Something else to keep an eye out when checking valves

nino209

New Member
my bike is 2015 cup bike I got it new in 2015, it has about 15 sprint races on it and a probably about 10 track days, i check valves religiously and oil changes are done after every outing, the one thing i have never bother to check is the cam sprocket bolts, well the intake bolt decided to back out, cracking the head and valve cover as well as bent intake valves.
I have never touched that bolt, so there is no chance i loosened it up.
something to keep and eye out for when checking valves, i will check them from now on.20170313_201423.jpg20170313_201443.jpg
 

cjwell

Supporting Vendor
Vendor
Country flag
I have had that happen too. Luckily I was on dyno and heard it slapping around. It did manage to break the cam though, the key way tab in cam. All my cams the sprockets are welded on the backside to the cam, and I reloctite/torque sprocket bolts! I learned the hard way. That was on my first set of my cams, so the bolt had been out, but I torqued when putting sprockets back on. Who knows but I take no chances anymore.
 

nino209

New Member
I have had that happen too. Luckily I was on dyno and heard it slapping around. It did manage to break the cam though, the key way tab in cam. All my cams the sprockets are welded on the backside to the cam, and I reloctite/torque sprocket bolts! I learned the hard way. That was on my first set of my cams, so the bolt had been out, but I torqued when putting sprockets back on. Who knows but I take no chances anymore.

What about tack welding the on the original sprocket and cam, good or bad idea?
 

Xquzme

New Member
Country flag
I just had my KTM 390 RC in for service work. They were diagnosing for no start when hot. I just did valve shims myself and set everything back into spec. The bike would run fine cold but would maybe start once out of 8 times when hot. I couldn't figure out the hot start so KTM diagnosed it by a leak down test and said the rings were possibly bad. KTM replaced the piston and rings and had it all back together. They took it out for a 10 km test ride and one of the cam bolts backed out and cracked the head and bent the valve cover. Who knows what else is damaged. I am glad it happened when they were the last ones in it. Now they are hoping KTM Canada will go good for the parts as they said the cam bolt should have never backed out as they are usually torqued in a cam alignment tool/jig.

It is just more delays the bike has been in the shop for 3 weeks and likely another 2 weeks to get parts and put it back together.

Sorry no pictures as the bike is at the dealers out of town. I would love to see the damage.
 
Last edited:
Top