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Engine Compression/ LOW UPDATE
http://www.mudmotortalk.com/mmt_v2/viewtopic.php?f=3&t=8312		 Page 1 of 2
Author:  fowl habbit [ Tue Mar 09, 2010 2:04 pm ]
Post subject:  Engine Compression/ LOW UPDATE
I went and double and triple checked my compression just to eliminate that but.. Thats the problem Im getting 102 on one cylinder and 107 on the other Tried 2 diffent testers and both read the same. So know what do I do I noticed my intake valves are a little loose about one was at 10 the other 8 same with exhaust valves both about 7 thousands. What do I look for first, bad ring or bad valves its not burning any oil so thinking It might be a valve. The motor was running lean for awhile so i think thats what caused my issue. What do I need to do know to get the valves out and look at them if thats the problem :!: :!:
Author:  Jamie B. [ Tue Mar 09, 2010 2:22 pm ]
Post subject:  Re: Engine Compression/ LOW
Try to reset your valves between .004and .006 and re run a compression check. Even though you think that your compression is low, it is within tolerance of each other. Reset your valves and your compression should come back up a little.
Author:  fowl habbit [ Tue Mar 09, 2010 2:24 pm ]
Post subject:  Re: Engine Compression/ LOW
Author:  Jamie B. [ Tue Mar 09, 2010 2:27 pm ]
Post subject:  Re: Engine Compression/ LOW
If I am not mistaking with a stock motor the compression is only between 100 psi and and 120 psi they are not any higher than that.
Author:  fowl habbit [ Tue Mar 09, 2010 2:44 pm ]
Post subject:  Re: Engine Compression/ LOW
Author:  Jamie B. [ Tue Mar 09, 2010 2:49 pm ]
Post subject:  Re: Engine Compression/ LOW
pm Drake 1 he will know, but i dont thinks its 140 psi. I have a friend with a 6000 mudbuddy and he is only at 156 and 153
Author:  Jamie B. [ Tue Mar 09, 2010 2:58 pm ]
Post subject:  Re: Engine Compression/ LOW
Just made a phone call and was told by a reliable source that stockers run abuot 120 to 140 psi. He said that 107 is a lil low but the difference is ok so no real cause for concern
Author:  fowl habbit [ Tue Mar 09, 2010 3:17 pm ]
Post subject:  Re: Engine Compression/ LOW
Author:  bjg [ Tue Mar 09, 2010 9:01 pm ]
Post subject:  Re: Engine Compression/ LOW
Author:  coondik [ Tue Mar 09, 2010 9:02 pm ]
Post subject:  Re: Engine Compression/ LOW
i predict a 3-angle in your immediated future :mrgreen:
Author:  fowl habbit [ Wed Mar 10, 2010 9:05 am ]
Post subject:  Re: Engine Compression/ LOW
Author:  Jamie B. [ Wed Mar 10, 2010 9:24 am ]
Post subject:  Re: Engine Compression/ LOW
Sorry for the misleading information, guess I will be using a different briggs mechanic from now on :?
Author:  fowl habbit [ Wed Mar 10, 2010 9:27 am ]
Post subject:  Re: Engine Compression/ LOW
Author:  coondik [ Wed Mar 10, 2010 9:27 am ]
Post subject:  Re: Engine Compression/ LOW
chances are that u'r problem lies in the valve seats. the compression test will somewhat signify a valve / seat related problem, but u'r gonna need to need to do leak down test to really get a handle on them. what i know and what i've seen, it wouldn't be a bad idea to pull your heads and get them to a shop that can do a triple angle valve job!
Author:  fowl habbit [ Wed Mar 10, 2010 10:36 am ]
Post subject:  Re: Engine Compression/ LOW
Author:  coondik [ Wed Mar 10, 2010 10:43 am ]
Post subject:  Re: Engine Compression/ LOW
Author:  craig [ Wed Mar 10, 2010 11:21 am ]
Post subject:  Re: Engine Compression/ LOW
Author:  craig [ Wed Mar 10, 2010 11:25 am ]
Post subject:  Re: Engine Compression/ LOW
If your clutch isn't slipping you may want to look at your prop. You said your boat will get up and run in shallow water but won't run in deep water all the while turning 4100 rpms..............sounds like you may be cavitating. Check transom height and prop for correctness. Make sure water isn't plowing up against your belt housing.
Author:  BROOKS [ Wed Mar 10, 2010 2:23 pm ]
Post subject:  Re: Engine Compression/ LOW
When you be doin' yore preasure check ... are you openin' up the throttle wide open?

