Posted 28 April 2012 - 06:16 AM
Do you all agree that the metal was most likely from the cylinder?
Also would a big bore kit be best or a high comp cylinder kit? There both very close in price
Posted 28 April 2012 - 07:03 AM
I am not sure if the metallic particles are the nikisil but It sounds like your bike has the expected high hour count as most '02's would. Did you hone or Scotchbrite the cylinder to remove the glaze yet and spec it?
The 02 has a very good cam. One of the best stock CRF OEM cams. It is a long duration cam and the piston is under compressed for it at 11.5:1 so a higher comp piston is the way to go. You can run 13.5:1 safely on pump gas. A big bore would be good to.
But what is very important is that if the bottom end has a high hour count and you throw a high performance top end on it, it most likely will not hold up so I highly suggest you rebuild the bottom end, or at least pull it apart and spec it first.
Mine is basically stock except for a few things. I bought a '04 flywheel on ebay for $15.00 as it is lighter then the '02. I also replaced my entire ignition with '05 as the newer flywheel does not use the same magnet config as the stock '02 This is a common mod and you might not need to do it if you are riding woods/trails etc. I ride MX tracks. I never stall my bike because of it so it has worked great for me.
There is a water pump impeller mod you will want to do as well. Do a search on that.All you do is drill a hole in it a a certain place. Very easy to do.
I have '05 forks, an '05 carb, And I highly recommend an MRD exhaust. My bike had a full FMF exhaust but I ditched it and got the MRD. I was very happy I made that move http://www.mrd-racing.com/
Edited by mrmoto35, 28 April 2012 - 07:19 AM.
Posted 28 April 2012 - 07:18 AM
As suggested by mm35 measure the cylinder per your manual and after scotchbriting the walls, you may see more crosshatch. post some photos of the piston skirts and cylinder. That "edge" you feel now, could just be a bit of carbon build up above the ring and may go away after scotchbrite.. aluminum oxyde ball hone is sometimes used too but i have never had a need yet, if it had bad enough scratches, i just replaced the cylinder.
Good advice on NOT to do big bore too mm35. These crf's have finniky enough low ends, adding more power could just reduce what reliability it has now. Get a newr year piston (higher compression) in my opinion, but there is LOTS of info on different ways to go on builds (search).
Edited by MELK-MAN, 28 April 2012 - 07:20 AM.
Posted 28 April 2012 - 07:18 AM
Posted 28 April 2012 - 07:31 AM
Posted 28 April 2012 - 07:34 AM
Posted 28 April 2012 - 07:38 AM
you need to post photos of this mystery piston, you can believe what you want till the cows come home but if the piston still looks like new with the black teflon coating still in great shap, i don't think the cylinder can have ALL the nicasil gone. The bore size would be larger, and you would have the piston riding on a very concentrated area of the front and back of the cylinder and piston skirt. NOT good. These are pretty close tolerance machines, most pistons have a bit of taper from top to bottom (thus why you measure the piston skirt at a specific area above the bottom). You would have significant play and i don't think the motor would last very long before going "BOOM". The nicasil is VERY hard, it takes something going WRONG for it to come off, and as i said, i have never seen it just wear off evenly. It would wear in a problem area, then begin to peel off. that little bit of metal would get in some places and you would end up with a motor making bad noises in short order..
POST A PHOTO of the cylinder..
Edited by MELK-MAN, 28 April 2012 - 07:39 AM.
Posted 28 April 2012 - 07:41 AM
Edited by mrmoto35, 28 April 2012 - 07:45 AM.
Posted 30 April 2012 - 06:27 PM
it has a 175main, 48 pilot and clip at 4th position.
the problem is mostly it has a bad hanging idle, it had a 45 pilot in it, i could turn the fuel screw out a lot and it would have less of a hanging idle so i changed the 45 pilot for a 48 thinking it was too lean. now the hanging idle is a lot better but still bad. and the bike seems way too rich. i have trouble starting it now because the plug keeps getting messed up from running rich. also have the black smoke when i pop the throttle.
im asuming the carb isnt sep up right. i am in utah elevation is about 4570 where i live. how should i set up the carb?
i have checked the throttle cables, hot start, choke, and ive unplugged the tps. i also checked the slide plate and its installed right.
i am spending more time with the carb than anything else on the bike. does anyone have any suggestions?