View Full Version : PowerSpeed problems Someone PLEASE help

06-09-2009, 11:54 PM
"I everyone, I am new here and was wondering if you could provide me some knowledge/assistance... I have an '88 Bayliner Trophy 17' center console, with an 85hp Force.. NOT GOOD right? lol. Heres the deal... I bought the boat from my dads friend whos owned it for years. He said it only goes about 25 mph and I figured it was because of the prop being ate up. After checking everything, adding a tach, decarbing, new plugs, and new 17 pitch prop I can only get 30 mph, by myself at 3200 rpm max in optimum conditions. The carbs are spit shine, timing is right, compression is 120 on all 3 cylinders. I feel like it should go 40? Ive read people with the 16' bayliner bowrider with the same motor claiming 40-45 with 2 people on board? ANYTHING YOU MIGHT HAVE TO SAY WOULD HELP...


06-10-2009, 12:09 AM
"And just to clairify a little more, the spark is a crisp blue at all 3 cylinders, all wiring is correct, good fuel and pressure, ive ran it with the cowling off with no change, carbs have been synced too. The boat has been this way ever since my dads friend owned it. It does start and run very smooth through all RPMs. I took 2 girls from college out yesterday and achieved 25 mph tops, trimmed out and all... and we literally got passed bt a crane(bird) at full throttle!"

06-10-2009, 03:01 PM
"why not try a lesser pitch. (i have an 89' 85 hp)and I run a 15 pitch, it should inc rpm at wot. I would not pay so much attention to the speedo, its not like a car and can be inaccurate. the rpm though should be between 4500-5500rpm. also when was the last time the lower oil has been changed?


06-11-2009, 04:16 AM
"Well mainly because its so slow. I know that the last prop was pretty ate up from corrosion but a prop shop measured it to be a 16 pitch probally because it was bent but even with that my max RPM was 3600. If I drop to a 15 pitch Ill still only get it to 3400 probally. I have know idea about the lower oil though, probally a long time but I couldnt see that reducing the RPM 1500. I feel like I have a 50 out back or something. How fast can you go with your boat? My speedo is definetly close though, it takes along time to go places in this boat. And what do you idle in/out of gear? I was wondering if mine was right/"

06-11-2009, 10:59 AM
"it could be a combo of things. what rpm do you do get with ear muffs and reving up motor? If its hi then there is a strain on the motor somewhere in the drive train. My idle speed is about 1000. in gear a little lower, planing in a few seconds. I disconected my speedo, but the gps puts me at about 30 mph at wot, but if seems faster. Good luck


06-11-2009, 01:16 PM
I can rev it to 5000 at the house no problem. Well I guess Ill change the oil then just to be sure. what rpm do you get at WOT?

06-11-2009, 04:19 PM
"almost 4800 at wot, also check the impeller housing. It could be binding as well. does the prop spin free out of gear? all these things can add up to low revs. good luck


06-11-2009, 04:29 PM
ok thanks. yea it spins freely out of gear and i just put a new impeller on and nothing is different. Ill try changing the oil and see what happens


06-11-2009, 05:25 PM
"If the timing is advancing and is correct, you're gonna have to take some pitch out of the prop to get the rpms up.

The other item is to make sure the bottom is clean. I've seen "stuff" accumulate on lightly used boats - some worse than others. If the trailer sits high enough (or you can elevate it) clean it really good & wax it."

06-12-2009, 09:41 AM
"Have you adjusted the linkage, maybe the carbs are not opening up all the way at WOT, or the hi speed jets are blocked?. I`m grasping at straws.


06-12-2009, 10:24 AM
"Have you checked the fuel pump, fuel delivery lines, primer bulb? Needs to be air tight and clean.

Have you tried pumping the primer bulb while at WOT and your only getting 3200 rpm?"