Will A Performace A8 or A14 Cam Work On A Stock 150cc GY6 Head?


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Posted

Throwing this topic out the the forum members for tech advice. Can I install a performance A8 or A14 type performance cam using my stock 2 valve GY6 head and timing chain without issues, or do I have to get a certain type of performance head and or a longer timing chain? My 150cc engine rebuild is getting a 61mm Glixal BBK, but I'm spending a lot more than I planned and just want to get up and running for now.

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Posted

Throwing this topic out the the forum members for tech advice. Can I install a performance A8 or A14 type performance cam using my stock 2 valve GY6 head and timing chain without issues, or do I have to get a certain type of performance head and or a longer timing chain? My 150cc engine rebuild is getting a 61mm Glixal BBK, but I'm spending a lot more than I planned and just want to get up and running for now.

Yes. Its is Supposed to be able to drop in.

The only real issue anyone may have is Coil Bind on Higher Lift performance Cams.

You will want a Minimum of .060" More Valve Spring Travel Before the Coils Bind when the Valve is at Maximum Lift.

From what I read of the cam shaft specs you should be, Should Be ok.  

 

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Posted

Throwing this topic out the the forum members for tech advice. Can I install a performance A8 or A14 type performance cam using my stock 2 valve GY6 head and timing chain without issues, or do I have to get a certain type of performance head and or a longer timing chain? My 150cc engine rebuild is getting a 61mm Glixal BBK, but I'm spending a lot more than I planned and just want to get up and running for now.

The suppliers that acquire my camshafts from do not supply specs for me to give proper advise/helpful tips on camshaft selection.... All I have is the graphs that have been provided. 

Pistonguy pretty much covered it... You only have to watch out for coil bind, other than that, it's just a matter of selecting the cam profile you want....

 These are all the different camshafts I offer LINK

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Posted

Thanks Pistonguy and Dan.

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Posted

I want to continue this thread a bit. I just bought an eHaze A8 cam and NCY valve springs from Amazon. The cam was half the price of the Hoca, so I was questioning it's legitimacy. To my surprise, the cam was exactly what it was advertised, 6.4mm lift on the intake, 6.6mm lift on the exhaust, crazy overlap, and a ground-out base circle, so it doesn't have the reverse-start lobe. Now it's the NCY valve springs that pissed me off a little. I've heard many people agree that the springs are made completely of titanium, weigh less than stock steel springs, and handle higher lift. This probably doesn't surprise you but the springs weigh the same, measure the same (free length, wire gauge, # of coils), and both stick to a magnet. These are just stock springs with a "cool looking" finish that you never see because it's inside the engine!

Okay, done with the rant...I tried the cam on for size with checking springs to check P/V clearance. I tried turning the engine over by hand but I had an issue with the valve retainers hitting the stem seals. I have a surface grinder, so taking 0.060" off the bottom of the retainer was not an issue.

Just today I got the valve stem seals I was waiting on (the old ones were starting to blow by anyway). I installed everything and set the lash to a sloppy 0.005"-0.006". The intake had no problem turning over but the exhaust had coil bind.

Any thoughts?

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Posted

I forgot to list the stats on my engine:

2008 Tong Jian GY6 150 with oil cooling (rounded port on engine)

54mm A-case

original head, cylinder, piston, etc.

stock CDI (the current one blew up, I took on this build because I'm still waiting on the new stock CDI to come)

2 degree timing advance mod

CR8HIX spark plug

orange racing ignition coil (probably what blew up the CDI in the first place)

26mm Yerf Dog carb with 35/122 jets, needle in middle slot

variator tuning

head lightly ported, exhaust polished, intake matched

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Posted (edited)

Yup your in trouble.

There aren't any different thicknesses of Spring Seats out there, your the one in a Trillion that checked for Coil Bind.

There also are no Retainers available to move the Installed Height or your Coil Bind issue you have..

I have some TI retainers but they are .015 Tighter the the OE I have.

To have anything made in such a small batch would cost a fortune.

You wil also notice that those Fake TI Notebook Binding Springs NCY calls Valve Springs, the Inner Spring is going in the same direction as the Outer Spring, This goes against All Conventional Wisdom we know about Valve Springs and there harmonics...

Shocking anyone debates if there TI or not, takes one simple Magnet test..

I have three sets of Valve Springs and there all the same, jack up! I'm not moving forward on my Hot rod until I can source a proper Spring.

Me personally would snit can the Cam rather than Butcher your Head up, get some new Retainers also..

 

Valve Springs, The Mystery

Lots of pictures

78-valve-springs-the-mystery

Edited by pistonguy

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Posted (edited)

I took notice to the way the inner and outer springs are wound, just forgot to mention it. Also, I did the magnet test, stuck better than McDonald's to (insert name of fat person here).

