New to me a 1986 two stroke 90 Hp. Mounted on G3 185 Pro
looks new under cowling
compression on all three cylinders 150 psi
rebuilt all three carbs Yamaha kits used.
hose from bulkhead to engine replaced, fuel filter cleaned and flows well, replaced fuel pump, Yamaha parts, spark on all three cylinders shows bright blue half an inch or longer in bright sunlight.
water pump replaced, oil pump is pumping oil to carbs. First half tank I used oil at a50:1 mix for safety until oil pump proved it was working.
* NGK plugs per spec, thermostat replaced, all linkages set and sync,d, butterfly,s all set and sync,d
low speed air needle valves set on each carb and tuned by an outboard tech of 35 years experience,
After adjusting carbs, he pulled plug wire and there was no rpm drop difference between cylinders. Also he shot short burst of starting fluid one at a time into each cylinder and tach never varied on any one cylinder thus proving carbs were fueling equally well across the board.
high speed spark advance not set since he did not have a way to run at full throttle , starts quick, idles at 900 in gear, with a 13x20 Turbo prop , boat bogged down while throttle was quickly pressed to full throttle. Finally got to plane in a long long time. *Top end rpm,s 4000.
changed prop to 13x15 four blade, hole shot plane 3.5 seconds. Top end 4000. With no load engine rev,s past 5000 plus, won,t let that happen for more than a few seconds. Idle is fairly smooth. *Dropping the pitch by five inches should have raised top end rpm,s book says top end 4500_5500.
Any ideas as to what could be wrong. The boats speed is good as in pretty fast but since speedo is not working don,t know what top end is.
Thanks for your suggestions
Clif
looks new under cowling
compression on all three cylinders 150 psi
rebuilt all three carbs Yamaha kits used.
hose from bulkhead to engine replaced, fuel filter cleaned and flows well, replaced fuel pump, Yamaha parts, spark on all three cylinders shows bright blue half an inch or longer in bright sunlight.
water pump replaced, oil pump is pumping oil to carbs. First half tank I used oil at a50:1 mix for safety until oil pump proved it was working.
* NGK plugs per spec, thermostat replaced, all linkages set and sync,d, butterfly,s all set and sync,d
low speed air needle valves set on each carb and tuned by an outboard tech of 35 years experience,
After adjusting carbs, he pulled plug wire and there was no rpm drop difference between cylinders. Also he shot short burst of starting fluid one at a time into each cylinder and tach never varied on any one cylinder thus proving carbs were fueling equally well across the board.
high speed spark advance not set since he did not have a way to run at full throttle , starts quick, idles at 900 in gear, with a 13x20 Turbo prop , boat bogged down while throttle was quickly pressed to full throttle. Finally got to plane in a long long time. *Top end rpm,s 4000.
changed prop to 13x15 four blade, hole shot plane 3.5 seconds. Top end 4000. With no load engine rev,s past 5000 plus, won,t let that happen for more than a few seconds. Idle is fairly smooth. *Dropping the pitch by five inches should have raised top end rpm,s book says top end 4500_5500.
Any ideas as to what could be wrong. The boats speed is good as in pretty fast but since speedo is not working don,t know what top end is.
Thanks for your suggestions
Clif