Have you tried what BJG asked you to try ?? I'm pretty sure thats the problem myboy!
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| Low compression, what are my options?? http://mudmotortalk.com/mmt_v2/viewtopic.php?f=3&t=10691 |
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| Author: | SmokeEater829 [ Tue Jul 06, 2010 9:50 am ] |
| Post subject: | Low compression, what are my options?? |
I did a compression check on my motor yesterday and it is low on each cylinder. 82 PSI on one side and 86 PSI on the other. I know i need to do something, but what are my best options. What have y'all done? What works best, what don't work? I'm definately not mechanically inclined enough to tackle this job myself. Will the cylinders need to be bored? I'm thinking they will. Are these cylinders coated? I want to get it right, but i don't want to spend a ton of money. The boat is probably going up for sale after the Mud Run. Its time for a new hull!!! |
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| Author: | bayouboy [ Tue Jul 06, 2010 10:05 am ] |
| Post subject: | Re: Low compression, what are my options?? |
Have you tried what BJG asked you to try ?? I'm pretty sure thats the problem myboy!
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| Author: | Pooh Bear [ Tue Jul 06, 2010 10:22 am ] |
| Post subject: | Re: Low compression, what are my options?? |
first you need to follow Preston and BJG's advice and redo your compression test. If it's still low it could be something as simple as a re-ring job. Not always does a motor need to be bored during a rebuild,only if the cylinder has scaring or is burnt. This is a fairly simple task to rering a small engine as long as you have small sence of direction. Get you a manual and a few tools ,like a torque wrench,ring compressor,some engine assembly lube and your on your way. Good Luck. If my shop was finished and you were closer I would say Ibring it over and I could help,but I'm not quite ready for that yet. Metal building willl be put up this weekend. |
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| Author: | SmokeEater829 [ Tue Jul 06, 2010 11:21 am ] |
| Post subject: | Re: Low compression, what are my options?? |
Not yet P. Gotta get the compression tester from my buddy. And i dont think he adjusted my valves right. I was working on something else while he was fooling with it. I think he found TDC, and adjusted both intake and exhaust valves like that. I thought you should adjust when each valve is closed. Which one is right? Could him adjusting the valves wrong be causing my low compression? I either need to learn more about these motors, or find someone who does!!!!!! |
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| Author: | bayouboy [ Tue Jul 06, 2010 12:14 pm ] |
| Post subject: | Re: Low compression, what are my options?? |
| Author: | bjg [ Tue Jul 06, 2010 9:01 pm ] |
| Post subject: | Re: Low compression, what are my options?? |
| Author: | SmokeEater829 [ Tue Jul 06, 2010 9:18 pm ] |
| Post subject: | Re: Low compression, what are my options?? |
Didn't get a chance to mess with it today. Gotta work the next 2 days. If I'm off this weekend I'm gonna try to get some help messing with it. I just want to make sure it's right for the mud run and then to sell it. Not gonna sell it to someone until it's fixed or at the very least without letting them know what's going on with it. Preston, maybe if we are both off one day I can bring it down to you? |
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| Author: | shallow water master [ Tue Jul 06, 2010 9:37 pm ] |
| Post subject: | Re: Low compression, what are my options?? |
| Author: | SmokeEater829 [ Wed Jul 07, 2010 8:35 pm ] |
| Post subject: | Re: Low compression, what are my options?? |
Does anybody have any suggestions on places to order parts if I end up needing them? I'm not really looking to go with any upgrades, just get it back in good shape. Any websites I chould check out? |
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| Author: | hunter [ Thu Jul 08, 2010 5:35 am ] |
| Post subject: | Re: Low compression, what are my options?? |
you might want to check with Warren at Go Devil, he has a large inventory |
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| Author: | MaXXis85 [ Thu Jul 08, 2010 6:59 am ] |
| Post subject: | Re: Low compression, what are my options?? |
Sounds like you are jumping the gun dude. |
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| Author: | cb5331 [ Thu Jul 08, 2010 7:25 am ] |
| Post subject: | Re: Low compression, what are my options?? |
| Author: | Pooh Bear [ Thu Jul 08, 2010 7:43 am ] |
| Post subject: | Re: Low compression, what are my options?? |
| Author: | SmokeEater829 [ Thu Jul 08, 2010 8:16 am ] |
| Post subject: | Re: Low compression, what are my options?? |
Slow down fellas. I'm not ordering anything yet. Just getting info for if I need to make an order. I'm going to recheck valve adjustment and the compression as soon as I find someone to give me a hand with it. I sent Preston a message hopefully I can meet with him. Or if anybody else would like to help within a reasonable distance just let me know. |
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| Author: | MaXXis85 [ Thu Jul 08, 2010 9:23 am ] |
| Post subject: | Re: Low compression, what are my options?? |
if you have a compression tester put it in the spark plug hole and pull the kill switch. Crank the motor over about 3-4 revolutions with the throttle WFO and recored your readin for each cylinder. Thats your compression. Valve lash is set/ checked at 1/4" Past TDC of the COMPRESSION stroke. |
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| Author: | bayouboy [ Thu Jul 08, 2010 2:39 pm ] |
| Post subject: | Re: Low compression, what are my options?? |
PM sent my boy. |
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| Author: | SmokeEater829 [ Fri Jul 09, 2010 12:51 pm ] |
| Post subject: | Re: Low compression, what are my options?? |
Well, i checked the compression again today. Everything identical to the last time we checked it. Only difference was this time i held the throttle wfo. Cylinder #1 128 psi. Cylinder #2 127 psi. Now i'm totally confused. Holding WOT can change compression that much? I have no clue about these engines. I was really happy with these results until my buddy that i borrowed the compression tester form asked how the recheck went. He claims false readings, because holding the trhottle open shouldn't make that much of a change. |
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| Author: | stumpgrinder [ Fri Jul 09, 2010 12:56 pm ] |
| Post subject: | Re: Low compression, what are my options?? |
good numbers it's an air pump. throttle open lets air in, engine builds compression. throttle closed restricts air in, engine struggles to build what compression it can wit the air it can get. your buddy doesn't deserve to own that compression guage. keep it. |
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| Author: | cb5331 [ Fri Jul 09, 2010 1:21 pm ] |
| Post subject: | Re: Low compression, what are my options?? |
Yeah, it makes a huge difference. First time I used a compression gauge, I did the same thing. Puzzled the hell out of me, the motor ran fine. Think without the throttle open it was 85-90. With it open was like 145-150. I think 130 range is within tolerance though. If your gonna reset your valves again, recheck the compression and see if it goes up any. |
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| Author: | SmokeEater829 [ Fri Jul 09, 2010 1:40 pm ] |
| Post subject: | Re: Low compression, what are my options?? |
I'm not touching anything. The motor has been running great. I did notice that i had lost some RPM's, but it was from when i put on the new prop. I'm gonna keep running her just like she is. Thanks for all y'alls help!!! |
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| Author: | quackconsumer [ Fri Jul 09, 2010 2:13 pm ] |
| Post subject: | Re: Low compression, what are my options?? |
| Author: | bjg [ Fri Jul 09, 2010 4:43 pm ] |
| Post subject: | Re: Low compression, what are my options?? |
Your motor is fine. Arent you glad I checked out your thread. You learn something new everyday. And make sure you tell your buddy, yes, it does make that much of a difference. How can you make compression if you dont have anything to compress, RIGHT, right. |
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| Author: | SmokeEater829 [ Fri Jul 09, 2010 5:09 pm ] |
| Post subject: | Re: Low compression, what are my options?? |
Yes i am. Thanks again!!!! |
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