I'm not ditching the cam, I'm going to make it work because I got little to lose with this engine.

I'm searching for a mid-groove keeper set that would fit a stock Predator 212. The ones that come with split keepers have 5mm valve stems.

If that doesn't work, I'll search for longer valves.

If that doesn't work, I'll try lapping-out the taper inside the retainers to get them to sit higher (at the sacrifice of some spring tension).

If that doesn't work, I'll try machining another groove into the valve.

And if all else fails, order the Taida...

 

Sorry if I'm coming across like a know-it-all fool. I have my own machine shop to experiment in. I just want to know what idea is the best and if I did anything wrong.

Edited by TheDullCarbide

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Posted (edited)

I probably should have thought of this in the first place. Just get different springs.

I measured the new stock springs I have:

 

Outer:

Free Length: 1.350"

OD: 0.877"

ID: 0.670"

Solid Length: 0.790"

Spring Rate: 85 lb/in

 

Inner:

Free Length: 1.250"

OD: 0.633"

ID: 0.490"

Solid Length: 0.630"

Spring Rate: 32 lb/in

 

I found these springs on centuryspring.com:

 

Outer:

Part #: 72298

Material: Music Wire

Free Length: 1.250"

OD: 0.850"

ID: 0.650"

Solid Length: 0.560"

Spring Rate: 95 lb/in

 

Inner #1:

Part #: B6-14

Material: Spring Steel

Free Length: 1.280"

OD: 0.625"

ID: 0.487"

Solid Length: 0.480"

Spring Rate: 38 lb/in

 

Inner #2:

Part #: 71769

Material: Music Wire

Free Length: 1.250"

OD: 0.600"

ID: 0.474"

Solid Length: 0.430"

Spring Rate: 31 lb/in

 

I tried to find springs with slightly higher rates than stock because of the high angle/high lift cam. I also tried to find springs made out of music wire because they're better at repetitive loading. I will use inner spring #1 first because it dimensional-y fits better than #2, but it's "spring steel." If inner #1 fails, then #2 will be my backup if it fits.

Now before I go ahead with this, is this a better idea than cutting the spring pocket or using mid keepers or cutting a new slot in the valves etc?

Edited by TheDullCarbide

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Posted

I would recommend to skip Century Spring and deal with a outfit that does nothing but Valve Springs for Motors.

PSI is the industry standard. 

about-performance-springs

The problem is they don't sell direct and the local distributor to me is a mess with a no nothing squid to deal with. I know, I use to work there.

Tough call on your choices,  I have a bunch of reference as I have done allot with Four Stroke MX'rs, some Stem diameters the same, but nothing close or workable that would drop in a GY.  Ive done a bunch of custom Keepers, Retainers and Spring seats in 8620,

I don't see any keepers, cotters or what ever we call them that is the correct valve stem diameter to do what you need to do.

Between butchering the head and cutting different grooves in I choose to butcher and ruin the head, playing with fire trying to cut in new grooves and not have them dump in the cylinder, even with the lawnmower rpm's the GY-6 pulls.. 

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Posted

Yeah, I was second guessing the Century's after I saw the stock springs are a progressive rate spring. I couldn't find the keepers either. The predator stock 5.0mm keepers were high keepers and all the aftermarket ones were 5.5mm...and still then who knows if they would have fit the retainers or the groove on the valve. I will check out PSI springs. Thanks for the link!

First look at PSI: What's the difference between pushrod and OHC application springs? Heat? RPM? Design of the spring?

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Posted

BTW DUllCarbide familiar with Sandvick?

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Posted

BTW DUllCarbide familiar with Sandvick?

Heard of the name, that's it.

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Posted

Just curious how you were abel to do the Cam Profile measurements.

Was this like some static stand alone or in relation to crankshaft rotation?

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Posted (edited)

I read off the online specs of the cam and "sort of" proved them with a degree wheel and dial indicator with checking springs.

On PSI the MX 24.03 ML springs look tempting, but the solid length looks iffy and I forget my exact measurements. I like tearing down my engine anyway (not).

Edited by TheDullCarbide

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Posted (edited)

What do you and Dan do to fit the big Taida cams like the T-ONE in a 28/23 head? What's the difference?

Edited by TheDullCarbide

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Posted

I just want to know what idea is the best and if I did anything wrong.

Any thoughts?

What is your engine stamp, 157QMJ or 1P57QMJ? 

If your stamped with the P, forget it, the cam under NO circumstances will work. 

In directly answering your question, if your EX coil is binding, short of milling your head, there really are no options. Your cam may  just have too much lift...

