force 120

[DJ. DJ.88]

I just bought a 1992 force 120 and 20ft bayliner capri. I has a vibration in mid range that shakes the hole boat. It also hunts 100 to 300 rpm from 1500 to 3500 rpm, it will rev out to 4800rpm but it is kind of lowsey out of the hole. It has good compression and a brand new prop(17pitch 3 blade). Also what octane of fuel should I be using. thanks for any info

 

[sproz]

Re: force 120

Hi,<br />I recently bought the same package and the motor does the same thing,I believd it was running too rich between idle and 1/2 throttle and it would oil the plugs if run too slow when cold,Ive set the mixture screws just over 1 turn out ( they were 1.5 turns) and it seems to be better in the test tank but I've yet to try it on the lake,it was also stalling when going for reverse(which is good for your pride and hull)when approaching the dock.Many moons ago I owned small 2stroke bikes and used to call this vibration 4stroking as its the motor only firing every other revolution and making sure the plugs were correct and oil ratios and carb settings usually cured it.<br />Hope this helps

 

[sproz]

Re: force 120

p.s. The fuel here in the uk is 95octane for unleaded which everyone seems to use.Mine also seems to gently come out of the hole but I'm not sure if this is due to the hull design(it has a sticker "progressive planing hull"on it),it seems to come out the same no matter how many is in the boat.