BannedCR500Riders.com

seanmx57 wrote:

2strokeforever wrote:that was just an example, it was way worse....
results came in, 14th place, not worth frying a engine for
decided im gonna do it proper, new crank bearings, big end is still good, send the cylinder to roosty and let him decide what to do with it, probably end up boring it
the weird thing is it just ripped the whole race, i figured it would start running shitty before any dirt got through
on the bright side now i realise how fast it really is, on the open areas im leaving way faster riders than me a facefull of roost, had ryan grafunder behind me for the entire grasstrack if he was on a 2 stroke i woulda let him by...

The way things are going for you , you might as well just rering the piston, flush the lower end and go hammer it some more.

I've raced a lot in talcum powder dirt. filters just plug and bike runns super rich. Running belray oil and a twin air.

If you have to bore it out your STR crank's sweet spot will be at a higher rpm now..........

Could just hone .002 it and coat the piston to gain the .002 back if the jug isn't too bad, then the piston weight change will be neglible.

x2...rinse out new rings and hammer some more these 500 are tough ...i just dont like seeing cracked pistons they cause big shit

2strokeforever wrote:......there was a few guys that changed their airfilter 3 times in that race.

Because they were pluging..... because they were filtering.... because they were most likey UNI FILTERS.

If you spend all this money to fix it, and still run that Moose filter ( or didnt find the cause of the dirt ingestion), expect to find more dirt and another rebuild.

2strokeforever wrote:...the weird thing is it just ripped the whole race, i figured it would start running shitty before any dirt got through
...

Thats just the opposite, it would have ran shitty if the dirt didnt make it through....

I run a filter skin, oiled with K&N oil, uni under normally with FFT or Belray.
Filter skin gets very dirty, uni stays clean. neer tried running the filter skin dry?
Something else you can do is run multible filter skins with a string for each coming out of your airbox, you'll have to color code so you don't pull them all off on the first pull,

you can oil the skins. it doesnt really matter. i prefer dry because it still keeps shit from hitting the filter and not as much shit sticks to the skin. never needed multiple skins but it may be good idea for extremely dust conditions. if its that dusty a respirator may be good idea also

layers of skins so you can peal layers mid race rather than just remove

i run my skins dry, that way you can throw them in the wash when the missus isnt looking..

also another option for skins are swimming pool skimmer basket filter socks... get a pack of them cheap

If I was racing in that dusty condition and had the side access airbox I'd be doing pitstop practice with spare filters all set up on cages and be prepped and ready to swap.

Not sure if you go to races alone but I've usually got my dad and girlfriend there and you wouldn't believe how fast those two can dump 10L of gas in the bike, swap my gloves and goggles, give me a drink, and dump some ice water down my back. New rules a few years ago mandated all bikes must be shut off for refueling so it was instant two stroke advantage!!

took it down to get properly measured, he was heading out the door, had 4 or 5 other bikes in his shop with dirt in the engine from the same race that got mine...
looked at it for a few minutes, spun the crank and told me the lower bearings were toast, and it was out of true ..... i know for sure i didnt knock it outa true, installed it with the tusk tool went in nice and i made sure the crank didnt get bumped before....
so either i nailed the flywheel on a rock laying it over.... i doubt it no gouges in the ign cover, or it was nailed during shipping, or STR didnt true it before sending it out...
didnt have time to measure the cylinder, but said dosent look too bad, if its round and clearance is whithin limits it will be fine

big end is good

so got it properly measured and i got 3.523 bore and 3.519 piston giving me 6 thou.... gonna call swaintech tomorow and probably ship the piston out

any machinist worth a shit will measure everything out to ten thousandths. lets you know if your on the high or low side of the thousandth. according to you numbers you got .004". swain tech wont gaurantee anything, but their minimum will be about .001, that .002 total. if your numbers are correct your between a rock and a hard place. run it at .004 or do swain tech and end up somewhere around .002.

im at 6 thou now... swaintech thin stuff is .0008 thick, that will close the gap .0016 which puts me at .0045 which is good

if roosty was closer id get him to do it, and since its that close i dont want to overbore till its a little worse

what im worried about is how the crank got out of true by at least .005...

3.523 - 3.519 = 0.004 not 0.006

dude i aint gonna argue. you got .004" from the measurements you posted. its simple math. swain tech says minimum is .0008, but thats a stab in the dark approximation. i have the swain tech at minimum, and they told me the same thing they will tell you, there is no way to tell with any accuracy how thick it will be. it might be .0008, but it might be .0014. any of this make sense ??? maybe bob can explain it, hes a engineer now from what i heard

sorry didnt meen to come off the wrong way but im just trying to help save you some grief. measure twice, cut once

thanks for catching that, wth was i thinking.... forget the coating.... ill just run it as soon as i take care of the bottom end and get roosty to do it right once it wears out

sorry didnt meen to come off the wrong

no, feel free to make fun of me... im using a calculator from now on

like i was saying before, it is important to know the ten thousanth measurement. you may actually have nearly .005, and swain tech could be a good option if thats the case

i was told 5 thou is still ok

its your call. me personally i wouldnt run any piston that far, thats just me though. dont get me wrong it will still work. was in your same situation with my ktm last summer, could of went either way but i chose thin coat of pc9, glad i did. remember a cast slug wont tolerate banging around like a wiseco

2strokeforever wrote: looked at it for a few minutes, spun the crank and told me the lower bearings were toast, and it was out of true ..... i know for sure i didnt knock it outa true, installed it with the tusk tool went in nice and i made sure the crank didnt get bumped before....
so either i nailed the flywheel on a rock laying it over.... i doubt it no gouges in the ign cover, or it was nailed during shipping, or STR didnt true it before sending it out...
big end is good

I'm curious how he determined the crank was not true without splitting the case. Runout on the crank is measured by centers on each end and indicating on the surface that is inside the inner race of the main bearing.
This might not be a bad thing thou because if it was me I'd be replacing the big end rod bearing also. If you got that much dirt to toast the mains,
it was getting to the rod bearing as well. It would be in your best interest to replace it now rather than later. Ask me how I know.

I'm curious how he determined the crank was not true without splitting the case

spinning it in the case and looking at it, everything wobbles the gap on rither side changes, the flywheel crank end goes up and down....
im no genius but i can guarantee its messed

AlisoBob wrote:

2strokekyle wrote:I've had filters look WAY worse than that, and not a speck went through. Granted it ran super rich and shitty until I got back to the cabin. But when I swapped it out the boot and inside of the carb were spotless.

X 2.

Thats why I commented on the air boot flange seal.

UNI + Super Sticky Blue Bel-Ray =

X2. Uni all the way. i have had mine so filthy out in dust bowl conditions that it got plugged up nearly solid. Not much dirt ever makes it past the RED layer of the filter, and then there is still the finer yellow layer.

I use Lucas oil stabilizer. its as tacky as filter oil. They are about the same price, the oil stabilizer is just more readily available.

So what kind of bearings are your junk mains? NTN, SKF, All BAlls? Could be why they are junk along with the dirt diet. If the crank was outta true your bike would be vibing badly.

I've had a brand new honda (NTN) mains last a couple hours, mechanic claimed is was defective.............who knows, I know it wasn't dirt.

I'd be looking closely at your big end bearing for sure.

That PC-9 will race clearance itself, if it's a bit tight, it's got some lubrication property to it, been there when I ran out of evans NPG-r and she got HOT. Didn't sieze due to the 927 and the PC-9.