Don't know what caused it to drop a valve?
Reving a 3500 RPM LAWNMOWER MOTOR to 5000 + would be a good bet
Just sayin'
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| Loosing rpms/compression? http://mudmotortalk.com/mmt_v2/viewtopic.php?f=3&t=18762 |
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| Author: | Caleb W. [ Mon May 23, 2011 10:13 pm ] |
| Post subject: | Loosing rpms/compression? |
I have a stage 1 23 mini, with a gear reduction and a big blade. It can rev 5000+ OOW but by myself I can safely run 4300ish in the water and hit 27-28mph. However here lately Ive lost some rpms somewhere. The engine runs steady, no problems, its just like im running less throttle. It isnt opening up. It will spin like a wildcat out of water but in the water by myself Im in the upper 3s, about 4-500 less than what I should. This also reflects proportionately down the line with loads. Where should I start looking? Whats a list of things I could rule out? Thanks for the help. |
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| Author: | craig [ Mon May 23, 2011 10:51 pm ] |
| Post subject: | Loosing rpms/compression? |
Compression check and a Leak down test should be first. |
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| Author: | Team Camo [ Mon May 23, 2011 11:07 pm ] |
| Post subject: | Re: Re: Loosing rpms/compression? |
| Author: | after elk [ Tue May 24, 2011 10:30 am ] |
| Post subject: | Re: Loosing rpms/compression? |
Might want to check and make sure that your throttle cable hasn't stretched a bit. I had a Hyper that had a stretched cable and didn't make full power. |
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| Author: | Durty [ Thu May 26, 2011 3:16 pm ] |
| Post subject: | Re: Loosing rpms/compression? |
That's exactly what I experienced a month ago right before dropping a valve. When I cracked the left head, the valve retainer was in 3 pieces and the intake valve was bent and stuck in the open position. Not saying that's your problem at all because honestly, I do not know what caused mine to do this. However, I lost rpms with the prop in the water and when I brought it out of the water I had most of my rpms back. And then when I would put it back in the water, I would lose almost all my power again. |
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| Author: | Mike W. [ Sun May 29, 2011 3:56 am ] |
| Post subject: | Re: Loosing rpms/compression? |
Don't know what caused it to drop a valve? Reving a 3500 RPM LAWNMOWER MOTOR to 5000 + would be a good bet Just sayin'
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| Author: | pooldoo73 [ Sun May 29, 2011 4:49 pm ] |
| Post subject: | Re: Loosing rpms/compression? |
The 5000+ rpm oow is likely the problem. U likely have internal engine issues. |
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| Author: | Caleb W. [ Mon May 30, 2011 1:42 am ] |
| Post subject: | Re: Loosing rpms/compression? |
Ive never sat there and done that or had my eye on the the tach when it did do that. All I know is it doesnt sound like its stopping anytime soon when I pump it to 46-4700ish. Its never been held down and gassed. |
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| Author: | pooldoo73 [ Mon May 30, 2011 4:17 pm ] |
| Post subject: | Re: Loosing rpms/compression? |
Has the prop ever kicked up out of the water when u had it wide open? U only have to do that once without a rev limiter to toast an engine. |
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| Author: | Durty [ Tue May 31, 2011 8:20 pm ] |
| Post subject: | Re: Loosing rpms/compression? |
| Author: | dguidry [ Tue May 31, 2011 9:19 pm ] |
| Post subject: | Re: Loosing rpms/compression? |
Vanny23, gear reduction, big blade prop, 4000+ rpms in water and bumping higher occasionally...expect trouble, I'm thinking. I run constant 3500 rpms lately with load and am thrilled. Finally my tach is stable after retwisting the spark plug wire a few extra times. |
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| Author: | Caleb W. [ Tue May 31, 2011 9:29 pm ] |
| Post subject: | Re: Loosing rpms/compression? |
Heck, stock it ran 4310-4320 OOW and 4100 by myself. |
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| Author: | fowl habbit [ Wed Jun 01, 2011 9:38 am ] |
| Post subject: | Re: Loosing rpms/compression? |
Just the other day I was siitin at the dock waitin for the wife to park the truck and I reached abck and realized that my carb wasn't opening up all the way it was a quik fix my cable just needed to be adjusted a little |
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| Author: | pooldoo73 [ Wed Jun 01, 2011 10:15 am ] |
| Post subject: | Re: Loosing rpms/compression? |
How did the compression and leak down test do? The folks on this site can't help you without u giving a little more info. |
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| Author: | Caleb W. [ Thu Jun 02, 2011 8:45 pm ] |
| Post subject: | Re: Loosing rpms/compression? |
Hey guys, sorry for the delay. Im trying to track down a leak down tester right now. I hope to get the results back and start walking through this stuff with yall so we can get it knocked out. Im starting to lean toward a gasket leak, its usually got a decent oil sheen/residue below the left head if your looking at it from the back. |
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| Author: | cb5331 [ Thu Jun 02, 2011 8:51 pm ] |
| Post subject: | Re: Loosing rpms/compression? |
There is some old posts on how to make one. Harbor freight has a cheap one if you have one close by, you could grab one from there. May also check your local autoparts store. A lot of them rent stuff out like that for free. |
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| Author: | bowfishingnut [ Sat Jun 04, 2011 8:12 am ] |
| Post subject: | Re: Loosing rpms/compression? |
Caleb where are you located...I'm in the Morgan City area and have one I just bought that you could use |
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