200X Video and Sound of "bad bore"

[ctbale]

Ok, honed the cyl, looked perfect, put it all back together ... still sounds like crap. This is the only 200X I have ever heard so please comment, at idle, its sounds bad, but it runs like a raped ape. My buddy had a regular atc200 and his sounds like a Cadillac its so smooth. WARNING: if you watch this video more than twice, you WILL have a screaming headache!! Too painful to watch.

http://www.youtube.com/watch?v=mONCCzQU23E

[just ben]

ok that cylider does not look perfect or anywhere near that,and I am sure the piston looks just as bad. heres your options: tear the top back of and do a proper bore and piston kit or just run it and wait for the piston skirt to grenade and then do option 1 and likely a rod kit also maybe even a crank

[Tri-Z 250]

^^ spoken, like a true poet ^^

[ctbale]

yea, does not look too good to me either, I should have posted the vid on the orig "bad bore" post.

http://www.3wheelerworld.com/showthr...-bad-bore-quot

[zackwhite]

u need to do a topend job and the sound i dont think that is top sounds like pipe is just that way

[shortline10]

Hard to tell but for the most part what I here is valve train noise . Are the cam journals still tight and the valves adjusted correctly ?

[RodKnockRacing]

X2 with what Mike said

[ctbale]

yea, listening to the vid it does sound like valve train noise, but in person its piston/cyl, I am sure of it. I have had hondas that sound very close to this, and have had them bored (by the same guy in fact) and they get put back together and NO sound, one 90 I have I ride it 2 times a day to run my dog, has several hundred hours, beat the heck out of it, sounds/runs great. Mike, I checked the cam journal on the head I got from you, and its golden, no step, and very little up and down on the cam, I have swapped cams, no help, adjusted valves to .002, .003 and .004, no help. I think shortline nailed it on my other post, the piston is miss ground/egg shaped. I know that these pistons are cam ground, smaller across the pin than front to back, but this one is .016", and maybe the taper is incorrect too, My new (too small to use now) Wiseco had .008 or .009. anyone have a new 65/66mm jap cast piston they could measure for me? .016" is a huge number when talkin about piston to wall clearance, when the piston is in the cyl, I can see thru the crescent with the rings off, and the skirt is .0015 to.002. That one egg shaped/elliptical piston!!!!!!!!!!!!!! I have new 47 and a 50mm pistons, I will measure those, but it would be interesting to compare apples to apples

[ctbale]

http://www.3wheelerworld.com/showthr...uot&highlight=

Tear Down #3

Above is my first thread, this is "bad bore" round two. That if you want to catch up on my little saga.

So I am looking at one of my pictures and I notice that on the new tensioner the new wear marks are not parallel with the tensioner itself. Like BIG TIME NOT PARALLEL!! (seethe bottom three pics from teardown #2) So now I am thinking f@#k!! the tensioner assy is bent, but after investigating (on "tear" -down #3) I find thats not it, the lower cam sprocket is too far in. I didnt change the forward tensioner, and its wear marks confirm this. (pic with the finger) So how the hell does this happen, I could see if the ass who rebuilt my crank forgot the thrust washers, it would make the crank more narrow, but the guy bent one washer when he put it together, so thats not the case. The only variable is the side play on the lower rod, new is .002 to .020 and .032 max and its at .012. I measured it, and the sprocket is about 2mm or .080" too far in. I could see if I used a thicker case gasket, that would give the crank too much axial play, but its got .005 to .010 max in the cases. The other weird thing is I dont see any fresh wear marks on the case, lots of wear from before I owned it, but the chain does not look like its hitting now, dam close though. And the tensioner wear confirms that. I have exactly 30mm to the end of the crank. What do you guys think, and if anyone has a crank laying around, could you tell me if 30mm is correct, should be, the sprocket is tight to the shoulder on the crank web

I have new oem thrust washers and a 6th over wiseco piston, and a new machinist, but want to get this sprocket thing figured out.

[ctbale]

more pics

might just not press on the sproket all the way this time, but it sure is strange

[shortline10]

Strange !!! The cam sprocket is def supposed to be flush against the bearing . Are you sure you have the correct sprocket ? Only other possibilty is the crank was pressed together to much and its floating in the cases . I dont think the bearings have a sholder to them .

[ctbale]

Yea, your right on, the bearings can go either way, no shoulder, that crossed my mind, but they are idiot proof.

"Wrong sprocket" After looking at it, thats what I thought too!! wrong sprocket or the guy ground on the inner face, there should be no variable, the sprocket gets pressed on till it stops, I have no idea where the 2mm (.080") is coming from. if the Vesrah rod is skinnier then stock, and it was pressed to .012" at the thrust washers, like you were saying, the crank would be movin left to right. The left to right (axial play) is perfect, there was not any till I pulled harder and squeezed the oil. It has between 5 and 10 thou, my .005 wire feeler gets in there, but not the .010, cant find it in the book, but thats pretty normal. I have never seen a axial preload from the cases, and I would not want 30 or 40 either.

I got 8mm from the bearing face to the outside of the tooth root. For the lower sprocket to be lined up with the cam sprocket, tensioners and centered in the chain case cavity, it needs to come out about 2mm, to 10mm from the bearing face.

Thats a bunch!!

If anyone has a crank laying around, I would be pretty interested in what their measurement is thats for sure.

[shortline10]

I' getting 8mm as well .

Yea, your right on, the bearings can go either way, no shoulder, that crossed my mind, but they are idiot proof.

"Wrong sprocket" After looking at it, thats what I thought too!! wrong sprocket or the guy ground on the inner face, there should be no variable, the sprocket gets pressed on till it stops, I have no idea where the 2mm (.080") is coming from. if the Vesrah rod is skinnier then stock, and it was pressed to .012" at the thrust washers, like you were saying, the crank would be movin left to right. The left to right (axial play) is perfect, there was not any till I pulled harder and squeezed the oil. It has between 5 and 10 thou, my .005 wire feeler gets in there, but not the .010, cant find it in the book, but thats pretty normal. I have never seen a axial preload from the cases, and I would not want 30 or 40 either.

I got 8mm from the bearing face to the outside of the tooth root. For the lower sprocket to be lined up with the cam sprocket, tensioners and centered in the chain case cavity, it needs to come out about 2mm, to 10mm from the bearing face.

Thats a bunch!!

If anyone has a crank laying around, I would be pretty interested in what their measurement is thats for sure.

[ctbale]

thanks for the info Mike.

I might just have the rebuilder press the sprocket on 1mm short of the stop, that will get the chain away from the chain case cavity wall in the cyl, and get it more centered up on the tensioners, 2mm wouldnt hurt, I can press it on more if it needs it at work, problem is I dont have any way to draw it off the shaft.

[dmfaulks85]

Exactly 30mm on my crank too