give me vtec
Active Member
nope... I didnt even know about them until I chance swapped it out cause I was bored one day. It was off a zoom engine though, so I would assume that that might be the only place to source them from.
Weak 80 cc motor improvements + dellorto main jets
- Thread starter chrisnbush
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nope... I didnt even know about them until I chance swapped it out cause I was bored one day. It was off a zoom engine though, so I would assume that that might be the only place to source them from.
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Head Swap
Hey Vtec,
I just tried the same slant head swap onto a Grubee. I used the BGF 80cc slant head off of ebay and bolted it to my 80cc Grubee. Noticed a couple things right off. The slant head has larger stud holes in it, the O.D. of the head fins are just a little smaller than the cylinder diameter of the Grubee, and finally the piston would just contact the head using the stock replacement Grubee head gasket. Looking at my new PK80J I just bought for another build I can see that engine has two head gaskets. I understand the current PK80J have the pop-up piston so the two gaskets are necessary. When I had my Grubee head off I could see that it also has a slight dome to the piston as well. Vtec, was your Skyhawk engine piston flat or a pop-up design? I may try two head gaskets to run the slant head or may elect to just deck the Grubee head. Currently this Grubee has an expansion chamber and CNS carb and runs really nice.
Hey Vtec,
I just tried the same slant head swap onto a Grubee. I used the BGF 80cc slant head off of ebay and bolted it to my 80cc Grubee. Noticed a couple things right off. The slant head has larger stud holes in it, the O.D. of the head fins are just a little smaller than the cylinder diameter of the Grubee, and finally the piston would just contact the head using the stock replacement Grubee head gasket. Looking at my new PK80J I just bought for another build I can see that engine has two head gaskets. I understand the current PK80J have the pop-up piston so the two gaskets are necessary. When I had my Grubee head off I could see that it also has a slight dome to the piston as well. Vtec, was your Skyhawk engine piston flat or a pop-up design? I may try two head gaskets to run the slant head or may elect to just deck the Grubee head. Currently this Grubee has an expansion chamber and CNS carb and runs really nice.
give me vtec
Active Member
my piston was flat... I did notice the holes were a little bigger on the slant head. You just have to feel around until you find the original groove in the gasket.
I rand mine up and down the street first with no spark to see if the plug would hit... took the head off and there was no contact. I am currently running one of the thin gaskets from sick bikes, and the 8.8 head studs too (I highly recommend them).
I rand mine up and down the street first with no spark to see if the plug would hit... took the head off and there was no contact. I am currently running one of the thin gaskets from sick bikes, and the 8.8 head studs too (I highly recommend them).
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Vtec,
Flat top, huh? That's why it worked on your set-up and not mine. I have not pulled my jug so do not know what it would take to upgrade the cylinder/head studs from 6mm to 8mm. Well, I know what it would take which is redrilling and the taping for the larger size, I just don't know if there is enough material around the existing holes to enlarge. I mentioned to a machinest friend about what I ran into. He is really into two strokes. He has a tool he made from the threaded end of a spark plug welded to a piece of round bar. The tool threads into the spark plug hole on a non-slant head. The round bar gets chucked up on a lathe so you can easilly spin the head and do a skim cut on the gasket surface to raise the compression. I hear 1mm or .040" cut is pretty standard. I will try a little less at first and see what kind of results I get.
Flat top, huh? That's why it worked on your set-up and not mine. I have not pulled my jug so do not know what it would take to upgrade the cylinder/head studs from 6mm to 8mm. Well, I know what it would take which is redrilling and the taping for the larger size, I just don't know if there is enough material around the existing holes to enlarge. I mentioned to a machinest friend about what I ran into. He is really into two strokes. He has a tool he made from the threaded end of a spark plug welded to a piece of round bar. The tool threads into the spark plug hole on a non-slant head. The round bar gets chucked up on a lathe so you can easilly spin the head and do a skim cut on the gasket surface to raise the compression. I hear 1mm or .040" cut is pretty standard. I will try a little less at first and see what kind of results I get.
give me vtec
Active Member
sorry... not 8mm studs. Grade 8.8 studs... sick bike parts sells them. Make sure you get the correct thread count. If you are using a grubee I think they use the 1.25 thread pitch, and the zoombikes engine used the 1.0 thread pitch.
Stronger steel studs with good bolts/lock washers will allow you to really tighten the head down good for a better seal. The stock studs will just sheer off.
And I am pretty sure my piston was flat... it might have been slightly domed but not much if any. The spark plug definitely clears... I took the head off and checked the piston and the plug for any signs of contact.
Just getting back to you. Yesterday, I mounted a chainsaw carburetor. I took it on a 30 mile run. Runs GREAT!! I tried the stock NT the so called improved CNS. They are garbage! (as you know). Chainsaw carb should come stock with these kits. My bike looks sweet too. 1936 Shelby frame, Monark forks, copper fuel tanks. I'm usein a iPhone to do this, I have no PC. I can only Email pics. I'm dyin to show my machine off.
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