GX390 Info
- Thread starter Slick Rick
- Start date
- Tags gx390 info
I have all my stock spec's info lock into my computer. Lately I have been having computer problems, so I can't remember off the top of my head what they are.
The spec's are in metric which makes it even harder to remember. But I do know the stroke is over 2.5?? and can't remember the journal size.
Tom from ARC can tell you if you need exact spec's. They are the rod makers.
The spec's are in metric which makes it even harder to remember. But I do know the stroke is over 2.5?? and can't remember the journal size.
Tom from ARC can tell you if you need exact spec's. They are the rod makers.
Man that could have helped a long time ago. LOL
So you wanting to make it into a gx390?
If so make it bigger, the bigger the better. you can easy get over 3" stroke and maybe bore the stock sleeve up to fit a 3.490" JE piston.
That's what I would do, but you gotta just find a rod with a bigger journal than 1". Maybe a 1.25" journal should work, but it needs a ,490" wrist pin hole.
Do you have a picture of this motor?
So you wanting to make it into a gx390?
If so make it bigger, the bigger the better. you can easy get over 3" stroke and maybe bore the stock sleeve up to fit a 3.490" JE piston.
That's what I would do, but you gotta just find a rod with a bigger journal than 1". Maybe a 1.25" journal should work, but it needs a ,490" wrist pin hole.
Do you have a picture of this motor?
If the crank is solid in the center I would offset grind it for more stroke, and run a JE piston.
I just notice you do lawnmower racing. And I was thinking as in minibike racing.
If you can get the journal down to 1" you have a good choice of rods and pistons to choose from. If you try the gx390 setup it may, or may not work. Your limiting yourself to only 1 rod, and 1 piston.
I just notice you do lawnmower racing. And I was thinking as in minibike racing.
If you can get the journal down to 1" you have a good choice of rods and pistons to choose from. If you try the gx390 setup it may, or may not work. Your limiting yourself to only 1 rod, and 1 piston.
That's the thing the crank isn't solid in the center.
Here's a drawing of the crank. Vanny Single Crank.
One more question as well, How thick does a sleeve have to be. I Have a 3.43 bore and want to do a .120 overbore but, I'm not sure if I'll be able to still use the sleeve or, if it will be to thin. Right now I have a .160" thck sleeve.
Rick
Here's a drawing of the crank. Vanny Single Crank.
One more question as well, How thick does a sleeve have to be. I Have a 3.43 bore and want to do a .120 overbore but, I'm not sure if I'll be able to still use the sleeve or, if it will be to thin. Right now I have a .160" thck sleeve.
Rick
I'll actually have .100 thick sleeve but, the thing is if it's to thin I'll have to bore the existing sleeve out and have it re-sleeved and, if I'm going that route I mine as well go as big as the block allows.
Another question, How much "meat" so to speak do you want in between the threads of the head bolts and the cylinder wall? I don't want the threads of the head bolt to get weak.
Another question, How much "meat" so to speak do you want in between the threads of the head bolts and the cylinder wall? I don't want the threads of the head bolt to get weak.