Again..Yamaha 300hpdi pistons?

[Superbender]

Hpdi's are torque monsters and will spin to 6000 all day.
key to a good hpdi is proper breakin,filter services good oil and gas.
there is plenty of reliable power from these motors.
I prefer Wsm Pistons that are Teflon coated skirts, Pistons that drop the locating pins will have a deformed piston dome usually from lugging motor (prop to big)or poor fuel quality.have not seen these problem with the Wsm pistons.
reeds I like Chris Carson reeds with cleaned up cages
no spacer plate,as you can not take advantage of high rpms needed to see improvements
solid motor mounts,exhaust modification are good like to cut the liner out.
i would not cut heads unless you can run premium fuel.
biggest improvement is just clean up porting

[Finman]

Hpdi's are torque monsters and will spin to 6000 all day.
key to a good hpdi is proper breakin,filter services good oil and gas.
there is plenty of reliable power from these motors.
I prefer Wsm Pistons that are Teflon coated skirts, Pistons that drop the locating pins will have a deformed piston dome usually from lugging motor (prop to big)or poor fuel quality.have not seen these problem with the Wsm pistons.
reeds I like Chris Carson reeds with cleaned up cages
no spacer plate,as you can not take advantage of high rpms needed to see improvements
solid motor mounts,exhaust modification are good like to cut the liner out.
i would not cut heads unless you can run premium fuel.
biggest improvement is just clean up porting

Thanks!
what did you mean ,exhaust modification are good like to cut the liner out ?
-Should i leave powerhead stock,or litle porting exhaust holes upper?-Bobs tuner?-biggest improvement is just clean up porting?
Do you mean"clean up" all sylider air/exhaust holes? or only exhaust holes?


I have read positive efect lightweight flywheel,maybe i do this mod also.

[Superbender]

Light weight fly is good,once you have the block apart you will see about cleaning up transfer ports don't raise any ports just a clean up,also check rod weights

[lance]

Yes, I would call HydroTec. I bought a newly rebuilt 3.3L phase III that previously had the typical locator pin piston failure. I ran it for 5 years with relatively low hours and then had another piston failure. It has been rebuilt again by HydroTec. In both cases there was no sign of fuel or ignition problems. My understanding is that HydroTec is using another brand of piston now and they have not had a failure in 2 years. Clearly there is a problem with pistons used in the 3.3L Yamahas.

Excluding the piston issues, my 3.3L phase III has been great. I use mine for family boating, fishing, water sports. Sometimes with 6 people + gear in the boat. Just prop accordingly.

[Finman]

Locator pins become loose and come out commonly on Yamaha Hpdi pistons.Nothing to do about mixture and timing,so run a higher grade fuel and prop to top rpm...I've had great success with this approach,Chris

Agree! I take motor apart,locator pins are loose several pistons!They move sideways and drowning up piston.
Exhaust holes and heads are black,mixture dont had clean.

[Finman]

Light weight fly is good,once you have the block apart you will see about cleaning up transfer ports don't raise any ports just a clean up,also check rod weights

ok!
I cant belive how unfinised Yamaha block ports had! I clean all ports

My setup:'
*WSM pistons.
*Block ports clean.
*Bobs tuner.
*BB throthle body(1 3/4" -> 2"plates).
*CCMS reed valve.
*1 1/4"Intake spacer.
*Light weight flywheel.
*Rods/pistons weight balance.

Heads will be stock,because sheap regular gas 90(USA, same gas europe is 95.okt). 1.75$/gallon.

[mn808gade]

post # 16..-th

[Finman]

post # 16..-th

Agree,but i think that with BB-throtlebody intake spacer is good idea.

[DoktorC]

Agree,but i think that with BB-throtlebody intake spacer is good idea.

Nope...listen to the man with the dyno and the experience lol.

[Finman]

ok

If i leave s.plate off, how about all the rest setup...

*WSM pistons.
*Block ports clean.
*Bobs tuner.
*BB throthle body(1 3/4" -> 2"plates).
*CCMS reed valve.
*Light weight flywheel.
*Rods/pistons weight balance.

Does anybody know engine balanse;are crankshaft&rods&flywheel balansed together? or everything separate?

[DoktorC]

Deadly!

The spacer plate doesn't hurt (much) but it doesn't give you anything at all. It may take away some bottom and mid but it's hard to tell because the motors make a tonne of power there.

[joneill]

I get answer HT; Stage 3 work only very light boat,stage 2 basic(light)boat,st1 normal fising boat.
-Heavier boats they dont recoment anything.

So Hydro Tec is making 50 more hp on a light boat but not on a heavy boat, something doesn't sound rite there to me. Are they really making 50 more hp at all?

[Finman]

So Hydro Tec is making 50 more hp on a light boat but not on a heavy boat, something doesn't sound rite there to me. Are they really making 50 more hp at all?

Nope,i belive that their recommend about boat weight/phase kit has something to do fuel mixture?
-Hevier boad need bigger torque move the boat;Bigger torque need more gas all rpm,HT mods dosen't do anything fuel mixture. This is only my thought,Not fact.

[joneill]

Nope,i belive that their recommend about boat weight/phase kit has something to do fuel mixture?
-Hevier boad need bigger torque move the boat;Bigger torque need more gas all rpm,HT mods dosen't do anything fuel mixture. This is only my thought,Not fact.

So HT doesn't change fuel mixture, doesn't change the ECU/limiter and only gets 50 more hp on a light boat? Seems to me 50 hp is 50 hp no matter which boat it goes on or am I wrong?

[DoktorC]

So HT doesn't change fuel mixture, doesn't change the ECU/limiter and only gets 50 more hp on a light boat? Seems to me 50 hp is 50 hp no matter which boat it goes on or am I wrong?

They get 50hp from the mods....but HT doesn't want the phase3 HPDI's Subjected to extremely heavy loads because it can't fuel itself to compensate for the load and the mods...so...boom goes the dynamite...