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| New Prop, RPM drop https://www.mudmotortalk.com/mmt_v2/viewtopic.php?f=6&t=62572 |
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| Author: | Duckaholic-Anonymous [ Wed Jul 08, 2015 12:03 am ] |
| Post subject: | New Prop, RPM drop |
Tried finding an answer to this elsewhere, had no luck. Recently switched to a backwater 9x8 prop from the stock Beavertail 9x6. I don't have a tach but RPMs dropped and speed went from 17mph to maybe 12. I took the throttle cable off to disassemble the entire motor/frame to install a new shaft/yoke so I wonder if I installed the cable back incorrectly. This doesn't seem right though because when I push my throttle WOT on the control, there's no more pull in the throttle, but I can push on the governor or some mechanism next to the carb and the RPMs fire right back up. Do I just need to adjust the governor? Hope someone else has had this issue before. Thanks! Sent from my iPhone using Tapatalk |
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| Author: | SwampDonkey1 [ Wed Jul 08, 2015 12:48 am ] |
| Post subject: | Re: New Prop, RPM drop |
What engine are you working with? If i read what your saying correctly, the throttle arm on the engine gets 100% travel when the lever on the handle is in engaged; but the engine will not throttle up all the way; and you can increase the RPMs by bumping the governor arm? If you can increase the throttle by bumping the governor arm sounds like something is thrown outta whack with your throttle cable... Sounds like it was reinstalled incorrectly... especially if everything was good before disassembly... |
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| Author: | LB200 [ Wed Jul 08, 2015 5:07 am ] |
| Post subject: | Re: New Prop, RPM drop |
I cannot answer the throttle question but it sounds like you have too much prop for the motor. Going from a 6 to an 8 is a lot more added bite. With out a tach it is hard to know but it would be helpful to know if your out of water RPMS have changed dropped too or if it is just under load.. |
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| Author: | Duckaholic-Anonymous [ Wed Jul 08, 2015 6:59 am ] |
| Post subject: | Re: New Prop, RPM drop |
Motor is 35 HP, same motor that backwater puts that 9x8 prop on. I'll jack with the throttle cable a little more, but it's odd that it was fine before and not anymore. I could always put the old prop on as a test. Sent from my iPhone using Tapatalk |
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| Author: | SwampDonkey1 [ Wed Jul 08, 2015 10:47 am ] |
| Post subject: | Re: New Prop, RPM drop |
Heres a question... Is the difference while on the water or are you test running out of the water... If you can bump the rpms while underway in the water Id say its a cable issue (like LB said a pitch bump like that is pretty steep)... If you are just running while tailored and you bypass the governor you could easily be just over-revving the engine... A tach will also tell you right away what the issue is... |
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| Author: | SETx Longtail [ Wed Jul 08, 2015 11:04 am ] |
| Post subject: | Re: New Prop, RPM drop |
Really really need a tach on it. |
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| Author: | MaXXis85 [ Wed Jul 08, 2015 12:04 pm ] |
| Post subject: | Re: New Prop, RPM drop |
Here is how I set my throttle cable. Tape or tie the throttle lever in the wot position. Loosen the casing clamp on the control bracket and pull the cable sheath so that it is pulling on the slide that pulls the governor arm/ throttle linkage. Make sure you see the butterfly arm on the throttle opening fully. Then check WOT RPM with a tach to verify. |
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| Author: | Duckaholic-Anonymous [ Wed Jul 08, 2015 2:48 pm ] |
| Post subject: | Re: New Prop, RPM drop |
Thanks guys. I'm being cheap and need to buy a tach, just don't want to get anything but a tiny tach for fear of inaccurate cheapos Sent from my iPhone using Tapatalk |
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| Author: | SwampDonkey1 [ Thu Jul 09, 2015 8:39 am ] |
| Post subject: | Re: New Prop, RPM drop |
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