engine tapping/knocking

[gonefishin485]

so the story goes, early this morning my younger brother took my bike for a ride to warm it up before i went out riding today. i had a sort of date and the girl wanted to go riding, we had a blast but i noticed midways of probably a 70 mile ride, that my engine was making a tapping.

its not a loud tap, or a fast tap, but its a definite tap on the left cylinder. i noticed it leaving the gas station after fueling up, when i left off the clutch to ease into traffic. i dropped her off, came home, let it sit outside and cool off. when i fired it up to put it in the shed about 2 or 3 hours later, it was knocking something fierce, so i pulled it in the shed and started trouble shooting.

valve lash is good and cam chain push rod is even, but its still knocking on the left side. it doesnt sound like its knocking down low it sounds like mid cylinder to head region.

any ideas?

 

[inxs]

- whats the compression like? are the collets still in place?

 

[yamaman]

I think when you dropped her off, you were supposed to go inside for a "coffee". God is punishing you for letting mankind down!

Maybe camchain guides??????

 

[inxs]

- heaven must be such a lonely place

 

[matt81xs]

is it getting oil to the top side???

 

[gonefishin485]

im not sure about compression numbers, i know the left pipe has always been louder than the right, regardless of what you do to anything, carbs, valves, whatever, the left pipe has always been louder than the right.

its getting plenty oil to the top side, cranked it with the tappet covers off and its got good oil pressure

 

[matt81xs]

if youve got a long screw driver you can use it like a doctors stepho-scope....spelling on that??? And while its running you can pinpoint the item in question...

 

[C-Los SD]

I had a loud noise coming from the cylinder head area. Turned out to a worn crank pin bearing, but you would hear the noise from the top of the cylinder head.

 

[gonefishin485]

ok, edit, i took a long screw driver, jammed it in my ear went poking and proding around the left side of my motor.

the cylinder and bottom end sound like a low hum, the left rocker shaft has a little noise to it, but the right (intake) rocker shaft sounds like someone is jack hammering inside my head.

worn shaft? worn rocker? cam?

 

[gonefishin485]

ok, so i narrowed it down to the rockers tapping. this sound right? im thinking about popping the head and valve cover off, replacing the rockers with some from mikes, re-lapping the valves and putting it back together.

how does that sound? anything else i should do while i have the head off?

 

[xsjohn]

Valve seals............like C_los SD said crank problems including the bearings will sound like it's in the head area too.........been there myself.......

xsjohn

 

[gonefishin485]

also, what all gaskets will i need? i know a head gasket, but is there a valve cover gasket? or anything else i will need?

 

[gonefishin485]

Valve seals............like C_los SD said crank problems including the bearings will sound like it's in the head area too.........been there myself.......

xsjohn

well im pretty sure its the rocker, and im pretty sure its the intake one, i put a philips screwdriver in the cap cover, put it to my ear, and it sounds like a jack hammer in my ear. i put it on the exhaust rocker cover and i dont hear it, i took it for a short ride today, and its its not a fast or hard knock, its not running bad, its just aggrevating, i like to have my engines running and sounds top notch.

 

[Sundie]

anything else i should do while i have the head off?

General crap cleaning out of the runners and top of the pistons and combustion chamber. Check your valve guide clearances. A new head gasket is a "might as well" if you don't knwo it's age. Aside from valve seals (already mentioned) it should be good to go.

If you don't disturb the bottom gasket/cylinders you shouldn't have to do any more.

What's your compression like? If it's good, don't go any further than the head. If it's not, you may as well do rings as well (which means new bottom gasket, and at a minimum honing the cylinder). The plus side of this is you'll be able to check your slop in the con rods and probably determine if you've got a bad bearing on the bottom end.

At that point - in for a penny, in for a pound.

also, what all gaskets will i need? i know a head gasket, but is there a valve cover gasket? or anything else i will need?

the 1194 sealer from Mike's is excellent for sealing the rocker cover to the head with zero leaks. There's no gasket for it, so you'll have to do something.

 

[xsjohn]

No valve cover gasket.........a bottom cylinder gasket might be handy to have since you are fishing.........you will be able to tell if its a piston generally if it rock front to back is very much.........can also compare that movement with the right side............

xsjohn

 

[Gordon]

If you pull the head, besides the head gasket, you will need gasket's & 'o' rings for the side plates, ( the points plate area), 'o' rings for the dowels that have to be removed to remove the rockers, possibly intake & exhaust gaskets as well.You did mention valve seals, right?

You want to look at the cam very carefully for wear, as you cuold have one thats not perfectly concentric. Check the ramp & dome ares for flat spotting, does happen more often than you'd suspect.

 

[gonefishin485]

allrighty, sounds good to me, its about what i figured it was going to be, ive pulled down and rebuilt a lot of four wheeler and dirt bike top ends, so im not a stranger to the territory

as far as compression, its good enough that i can half choke it, a few spins from the starter and it pops right off and i can go riding. HOWEVER ive noticed for a long time that its had a sort of miss on the bottom end, and the left pipe in a general consensus is louder than the left.

im hoping re-lapping the valves will handle that, but it could be lower compression on one side, so who knows, i guess ill find out when i tear into it

 

[Sundie]

If you've torn down anything newer, you'll laugh at how simple these are.

 

[gonefishin485]

well, i thought i had it pinned down, but now it sounds like its coming from the front of the motor, ughh, aggrevating.

whats at the front of the motor? is there a cam chain tensioner that could be worn out?

its aggrevating because i cant nail down what EXACTLY is making the noise, and the noise doesnt really go along right with anything, it sounds different at different rpms. at a high idle its almost non existent, when you left off the clutch and load the motor you can hear it clear as day, just an easy cruise going down the road its just barely noticeable, i give up

i think its just going to be in my best interest to take it to a shop and have someone look at it, my cousin has some friends that own a shop just outside of new orleans that do killer work.

in the mean time, does anyone see a problem with riding it like it is?

 

[jay760]

The cam chain guide at the front of the engine is the one that normally goes, unfortunately the only way I know of getting to it is through the head.