GY6 Project By Bashan (Read 37,511 times)

[cdoublejj]

May 20, 2012 11:56:12 GMT -6 sprocket said:

I don't hink the chain guide is a problem, but i would replace it just for chuckles..ya..the piston has been slapping...it is a design flaw in these pistons the rings should be spaced out more to pervent the skirts from contacting the cylindar walls...get some wear on those oil rings..and the slappin' starts.

I compared a gy6 piston to a honda s65 piston. the original honda design has the rings much further apart.

[Bashan]

I'm still waiting on a few parts to finish the reassembly so I thought I'd post a bit on the oil system. There's a few functionality checks that you can do here also. A lot of this is old news to you jaded pros but some of the new guys might find some of this interesting. This is the inside of the right crankcase cover, the green arrow is where the oil comes in when you fill from the dipstick spout. The red arrows show the oil path up from the oil screen:

From the bottom, here's how the oil moves from the crankcase through the screen:

Here's a macro view away so you know what we're looking at:

Here's the crankcase cover and the right crankcase:

After the oil passes up through the screen it follows this path to the oil pump:

Here's the case plug and intake channel on the oil pump intake side:

The oil then moves through the pump and out into the vertical channel:

From the vertical channel the oil is pumped down to the crank bearing and up towards the top end:

So if you're reassembling you should squirt some WD-40 down into all of these passages and then some air to make sure they're clear, the green arrow shows the case plug on the pump output side:

]

Here's the outline of the oil pump from inside the crankcase, the yellow arrows show the oil path through the intake and output. The red arrow shows the oil path towards the oil screen:

Here's the oil delivery port at the crank bearing, it's designed to squirt oil onto the connecting rod:

The other side of this channel delivers oil towards the top end:

It moves through this channel on the cylinder and up through the dowel rod shaft:

Once at the top the oil travels into rocker pin and out the top through the two holes:

There's also a small hole that squirts oil down onto the top of the head:

I'll start the reassembly tomorrow, if anybody wants me to show them anything in particular let me know before I start buttoning it up. Rich

[Deleted]

Nice! I did not know that you can use those plugs for an oil cooler setup i have always wondered about that!

[Bashan]

I'm not sure you can. They plug is a short rod that spans the channel and inserts into a hole on the other side. I'm not sure how you would cleanly get it out of there, it's not just on the outside of the case. Also, if you did get it tapped out the oil flow would be split. Some would travel through the cooler back to the intake channel and some to the crank and top end. Also, the suction on the intake through the filter would be compromised. It sounds like a formula for disaster. It seems to me that the output channel would have to be directed towards the cooler without diversion, and then continue on towards the crank bearing and top end. Am I missing something here? Rich

[Alleyoop]

Yep, I agree with Rich, Where those plugs are out I would think it is asking for a disaster to happen and the flow of oil would be compromised and something would not get lubricated properly.
I would want the pump to directly pump into the inlet side of the Cooler and back out into the channel that distributes the oil through out the motor. I mean how else would you want it.
So I think if the case is not bored out to accomadate an Oil Cooler your asking for trouble.
my .02
Alleyoop

[Bashan]

I agree with Alley and I drew a couple diagrams to illustrate why. Also, I din't want somebody tapping these out without thinking it through. Here's the system with the taps in. I put a question mark on the inside of the plugs because I'm not sure how they terminate on the inside of the channel:

If you drill them out you now split the flow between the crank bearing, top end, and cooler:

It seems to me you'd need something like this that feeds right back to the top end and crank:

[jonglauser]

I've also been interested in adding an oil cooler and found this info: buggynews.com//topic3789.html?highlight=oil%2520cooler%2520drill%2520tap

Looks like it's possible to do, but you'll need to modify the case a bit.

[Alleyoop]

The only other way I see it working is The Inlet From the Radiator goes on the Drain Plug where the filter is and the Cooled Oil goes back using the plug next to it so the cooled oil gets pumped through the system.
Alleyoop

[Bashan]

Jun 11, 2012 15:29:31 GMT -6 jonglauser said:

I've also been interested in adding an oil cooler and found this info: buggynews.com//topic3789.html?highlight=oil%2520cooler%2520drill%2520tap

Looks like it's possible to do, but you'll need to modify the case a bit.

I think the guy did just what I was saying you'd have to do. He blocked the passage where the red line is, forcing the oil to flow from the right hole over to the left hole:

That way if you connected the feed to a cooler to the right hole the oil would flow through the cooler and right back to the top end and crank. That "irregular shaped" plug he fashioned looked like a real PITA and a good way to have bits of metal get into the system. Also, I wouldn't be comfortable with JB Weld used to fill in the gaps. I've had experience with it decaying and crumbling under heat and exposed to oil.

The output plug he drilled out looked like it was meant to be drilled unlike the one on my case. However, the intake plug on my case looks like it WAS meant to be drilled....go figure:

Rich

[Bashan]

I'm still waiting for some parts so I can proceed with putting the case together. In the meantime i thought I might as well put the tranny together. I use a little high temp, high pressure grease for the spindle and any of the bearings:

Some guys say not to do this because it changes the weight of the oil after it mixes but I don't think it hurts anything. The gears go together in this order:

Before buttoning it up I used Red RTV on both gasket faces as suggested by Sprocket:

Don't get too carried away with it, but you want a continuous coverage with no gaps. Then the gasket:

Then use the dowel pins to guide the cover on. You may have to turn the spindle a little to get the gears to engage:

The way I've always used RTV is to hand tighten the bolts and leave it for one hour. Then go back and tighten one quarter turn. Leave it another 24 hours and go back and wank it down to normal tightness. If you immediately tighten it down all the way you squeeze the RTV out and it doesn't have a chance to fill gaps. Rich

[Bashan]

Well onward with the thread. I'm using this as a way to sort out the pics and text for a comprehensive GY6 section in the library. So if it seems a little helter skelter that's why. My wife the web designer says that nowadays it doesn't matter how many sized pics you put on a thread, the internet and modern computers can handle it. So I'm just going to string a bunch of pics together. If anybody has trouble viewing them let me know.

