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Post by 90GTVert on Jun 8, 2014 15:24:06 GMT -5
The stock Polaris crank should be 42mm.
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Post by nelson on Jun 8, 2014 17:46:36 GMT -5
Ok its a total dog with the 50mm kit. I think it is the port layout and size. Wont let me rev above 7500 rpm and I have tried 90-95-100 jets. I think my best bet is new rings for the 52 and somehow take a mm off the head
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Post by 190mech on Jun 8, 2014 19:36:32 GMT -5
The 50mm cylinder is designed for the 45mm crank,if run with a 42mm crank,the port timings get much less..I got my hands on a 50mm ATV jug a while back and was saddened by the terrible port arrangement and poor casting/finish.Sent it back to the seller,,my bud later found a 52mm jug in the trash,ported it,here it is today;  |
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Post by nelson on Jun 8, 2014 20:02:40 GMT -5
I am running a 43.5 crank, I replaced the bottom end of polaris. I think the 52 is the way to go without sinking too much. The port look way betyer than the 50mm. Only issue is the 52 I have is tall. I have to get the head shaved. I guess I can just sand it on glass for a few hours til I lose a mm or get to about 10cc head
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Post by nelson on Jun 8, 2014 20:04:52 GMT -5
And yea skeedr is my hero!
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Post by 190mech on Jun 8, 2014 20:26:44 GMT -5
Sometimes a "step cut" is needed to recess the head into the cylinder for proper squish as illustrated on the right;  Dont let a tall cylinder keep you from getting good power!There is always an answer to a problem!!  |
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Post by moofus02 on Jun 8, 2014 20:39:27 GMT -5
Sometimes a "step cut" is needed to recess the head into the cylinder for proper squish as illustrated on the right; Dont let a tall cylinder keep you from getting good power!There is always an answer to a problem!! I like that idea Sent from my SPH-L720 using proboards |
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Post by 190mech on Jun 8, 2014 20:50:42 GMT -5
It works well when a cylinder base spacer is used to increase port durations,heads seem to leak less with the step cut too..  |
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Post by moofus02 on Jun 9, 2014 5:59:04 GMT -5
Looks easier than cutting the Cylinder shorter lol
Sent from my SPH-L720 using proboards
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Post by nelson on Jun 9, 2014 7:40:29 GMT -5
There is no way I can cut it myself and the sealing surfaces be correct. I do have a friend who offered his machine shop services. I just dont have a lot to spend. I think they also call that a "flycut" head. Either way that is what I will need. And maybe a spacer of about 2 mm
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Post by nelson on Jun 9, 2014 8:53:02 GMT -5
190mech I looked through you photo bucket pics. Man, you have put in some work! Is that a tz350? Identical to the banshee but aircooled? That adapter you made for intakes and cr80 cylinder is great work. I wish I had the time to play in the garage, I have 4 sons and a wife that loves to stare at me. But in the future there will be more time to play. I have built a few quads and have been a member on everything 2 stroke.com for about 10 years. Just something about a 2 stroke man..
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Post by nelson on Jun 9, 2014 12:38:25 GMT -5
I am just going to make my own lathe. I have an old drill press and I think if I can put an adjustable speed controller other than 3 speed and support the far end so no wobble I can do it. I would much rather be able to do it myself than keep paying someone to do it to get it right
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Post by 190mech on Jun 9, 2014 18:57:36 GMT -5
190mech I looked through you photo bucket pics. Man, you have put in some work! Is that a tz350? Identical to the banshee but aircooled? That adapter you made for intakes and cr80 cylinder is great work. I wish I had the time to play in the garage, I have 4 sons and a wife that loves to stare at me. But in the future there will be more time to play. I have built a few quads and have been a member on everything 2 stroke.com for about 10 years. Just something about a 2 stroke man.. Thanks Nelson!I have no extra time either as I work a 7day week all the time and squeeze in moments in the garage..Its an old Yamaha RD250 that I wedged into a Ninja 250 frame..Lost interest when it got to the paint and back into the scoot world..I love 2T's also and surf the planet each night for the latest tips on how to get them a bit faster.. The old drill press for a lathe has worked for me a few times..I lay it on its side and use the table to bolt a "tool post holder" to..Post some pics if you get it working!  |
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Post by nelson on Jun 9, 2014 22:49:46 GMT -5
That is where I am at right now with the drill press, the thing is a beast. I will get pics of it. I know flotek does some nice port work put as for sharing info yoh wont get much out of those guys. I understand thought, its their livelihood. I am going to have this scoot roasting tires, if it take another month! It hit 52 mph pretty quick up hill with 100 psi and port timings off, but not far off because it was in the band just not making the power it should.
How did that yellow fan cool your a/c cylinders? Was it better than the 50cc fan? It does have more surface area on the blades than the 50 fan but I dont have a true 90 fan to compare it to. 90vert and I were discussing, what's ur thought?
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Post by 190mech on Jun 10, 2014 4:33:03 GMT -5
Thats an Autotech355 fan I got years ago,the squirrel cage fans do put out more air than the stock blade type stuff.It runs around 250F at cruise power..Brent did some tests about fans in one of his builds a while back..
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