Bonneville America Forums Forums Technical Forums General Tech Spring loaded gears on camshaft question.....

What kind of problem should I expect if the cam split gears weren't installed under tension?
Long story....I decided to check the valves on my America and noticed the holes weren't lined up on the spring loaded gears. I measured each valve, removed the cams and saw that the spring mechanism worked as it should, put them back under tension - holes properly lined up, put the holders back, torqued correctly....and the measurements were now different. I bought the bike last fall, third owner, and I always felt that it sounded like a sewing machine and given I'm at the 17,500 mile mark decided a valve adjustment was in order. I had enough shims to do the exhaust side, waiting on the shims for the inlet valves, with one exception they were all on the tight side below the bottom end of the range. So I haven't fired it back up yet, wasn't sure if I needed to check anything first before doing that to avoid making a bad thing worse??

is your bike still under warrantee

If not I would load the cam springs as they are supposed to be and shim accordingly. If it is under warrantee I would make them replace the whole motor.

Maybe you should pull your alternator cover and verify that your cams TDC marks align the same as the TDC marks on the crank? If so, and the pretension is enabled on the cam gears, you should be good to go and you will get the true readings per valve/cam gap. Our engines are referred to as interference design, mess up the timing and things collide, or as my dearly departed father would say, "Son, looks like the wigglin' pin ain't right with the wobblin' box".

Thanks Ryk, that's a good idea, I will do that. The fact that it runs ok but just sounds a little noisy on the top end, makes me think the previous owner just did a lousy job (or the shop he took it to) with the valve adjustment.

Loco, bike is a 2005, and I'm the 3rd owner, so way out of warranty I'm afraid.

The springs loaded gears are there to make the camshaft revolution a smooth transition and help keep down the noise caused by chain slap. Whether or not the springs are preloaded shouldn't make any difference in the clearances.

Should still have push rods and solid tappets, so much easier to adjust.

If the springs were installed and not tensioned you will hear more valve lash or tappet type noise than normal.

There was a post a few years ago of a fellow who tracked down a noisy valve train on his twin to a defective split cam gear tensioner spring. Posted several short video clips showing how he tracked down the noise by rotating the engine by hand with the valve cover off then removed each cam until the noise went away. Found the defective spring.

Jeezum Chrymin - Even lawnmowers have hydraulic lifters these days
(My Kohler twin CV23S)
In fact, I "adjusted the valves" just yesterday with 2 & 1/2 quarts of fresh Castrol 10W 30 shim juice and a Wix 51056.
(Or was it tappet tonic?)

Thanks for the info guys, the new shims just came in tonight. As soon as I get them installed I'll post an update. I'm hoping this will quieten down the cam area and allow me to start riding with no worries!

Got the new shims in, put the cams back with the gears springloaded this time....started her up and it sounds like a new bike. Basically no "chatter" from the cam area - everyone in my shop noticed the difference right away! Will take it out for a longer ride tomorrow see if everything remainds ok.
Thanks to everyone for their input and help with this!
Max