GY6 Project By Bashan (Read 39,728 times)

[Bashan]

I'm not sure, they only thing I can figure is that they use that crank in many different applications. Maybe they use that in engines for ATVs and such and it drives another chain in a different type of case. There's one on the stator side too next to the oil pump gear. However, the chains simply will not fit on the wrong gear so you'd have to try really hard to botch it. It's possible I guess. Rich

[Bashan]

Push the head down on the cylinder. The copper spray does not dry, it just gets tacky. So don't sit around waiting for it to harden. By the way, don't forget the dowel/locater pins. There's two between the cylinder and case, two between the cylinder and head, and two under the cam bearing bracket.

Speaking of the cam, look how much bigger the lobes are on the A12 compared to the OEM:

Alright, we're going to figure this timing mark TDC thing out once and for all. Bring your piston up to top dead center by sticking the flywheel over the woodruff and turning the crank. Just look inside the spark plug hole, you can see the piston:

When my piston was exactly at TDC the "T" timing mark on the flywheel was exactly under the tab:

The "F" mark is for using a timing light which we don't do with a CDI. Now get your cam under the chain with the large hole on the cam sprocket out and the two small holes with their timing lines parallel with the head:

It turns out that with the cam in this position the flywheel migrates back to what I always thought was the correct "T" mark position which is slightly advanced:

You cannot get the "T" mark and cam lines perfect on my GY6 and probably nobody else can on any of the engines. It doesn't matter, this is the correct timing orientation even if it's a little off. Members post all the time thinking they're a hair off but as long as the marks are close it's correct. Remember, the flywheel turns twice as fast as the cam so if the cam sprocket was off by a link the flywheel T mark would be WAY off. So IMO the best method is to get the piston to TDC then put the T mark on the case tab. Then orient the cam sprocket with the large hole out and the timing marks as close as possible to parallel with the head without moving the chain. The engine will then be timed correctly.

[sprocket]

Ya I agree close counts in horseshoes and GY6. ;D I think the T is actually the firing mark, which is about 8 degrees advanced, but never the less, if you set it up like you describe Rich, the cam chain is on the right link...

That's all the matters...

[Bashan]

OK, the head is on and the cam is timed so lets put the rockers and cam retainer together. The new A12 cam does not have the cog on it for the rotation limiter. So I just installed it anyway as a spacer but I guess you could use washers of the same width. It goes in this position:

If you wanted to use washers they'd go here:

The two rockers are the same and the pins can only go one way. The intake pin is longer and goes through the top:

By the way, keep a squirt can of oil handy and give everything a little dose as you're assembling:

Put the retainer on the head with the four 12mm nuts, don't forget the locators:

Torque to 17 ft/lbs:

[jct842]

I used permatex copper in the dauber can (like pvc cement comes in) the guy at the auto parts store recommended it over the spray. I used it on the base gasket and head gasket on my majesty. and most of the other gaskets too.

[Bashan]

I thought of using the Permatex copper but I still have nightmares about trying to get that stuff off of some metal parts on a previous project. I'll mention that later in this thread. It is a serious sealant and won't degrade with heat including atomic detonations.

One thing I forgot to mention is the two 8mms on the side of the head, they need to be stagger tightened with the dowel nuts. There's a torque setting for them but I just give them a solid hand set:

Now that the cam is installed you can put the chain tensioner on. You use a small flat blade screwdrive to release the plunger:

Then while holding it set the tensioner down into it's well. This can be a bit of a juggling act and new tensioners come with a little key that simplifies this:

The right case cover had no RTV or gasket on it so it taps right off:

The oil pump has an arrow that points up:

The oil pump gear has a flat spot that fits into a flat spot in the pump:

Get your pump drive chain over the crank drive gear:

Then you'll need to pull the chain out from the pump a little, fit the gear on the chain with the flat spots hopefully lined up, and insert the gear. This is a little tricky:

[Bashan]

OK, put your starter reduction gear on:

The starter clutch is made up of an outer drive gear and the inner clutch assembly:

The collar on the drive gear fits down into the recess on the assembly where the round cylinders that you see will engage when it turns in only one direction:

So when the starter engages it pushes on the clutch and it locks forcing the engine to spin. When the engine starts the inner clutch assembly moves clockwise within the drive gear so it releases. You can take the inner assembly apart if you're a sucker for punishment. I just don't see the need for doing real PITA things like that anymore when there's parts available fully assembled like this or a head with valves installed, JMO.

