Has anybody skimmed the head or the block of their joyner 650 to raise compression ratio. If so how much have you had milled off and what difference did it make is it worth doing or is it a lot of work for very little gain.

I am wondering the same thing. Anyone have an answer?

JF

Ditto, anyone?

I would like to find out if anyone has skimmed and or gas flowed the head?

There does not seem to be much on the head to skim but it seems that it might work if you do the block and the pistons together.

Has anyone played around with the balance blocks? Made the lighter or disconnected them?

Thanks for the input.

check posts under large buggy modifications.

I feel if you disconnect the counter balance on this engine, it will shake itself to death. Mite be ok on a drag racer or something that only runs for a short time,but the way this engine is designed i think see come apart.

Well obviously porting the head would help it and ghosthunter has showed us the way, but the real question is how much would have to be shaved from the head to raise the compression to say 9 to1. Would .040 be enough? Somebody that knows the chamber cc and stuff like that would maybe know?

From my drag racing days,if you shave a head .060 you would gain 1 point in compression and most times you could not go ovev 100 thou. There plenty of piston to valve clearence,plus i don't see any cam tension problems either. I don't see any reason why this wouldn't work. Not as good as new pistons,but better and cheaper. I never realized when i bought this buggy how well built the lower end of this motor is built. Steel crank,steel rods, i mean big and built stout,if more people saw what i saw they would buy this buggy. In fact it looks built so well you could probley supercharge this motor and run nitro. Very impressive,i never heard of anyone throwing a rod or breaking a crank on this engine. So as far as mods go the sky the limit. Ghost

Scott at Unleashed Turbo's once told me he had a 650 engine up to 32 lbs of boost on a turbo, with out blowing anything, they are a very stout engine. Van

I really want to do this mod. but after i buy a new carb. considering tuk tuk's carb. its supposed to flow more, but don't know if i can justify the cost, someone said 428$ not sure though. So if i shave the head .060, what would the compression be? Also does anyone know how much the top end gaskit set would be? Thanks for everything guys, hope i can do this mod. soon.

Hi, these are thunder prices as of 6/8/09. Thermostat gasket 1.99,cylinder head gasket 10.99 intake manifold gasket .99,exhaust manifold gasket 8.99 Thunder because of new ownership has been raising their prices,so check around. On the tuk tuk carb im sceptical,it uses the same right angle manifold very restrictive.The 40dcoe side draft weber was used on thou of vw dune buggyy's, cars etc. Lots out their for sale,one time i saw a pair of them for 200.00. The parts and jets are readly available. You can have the intake made,look at the pictures of my blogs its pretty simple. This carb is proven and easy to tune,i don't know what your getting from tuk tuk. I give you any help i can. Ghost

So any idea what the compression might be after .060? And i've thought about doing the carb. mod just need more info. Is the intake all one peice? Do you block off the water line to the manifold? And what fuel pump and regulator are you guys running? Fuel pressure? Thanks for everything.

You have to find a good speed shop that does in house machining on small engines. Take in the cylinder head and tell them how deep the intake valve relief pockets are on the stock flat top pistons. They should be able to tell you how far you can mill this head and what the comp. will be. Ghost

Yes the intake water port is plugged with the gasket for new manifold. With the carb that much closer to the engine,i don't think you will have any trouble running in cold wheather. The intake is in two pcs,i feel it this way because it cheeper to machine. Get back to you on fuel pump and regulator. Ghost

The intake manifold design from Fast Freddys is a two piece design because since the Weber is so much bigger than the stock intake manifold in order to mount the Weber you need a bigger, meaning taller and wider intake manifold. Since the studs on the head are close together the first half of the Weber manifold mounts to the head. Then the second half to the first half and finally the Weber to the second half. If not done this way the head studs would be right in line with the barrels of the Webers if I remember correctly.

See my old post for a little better idea of what I am talking about.

topic-t5328-50.html

I shaved mine .030 and had to notch the top of 1 of the pistons because i had a valve hitting but it did feel stronger and climed better when i got it done.

really from only .030 wouldn't have thought that. How much did you have to notch? and has anyone messed around with the idea of having a straight manifold for the stock carb. made? May be more money than its worth, but i have access to a machine shop and for little money could have something made up. or has anyone retrofited a weber carb. on their 650? I'm toying with some ideas on how to make the manifold easier, any help you guys give is much appreciated.

You would have clearance problems with a straight manifold and stock carb I would think. One thing I was thinking about doing was putting on dual atv pumper carbs from the Honda 300 or 400EX. They are much shorter than stock or Webber carb and perform well. You would want to run an exhaust setup similar to Ghosthunters but the intake manifolds shouldnt be that hard to fabricate. Just use the intake manifolds from the atv you are taking the carbs from and make a 1/4 to 1/2 inch plate that would block the coolant passage and mount the carbs to that. From there all you would have to worry about is throttle linkage and jetting.

Hi 650 joyner, after you milled the head and recut valve relief pockets did you do a clay test when you assm the motor ,if so what tolerence did you have on the valve pocket.

Hi bigt,here the info i promised you,fuel pump demn.15/8 dia.x51/4 long,made by Red Line 3-6 lbs theres no no. on the pump,any pump that puts out 3lbs plus will work,lfeel freddy used this one because it so small. Red line use to be a division of Sterwart Warner. The regulator is from Italy,demn.3"dia.x21/2"tall,again small and adjustable,made by Petro King Fuel Saver.