Ok, here is the deal.. My blaster has a 240 kit it in. I recently had the jug come lose and tear up the pistons.. Sooo leading to my current problem.. I bought a new piston from vitos a 72mm forged weisco psition, and all the needed parts ..anyway got it back together..started it up and bammm ..the motor vibrates like hell shakes the bike badddd when you blip the throttle..and there is a sound int he top end that is nasty like piston slap..clink clink clink clink etc..Sooo i let it warm up to see if it were to go away see if the motor tightend up..nope still there.. so i took the head off to see whats up.. there is alot of side to side play.. the bore i mic'ed out to 72.19mm piston is stamped 71.97 and the rings are supose to take up that .22 thats a decent amount...I dunno im at a stand still with ideas.. any way compression so far is 120psi. and im stumped
if it aint one thing its another...check it out`
- Thread starter hondaruss
- Start date
did you hone the jug after the jug came loose. sure the rings are on the locator pins. the only time I have felt vibration like that was after I overheated from an airleak and just cleaned up the piston and got the rings free from the melted aluminum put it back together and hit the trails. vibrated like a SOB for about 15 min and then smoothed out. wouldn't recomend that I just was 200 miles from home and only rode for an hour before it locked up
ok..who set up the motor, when you had it bored/honed did you take them the piston?
You stating .22 mm clearance, that comes out to 0.00866120002 inches... that is way to much clearance, you want less then half that. you want to be running.003~.004 depending on the piston you are using. what else did you take apart?? any gears on the side of the motor??
You stating .22 mm clearance, that comes out to 0.00866120002 inches... that is way to much clearance, you want less then half that. you want to be running.003~.004 depending on the piston you are using. what else did you take apart?? any gears on the side of the motor??
The .22 is what the piston is marked (71.97mm)- (72.19) what i got when i mic'ed the bored..I honed it prior to installing the new piston of course .. unless for some reason the jug got cocked just a bit when i installed it. Never took any gears apart.. just topend..the piston i got from vito the forged big bore weisco piston..
Yes honed the jug ..the rings from what i understand wont go in to the cylinder i there not in the locator pins.
Here is a bender to this whole situation.. the piston i took out the of bike measures 71.65 checked 4 points on the pistion north to south, east to west.. How in the damn nation a bigger piston 71.97 ..be more trouble. i cant wrap my head around this. If anything i should be closer to minimum clearances..hmmm hmmm There is a reason i shoulda stuck to 4 stroke (ewww ouch lol) its all good though.
That i am not to sure. I just went and did some measurements just to double check.. piston to cylinder wall .50mm ...core size 72.19mm. piston 71.97mm...compression reads 120ps before i took it apart
.50 mm is 0.0196845455 or rounded between 19 and 20 thou, proper clearance is 3 to 4 thou. If your numbers are accurate your piston is bouncing around like a pinball machine.
Did you bore/hone it or did a shop?
Did you bore/hone it or did a shop?
I used a ball hone per the clymers manual. im thinking since the rings are for a 72mm bore. I am about 72.20mm rounded up . I wounder if i can run 72.25mm rings and make the piston stable.
Dude, Phragle is trying to tell you that you are F____d. 20 thou is huge clearance, if correct. The bore was supposed to be 72 even.
No.
First do yourself a favor and throw the ball hone in the trash. the do very ugly things when they hit ports and can knock the cylinder out of round with the wrong pressure. You need to take the cylinder to the shop, probably have them dyechem it and run a long hone thru it to see if there are low spots. then mic it for the correct piston. It will then get bored just undersize and then honed to final dimension with stones that are flat and longer than the bore. they are also manually adjusted.
An expensive lesson, but since your current piston and rings are basically zero hour, you may be able to resell them.
First do yourself a favor and throw the ball hone in the trash. the do very ugly things when they hit ports and can knock the cylinder out of round with the wrong pressure. You need to take the cylinder to the shop, probably have them dyechem it and run a long hone thru it to see if there are low spots. then mic it for the correct piston. It will then get bored just undersize and then honed to final dimension with stones that are flat and longer than the bore. they are also manually adjusted.
An expensive lesson, but since your current piston and rings are basically zero hour, you may be able to resell them.
sorry the .50 was the big end of the rod ...piston to wall is .40mm
i'll take some pics tomorrow of the measurements i got. i understand im prolly f'ed and prolly need to buy a new sleeve..
nah...unless you really really went to town on it with the ball hone, a bore to the next size should fix it.... but before you go start ordering sh*t, take the piston and cylinder to the shop and have them mic it out and see if its got bad spots
I've been working on it all day and really tired i over looked my clearances... been a long long day.. anywho.. min/ max piston to wall clearance is .03-.04 ..i have .40.. way way out of rang. its close enough to where i can take it have them bore it out to 72.50 and just suck it up and get a new piston for the 72.5 and put it together and ride this damn thing lol Thank you for all your help. sorry once again for not thinking clearly
awesome yea we will have to meet up some time! . A group of us like to ride around beaverdamn and bluffton and cairo ... there are trails that start at b-damn..go to bluffton then to cario.. its a nice ride, we have to meet up some time and ride!
have you ever been to pusheta creek mx park? i think its towards the lima area and me and a couple friends are gonna be hittin that place up on the 7th. i've never been there but ive heard its nice
I just looked it up its in wapak which is literly 10 min drive from me and i NEVER knew it was there or existed. iv'ed around here all my life! .. Lol there is a place here in lima that is 10 bucks to ride all day that is huge guy has 400 acers of land. there a min track and alot alot of trails. We shoulda hook up some time also and ride.. hell have a get together who is ever in ohio and close lol