Also ~ Ifin' you git 4100 out of water ... what do it do in the water ... you type no power .... is both jugs firin' ? I ain't much of a mech .... but I do like to post !!!! ;)
Author:  fowl habbit [ Wed Mar 10, 2010 2:37 pm ]
Post subject:  Re: Engine Compression/ LOW
Author:  Jamie B. [ Wed Mar 10, 2010 2:41 pm ]
Post subject:  Re: Engine Compression/ LOW
Are you sure the belt or clutch is no slipping under the force of the water
Author:  fowl habbit [ Wed Mar 10, 2010 2:47 pm ]
Post subject:  Re: Engine Compression/ LOW
Author:  Jamie B. [ Wed Mar 10, 2010 2:58 pm ]
Post subject:  Re: Engine Compression/ LOW
Is it a new prop are one thats messed up
Author:  WestEndAngler [ Wed Mar 10, 2010 3:04 pm ]
Post subject:  Re: Engine Compression/ LOW
If your hearing any sort of noise you'd know the belt is slipping... In deep water especially... I'm resorting to throwing darts now :lol: :lol:
Author:  BROOKS [ Wed Mar 10, 2010 3:19 pm ]
Post subject:  Re: Engine Compression/ LOW
I thankin' .... ifin' yore turnin' 4100 in the water .... yore slippin' somewheres. Prop slip (cavitations) .. clutch slip ... somethin' slippin' and not pullin'.

What would happen ifin' you leave it on the trailer .... enguage the clutch while engine is not runnin' .... try like the dickens to turn the prop?

Don't pay to much attentions to mines comments ... I'm just throwin' sum simple thangs out there fo you. Sometimes ... it's the simple thangs that git us all baffled.
Author:  coondik [ Wed Mar 10, 2010 4:01 pm ]
Post subject:  Re: Engine Compression/ LOW
Author:  coondik [ Wed Mar 10, 2010 4:11 pm ]
Post subject:  Re: Engine Compression/ LOW
Author:  fowl habbit [ Wed Mar 10, 2010 4:26 pm ]
Post subject:  Re: Engine Compression/ LOW
Its a brand new prop maybe an hour on it at most. In fact i thought that was the original problem thats why i forked out the money for a new prop. the motor is doing the same thing Im rippin out the clutch tonight so I should know more Is their any other reason the prop would cavitate like it does. I have pods on the boat and that skeg under the motor got a little bent other than that nothing has changed and its been like this for quite some time now
Author:  bjg [ Thu Mar 11, 2010 6:11 pm ]
Post subject:  Re: Engine Compression/ LOW
Are you keeping the motor trimmed high to get those rpms? Low compression will make your holeshot total crap. I had 145 on one side and 115 on the other and never could figure out why I had no low end power, buit the motor would still turn up WOT. Like I said I would like to see the engine myself because T@R over type talking is a bitch.
Author:  bjg [ Thu Mar 11, 2010 6:21 pm ]
Post subject:  Re: Engine Compression/ LOW
This whole scenerio is very strange does anyone else agree? I just read this again and you say you move about six mph and your turning 4100 rpms.
Author:  fowl habbit [ Thu Mar 11, 2010 10:02 pm ]
Post subject:  Re: Engine Compression/ LOW
Update finally did a leak down test and found out im loosing a shit load of comprssion through my exhaust valves. I pulled the heads and you can almost see daylight the one is so bad. Im figuring this is what has caused my low end to drop off and the ability to not push a load. I appreciate all the help especially Craig fell bad always bothering the guy but he knows his stuff Thanks for all the help. Ill be ordering the Iron Mountain Heads tomorrow so should be up and running next week :)
Author:  craig [ Fri Mar 12, 2010 7:18 am ]
Post subject:  Re: Engine Compression/ LOW
Author:  MaXXis85 [ Fri Mar 12, 2010 7:27 am ]
Post subject:  Re: Engine Compression/ LOW UPDATE
This goes to show you how shitty stock heads are.
Author:  sea-n-spots [ Fri Mar 12, 2010 9:47 am ]
Post subject:  Re: Engine Compression/ LOW UPDATE
Author:  coondik [ Fri Mar 12, 2010 10:49 am ]
Post subject:  Re: Engine Compression/ LOW UPDATE
Author:  fowl habbit [ Fri Mar 12, 2010 11:53 am ]
Post subject:  Re: Engine Compression/ LOW UPDATE
I just took my heads and valves to a guy in town that builds engines for nascar and drag racing he does this shit for a living know his crap. I decided to let him deck my head and do the valve work instead of odering the IM heads its saving me about 200 bucks so cant complain their. I also had him look at my engine. This whole time i have been thinking its running lean way lean and its not the plugs are just not the best indication as to how its running he looked at the heads and piston and said way to rich :o . He also said that having all that fuel is why I was loosing some of my power. Hope to get the heads and carb all done this weekend and have it up and running next week. Ill keep ya posted Thanks
Author:  coondik [ Fri Mar 12, 2010 3:23 pm ]
Post subject:  Re: Engine Compression/ LOW UPDATE
may wanna look into replacing the stock valves with some stainless ones. also, don't forget to shim your springs!
Author:  fowl habbit [ Fri Mar 12, 2010 4:15 pm ]
Post subject:  Re: Engine Compression/ LOW UPDATE
Author:  Belchos [ Sat Mar 13, 2010 10:52 am ]
Post subject:  Re: Engine Compression/ LOW UPDATE
The numbers are a little confusing, but did he give you an expected compression ratio?
Author:  BROOKS [ Mon Mar 15, 2010 3:13 pm ]
Post subject:  Re: Engine Compression/ LOW UPDATE
Huh ..... Can someone explain to me how you git 4100 rpm's and don't git the power to push the boat. I'm confused on how you still git all that rpm.
:oops: :?
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