engine pinging jackhammer noise

[Spare_Parts]

This won't help your tennis elbow.
View media item 61451

I've made my share of pistons look like that!

 

[LewieBike]

Loose rings will sometimes make that noise.

What that video is illustrating is a leaking head gasket, and yeah, a leaking head gasket can sound like mechanical looseness of parts. you might have a warped head

I recall an old Cycle World article that was discussing rod bearing sounds, Because 2 strokes have no reversal of forces on their rod bearings, ( it's the reason why most 2 strokes use needles and rollers top and bottom ends.) you will not 'generally' hear a 2 stroke make rod noises before it's too late. I've had direct experience with a needle bearinged 4 stroke Ryobi 845r weedeater engine that was destroying it's upper needle bearings. It's was making quite a clicking racket while it ran, especially at idle when it's under a lot of manifold vacuum.

You might want to disassemble the pinion/clutch ring gears and see if there some bad free play in the keyed shaft off the crank.

 

[TruewoC]

yes and visual inspection. Show us some pics. of the head and piston before you clean them.

 

[TruewoC]

don't always blame motor for a noise like that, it could easily be something rattling on bike or inside muffler

I am 100% sure it’s the top end making that noise. It’s deafening when I put my ear against the cylinder

 

[TruewoC]

yes and visual inspection. Show us some pics. of the head and piston before you clean them.

Piston and everything else looks fine. When I checked it there seemed to be a little up and down play. Also is there supposed to be side to side movement on the piston?

 

[gary55]

Yes on the side to side. No on the up and down. Might want to pull the piston and have a look at the wrist pin. Also freeze the crank at TDC and see if their is any noticeable play up and down in the big end. Sometimes it's even at the crank bearings. You can move the shaft at the bevel gear or the magnet rotor up and down. Usually it's at the wrist pin though. Oh and when you put it back together turn that c clip so the two parts of the clip you grab to remove are pointing up.

 

[TruewoC]

Yes on the side to side. No on the up and down. Might want to pull the piston and have a look at the wrist pin. Also freeze the crank at TDC and see if their is any noticeable play up and down in the big end. Sometimes it's even at the crank bearings. You can move the shaft at the bevel gear or the magnet rotor up and down. Usually it's at the wrist pin though. Oh and when you put it back together turn that c clip so the two parts of the clip you grab to remove are pointing up.

Thank you very much. And the wrist pins came stock like that. I haven’t touched it. What would happen if I ran the engine with the pins like that?

 

[crassius]

at speed, there is a really hard jerk at top and bottom when piston stops to go other way - that jerk can cause the arm on the clip to move out of the groove it sits in when the arm is horizontal

 

[gary55]

I think most of the clip problems occur just after TDC. That's when the rapid acceleration happens. At 6000 rpm the piston is traveling downward 100 times a second or 4000mm a second. This is a mean speed of 8.95mph. It don't sound like much, but it's being accelerated to that mean speed in 1/100 of a second. Thus if setting side ways the spring tension of the clip is overcome by inertia it pop out of it's groove and it's time for a new top end.

 

[Deleted member 27811]

I found the metallic tick @ low to just above idle was the carbon brass bushing I put in about 50 mi ago. Put the cage back in and it went away. Probably the wrong rod. It's in a GT5 from BMW. Need to revamp the cyl. this winter w/ port work/ boost port. Already have 6.0 fred. real Dellorto 16-16/ oz loop/ Jag CDI...just waiting to wear it out to give me a reason to tear it down.