Motorcycle valve clearance adjustment

[brainbug007]

So I tried adjusting my valve clearance at the weekend and I'm a bit confused to be honest. My engine says it's a 156FMI (no -1 or -2) and it's a 2012 lexmoto xtrs. According to the haynes manual this should be a pushrod engine which ties in with what lexmoto quote on their website for the engine. However when I tried taking the engine apart, it only has valve access covers and there doesn't seem to be a way to take the top of the engine off (ie rocker cover). There was also another large access panel on the left side of the engine at the top and under this there was what looked like a cam chain? Which is where I start getting confused. I thought pushrod engines had the cam at the bottom of the engine with the pushrods connected to it? If so does this actually mean my engine is a OHC not OHV? In which case the valve clearance settings giving the haynes manual are likely to be wrong as shouldn't the exhaust valve have more clearance than the inlet valve on a OHC engine?

So I carried on and set my valve clearences to 0.08mm based on it being an OVH engine. I set them by loosing the locknut on the rocker and then opening the clearance right up. I then stuck the feeler gauge under the rocker above the valve and then tightened the clearence right up until it pinched the feeler gauge to the point where I couldn't slide it out. I then loosened it ever so slightly so it would pull out with a bit of resistance and tighted the rocker locknut up. I'm hoping this was the right way to do it! Anyhow once I get everything back together and started the engine up from cold it sounded really good and ticked over much better than before (I was having all kinds of idle problems along with lots of stalls). Once the engine warmed up however it started making alot of noise. Sounds like a small hammer tapping on metal really quickly which I'm guessing is the top of the valve hitting the bottom of the rocker?

I rode the bike to work this morning and it does drive ALOT better now. It picks up speed much quicker and in 5th gear actually has pull. It will now get up to 60mph (speedo, 55ish gps) where as before it would struggle to maintain 50mph (speedo) and wouldn't even do 40-45mph(speedo) into the wind. The exhaust pulse sounds better now, a bit like a helicopter in the distance.

So is the tapping normal or do I have it too much or too little clearance? If it's not right, does anyone know what the correct clearance is? Also have I gone about adjusting it correctly?

[robo]

Does sound like you have adjusted it while `on cam`. Adjust the valves on tdc firing stroke. Thats not exactly right but near enough. Better than that take the bike back to the dealer and park it where the sun dont shine:eek: You should not be getting the grief you are with a new bike:(

Bob

[dogwood]

I would say 99% certain that is an OHC engine
And yes as Robo says, it sounds like you set it "On Cam"
Wind it round to TDC and check again, make sure it's on the firing stroke


Edit: Actually I have just done a Google search on your engine....
I can now see your confusion, so it could be a OHV
But the way you describe the rocker cover I still think it's a OHC
My RV125 valve clearences are about 0.03 to 0.08mm inlet and if I remember correct 0.15mm exhaust

David

[brainbug007]

Thanks for the replies guys. Joys of buying chinese :| So what you're saying about adjusting on cam sounds a bit confusing! The haynes manual simply said to put it in a high gear and rotate the rear wheel until the the rocker was in it's "up" position (with spark plug removed). When I did this I found that as I moved the wheel round it stay up and blip down quickly so to speak. So where I'm confused then is when the engine is at TDC, will I be adjusting both or just one valve?

[dogwood]

Not sure if this will help you
http://www.youtube.com/watch?v=pgZymnFuMe0

But defo need to find Top dead centre before setting the valves
Otherwise you can't be sure you got the correct clearance.
And yes at TDC you can set both valves at the same time

If you get completely stuck post up a close up pic of the left hand side of the engine. I may be able to talk you through it

[brainbug007]

Good stuff I'll have a watch of the video when I get home, cant view youtube from work :rolleyes: Hopefully getting it into TDC won't be too hard. Is it likely to damage the engine or cause a breakdown though riding it as is for a week as I may struggle to adjust it again in the evenings this week :(

[dogwood]

I don't think it'll cause any damage
Just not recommended..:D

I actually would be worse if you didn't have any clearance,
it could burn the valves.
But with the rattle you described it sounds like just too much clearance.

JMO of course ...Ass saving :rolleyes:
David

[brainbug007]

Thanks for the help with this one guys. Re-adjusted it on TDC at the weekend using the OHC settings from the haynes manual and it runs really nice now with no tapping, pinging, etc noises :)

Now just gotta work out how to fix the front caliper... Stupid thing seems to keep binding slightly on the disc as it spins round as it seems to have a bit too much freeplay on it's mountings :(