Grubee connecting rods?

MitchP

MitchP

New Member
I bought an F80 bottom half. It takes 110mm connecting rods. I was planning to use the top half of my grubee gt5 (2012). Duane from Thatsdax told me to check the deck(?) size on my jug. How do I measure this?
 
I do believe that would be the thickness of the mounting area for the head gasket. I don't know how long stock GT5 rods are, but the F80 likely has a longer rod, so it would be more likely to strike the top of the head if the deck is too short.
 
Yeah thatsdax has a simple trick for comparison. If they are the same length then all is well. I'm gonna do a side-by-side when it arrives.
 
Ok I think I got it! Deck height is how far the piston will go up. If you put a level over the top of the jug and raised the piston to TDC (top dead center) you'd measure the space in between. Shyte this is confusing.
 
Not just the rod length needs to be considered. There's at least 3 different pistons running around in china girls too. They have different length skirts, and different positions where the wrist pin is.

It's not that easy to mix and match cylinders and pistons from different engines, especially when one of the engines is a Grubee, or Flying Horse.
 
Yeah I know I started pulling out my hair last night looking for answers. Worst case scenario I order Power King pistons and jug. I'm gonna install the jug and piston and see where the piston hits in the jug. How can I check the timing though??
 
This what Dax's site says about the top half:

"Includes 47mm Bore Cylinder, 47mm Piston" How to find these measurements?
 
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I recently put my grubee jug on my flying horse bottom end. However, putting the pistons side by side -- i could not c any differences in total piston height nor wrist pin location. The jugs were pretty close in height as well. However, I did take a spare jug and chopped 3 mm off the bottom to make a spacer shim (fat base gasket) and removed a bunch off the top... just make sure when u put ur cylinder head back on to manually crank the motor over (w/ spark plug screwed in) to make sure nothing touches @ TDC -- allow a wee bit more for expansion. Best to do a compression test 2... i skipped that last part and ended up with a dieseling motor -- pulled the spark plug wire and the thing kept going... cause didn't hook up kill switch in hasty race to ride the bike this spring.,, Performed a compression test when I got home ---- 210 psi. Whoops -- almost destroyed my newly rebuilt motor! Lucky. Had 2 hold the brakes and dump the clutch. Slipped in a head gasket to reduce compression 2 170 psi. But don't go THAT high unless u have GOOD bearings, and GOOD synthetic oil ;) But it runs great now!
 
I know when I'm in over my head... This is one of those instances. So I ordered the top half, I'll have a complete F80 for $120 said and done. Quite frankly I want to ride more than I want to fidget with 2-3mm differences. Jesus I miss having a motorbike. There's nothing like it.
 
Actually there are four pistons and four c.rods. Plus there three different piston domes as well. From I what have red DAX pistons will loss power if you run a High Compression Head like Soap dish , manic flower or a RC head. DAX piston dome measures a flat .0100 . And even if doesn't hit the head @TDC it can Crash on the crank. Mixing motors is not for newbies it takes Years to do it correctly .
 
we need someone with youthful energy to list out all the diff rods, pistons, barrels in a chart with where to get each type - maybe same for wide woodruff keys & fitments vs narrow keys & fitments
 
I'll take measurements off my Grubee GT5 and F80 (a pk80 clone). Really though you guys gotta give me some directions on what kind of measurements to take. Then we can compile it all in the 2 stroke section.
 
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