compression terror

[royboy321]

Re: compression terror

I did get the book. There are not but a few screws to play with in this engine and I have adjusted the best I can. But the book says things like - "Be in forward gear on an unrestrained boat to check the WOT..." - This is where I am trying to save a little by asking questions here since the river is ten miles away and I am a bit nervous about leaning over an engine at WOT in the middle of a river with a timing light and such.

But you are correct, I have not played with the timing yet. So next question - Wouldn't an engine with off-timing smoke, misfire, backfire or something - cuz this one sounds good and starts easily?

Thanks

 

[MercHelp]

Re: compression terror

Have you checked the fuel pump?

 

[royboy321]

Re: compression terror

I completely disassembled the carburetor and the fuel pump is attached. The diaphragm was not ripped, no leaks, cleaned it all out and put back together. I also made sure the float in the fuel bowl was at the specified height. Changed spark plugs, also. Engine now starts very easily, idles fine, revs well (wwwaaaaaaahhhhhhhhhhhhhhhh). Don't know top rpm exactly but if it reved much higher it would hurt the ears.

Up next is to check impeller and change lower gear case oil but have to loosen some very tight screws. My first thoughts were the prop but now I'm wondering if some gears or linkages need adjusting.

 

[j_martin]

Re: compression terror

Hey - anybody still monitoring this thread?

As suggested, I cleaned out the carb. I found quite a bit of dirt in the high speed jet. I took it to the river and it now seems to idle and rev well. I also broke down and purchased a compression gage and both cylinders seem ok.

So now, engine seems to rev well and no longer dies when applying throttle. Haven't yet measured with tach but sounds good. Still not getting enough power to get out of the hole (runs like a 5 hp). At first I thought the pitch on the prop was too low. It has the number 9 stamped on it (apparently by someone who worked on it) but a prop shop said it was indeed an 11 (manual says 10.5).

So question is...what is robbing my power? The next thing I will do is replace lower gear case oil. Can old oil in the gear case cause a 10hp (engine is supposed to be 15hp) loss?

Thanks

I helped a guy with a doggy V6. After he went through all the technical stuff he could think of, I suggest he have his significant other mash the throttle (hot foot in this case) and peer down the carb throats. Sure enough, the hotfoot wasn't installed right and the throttle valves only opened up half way.

Sometimes it's the simple things.

John

 

[royboy321]

Re: compression terror

John, thanks for reply,

I did take a screwdriver with me on the river to make carb adjustments. When at WOT, I had the cover off and twisted the throttle valve lever by hand all the way. I made several adjustments to the idle screws and the WOT stop screw until I could go from idle to WOT smoothly. I over adjusted, then backed off until everything worked. There is not much more to adjust except for the timing advance and I don't think the problem is timing.