how tough is it to adjust the valves on a big bear 400. I have a friend who needs it done and I want to help him. Any help would be greatly appreciated. Anyone having a step by step sequence would be the yamaha god in my eyes!

 

Can't be any different from my Wolverine,first,the engine must be cold,best to do it in the morning,or after it has sat without running for at least a day.Remove the front fenders(might need to take off or loosen the bumper)Turn off the fuel valve and remove the gas tank(should be held on by 4 bolts,2 in front,2 by the air intake in back.With both of these off,the top of the engine is easy to get at,the valve covers are held on with a metric 5mm allen bolt,use a rag to catch the oil that will run out the exhaust side,a little is always caught there. I don't know what the valve specs are for yours,mine is intake .003,exhaust .006,but you will need to find that in a manual,or just ask a shop or dealer. You will need to get the engine at TDC,remove the spark plug, take the plastic slotted plate off the side cover(by the foot shifter),and the little black plastic plug above that. put a metric socket on the bolt on the side,and turn counter clockwise,watching the small hole for the timing marks,and the valves for operation.You will see an F and a T mark,you want to be lined up with the T,and on the compression stroke,this will be when the T is lined up,and both valves are up,you should be able to wiggle the rocker arms slightly,if you want to be real sure,stick a small long screwdriver in the sparkplug hole to see if the piston is at the top. Check the slack between the rockers and the top of the valve stem with the feeler guage,you should feel a decent drag,if it is real loose,or the feeler won't fit, you will need to adjust to the proper gap.First loosen the lock nuts (10mm I think),then turn the adjuster to tighten or loosen,as needed.Lock the nut back down,holding the adjuster so it won't turn,then recheck the settings. If it is ok, put the valve covers back on,set the gas tank back on,(don't bolt it on yet) and hook it up to the carb. Run it for a while,and if you don't hear any funny noises(like valve clatter) you got the settings good, put it all back together,and ride,you earned it !!!!

 

IF this comes up for anyone else! i noticed on my 07 bb 400 irs, the "T" mark on the flywheel was not dead on with the "I" mark on the cam shaft sprocket, so i take off the timing inspection cover right there next to intake and exhaust valve inspection ports and got my TDC from the "I" mark on the cam chain sprocket, along with the spark plug hole.. (i used a plastic flag marker to ensure it was at the top. just make sure you're on compression stroke.
i'm new to this stuff, i'm learning... but doesnt it make sense if the T on the flywheel (correct part?) one at bottom with plastic plug...
and the I on the cam chain sprocket dont exactly line up, theres a little play.
i kept getting chatter, so i ran it off the cam chain sprocket mark and i was good to go.
i guess wear on parts is the cause? my bike has about 1200 miles on it.
if anyone has a suggestion here i'm all ears

 

He is doing a 350 but is the same motor as the 400 just punch out.
Its a 3 part video this is Part 2.