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Post by turboaz2 on Sept 15, 2008 12:04:26 GMT -5
After searching all over for parts for my 1P57QMJ-2A. I found a website that shows all 4 types of gy6. motor.mortch.com/products/scooter/mainsc.html#Apparently the -2 and the -2A make the most power in stock form. Like we don't already have enough problems finding parts. Now 4 variants to keep track of. So far as I can tell the biggest difference between the old 157qmj and the newer variants is the cylinder head. The taller (2.88in vs. 2.2) head also requires longer studs, chain, and guides. It also uses a different cam holder/rocker arm fixture. It comes in both 2-bolt and 4-bolt valve cover types. The jugs/ cylinders are the same. The individual rocker arms are the same. The combustion chamber is smoother and more rounded. Also the gasket side of the head is almost identical in shape to the head gasket with not additional milled material. The 157qmj head has a large milled area next to the combustion chamber. Here are some pictures to help you better identify. 1P57QMJ Head www.chineseatvpart.com/images/products/large/221.jpgwww.worldofscooterparts.com/images/products/detail/NMP09512.jpg157QMJ Head www.worldofscooterparts.com/images/products/detail/NMP09442A.jpgLet me know if this makes any sense. |
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Post by kmesse on Sept 15, 2008 13:38:40 GMT -5
BONE for that! Wow, that may explain the wrong chrome air intake I got (another thread).
It also shows good views of all sides of the engine.
I ordered the chrome intake and it didn't fit. Looks like I have a Qmi2 where the bolts are inline, and the QMI look staggered like the chrome intake I got in.
Shoot. Now I can wonder if there's a good intake for MY engine.
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Post by earlwb on Sept 15, 2008 14:29:16 GMT -5
I like to break it down as two main types of engines, one is the Linhai clone engine with the two bolt valve cover, versus the Honda derived clone engine with the four bolt valve cover. Externally the two main types of engines are compatible and interchangeable, but internally the parts are all different. For example, a Linhai engine has a slightly rectangular head bolt stud pattern, so the Honda head won't fit as it has a square head bolt pattern.
Then you have the short case and long case version of the engines as well. the ATV chain drive short stub axle sort of doesn't apply. There is likely a longer case engine design for the 16" wheels too. But I don't remember looking to see if it was or not.
Finally, you have A) a head with two small valves and two small ports.
then B) a head with two small valves and large ports.
then C) a head with two large valves and small ports.
then finally D) a head with two large valves and two large ports.
So for performance you want the head with the large valves and large ports.
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Post by Jason on Sept 15, 2008 18:33:18 GMT -5
I have a 157QMJ-3 on my Flyscooters Cadenza.
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Post by turboaz2 on Sept 15, 2008 18:43:55 GMT -5
I like to break it down as two main types of engines, one is the Linhai clone engine with the two bolt valve cover, versus the Honda derived clone engine with the four bolt valve cover. Externally the two main types of engines are compatible and interchangeable, but internally the parts are all different. For example, a Linhai engine has a slightly rectangular head bolt stud pattern, so the Honda head won't fit as it has a square head bolt pattern. Then you have the short case and long case version of the engines as well. the ATV chain drive short stub axle sort of doesn't apply. There is likely a longer case engine design for the 16" wheels too. But I don't remember looking to see if it was or not. Finally, you have A) a head with two small valves and two small ports. then B) a head with two small valves and large ports. then C) a head with two large valves and small ports. then finally D) a head with two large valves and two large ports. So for performance you want the head with the large valves and large ports. But added into that mix is the fact that there are now 2 types of each cylinder head for a total of 8. |
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Post by mx5tc on Sept 16, 2008 17:03:50 GMT -5
Sure would be interesting if we could get what the port volumes were on some of these heads! The taller head variants may have better breathing if intake port/entry angle and exhaust port/exit angles are improved over the "short" head.
The specs also make it pretty clear that the EGR heads/system hurts power.
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Post by 2t4tsim on Nov 20, 2008 18:03:15 GMT -5
Hello ,
I bought a Autotech 58.5 head for 1P57QMJ to a guy who own a 157QMJ.
This a beautifull head but rocker arms holder (157QMJ) is not compatible.
1P52QMI :
Head is 13mm taller with port inlet / outlet much higher that gine better flow efficiency.
Combustion chamber is 13mm deep and have external diamter of 50.5mm (squish is 4mm each side.
inlet valve = 27.75mm
inlet port outlet = 22.5mm
exhaust valve = 24mm
exhaust port outlet = 22.5mm
Sufficant for 16hp @ 9000rpm with good torque. We are near to acquire several valve lift profile from several Ax cams and would advise in time.
Does any one of you compared the two holder ? Problem with holder ? rocker arms ?
No problem to install holder alone on camshaft bearings. Tappet adjusting screw side to low and hit valve retainer. Alignment with valve axis is not perfect.
