RockSolidEngines billet head.

[Fabian]

Hi Rich

No, i don't know which motor is used for the base parts but i do know that Tony has Visited China in 2008 and selected a supplier who makes the legs for Yamaha outboard motors.
He imports the component parts and then assembles the engines in his Adelaide workshop, using NTN bearings and high grade bolts.
Where the wires exit the magneto engine case are very well sealed and the casting in this area is different compared to my other motors.
I was surprised to see that the cylinder ports on my engine have had a going over with the die grinder - no casting flash anywhere.

My two previous Chinese engines had shocking amounts of casting flash - was amazed that they were allowed to leave the factory in that condition.

 

[210061741]

The Grubee that i have had clean ports.
But the crome plating wore off the cylinder walls in most spots.
Must be alot of piston scuffing going on in there.
It sure looked like it.

I'm thinking there is too much play in the piston assy.
Or too much clearence in the piston itself.

 

[Fabian]

I wouldn't mind betting that the bore scuffing is caused more from bore distortion that incorrect piston to wall clearances.

The aluminium used by these Chinese factories is absolute rubbish from my experiences. Combine that with the thermal characteristics of cool mixture entering one side of the cylinder barrel and hot mixture exiting the other side (with minimal cooling surface area) and you've pushed the low quality aluminium casting beyound it's ability to keep these distortion forces in check.

This in turn will reduce the ability of the piston rings to maintain a good seal against a distorted cylinder bore and (in my opinion) the requirement for 20:1 oil ratio to create a heavy hydrodynamic seal assisting the cylinder rings to do their job and also to pull heat away from hot spots to limit bore distortion.

Fabian

 

[210061741]

Yes maybe true.
But actually i think Manic Mechanic said that these castings are actually pretty good quality.
They are Die Cast which actually strengthens them.
I think part of the reason soo many bolts get stripped out is because.

Everyone seems to completly bottom out the studs.
Then you put the nuts on.
Well if the stud turns wile you put the nuts on.
Your gonna rip the threads out.
The stud is bottomed out and pressing on the bottom of the hole.
Sonner or later its gonna give.
You think your tightening the nut but your actually tightening the stud.

I usually bottom them out then back them off 1 to 2 turns.
Then double nut the other end.
Haven't stripped any out this way.

So the casting might not be all that bad.

Now the fin area is bad.

I was thinking of adding some copper fins around my exhaust header.
The pc of pipe between the motor and the neck of the header tube.

 

[Fabian]

I agree that the lower engine case halves and cylinder head are die-cast (you can see the ejector pin marks) but i'm not so sure about the cylinder barrels, just by looking at the woeful casting flash on the cylinder fins.

Maybe i'm wrong, but in my case, both cylinders look like they've been badly sand cast.

 

[210061741]

Yep i bet the jug may be sand cast

 

[AussieSteve]

Got my billet head from RSE a couple of days ago and bolted it on yesterday. Amazing compression. Unlike EnFlaMEd, No clearance problems. 1mm clearance piston to plug using an NGK B6HS gapped at 0.7mm. I usually gap at 0.6mm, so my usual clearance will be 1.1mm.
It's been raining all day so no test ride yet.
... Steve

 

[210061741]

Fabian
He imports the component parts and then assembles the engines in his Adelaide workshop, using NTN bearings and high grade bolts.

Thats cool about the bearings.
My PK has NTN stamped on the outer bearig race of the main bearings.
Guess there good.
I'll take a pic.

 

[AussieSteve]

Finally, no rain this afternoon, so I had my test ride. The billet head makes a noticeable difference right through the rev range. It doesn't turn the bike into a YZ80, but the money was well spent.
I have emphysema and was concerned about still being able to pedal start with 16:1 CR, but no problems. It actually fired more quickly, too, in less than 10 feet.
I'm happy.
Still need to sort my mixture problems, it's running rich, but that's next.
Incidentally, due to the high compression and our low 91 octane fuel, I added an octane booster to bring it up to about 98. No pinging, but it might have been OK on the normal 91 octane unleaded. I'll try it sometime.
N.B.I think that US ratings are different.
... Steve

 

[Mike Hunt]

so you absolutely have to use the high octane fuel? all i can get around these parts is 87, 89, 91.

im considering getting one but i dont know if i should get the tuned pipe first, currently im running the stock muffler without baffle or endcap