vvtr
Scoot Enthusiast
Posts: 243
|
Post by vvtr on Jan 31, 2012 2:13:51 GMT -5
yeh theres no reason you cant do this mod straight off a 40mm 50cc barrel? assuming you get the port mapping right. probably best to turn it out on a lathe first to get it close then off to the rebore shop for the final cut. might give it a go tbh. you can pick up wrecked 50cc cylinders for peanuts  |
|
|
|
Post by 190mech on Jan 31, 2012 6:45:46 GMT -5
All the stock 50cc barrels Ive seen have smaller port layouts than the 70cc stuff.Even overboring a 70 should make the port timings milder...
|
|
vvtr
Scoot Enthusiast
Posts: 243
|
Post by vvtr on Feb 5, 2012 7:23:59 GMT -5
last night i recut the exhaust port to 65% cord with same profile as the 47mm cyl that's on atm....  (the blue is for marking and checking piston - head contact points) today i spent all morning recutting the cyl head to match the new domed piston the difference in the piston crown is quite extreme!....   (they're both polini heads but i'm using the one without the o.ring cutout as it would be too close to the bore - you can see the difference in chamber profile!) with standard gasket it gives a .6mm squish so far but will check in a bit when it's bolted up. that's with a 1.2mm base spacer & 2 base gaskets to get round the 1.4mm piston to pin difference. got to trim a new head gasket out to match the bore then put it together |
|
vvtr
Scoot Enthusiast
Posts: 243
|
Post by vvtr on Feb 5, 2012 10:00:22 GMT -5
FEK FEK FEK!!! all back together and great compression.... but - spark plug hits the piston lol. thank fk i didnt hit the starter! :s is about 2mm proud - 2 copper rings should do it dying to start it up lol. i might give it a try with the short reach plug, but that's too short & sparks in the thread. only problem is, mrs has gone out in my van, and my box of copper washers is in my van lol  |
|
|
|
Post by 90GTVert on Feb 5, 2012 11:00:20 GMT -5
Nice work. Sounds like it should have a lot of compression.
|
|
vvtr
Scoot Enthusiast
Posts: 243
|
Post by vvtr on Feb 5, 2012 12:46:35 GMT -5
yeh bud, got it running with a short reach plug for now, which isnt ideal but i couldn't wait! revs up great and can feel the front end lifting. did a nice little burnout in the garage lol!! havent been able to road test it proper yet as the roads are thick with ice hopefully tomorrow they will be thawed and i can get a few miles in |
|
vvtr
Scoot Enthusiast
Posts: 243
|
Post by vvtr on Feb 9, 2012 18:06:56 GMT -5
fkin ouuuuuch! just tried kickstarting the bitch in the garage... compression is so high lol, it needs a decompressor! bloody kickstart lever went right through the sole of my shoe & made a right mess of my foot!!  bastid thing! leccy start struggles to turn it over as well - need a bigger battery on it. cba now but i'll fit my spare firestorm 14ah battery next time im in the garage. |
|
|
|
Post by 90GTVert on Feb 9, 2012 18:46:33 GMT -5
I don't recall ever reading of foot injuries as an indicator of high compression, but I'd say that would be a pretty good one. Damn.
|
|
vvtr
Scoot Enthusiast
Posts: 243
|
Post by vvtr on Feb 9, 2012 19:08:43 GMT -5
could do with a longer kickstart lever too i think, for a bit more leverage and travel.
think i'll take a spare one into work and weld a piece in the middle, maybe extend it 2-3" or so?
last time i had a bike that kicked like this was a husquavarna 490 trials lol!
reckon i'll have to reduce the compression a fair bit or it''ll detonate itself to death before too long.
|
|
vvtr
Scoot Enthusiast
Posts: 243
|
Post by vvtr on Feb 11, 2012 9:25:55 GMT -5
took off the variator case to take a look at the kickstart gear, which seemed to be sticking. as i expected, the gear is stripped :/  same as on my spare one...  so by chance i took a look at the gear from a spare chinese 4t engine in the garage.... it's an identical match and undamaged  amazes me how so many parts are interchangeable! while the casing is off i'm going to cut some more cooling holes then strip it bare and repaint it |
|
vvtr
Scoot Enthusiast
Posts: 243
|
Post by vvtr on Feb 11, 2012 14:34:50 GMT -5
what a dog that was to fit lol. the kickstart spring kept binding up on itself so the kickstart lever wouldnt return - sorted it after about 2hrs! need to retap the casing holes though as some of them are stripped out & can only get 4 bols in the vari cover. i decided to polish up the casing instead of painting it. as ive got a spare one i'll take my time with it and do a nice job finally got to road test it.... never really been one for running in 2 strokes, instead i like to load the rings, hard throttle then back off, then again, then again for just a few miles to get the rings to bed then nail it lol. anyone want to take a guess how far i got before it seized lol :/ about a mile lol.  no biggy. was only a nip and it got me home no probs. i'll whip the head off tomorrow and make sure it's ok! oh - & it's fast lol! not sure about top end as i didnt want to leather it but it takes of like shit off a shovel & gets to 50mph as quick as it hit 30 with the 47mm kit  |
|
Aaron420e
Scoot Enthusiast
2008 Keeway F-ACT Racing
Posts: 430
|
Post by Aaron420e on Feb 11, 2012 17:36:02 GMT -5
Best smiley face ever!!! BOING! :lmao:
|
|
|
|
Post by ninjascoot on Feb 11, 2012 19:18:17 GMT -5
thats a pretty sweet ride
|
|
vvtr
Scoot Enthusiast
Posts: 243
|
Post by vvtr on Feb 21, 2012 18:08:41 GMT -5
managed to graft on a 26mm keihin copy carb off a kx80 need to make an insulator tomorrow out of some nylon plate ive got... and clean the filter lol!  need some heavier rollers as well cos it's wheelying too easy lol  |
|
vvtr
Scoot Enthusiast
Posts: 243
|
Post by vvtr on Feb 22, 2012 18:43:03 GMT -5
finally got round to making the spacer / adapter for the bigger carb  this stuff is proper hard to work with lol. wish i had a miller! then the only holesaw i had for the venturi hole was 19mm and i had to file the rest! got one arm like popeye now! |
|
