2003 yamaha 115 need advice

[huntsugar]

Default 2003 f115 need advice

i have a 03 yamaha 115 txrb, It started to idle rough so i took it to a dealer to have it checked. it has 187 hours on it. it also has oil coming out the breather hose and going into intake. the mechanic checked it out and said
#1 cylinder 10% leakdown
#2 cylinder 90% leakdown
#3 cylinder 30% leakdown
#4 cylinder 30% leakdown
he also said the intake temp sensor was bad and the tps sensor was bad,
he said i needed a new powerhead and this would cost 7100
the # plug keeps fowing after a couple hours run time. I got the boat back and told the dealer i would run ringfree shock treatment and see if it helped and it didn't. i run two tanks full and it still blows oil out the breather. i took it out today and took the breather hose off and it idle great and run great until it got warmed up, then it started idling rough but above idle it ran perfect. it will pull about 5600 rpm unless i trim it up high then i can get 6000. will the thermostat be a problem. i have had the injectors cleaned and all filters changed and the vst filter cleaned. also changed the its and tps. what can i do now, hate to spend 7100 on new powerhead,thanks for any help.is this motor hard to rebuild if i had a service manual, i have rebuilt several two strokes.

 

[huntsugar]

Re: 2003 yamaha 115 need advice

ok, i bought a leak down tester and tested the motor for myself, here are results
#1=4%
#2=65%
#3=7%
#4=8%
as you can see #2 is not good, the air was blowing out the breather hose on the valve covers, would my problem be a ring or a valve seal.

 

[Bamaman1]

Re: 2003 yamaha 115 need advice

There's no reason to put a new powerhead on such an old engine. You can get a brand new 115 hp 4 stroke for $8k-$9K.

You can always look for a used motor or rebuilt powerhead on the internet.

Good luck!

 

[SparkieBoat]

Re: 2003 yamaha 115 need advice

sounds like a bad valve to me..but could be piston..need to take the head off to know for sure.

 

[99yam40]

Re: 2003 yamaha 115 need advice

bad ring or melted piston is my thought as a valve seal would not leak that much, but this is just an opinion. If it was a valve not sealing then it would leak to the intake or exhaust
You need to open it up and see what is going on and what it will take to fix.
If you are lucky it is a hole in piston and no damage to cylinder

 

[huntsugar]

Re: 2003 yamaha 115 need advice

ok, thanks for the replies, i am going to open it up

 

[huntsugar]

Re: 2003 yamaha 115 need advice

ok, got head off, broke ring on number two and it scared the block, i am going to have it bored out. my question now is should i do them all or just the bad one and the rods look good so can i buy just the pistons or do i have to buy rods and all,if so where can i buy just the pistons.

 

[SparkieBoat]

Re: 2003 yamaha 115 need advice

You could get away with just the piston and honing out the one cylinder..not sure where to buy, google it maybe.

 

[huntsugar]

Re: 2003 yamaha 115 need advice

i took the block to a machinest and it is going to have to be sleeved, i ordered 4 oversize pistons. i tooked the head also because there is carbon caked up on it real bad.my question now is should i let him do a valve job on it and clean the head or just try to scrape or clean it off. i hate to have someone go messing with the vales when they seemed fine, i dont want to get them all out of alignment. however some of the valve could barely be seen because of the carbon. is it easy to take the valves out and clean them without getting them out of adjustment or should i just clean the face of the head and valves myself,if so how cause seafoam or ringfree wouldn't budge this stuff

 

[Bamaman1]

Re: 2003 yamaha 115 need advice

If your engine is so carbonized and you're going thru sleeving, you should go ahead and get the valves ground. To a good auto machine shop, it's just a routine little job. They're setup to do such tasks.

Then, your engine will perform as it should, and it'll last you a long, long time.