I was wondering if anyone has experienced or has heard of anyone having problems getting compression after having their top end bored and honed because they did not wash the jug/cylinder good with soap and water before reasembly. Thus being to slipperry for the rings to grab, resulting in air passing the rings causing the atv not to fire.

This is assuming piston and rings are proper size.

I know other possibilities of low to almost no compression, I just would like any comments on this scenario in particular.

THANKS!!!!!
KELLY

 

Sounds like you may have broke a ring during installation.Or it wasnt set up right from the shop.I have put them together a time or two with out washing with no problems

 

having pre-assembluy lube inthe cyclinder doesnt hurt either a little. was the rings put in correct as well?

 

Rings are in right- I have top end dissassebled again, piston and rings look good.

Took old piston and cylinder too a good machinist so he could tell me what size to order and he did the work with new piston and rings in hand- thought maybe specs were off but I just remeasured, looks good. He did a really nice job.

Called Namura up today and the tech told me it was probably cause I didn't deglaze the cylinder with soap and water before putting it all back together.

Had it apart twice- both times when reasembled had great compression with just quick thumb test but when I put spark plug in it lost compression completely.

 

is it a 4 stroke or 2 ? could be valve timing is off that would caulse compresion with thumb but none to run

 

I'm really not looking for a diagnosis on this thread, just an answer to the initial question. (2-stroke though)

Thanks

 

It doesn't look like your getting anywhere. Now you said you took the new piston and rings and the barrel to a machine shop and had them fitted. Correct piston to barrel clearance with correct ring gap in the bore fitted to spec. Now the machine shop says you didn't deglaze the barrel! Could be this moron doesn't know what deglazing and boring to fit means? If you got the the barrel back with no crosshatch then he didn't bore the barrel! After boring or using a hone it will requirer soap and water to remove the dirt from the parts.Grit or particle from the deglaze hone will get between the ring surface and the barrel causing low compression at a later date. Sound like all the machinist did was mic parts and gave them back to you. Installing new rings you should always knock the glaze off or shine off the barrel.Do you have shop air handy if so use a rubber tip blow into the cylinder and tell us what happens.

 

Okay,

Reread my post please.

I said, I called Namura, the company who makes the piston I bought and their tech told me.... that without deglazing the cylinder it is a good chance this is the reason I am losing the compression in the manner I am-because I did not deglaze the cylinder.

The machinist did a rebore and hone on my cylinder which was damaged after the top end went out. The machinist did just the rebore and hone to spec w/out deglazing.

I did not deglaze the barrel- so really I am the moron.

So- I am really wondering if this may be the cause of my drastic compression loss. (similar to air blowing past the rings)( example; 50psi)

ALSO- I was wondering if anyone else has also made the same mistake with the same consequence?

Thanks for your response!!!
Kelly

 

Deglazing is the honing process.

 

It is common procedure to grab a 5 gallon bucket fill with soapy water, and run your cylinder up and down a few times, then wash out just with clean water. Sure, we all have by passed this step a time or two. But when you call Namura and they tell you about missing the deglazing step, that is where a "hone" by the machine shop is preformed or a "cross hatch" is done to help catch oil on the cylinder for additional ring lubrication. Your problem with compression has to do with either assembly, i.e., bad gasket seal, incorrect bore size to piston/ring size, and or possibly a cracked and or warped cylinder base and or top. Your cylinder and head is not sealing up and holding compression my friend. So, washing the cylinder out and leaving soapy water film in the cylinder wall, I find hard to believe would lose your compression.