Do you know a web place to buy "genuine" 1P57 parts ? I ma looking to buy rocker arms and a timing chain...
Thanks in advance
Regards from France
Alain
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Post by swakk on Nov 20, 2008 19:54:20 GMT -5
don't you have a bearing of a different size, like on quiangjang (keeway) engin ?
you just have to change it in this case
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Post by mx5tc on Nov 20, 2008 20:04:07 GMT -5
Hello , I bought a Autotech 58.5 head for 1P57QMJ to a guy who own a 157QMJ. This a beautifull head but rocker arms holder (157QMJ) is not compatible. 1P52QMI : Head is 13mm taller with port inlet / outlet much higher that gine better flow efficiency. Combustion chamber is 13mm deep and have external diamter of 50.5mm (squish is 4mm each side. inlet valve = 27.75mm inlet port outlet = 22.5mm exhaust valve = 24mm exhaust port outlet = 22.5mm Sufficant for 16hp @ 9000rpm with good torque. We are near to acquire several valve lift profile from several Ax cams and would advise in time. Does any one of you compared the two holder ? Problem with holder ? rocker arms ? No problem to install holder alone on camshaft bearings. Tappet adjusting screw side to low and hit valve retainer. Alignment with valve axis is not perfect. Do you know a web place to buy "genuine" 1P57 parts ? I ma looking to buy rocker arms and a timing chain... Thanks in advance Regards from France Alain Alain, Many thanks for posting detailed specs on the "P" head. I knew it had improved ports with better entry and exit angles but I did not know what the port and valve sizes were. AFAIK, the 28/24mm valves (stock on the P motor) are considered as oversize on the non "P" 150cc GY6. Akunkar (out of Thailand) has both 28/24 and 30/26 valve sets available for about 15.00 USD. For "P" parts, just send an email to Carlos Chiu (autotech355@gmail.com ) telling him what you need; he should be able to supply the parts (he sells a lot of high quality Taiwan sourced GY6 parts). I think you will need the following to run your "P" head on a standard QMJ engine: 1. 4 longer cylinder/cylinder head studs (stock are too short for the P head) 2. Longer P cam chain 3. P Cam holder assembly complete with intake & exhaust followers. 4. Check with Carlos on cam interchange or Jake318 on this site (Jake spent a month going thru a "P" head learning curve earlier this year) The P head (at least some of them) seem to have shallower valve seats and a lower installed valve spring height than the standard QMJ. Needless to say, this prevents you from installing a high lift cam unless you machine the valve seats deeper or use an offset valve retainer. In any case, you want to check piston-to-valve clearance and for valve spring coil bind (both inner & outer) when using a high lift cam on a "P" headed motor. Lastly, Akunar also has high compression (look to be about 12.5:1) pistons in sizes that will fit a honed stock bore (57.5mm) plus oversizes for about 30.00 USD. Jake is running one of those high compression pistons on a 155cc "P" with a big cam and getting very strong results. Mitch |
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Post by budhastalin on Nov 21, 2008 1:05:31 GMT -5
Finally, you have A) a head with two small valves and two small ports. then B) a head with two small valves and large ports. then C) a head with two large valves and small ports. then finally D) a head with two large valves and two large ports. So for performance you want the head with the large valves and large ports. So how can one tell if they have a small/large, large/small, small/small, or large/large without having the 3 other heads to look at? And can all 4 engine types have any of the 4 head types or is it strictly "if this is your engine, this is the head you have and you are stuck with it."? And how inferior one must feel to be stuck with a small/small  |
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Post by earlwb on Nov 21, 2008 6:57:28 GMT -5
budhastalin,
Yeah I have pondered that screnario myself too. Not sure of a answer for that. The easy one is to measure how tall the head is.
I think the "D" type of head I mentioned is the taller one that the others have found. Six tenths of a inch taller is pretty significant as yeah one would need longer cylinder head studs and a longer cam chain for sure. Putting on a longer camchain without having to split the crankcase is really tricky to do.
Ideally it would be nice to to have pics of all the heads and measurements from all the heads so one could see the comparisons better. But no one has been lucky enough to have all four basic types on hand.
I didn't mention that the heads can come with the PAIR system reed valve block built in as a casting on the head. But since the heads come either way, it is easy enough to either use it or leave it off. Granted if you don't use it, there is a huge urge to cut off the protrusion and file it down and make it look better.
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Post by mx5tc on Nov 21, 2008 11:57:03 GMT -5
The heads on the "P" engines (you can read this right off the engine ID number) are the tall heads and "should" have the big ports and big valves (at least on the 150cc and up size engines). The "P" head measures approximately 73.19mm from the deck surface ("bottom") to the valve cover surfaces ("top"). If you have a stock non-"P" engine that was on a US emissions equipped scoot, it is most likely that you have "small ports and small valves". Non-PAIR equipped heads "supposedly" had slightly larger ports than PAIR equipped heads.
