exhaust valve impacting piston?

[MRock]

Has anyone seen this? put a durability kit in my 09 dragon @ 4100mi. set
ring gap @0.20 engine started 2nd pull was running fine out to about 200 mi. then let go. Tore it down and mag side piston had seized from score marks that mysteriously line up with exhauast valve blade. Checked the PTO side and you can definitely see the same marks, any Ideas what could cause the valve to get that close. Will be glad to post pics if this will help.

 

[NapaMatt]

did u have the cyl.. renickled?

 

[mtncat1]

if you install the power valves into cylinders you should be able to see if they protrude into the cylinder. also the valve itself will have witness marks on them pictures would always be a help .

 

[Kraven]

EXHAUST VALVES HITTING PISTON

Has anyone seen this? put a durability kit in my 09 dragon @ 4100mi. set
ring gap @0.20 engine started 2nd pull was running fine out to about 200 mi. then let go. Tore it down and mag side piston had seized from score marks that mysteriously line up with exhauast valve blade. Checked the PTO side and you can definitely see the same marks, any Ideas what could cause the valve to get that close. Will be glad to post pics if this will help.

The exhaust valves contact the aluminum jug (on he inside of the ex valve bores) and over a period of time, the aluminum gets hammered and allows for the ex. valve to go deeper into the bore resulting in contact with the piston (as you've experienced)

You have to either;

1) Grind the exhaust valves (as in both) to obtain desired clearance

2) Swap out for a rebuilt cylinder (s) from MILLENNIUM (or ?/) as they REBUILD the ex. valve stops by drilling and pressing hardened "studs/stops" for the exhaust valves to contact

 

[MRock]

The mag side bore is cracked so am definitely going to have to swap the cylinder out for a reman. Getting mixed input from a few people on using the durability kit. Mine came from Mtntek. No one is saying don't use it, just that its unnecessary. Any thoughts on this as I start my parts list. Does the increased crank case volume really give a noteable HP boost? I have heard numbers from15 to 30% . Any thing I really need to look at in the bottom end as well. I am using the SLP stage three kit and clutching off SLP specs riding @ 8-10,000 ft ocassional trips above 11k