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Post by jkstihl on Jul 12, 2020 2:06:56 GMT -5
Well I don’t have a scooter but I have a quad with the 90cc jog style engine and cvt. What is the correct name for this engine? It’s on a 2001 yerf dog 90cc, the thing rips but I’m wanting to get a little more out of it. So far I have came up with these mods- I build saws so I’m familiar with 2t
1. Delete head gasket and use dirko or motoseal, check squish.
2. Get some lighter variator rollers stock is 7g I’m thinking maybe 5g ?
3. Advance timing and tips on doing this and a technique?
4. Get some stiffer clutch springs.
And any other mods that y’all would recommend doing ? I weight right at 200lb this thing already rips for what it is but I could def use a little more acceleration.
Thanks and this board seems like the most knowledgeable info I’ve found on these engines!
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Post by jkstihl on Jul 12, 2020 2:50:37 GMT -5
And what are some good budget aftermarket parts?
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Post by 190mech on Jul 12, 2020 4:01:37 GMT -5
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Post by jkstihl on Jul 12, 2020 17:28:30 GMT -5
Thanks That was a very informative read. And how would I distinguish between a real Minarelli and a China one? |
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Post by 190mech on Jul 12, 2020 17:56:12 GMT -5
Youve got a China one(or Taiwan),they are great build platforms,just gotta do more hands on work compared to the Yamaha/Minarelli bolt on mind set..
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Post by jkstihl on Jul 13, 2020 1:09:26 GMT -5
Youve got a China one(or Taiwan),they are great build platforms,just gotta do more hands on work compared to the Yamaha/Minarelli bolt on mind set.. So they are as reliable as a original Minarelli? Chinese parts are frowned upon in the saw world. And is it possible to upload pics on here from iOS? I don’t see any kind of options I’ll show y’all the beast haha. |
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Post by jkstihl on Jul 13, 2020 1:22:35 GMT -5
And man I could get lost looking for parts for this thing, Polaris sportsman 90 and predator 90 bring up a lot of good stuff for the 90s on eBay.
And another question is... 90cc saws rev reliably to 12.5 to 13k and make most their power around 10k will these hold together? And most saws I build are in the 180psi compression range, some over 200psi, right now my compression is 100psi and I’ve read on the predator 90 forum that’s that what these came with from the factory on the quads, it actually runs pretty healthy but in my experience with saws that is a low number. How much does a head gasket delete usually bump the compression up on these? If I can deck it and get to at least 150psi I’d be happy and as long as I have enough squish. Saws can run 87oct with no detonation @180# psi but I’ve read you got to watch for detonation on these at those numbers. I’m learning as much as I can on these cause usually when I get a new 2stroke I become obsessed with it. And if anybody has a good 90 ported jug I’d prob be interested.
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Post by 190mech on Jul 13, 2020 4:10:25 GMT -5
Look at Eton Viper 90,DRR 90,Kasea 90,CanAm DS90,etc.. The stock top ends have a terrible head profile,squish is waay too much,cylinder port layout is poor,transfer ducts only support around 10,500 RPM's at best..These engines were originally designed as 50 cc run abouts,increasing the bore and stroke makes for less flow as the bore increases..There are some high end kits that give much better power with a 50mm bore and 44mm stroke,thats what Brent is now running on his scoot,think its getting 14k RPM now.. 49ccscoot.proboards.com/thread/436/triton-2-t2-89-110cc?page=1He has a ton of utube vids on this subject also.. |
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