There's a woodruff on the shaft and note the thrust bearing:

Here's a tip, to hold the clutch while you tap the lock nut, jamb some gasket material between the gears:

Now I was using a BF screwdriver to tighten the nut (reverse thread!):

But I think I found something better:

It's the shaft on a quick release clamp:

It gives you a lot more contact with the nut and keeps you from gouging it. Well, I have just a few more things to install and maybe I can fire this thing up this weekend. Rich

[sprocket]

Great Rich..I just want to remind people that the clutch washer under the locknut only goes on one way.. the washer has a slightly beveled edge on one side and this goes against the locknut...facing out from the clutch.

I can see from the picture you have it right.

[Bashan]

Jun 21, 2012 20:41:28 GMT -6 Random Hero said:

What's a BF screwdriver Rich?

It's a beveled face screwdriver. What are you guys talking about....oh wait...I get it! You guys are SO naughty.

I hooked up a 12v power source for the solenoid on my test bench. I hooked two 6v batteries in series to get the 12v needed to engage the solenoid. Here's a diagram for the wiring on my test bench:

[Bashan]

Hello again kids, I guess I'll continue posting on this thread until I have enough to start the new GY6 section for the Library. If anybody has anything they think would help out in the final product feel free to add or comment.

I got the engine started on the test bench and put about an hour's total running time on it. I changed the oil and found just a couple specks of red RTV.....no big deal. So now I want to get the engine installed in my Frankenscoot and further break the engine in buzzing around Chelsea for the rest of the summer. After that I'm not sure what I'm going to do with it.

Here's the weird GY6 engine mount that everybody complains about:

I don't know who thought of this thing but it seems to be a compromise for cushioning the forward thrust of the engine and a pivot for the swingarm. It's called a silentbloc by the British and I'm not sure what they mean by that term. Contrary to what a lot of people believe, the mount does not provide weight bearing for the frame of the scooter. The rider's weight is distributed on the rear shocks and the front fork. The engine literally hangs in the frame and slides back forward and back to the limit of the bumpers.

One common complaint on this thing is that there's very little room for the carb or anything else for that matter. Some guys have tried to install one of those chrome performance intake manifolds only to find that it pushes the carb too far back into the mount. I happen to be one of those guys and got so frustrated I ground out a spot for the carb to nestle in:

Before you freak out there's very little metal on that spot to begin with and I've put a lot of miles on this mount with no incidences. However, this is obviously a stretch on safety and I wouldn't advise anybody to try this. Whatever I do with this engine in the future it will be with a new mount, possibly of my own design.

So we slide the 10mm bolt through the engine ears into the mount:

Put the lock nut on and the engine's ready to install. I don't crank the nut way down on the engine bushings. I just tighten it until there's no side slack. You'll know if it's too tight if the mount won't rotate easily on the engine.

Slide the engine up under the frame, it's not heavy and you can use the mount as a carrying handle:

The mount bushings need to slide up into the recesses in the frame:

Most of the time the mounting bolt on the right has a collar that fits into the frame. The left side doesn't have this, go figure:

Something that's handy with this Harbor Freight lift is that I can secure the handlebars with the Canyon Dancer tie downs and lower the scooter down on jack stands and a 4X4:

That gets the scooter up in the air and then I can put the center stand down or use a floor jack. It works on 250s like this also:

Put some grease on the axle:

Slide the wheel on, you might have to juke around the oil fill spout some:

Then the collar:

Swingarm:

And axle nut:

I installed the cooling shroud with CE's cool looking scoop:

I'm using the OEM muffler during the break in. I've got a stainless muffler I'll use when I install this engine in another scooter. I'll get the variator and clutch installed next and then wire it up. Rich

[Bashan]

Guess I'll finish this thread up. Gotta put the variator together. Check the ramps and rollers for flat spots:

Make sure you get the guides in, (yes, we've had people not do this=disaster ):

If you took the kickstart gear off you need to put it back on the crankshaft. I used some antiseize this time for future projects:

Slide the variator with boss on the shaft being careful not to let the rollers move. Use a LITTLE grease where the boss inserts into the inner pulley because the pulley moves back and forth on it. Don't get any on the pulley facing or the rollers and ramps. Contrary to what a lot of people think the rollers do not need lubrication:

Here's the needle bearings for the clutch assembly, they like a little grease. Again, be conservative, the clutch pads don't need any:

Speaking of the pads, here they are. If they look glazed you can skuff them up but you can't get grit down into the bearings....your choice:

Slide the clutch assembly on. You can buy whole assemblies at dirt cheap prices. If you want to try and put one together with the contra and tensioner springs click here and here:

