Please help if you can. I 'm having a local shop put together my 686. Well after they finished assembling it they started it up and now there is a knocking in the motor. The shop did the bore but the piston I purchased from curtis sparks and the head work was done at trinity. It still has the stock rod. Tell the starting of it today it had never knocked at all. well they turned it over by hand and it seems like the knock occurs right after hitting top dead center on the compression stroke. We have no idea what it could be. The shop is getting ready to dismantle it and check everything again. Just wondering if you guys would have any suggestions of what it could be. And another thing does anyone ever encounter problem because of the cylinder wall being so thin. Any help would be appreciated.

 

What cam are you using? Was the clearance checked?

 

696/697 and as far as I know The piston is 12.5 to 1

 

not enough piston/valve clearance

 

Could it be cam noise from the new cam? I have been told that after new springs and cam that there is alot of valve train noise.

 

That's what I was getting at! LOL


Kind of elementary, but did you guys check the intake valve adjustment?

 

Man guys you gotta let'em down easy. I know it would scare the heck out of me to hear some body say " oh it your piston hitting the valves ".[img]i/expressions/face-icon-small-sad.gif[/img]

 

I'm Kinda new to this if it is the piston hiitng the valves would it have dammaged them already. And I know they set the valves. I have not been there for much of putting it together so I'm just going by what I'm being told.

 

Trinity measured mine and ground down the the valve indentures on the piston to tollerences that would allow for heat expansion.

 

so did I just ruin evrything or is there still a light at the end of the tunnel.