300 and 250HP HPDI heads

**225XCL** · 01-06-2020, 06:39 PM

Hi Yamaha Guru's

I'm looking for details on the HPDI 250 and 300HP heads. In particular what the differences are in CC or even just PSI of the 2 motors.
I am taking delivery of a pair of 250HPDI's that need a rebuilding and would consider adding the 300HP heads if there is any benefit in it and i can still run it on standard unleaded (91 RON, 87 AKI for the folks in the states).

250HP head - 60V-11111-00-1S/60V-11121-00-1S
300HP head - 6D0-11111-00-1S/6D0-11121-00-1S

Also the reed cages, from my initial investigation the 250 and 300 have 6 petal reeds but the part number is different, do the 300 cages flow better?

Cheers

**DoktorC** · 01-10-2020, 10:28 PM

The 300 heads are definitely tighter than the 250's...but I don't know by how much. The 300 has an extra reed pedal...and a liquid cooled intake (I can't imagine that makes any difference).

**225XCL** · 01-11-2020, 01:05 AM

Hi Dok, longtime no chat. Thanks for the info so is that 7 reeds each side of the cage?

Cheers

**DoktorC** · 01-11-2020, 02:24 PM

Originally Posted by 225XCL

Hi Dok, longtime no chat. Thanks for the info so is that 7 reeds each side of the cage?

Cheers

Correct...the 250 has 6(12) and the 300 has 7(14).

**225XCL** · 01-13-2020, 01:16 AM

I've decided to relax my head and put the thing back together stock.
After all I want to run it on 91RON fuel.

After posting this I'm going through all the parts I have and I took it on face value that everything was for 250, I'm looking at the ECU to see if its compatible with my lowrance HDS12, when the part number strikes me 6D0 and not 60V. WTF I say.
I then look at he heads and I have a pair of 60V's and 6D0's, of course the 6D0's are pitted and damaged after the blown piston. argh!!

So I have a 250 and a 300, I'm so close I gotta go for a rebuild of the 300, better source another head.

**DoktorC** · 01-13-2020, 07:39 AM

Perfect. Just make sure you get the correct side head. There is a port and starboard lol.

**225XCL** · 01-13-2020, 04:36 PM

Yeah I know. I think I have found one as well, just confirm seller will ship from Miami to Australia.

**Chaz** · 01-13-2020, 05:25 PM

Some Yamaha info here ... >

https://www.screamandfly.com/showthr...5-HPDI-rebuild

**225XCL** · 01-13-2020, 05:33 PM

Thanks I have read through that already but now that I'm actually doing my self will read it again and pay more attention.

**jkassu** · 01-14-2020, 03:22 PM

DoktorC Show me 7pedal yamaha reed plate?

**allstock** · 01-14-2020, 03:48 PM

Originally Posted by DoktorC

Correct...the 250 has 6(12) and the 300 has 7(14).

Not to question your expertise on these but from what I've seen the 2nd gen HPDI 250 has a 6 petal front like a 300, but not water cooled. 1st gen HPDI 250 had a 5 petal like an OX66. I haven't seen a 7 petal?

**DoktorC** · 01-14-2020, 04:09 PM

Originally Posted by allstock

Not to question your expertise on these but from what I've seen the 2nd gen HPDI 250 has a 6 petal front like a 300, but not water cooled. 1st gen HPDI 250 had a 5 petal like an OX66. I haven't seen a 7 petal?

Ha! No question me...clearly I'm wrong lol. I ALWAYS thought the 300 had an extra set of reeds based solely on what Hydrotec was doing to the OX 3.1's and it sounds like I fell for the marketing. It was always the "300" front half on the 3.1's but there's not enough room for an extra reed on the 250 lol.

I swear I read it on the internet...it must be true! Thanks for the correction...little embarrassing but makes a lot of my HPDI fronts more useful lol.

**allstock** · 01-14-2020, 04:55 PM

Originally Posted by DoktorC

Ha! No question me...clearly I'm wrong lol. I ALWAYS thought the 300 had an extra set of reeds based solely on what Hydrotec was doing to the OX 3.1's and it sounds like I fell for the marketing. It was always the "300" front half on the 3.1's but there's not enough room for an extra reed on the 250 lol.

I swear I read it on the internet...it must be true! Thanks for the correction...little embarrassing but makes a lot of my HPDI fronts more useful lol.

**From what I've gathered** , ALL OX's have a 5 petal front reed cage, 2nd gen HPDI's have a 6 petal reeds and a front half that will accommodate. 300's have 6 petal reed
s and the front half is water cooled. I suppose the theory is IF you are going to change the front half on a OX66 to fit 6 petal you MIGHT AS WELL put the 300 front half on to also get the benefit of "Water cooling" the intake tract. Cold air is better in any event lol.

**DoktorC** · 01-14-2020, 05:04 PM

Originally Posted by allstock

**From what I've gathered** , ALL OX's have a 5 petal front reed cage, 2nd gen HPDI's have a 6 petal reeds and a front half that will accommodate. 300's have 6 petal reed
s and the front half is water cooled. I suppose the theory is IF you are going to change the front half on a OX66 to fit 6 petal you MIGHT AS WELL put the 300 front half on to also get the benefit of "Water cooling" the intake tract. Cold air is better in any event lol.

It's typical marketing BS and I believed it...I've rebuilt enough of this stuff I should know lol. I never even counted the 300...just always "knew" it had one extra...it doesn't. HT doesn't water cool the fronts when they swap them lol. Silly mistake...