but I've been in the mud motor club since 1997 and I've owned a 6hp, 16hp, 25hp, 27hp, 31hp and now a 35hp mud motor and in the water, under a load, I have never had one that would run more than 3600 rpms. This is a new sound for me and I wanted to make sure it was an ok sound. I stopped trimming the motor up when I hit 3900 rpms. |
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| Author: | keestan31 [ Wed Jul 07, 2010 6:29 pm ] |
| Post subject: | Re: How many rpms are a safe number to be turning? |
I try to keep mine between 4000 and 4200 like everyone else has said...this seems to be a pretty common answer from the guys on here that have experienced the KABOOM |
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| Author: | Tenpoint [ Wed Jul 07, 2010 6:32 pm ] |
| Post subject: | Re: How many rpms are a safe number to be turning? |
On these motors, the HP rating is at 3600 RPM. You can run it at what these guys are tellin you if you have to. My motor runs fastest at about 3750 light and about 3550 to 3600 loaded. I can trim up and turn 4100 but it loses speed. RPMs dont always equal speed. GPS it while playin with the trim and see where it runs best. I can turn 3600 and pass up someone turnin 4200 if their prop is just throwin water for nothing. |
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| Author: | bbb [ Wed Jul 07, 2010 6:45 pm ] |
| Post subject: | Re: How many rpms are a safe number to be turning? |
My best rpm speed monday in the boat alone was 3870 and it went as high as 3950 without a drop in speed. Sunday with my wife and 3 small kids, best speed came at 3750. Doubt I ever hit the limiter, unless I buy the Mikuni and MM exhaust. |
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| Author: | Tenpoint [ Wed Jul 07, 2010 6:47 pm ] |
| Post subject: | Re: How many rpms are a safe number to be turning? |
| Author: | deadbird8 [ Wed Jul 07, 2010 7:00 pm ] |
| Post subject: | Re: How many rpms are a safe number to be turning? |
On a stock motor you can run up to 4300 without shimmed valve springs, usually set the governor at 4250 OOW. I had a freaky hot motor for my last one and it would run 4350 in the water with only a K&N air filter and high flow exhaust. I ran that motor over 200 hours. My best speed on my stock CDI was at 4150 . The electronic rev limiter is 4300 built into the coils and its a smooth take down of RPM (better than the box limiter). You have nothing to worry about running anywhere under 4300. Briggs has a 2 year warranty on it (going to 3yrs this month) so its not a grenade up to that range- there is a buffer for sure and you have to be up around 4400 before the valves float (a little different on every motor). |
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| Author: | dog walker [ Thu Jul 08, 2010 4:47 am ] |
| Post subject: | Re: How many rpms are a safe number to be turning? |
My best speed on my stock motor was at just over 4100. I cracked a block on a modded motor that never went over 4400 and was only turning 3900 when she went. |
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| Author: | MaXXis85 [ Thu Jul 08, 2010 6:47 am ] |
| Post subject: | Re: How many rpms are a safe number to be turning? |
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