1990 60 hp i just cant figure it out

[hadaveha]

I have a 1990 60hp carbs have been rebuilt, getting spark on all 3 cylinders, compression somewhere over 110psi on all 3 cylinders. starts up great, idles great when she get warmed a bit. just will not get on plane. just no top end, motor ran great all year until a cpl weeks ago, and it has about spun my brain around ever sense. any ideas please

 

[Vic.S]

How are you testing the sparks ? Individually with a spark tester, with a set of in line spark testers or merely at the spark plugs.

Have you tried a cylinder drop test to see if its really firing on all three.

 

[Bosunsmate]

Have you checked timing at wot? Check the sticky threads at top of forum for timing joe reeves method

 

[hadaveha]

I checked the spark with a spark tester, and I haven't done a drop test I will this weekend, and I havnt thought about the timing at all, that may get a bit past my few brain cells I have left

 

[boobie]

As said above, the drop test is the best.

 

[hadaveha]

Can u drop test at idle

 

[boobie]

Best to do at about 2000 rpm. More accurate.

 

[hadaveha]

I forgot to mention something that may or may not be important, my tach has allways worked great, but when I had the problem it stoped working just sits on 6000 rpm any chance there is some conection

 

[hadaveha]

ok guys ive never been so confused, I tried the drop test very little if any change in all 3 cylinders, and this part confuses me it I take the boat out of gear and use the fast idle she revs up great, drop her in gear everything changes, I may go back and check the drop test at a little higher rpms I starting to run out of ideas

 

[hadaveha]

I finally got to do a drop test in the water with back pressure, and at around 2000 rpms and my problem is the number 1 cylinder. so I have orderd a coil, even though this coil has spark, any other sugestions

 

[Bosunsmate]

Top seal

 

[hadaveha]

I would think you would be loosing compression on the top cylinder if it was the top seal

 

[AlTn]

seal has no bearing on cylinder compression numbers as you lose all compression from each stroke once the exhaust port is uncovered...the compression tester has that shrader valve to retain the compression with each stroke up to a maximum compression number in psi for that cylinder....on the other hand the crankshaft seals help retain the crankcase compression which is necessary for a normally inducted 2 cycle to operate

 

[hadaveha]

this is starting to sound super expensive

 

[Bosunsmate]

this is starting to sound super expensive

No, on many motors you can just lift the flywheel and use a seal pick to remove the seal and then push the new $10 seal back in

 

[hadaveha]

is there anything I should look for before I remove the flywheel or does this sound pretty spot on for a seal problem

 

[Bosunsmate]

is there anything I should look for before I remove the flywheel or does this sound pretty spot on for a seal problem

Well what you can do is ground all the plug wires on to engine bolts and then spin the motor a few seconds with the starter. Remove all the plugs and see whether the top plug is as wet as the others.
If you are happy with compression and spark then the only other issue is fuel, and if you are happy with the carbs then in my book its normally the top seal and not the inlet reeds

 

[Bosunsmate]

is there anything I should look for before I remove the flywheel or does this sound pretty spot on for a seal problem

Well what you can do is ground all the plug wires on to engine bolts and then spin the motor a few seconds with the starter. Remove all the plugs and see whether the top plug is as wet as the others.
If you are happy with compression and spark then the only other issue is fuel, and if you are happy with the carbs then in my book its normally the top seal and not the inlet reeds

 

[hadaveha]

Fair enough thank you guys so much I'll update after this weekend with what I find out

 

[hadaveha]

I have another question I had orderd a new coil for the top cylinder so I went ahead and replaced it, but I noticed when I was doing the drop test that cylinders number 2 and 3 you can really hear the plug wire arcing when you pull it off the plug, but cylinder number 1 you can barley hear it at all with ether the new or old coil, im thinking ive got a pretty weak fire on cylinder number 1. does that sound like a power pack problem