Yamaha Hp40 c40tlrx Runs bad

[HP40Yamaha]

I just bought a used boat it has a Yamaha Model C40TLRX Motor. I mixed the gas 100 to 1. It fouled the plugs and runs real slow and rough. I switch to 50to 1 and change the plugs. It ran for about 4 hours now the same plus it idle to fast. Any suggestions Thanks

 

[rodbolt]

Re: Yamaha Hp40 c40tlrx Runs bad

me?
I would test spark and compression. if both are good then I would clean the carbs and replace the fuel pump.
keep the 50/1.

 

[HP40Yamaha]

Re: Yamaha Hp40 c40tlrx Runs bad

Thanks I replaced spark plugs and still runs bad. There s a lot of carbon in the water. Idle speed is still to fast.

 

[rodbolt]

Re: Yamaha Hp40 c40tlrx Runs bad

I dont recall saying any thing about plugs.
however test spark, test compression, fix the fuel system.
thats typically how it goes.

 

[99yam40]

Re: Yamaha Hp40 c40tlrx Runs bad

Check the timing also with a timing light to see if it is in spec at idle and WOT.
Mine was off to the point I had to replace the cdi.
But like Rod said always check compression and spark first.You cannot make a motor run properly if the compression is off and you were running it without the right oil mix for some time and if it was running lean because of carb problems you could have compression problems now