Anybody knows what this plug is for? - Page 3

spcamno · 09-17-2009, 02:07 AM

Quote:

Originally Posted by MrJ

The plug looks like the harness end for the left controls on the handle bars.

Thanks for your post and here's an update:

I pick up an used engine locally and do a swap and it starts and ran fine along with a new coil and everything seems working even the remote start / kill switch so that plug is highly likely for another model with signal lights.

I suspected the previous owner couldn't figure out what's wrong (it's a faulty coil firing intermediately) and he remove the spark plug countless time and stripped the thread.

However, this used engine seems has worn rings (it smoke a little bit when its cold) but other than that it ran fine.

If I am fuzzy about the motor and wouldn't mind take it about what will you guys suspected?

Worn valve guides / seats or piston rings?

Also,it seems a little noisy (loose sound) when cold but after it warm up it pretty quite.

Thanks again!

Weldangrind · 09-17-2009, 02:36 AM

I would certainly suspect Chinese valve stem seals. I'd be inclined to believe that's the cause of the smoky start-up. If the rings were bad, I bet it would smoke all the time, perhaps even more when warm.

TurboT, do you concur?

TurboT · 09-17-2009, 02:56 AM

Since it's only blowing blue when cold I would concur on the seals.

The noisy when cold thing is a bit strange though. I'd like a better idea of the noise you're hearing.. like rattling or ticking, or louder deeper knocks.

What kind of oil did you use?

boost_addict · 09-17-2009, 09:47 PM

smoke on startup and deceleration is almost always valve stem seals. The noise is probably bad rocker clearances which more than likely have caused the seals to fail.

spcamno · 09-17-2009, 09:53 PM

Thanks for all the reply!

The noise seems more like an irratic rattle but once warms its gone.

Can someone explain what is bad rocket clearance?

I know it is not feasible to repair it due the a new head with valves is around $30 or $40 on ebay but I just want to learn more about these engine.

Thanks

Weldangrind · 09-17-2009, 10:33 PM

The only analogy I can think of is a see-saw, which compares with a rocker arm. The center point of the see-saw is the fulcrum, the pushrod pushes up from the bottom on one end of the rocker and the other end pushes down on the valve stem.

There needs to be slight clearance between the valve stem and the rocker arm because lubrication is needed to maintain the metal surfaces. There is just enough of a gap for oil, but not so much that the two surfaces clatter as they operate. The valve will open and close with every second revolution of the crankshaft, which translates to about 42 times per second at 5000 rpm. You can imagine that excessive clearance between the valve tip and the rocker arm will make a racket. Either too much or too little clearance will accelerate wear between the rocker and the valve stem. As well, too little clearance can actually hold the valve open, causing a loss in compression and power.

This is why proper clearance and fresh oil are vital to engine longevity.

TurboT · 09-18-2009, 01:09 AM

Valve seals can 'harden' from having the motor sit for long periods as well. So if it's been in storage, sitting around, not moving oil around, they will dry out and not be as rubbery, which does not allow them to work as effectively.

Depending on the style, they can be a bastard to change, especially on small motors if they are 'press fit' onto the end of the valve guide. You need to remove the springs to get at them, and since we've discussed the small tools required to do so, you might have to live with it.

Cal25 · 09-18-2009, 08:30 AM

Quote:

Originally Posted by spcamno

I know it is not feasible to repair it due the a new head with valves is around $30 or $40 on ebay but I just want to learn more about these engine.

If you can get a new head cheap, buy it and put it on the old engine. A cheap way to get a up close understanding of how things work.

spcamno · 09-19-2009, 12:38 AM

Quote:

Originally Posted by Cal25

Quote:

Originally Posted by spcamno

I know it is not feasible to repair it due the a new head with valves is around $30 or $40 on ebay but I just want to learn more about these engine.

If you can get a new head cheap, buy it and put it on the old engine. A cheap way to get a up close understanding of how things work.

True!

Thanks everybody for your help!

09-17-2009, 02:36 AM	#32
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	I would certainly suspect Chinese valve stem seals. I'd be inclined to believe that's the cause of the smoky start-up. If the rings were bad, I bet it would smoke all the time, perhaps even more when warm. TurboT, do you concur? __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	0

09-17-2009, 10:33 PM	#36
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	The only analogy I can think of is a see-saw, which compares with a rocker arm. The center point of the see-saw is the fulcrum, the pushrod pushes up from the bottom on one end of the rocker and the other end pushes down on the valve stem. There needs to be slight clearance between the valve stem and the rocker arm because lubrication is needed to maintain the metal surfaces. There is just enough of a gap for oil, but not so much that the two surfaces clatter as they operate. The valve will open and close with every second revolution of the crankshaft, which translates to about 42 times per second at 5000 rpm. You can imagine that excessive clearance between the valve tip and the rocker arm will make a racket. Either too much or too little clearance will accelerate wear between the rocker and the valve stem. As well, too little clearance can actually hold the valve open, causing a loss in compression and power. This is why proper clearance and fresh oil are vital to engine longevity. __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	0

09-17-2009, 02:56 AM	#33
TurboT Join Date: Sep 2008 Location: Surrey, B.C., Canada Posts: 2,185	Since it's only blowing blue when cold I would concur on the seals. The noisy when cold thing is a bit strange though. I'd like a better idea of the noise you're hearing.. like rattling or ticking, or louder deeper knocks. What kind of oil did you use?
	0

09-17-2009, 09:47 PM	#34
boost_addict Join Date: Sep 2009 Location: Delta BC Posts: 74	smoke on startup and deceleration is almost always valve stem seals. The noise is probably bad rocker clearances which more than likely have caused the seals to fail.
	0

09-17-2009, 09:53 PM	#35
spcamno Join Date: Oct 2008 Location: Toronto,Canada Posts: 36	Thanks for all the reply! The noise seems more like an irratic rattle but once warms its gone. Can someone explain what is bad rocket clearance? I know it is not feasible to repair it due the a new head with valves is around $30 or $40 on ebay but I just want to learn more about these engine. Thanks
	0

09-18-2009, 01:09 AM	#37
TurboT Join Date: Sep 2008 Location: Surrey, B.C., Canada Posts: 2,185	Valve seals can 'harden' from having the motor sit for long periods as well. So if it's been in storage, sitting around, not moving oil around, they will dry out and not be as rubbery, which does not allow them to work as effectively. Depending on the style, they can be a bastard to change, especially on small motors if they are 'press fit' onto the end of the valve guide. You need to remove the springs to get at them, and since we've discussed the small tools required to do so, you might have to live with it.
	0