4tec 1503 keeps hitting valves

[Dereck0041]

Silly question but I hope someone has an answer... My #2 cylinder keeps kissing intake valves and breaking them ! 2 times we had to rebuild and it keeps happening.... But it's always after the engine has warmed up and into 30+ minutes of riding, it's never immediate... Any insight into why this keeps happening ?

Thank you

 

[dcm0123]

Suggest you check strength of the valve return springs.
Make sure there is adequate clearance between the valve stem and the hole.
Replace the rocker arm (in case bent) and hydraulic damper for the valve.

Are you running aftermarket parts such as valves or pistons?

How many hours on this?

 

[mkov608]

Suggest you pull out your service manual and inspect all the valve train components to make sure they are within spec. Check timing. Check camshaft lobes against specs. Pull valves to verify correct length & dcm's suggestions.

 

[brucegregorycalvert]

You have the cam timing wrong. The exhaust valves are usually the ones that hit because the piston is coming up as they are closing. I would say u r 180 degrees out. Go by the marks and use clay or solder to check the clearance before you bend more valves

 

[davus]

You have the cam timing wrong. The exhaust valves are usually the ones that hit because the piston is coming up as they are closing. I would say u r 180 degrees out. Go by the marks and use clay or solder to check the clearance before you bend more valves

I dont think engine would still even run if it was 180 degress out?

 

[brucegregorycalvert]

Ok maybe not 180 out but one or 2 teeth off will let it run and hit the valve. Ck valve spring pressure and tensisioner also.roll engine over and ck clearance

 

[davus]

Do you know the history of the engine? Any rebuilds or anything in the past?

It certainly feels a little like the valve isn’t returning fast enough once the engine heats up.

There should be dual springs for each valve. I’m assuming none of them are broken / missing?

I’m guessing you’ve replaced the valve(s) a couple of times yourself?….have you out tue same springs back in the same location?