The 20 on this belt means 20mm width, I think the tolerance is 3mm and you're supposed to replace it. You better check a manual on that.:

Put the belt on the clutch and then stretch it over the variator boss. It can be a little stubborn but you didn't do anything wrong, give it a stretch. When you put the outer variator pulley on (also called plate or fan) hit the nut a little bit at a time to work the belt up between the two pulleys:

Now I've taken some flak for using an impact to install things. It is absolutely true that using a strap wrench and torque wrench is the proper method. For reasons I won't go into these juggling acts are difficult for me. Over time I have found PSI settings on my air compressor and impact that come very close to torquing the nut to spec. You can also mark the nut with a magic marker before disassembly and use that as a guide on assembly. The argument there is that metal is subject to plastic deformation and nuts will always be in a different orientation on reassembly.

My feeling is that this isn't the space shuttle and you will be OK going back to the mark. So to save myself a lot of frustration and swearing I've found a way that makes doing these tasks almost pleasurable....to each his own.

OK, gotta get some wires run:

I needed a dash board, I kept it simple with a power switch, a kill switch, a volt meter, and a start button:

I'm using the Trail Tech R/R that required floating the ground on the stator:

It is well worth the trouble, it is a powerhouse. I've been reading up on R/Rs and stators. An R/R gets rid of excess energy on a scooter by shunting the energy BACK TO THE STATOR. This results in the coils heating up to dissipate the energy. So my thought is, can we get too carried away replacing everything with LED lights? That juice has to go somewhere and once the battery is charged the R/R starts getting rid of the electricity. This might explain why some stators keep burning up for seemingly no reason. That's why they immerse some stators right into the engine oil, to get rid of heat. It's something to think about.

Here's the battery mounted on the front. The Trail Tech requires that all circuits run back through the R/R without a frame ground. So I made a grounding busbar and mounted it right on top of the battery:

I ran a red cable off of the battery to an ATC board and then ran each circuit off of the terminals. Ground the other end of the circuit to the grounding bus and you've got a circuit. The othe bus is for the R/R:

I put the CDI under the seat:

Here is the wiring diagram, note no ground for the stator....floating ground:

I slapped the tank back on and cranked it up:

I rode it about 5 miles to get some gas and the thing is fast. It's much faster than the previous incarnation of this engine but that one was fading fast....so who knows. The engine has this "tap" each time it fires. I'm not sure if this is characteristic of the high compression kit or what. Does anybody have any experience with this? I'll ride it for the rest of the summer and get it broke in then figure out what I'm going to do with it. I'm starting some PC repair classes so I probably won't have as much time to devote to these things. Rich

[Bashan]

I did oil the cylinder walls with plain old dino oil. For the rest of the engine I pull the spark plug and hit the starter in short bursts until I see oil coming out on top of the cams. That way I know that the oil pump is working and all of the components have a coating of oil.

For the bozos that say I don't get dirty, I'd like you to carefully inspect my hands:

[dmartin95]

Nice! Very informative Basham!

This forum has a lot of awesome threads on GY6 rebuilds... Pretty cool!

[Bashan]

Well thank you for the kind words. I have a "B" engine I need to do a rebuild on too. That's the CF Moto 150 that really isn't a GY6. The plug is on the other side and it's water cooled. I don't think I've ever seen a rebuild on one of those so that may be new ground. I plan on doing that over the winter to pass the cold dark days. Along with working on computers and my regular job. I certainly need another project.

[dmartin95]

Nov 15, 2014 16:23:45 GMT -6 Bashan said:

Well thank you for the kind words. I have a "B" engine I need to do a rebuild on too. 

Although it's us that needs to be thanking guys and gals like you that take the time to post these types of threads... It's not like there's a GY6 school we can go to, so we're left to our own devices to try and figure this stuff out...  Because of people like you and Rapidjim, it makes it possible for us to work on our own scoots! If we ever meet in person, I owe you a drink! 


I have been looking up info about the GY6 232cc for quite a while now... It requires the "B" block and I would love to see a step by step on how to build one. 

My scooter is a 150cc Bintelli havoc and my motor is stamped with BN157QMJ, I was super stoked! Thought I had a "B" case motor... But the president of Bintelli had his tech guys look it up and it is in fact a A case (54mm) motor.... I was bummed...
I really wanted to turn my scoot into a 232cc..... 67mm, +8.2 stroker, water and oil cooled... Oh yeah, that's me all day long! 

Anyhow, I really look forward to the b case build if you decide to do it. Be sure to send me a PM if I miss it....