I put the rings on yesterday just to get them out of the way. This is the way I do it and it works for me, maybe another method is your cup of tea. First, I do them dry so I don't fumble around with oily rings. I do the second ring first, it will be marked with a "2" which goes up. Open the ring slightly and catch the opposite side down in the groove:

Gently push one open side down until it snaps in the groove:

If the other side won't snap in you may need to use needle nose pliers. Be careful, the rings are kinda brittle:

Then do the top ring (marked "1") the same way. The bottom groove has three rings in it, two thin ones and a wavy ring. I put the the top thin one in first, then the wavy (ends butt, not overlap), then the last thin one. There's no up or down to these. Rotate the gaps so they aren't right over each other. I just realized I need more pictures on this stage, I'll get more tomorrow:

Speaking of gaps, Walter from Scooter Elements told me that these rings did not have to be sized. That's a nice step to be able to skip. If you did have to size them what you's do is put the ring into the cylinder about a 1/4" down:

Then push the cylinder up until it evens the ring:

Push the piston down and measure the gap:

These came in at just over .006" which should be fine. From there to about .008" is OK for a 150cc. If they're too tight you have to use a mini file and open them up. If they're too loose you have to put up with some oil loss and lousy compression or get more rings...kind of a no brainer.

Sprocket suggested I go over the cam chain guides which I think is a good idea. He says while you have the engine apart that "if it rubs...replace it"; good advice methinks. The cam chain tensioner guide is held in place by a threaded plug with a o-ring seal:

The tensioner guide is the one with the little trapezoid on top:

The tensioner pushes down against it to supply tension on the cam chain:

To install the guide insert it in the tunnel until the plug shaft holes line up:

Install the plug with an Allen wrench, you don't need to really wank it down, the o-ring supplies the seal, it's just oil splash anyway:

We'll get to the lower guide when we install the head. Rich

[Bashan]

I got the cam chain, tensioners, oil pump, and some other things I needed from Greg at Mainely Scooters:

The nice thing about dealing with guys like him and Walter are they sell above quality stuff and they will answer your tech questions also. Try that with the Fleabay guys.

If you've never looked at an oil pump up close they're an eccentric gear type. As the inner gear moves around it picks up oil as the space between the teeth expands and the squeezes it out as they get closer:

Well let's clean all of the gasket surfaces with brake cleaner and blow the case out with air:

I use a special edition Scooter Doc Kobalt air compressor available only at Lowes:

The case gasket needs to be trimmed to get rid of the parts you don't need:

Some guys leave that lower strip in that spans across the gap in the case. It's only there for shipping and if you've ever had that tear off and end up in your oil screen, like I have, you'll want to cut it off.

Ok, the gasket is ready, now we got to get the cam chain over the drive gear on the crank. Get your cam chain down into the tunnel:

Feed the crank through while holding the chain up:

Get the crank in and you'll find the chain is setting next to the drive gear:

Use a hook like you saw in the previous pics and lift the chain on top of the drive gear:

Then rotate the crank backwards and the chain will plop onto the gear:

[Bashan]

I got some more pics of the rings, here's the top compression rings and then the bottom three oil rings that sit in one groove:

Make sure the gaps are spaced evenly about:

OK, totally out of synch here but put some red RTV on the right case half gasket surface:

Fit it over the crank and onto the left case half, then use the right crankcase cover to hold the case halves together over night to let the RTV set:

You'll want to tighten the bolts more than snug on the case because we don't want the RTV adding to the width due to the bearing specs. On the tranny case it didn't matter. We'll knock the right case cover off later to install the oil pump and starter clutch:

Might as well put the piston on while we're waiting for the RTV to set. The wrist pin slides through the piston and holds it to the connecting rod:

These clips fit into a groove on each side securing the pin:

It is mandantory that you swear while trying to get the clip in, it's a law. Rich

[Bashan]

Yeah these do have the little notch you see in this pic that makes it a little easier to use the needle nose pliers:

It's still no picnic though. Wow, 34 ponies, that's a boatload. I'd really like to get something like that into a smaller scooter so you could have a big trunk and saddle bags. You wouldn't have to even think about hills either. I don't know why something like that isn't made.

Time to slide the cylinder on. Maybe you need a ring compressor tool for bigger cylinders but these squeeze in pretty easy. You just work the cylinder down and finese the rings together. You do have to be careful that they stay in their grooves. First the base gasket, no RTV because there's no way to get things cranked down before it sets:

Then the lower chain guide slides in:

The tab fits into the recess on the cylinder and make sure the cam chain is on the drive gear before you proceed. Also, make sure the EX on the piston is DOWN for the valve recess or you'll be buying a new piston:

At Sprocket's suggestion I used copper spray on the head gasket:

The head gasket holds the chain guide in:

You can see how much bigger the performance cylinder is by stacking them up:

By the way, clean all metal junction surfaces with brake cleaner before you put the gaskets on. That dark stuff you see is just shipping oil, not rust.

[Alleyoop]

I have a question, WHY are there TWO DRIVE GEARS ON THE CRANK? I notice on some the Outer Gear is smaller in diameter than the inner gear?
Alleyoop