Keep this in mind, the "GY6" name that people affix to these 150cc's is rather meaningless in some cases. These engines are on Scooters, Buggies, Go-Karts, Marine-craft and even though they may called a "GY6 150cc", the engines are vastly different... Some have reverse, some are proprietary, some have water cooling, some have oil cooling, different stud spacing, and possibly your situation, different cylinder head. 

So, in short what I'm saying is that the A8 cam you have, may work great in a Buggy GY6, but bind your coils in your scooters GY6....

------------------------------------------

As to if you did anything wrong or missed something during the install, I doubt it. Installing a cam is a brainless job, pretty hard to get wrong. 

As to what Idea is the best, it's the one pistonguy initially gave you - "Me personally would snit can the Cam rather than Butcher your Head up - Pistonguy

-----------------------------------------

What do you and Dan do to fit the big Taida cams like the T-ONE in a 28/23 head? What's the difference?

My guess, rocker arm ratio and/or valve length. 

When you say "28/23" head, that's a rather meaningless number by itself.... The 1P57QMJ also uses 28/23 valves, but are a different length than the ones in the 157QMJ. 

Taida makes a few different heads for the GY6, some have the 28/23 valves and other have the large 30/26 valves, but both are the same length and with the taida rocker arm assembly, it's all simple install with no mods required.....

 

 

 

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Posted

Wow, realizing what a thick-skulled millennial I am. I put the stock cam back in for now to practice a few donuts.

I haven't taken the time to learn all the "157QMJ" designations yet. I'll have to sometime.

I looked all over the engine and can't find sh*t about a 157QMJ model number. All I found was this:

Engine Family: Y:8TJPX

8D8D1-17F

This is what I know about the engine:

Made by Tong Jian (Fun fact, in english it means adultery. Go figure.)

A-case

57.4mm bore

oil-cooled with the square ports like the Puerto Rican model in your case boring video

62.7mm cylinder skirt diameter

I think a 90 link timing chain (I counted a long time ago and forgot to this last time)

24mm CV carb

DC CDI

8 Pole stator

PL20707 or PL30707 Gates belt (743 length)

built-in reverse gearbox

blower cooled

no EGR

As to if you did anything wrong or missed something during the install, I doubt it. Installing a cam is a brainless job, pretty hard to get wrong. 

As to what Idea is the best, it's the one pistonguy initially gave you - "Me personally would snit can the Cam rather than Butcher your Head up - Pistonguy

Yup, that reality is kicking my ass. I was originally relying on the fact that some other forums said that the NCY springs had a shorter solid length than stock. Now after dropping $18 on fake springs, I see the forums claiming they're fake. Pisses me off, but what 'ya gonna do? I'm starting to think about hanging up the A8 on my art (another word for failed mechanical designs) wall and buying the A12because it has a 6.0mm/6.25mm lift. I've seen buggy forums claim the Hoca A9 and A12 are drop-in. I wanted the top-end power and the A9 wasn't in stock, therefore the A8.

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Posted

You can likely find your engine stamp in this location:

 

GY6_150cc_Engine_Stamp_Location.JPG

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Posted

You can likely find your engine stamp in this location:

 

GY6_150cc_Engine_Stamp_Location.JPG

This is starting to get hilarious. There's nothing there.

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Posted

This is starting to get hilarious. There's nothing there.

Not all engines have them. The one in the picture doesn't either (they're ones I sell).....

At first I thought you were working on a scooter.... If it's a buggy GY6, I don't have much experience with them.... A lot of people buy parts from me for buggies, but I don't get them in my shop..... Could be the engine stamp is somewhere else or maybe doesn't even have one.....  :dunno: 

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Posted

It seems to take all the parts a scooter engine does up until the gearbox and the CVT belt. I confirmed it has a 90 link timing chain which would mean it is not a 1P157QMJ. So, maybe there's a little hope???

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Posted (edited)

If it helps any, the valves are both 65.5 mm long.

I can also measure and take pictures of anything you need.

I'm starting to think this is just a standard 157QMJ

Same engine as @fastwipp04 has in his Helix. His is much older than mine and doesn't have oil cooling.

Edited by TheDullCarbide

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Posted

Here we go...

According to Hammerhead the engine is a standard 157QMJ short case with a reverse gearbox that's specific to Tong Jian. Hammerhead and my American Sportworks use the exact same engine.

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Posted

Here we go...

According to Hammerhead the engine is a standard 157QMJ short case with a reverse gearbox that's specific to Tong Jian. Hammerhead and my American Sportworks use the exact same engine.

It can not be a 157QMJ if it has factory installed external oil cooling....

1 = 1 cylinder

57 = Diameter of piston 

Q = Cooling type

M = Motorcycle (application type

J = 150cc (cc's affix)

---------------------------------------------------------

Here's a nice little chart I snatched off the web

 

Engine_Stamp.JPG

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