jlebh1
Member
not meaning to take the thread off topic but just try SBP, or even tony himself im pretty sure he has them on his site.
How much compression do you have with standard head and RockSolidEngines Billet Head
- Thread starter Fabian
- Start date
AussieSteve
Active Member
I emailed Tony a couple of days ago, just waiting for a reply. (Couldn't find them on his site, only engines with them fitted.) Shouldn't be a problem, I hope. Meantime, I went into town today to a bolt 'specialist' but they don't have M8 x 1.0 threaded rod.
... Steve
... Steve
Fabian
Well-Known Member
Hi Steve
Thanks for the compression test on the standard cylinder head - 115 PSI on the standard cylinder head is a nice number and explains my hunch that the Rock Solid Engine with billet cylinder head felt like it had quite a bit less compression than the previous standard engine.
It was much firmer to pedal start.
I wouldn't mind betting that you'll get somewhere close to 150 PSI with a properly torqued down RSE billet head - if that's the case then there's something funny going on with my Billet Head RSE engine only putting out 90 PSI.
Fabian
Thanks for the compression test on the standard cylinder head - 115 PSI on the standard cylinder head is a nice number and explains my hunch that the Rock Solid Engine with billet cylinder head felt like it had quite a bit less compression than the previous standard engine.
It was much firmer to pedal start.
I wouldn't mind betting that you'll get somewhere close to 150 PSI with a properly torqued down RSE billet head - if that's the case then there's something funny going on with my Billet Head RSE engine only putting out 90 PSI.
Fabian
2
210061741
Guest
I will try to go and compression test my engine this weekend.
I have shaved the head and jug and removed the base gasket and head gasket.
On my 48cc.
Now the PK80 slant appears to have the same size if not smaller combustion chamber as the 48.
I like the RS Billet head but if i can get the same performance out of a standard Milled head i'll take the $90.00 and buy another motor.
I have shaved the head and jug and removed the base gasket and head gasket.
On my 48cc.
Now the PK80 slant appears to have the same size if not smaller combustion chamber as the 48.
I like the RS Billet head but if i can get the same performance out of a standard Milled head i'll take the $90.00 and buy another motor.
AussieSteve
Active Member
Tony just got back to me on the studs. In his engines, he fits helicoils and high tensile studs to suit the billet head. He has no longer studs with standard thread to suit, for those of us who buy a billet head to go on a stock engine.
Now I have a slight problem. A friend in Sydney is looking around - I hope he finds some.
* Any Australians know of a souce that will post - M8 x 1.0mm x 1 metre threaded rod, or minimum 110mm lengths?
... Steve
Tony RSE said:
Now I have a slight problem. A friend in Sydney is looking around - I hope he finds some.
* Any Australians know of a souce that will post - M8 x 1.0mm x 1 metre threaded rod, or minimum 110mm lengths?
... Steve
2
210061741
Guest
The Helicoils are pretty cheap.
A small drill press and you can change the thread.
Seems like it would be the easiest thing to do.
A small drill press and you can change the thread.
Seems like it would be the easiest thing to do.
AussieSteve
Active Member
2
210061741
Guest
Well guys look like this thread died.
Lets bring it back to life.
#1 different brands of motors have different pistons in them.
flat top and dome shape.
#2 the distance of the piston edge from the top of the cylinder makes a big difference.
I have got my hands on a few diff motors now.
Grubee GT-5 66
Power King aka Jet Stealt aka PK80-J or Jet silver. 68.5cc
The PK has high compression out of the box.
9.43:1 corrected compression ratio "True Compression"
The dome piston pops out above the cylinder by .145 inches.
The piston edge is about 1mm below the top of the cylinder.
The combustion chamber is approx 5cc
No psi reading but i'll get one.
Anyway for what you spent on that billet head you could buy a whole high comp motor.
9.43 : 1
I have a hard time cranking the peddles if my bike is in high gear.
And this thing is pure delight.
Lets bring it back to life.
#1 different brands of motors have different pistons in them.
flat top and dome shape.
#2 the distance of the piston edge from the top of the cylinder makes a big difference.
I have got my hands on a few diff motors now.
Grubee GT-5 66
Power King aka Jet Stealt aka PK80-J or Jet silver. 68.5cc
The PK has high compression out of the box.
9.43:1 corrected compression ratio "True Compression"
The dome piston pops out above the cylinder by .145 inches.
The piston edge is about 1mm below the top of the cylinder.
The combustion chamber is approx 5cc
No psi reading but i'll get one.
Anyway for what you spent on that billet head you could buy a whole high comp motor.
9.43 : 1
I have a hard time cranking the peddles if my bike is in high gear.
And this thing is pure delight.
2
210061741
Guest
Also the PK has the Standard 8mm thread thats easier to find.
And longer studs.
The grubee has the 8mm thread with the non std pitch.
And longer studs.
The grubee has the 8mm thread with the non std pitch.
Fabian
Well-Known Member
Ok
Been a while since i've posted as i've had some technical issues i've had to resolve.
I have returned my 70cc Rock Solid Engine and Dellorto clone carburettor to Tony and received a full refund.
There is no question his engine with the billet cylinder head is a much better quality item than the standard Chinese engine but in my application it simply did not work, nor did it make any power improvement over the standard engine.
I rebuilt one of my damaged engines with a new crankshaft assembly and began the infuriating process of trying to make the Billet Cylinder Head work on the standard engine.
With the standard cylinder head the engine had typically high compression and ran reasonably well, but with much less vibration and gear noise than the Rock Solid Engine.
The engine (like all the other engines) was difficult to pedal start due to strong compression.
I have no idea why, but the Rock Solid Engine vibrated like you wouldn't believe above 4,500 rpm and the gear noise was amazingly loud - i'm a victim of industrial hearing loss and for me to say that the gear whine was loud is saying something!
Now we come to trying to start the thing with the Billet Cylinder Head.
My god, it had so much compression that i was virtually unable to pedal through the compression stroke.
Now this may sound like a good thing but i can assure you that it created it's own set of difficulties.
The compression was so high that the magneto didn't have enough spark energy to fire the mixture and due to the reduced combustion chamber volume, air/fuel mixture was being squeezed into half the normal space, saturating the sparkplug with fuel.
The only way i could get the engine to fire was to add another cylinder head gasket.
The compression was still so high that the engine did not have enough flywheel effect to push the piston through compression, even with the idle screw being wound all the way in.
I had to hold 1/3 throttle to allow the engine to idle.
Performance: completely c.r.a.p
The extra compression just had the fuel mixture (of a standard NT carburettor) detonating like crazy (with 98 octane fuel) and the heat buildup was extreme.
The power was totally useless; the engine being gutless and unusable.
Even bottom end power was non existent with the sky high compression.
In the end i went back to the standard cylinder head and typical performance was returned.
To make the Billet Cylinder Head work, i'm figuring you'll need to add 5 cylinder head gaskets.
It's strange as so many other people report an amazing performance improvement with the Billet Cylinder Head.
I had exactly the opposite experience.
I'm in the process of modifying another engine to take a pressure line from the crankcase to run a Walbro twin screw carburettor.
It's my opinion this is the only way to go (unless using the Rock Solid Engines fuel injection system) as the Walbro carby allows fuel to be drawn from a point below the carburettor, just like a chainsaw, with options to have the fuel tank mounted as low as possible on the bike for a stealthy look.
The benefits are mainly in having screw adjustable high and low speed needles, instead of mucking about with an endless array of fixed jets.
Hope everyone had an enjoyable Christmas break
Cheers Fabian
Been a while since i've posted as i've had some technical issues i've had to resolve.
I have returned my 70cc Rock Solid Engine and Dellorto clone carburettor to Tony and received a full refund.
There is no question his engine with the billet cylinder head is a much better quality item than the standard Chinese engine but in my application it simply did not work, nor did it make any power improvement over the standard engine.
I rebuilt one of my damaged engines with a new crankshaft assembly and began the infuriating process of trying to make the Billet Cylinder Head work on the standard engine.
With the standard cylinder head the engine had typically high compression and ran reasonably well, but with much less vibration and gear noise than the Rock Solid Engine.
The engine (like all the other engines) was difficult to pedal start due to strong compression.
I have no idea why, but the Rock Solid Engine vibrated like you wouldn't believe above 4,500 rpm and the gear noise was amazingly loud - i'm a victim of industrial hearing loss and for me to say that the gear whine was loud is saying something!
Now we come to trying to start the thing with the Billet Cylinder Head.
My god, it had so much compression that i was virtually unable to pedal through the compression stroke.
Now this may sound like a good thing but i can assure you that it created it's own set of difficulties.
The compression was so high that the magneto didn't have enough spark energy to fire the mixture and due to the reduced combustion chamber volume, air/fuel mixture was being squeezed into half the normal space, saturating the sparkplug with fuel.
The only way i could get the engine to fire was to add another cylinder head gasket.
The compression was still so high that the engine did not have enough flywheel effect to push the piston through compression, even with the idle screw being wound all the way in.
I had to hold 1/3 throttle to allow the engine to idle.
Performance: completely c.r.a.p
The extra compression just had the fuel mixture (of a standard NT carburettor) detonating like crazy (with 98 octane fuel) and the heat buildup was extreme.
The power was totally useless; the engine being gutless and unusable.
Even bottom end power was non existent with the sky high compression.
In the end i went back to the standard cylinder head and typical performance was returned.
To make the Billet Cylinder Head work, i'm figuring you'll need to add 5 cylinder head gaskets.
It's strange as so many other people report an amazing performance improvement with the Billet Cylinder Head.
I had exactly the opposite experience.
I'm in the process of modifying another engine to take a pressure line from the crankcase to run a Walbro twin screw carburettor.
It's my opinion this is the only way to go (unless using the Rock Solid Engines fuel injection system) as the Walbro carby allows fuel to be drawn from a point below the carburettor, just like a chainsaw, with options to have the fuel tank mounted as low as possible on the bike for a stealthy look.
The benefits are mainly in having screw adjustable high and low speed needles, instead of mucking about with an endless array of fixed jets.
Hope everyone had an enjoyable Christmas break
Cheers Fabian
Last edited:
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