If you have an aftermarket "big bore" head, it most likely has big ports and big valves. If you are interested in maxiumum performance the "P" head is really the best way to go (excepting costly 4V conversions) due to its larger ports, larger valves and improved port entry/exit angles. The cam chain cam be changed without splitting the case, Syn details how he did this on his 4V conversion.
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Post by palmoster on Nov 22, 2008 1:55:36 GMT -5
Forgive my ignorance but can you tell me where I find the numbers, etc., that tell me what 150c.c. gy6 engine I have?
Would love to also know where to find the CVT belt No. to upgrade to a better quality version in the future?
The scooter is a Palmo T150, 3 wheeler, 2008 model.
Still breaking in the engine but it runs great!!
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Post by earlwb on Nov 22, 2008 9:05:10 GMT -5
There is typically, a engine serial number that is lightly engraved or stamped into a engine crankcase. They usually put the serial number on the left crankcase half, just below where the cylinder and head bolt onto the crankcase. The first few digits or characters tell you the basic model type of the engine that you have. The 157QMJ is what you are interested in:  |
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Post by 2t4tsim on Nov 23, 2008 6:31:43 GMT -5
Hello , Thanks for information mx5tc , I will email Carlos to buy the right , holder , chain, ect... At Scooterchinois 's forum , we have discussion about using cam or valve lift profile. A colleague have all the cam collection but did cam profiles. I own only 2 cams and did valve profiles. Both profile seems very differents and ! My 2 cams are normally : stock cam from 152QMI H2 cam from 1P57 Autotech 58.5mm head kit On the stock 152QMI head , impossible to fully open cam valve : spring coil fully compressed with the "stock" cam ! I set lash to 0.7mm to make the measurement I try a 59mm big valves head for 152QMI with this same "stock" cam and no problem this time. Impossible to install rocker arms holder on the 1P57 head (SYM) , so I place the H2 cam in the 59mm head. Stock cam have a 26.6mm lobe height and H2 have 30.0mm Stock lifts are 6.7/6.6mm and H2 lifts are 6.3/5.5mm ! So base circle is different : 21.6/21.0 for stock cam and 25.4mm for H2 cam. Now , we know that we must advise the base circle diameter / cam width in same time than lobe height. At the end is the "stock" cam really a stock cam ? I think no as there a lot of overlap that is not good for emissions (European setting). It should be a performance cam but wich one ? I inserted data in EngMod4T simulator : stock 152QMI (low performance head) with 24mm carb and 23.5 * 650mm exhaust track length Autotech Sym head (good performance) with same 24mm carb and exh pipe...     Regards Alain |
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Post by earlwb on Nov 23, 2008 11:11:17 GMT -5
Nice information Alain, thanks for sharing.
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Post by mx5tc on Nov 23, 2008 23:09:35 GMT -5
Alain, welcome to the "wonderful world" of vague, nonstandard and meaningless Chinese engine specifications! I have absolutely no use for a cam "spec" that consists of the gross lobe height! i was looking at the 30mm "lift spec" on the G2 cam and was puzzled because I've measured the lobes on new A10 cam and they are about 27mm! How could the G2 offer 3mm more lift unless the base circle was different???
Thus, I think we have answered why P cams are NOT interchangeable with standard GY6 cams; the lobe circles of the cam are different and the geometry on the cam followers/cam holder is also different. The difference is NOT in the distance between the cam roller bearings; I've measured the bearings on my new A10 cam and they are the same 58mm distance that Carlos shows for the "P" G2 cam.
Lastly, in addition to posting proper cam specs (lobe lift & base circle vs. lobe height), we also need to start posting installed valve height & spring information. Can you supply installed valve height measurements for both the 152QMI and P heads?? It would also be nice to know the uncompressed lengths of the inner and outer valve springs on both heads too.
Mitch
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Post by 2t4tsim on Nov 24, 2008 13:54:34 GMT -5
Hello ,
mx5tc , good analysis. I will make spring measurements next week end (I have only 2 different heads).
I really need now to buy a 1P57 rocker holder to if cams could be interchange froma model to another.
This could extend our range of parts ! I am not sure , Carlos would have offer it before...
Regards
Alain
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Post by palmoster on Nov 25, 2008 1:44:48 GMT -5
There is typically, a engine serial number that is lightly engraved or stamped into a engine crankcase. They usually put the serial number on the left crankcase half, just below where the cylinder and head bolt onto the crankcase. The first few digits or characters tell you the basic model type of the engine that you have. The 157QMJ is what you are interested in: Thanks for your great pic., a big help. Palmoster |
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Post by 2t4tsim on Nov 30, 2008 12:22:13 GMT -5
Hello , Fbartolo from Scooterchinois lended me several cams : A9 , A10 , A12 and stock from 125cc Jialing. The stock cam is best built with silent ramp up / down from 2 to 3 teeth (performance cams have none !). Maximum lift at TDC is around 3.0mm max (only 0.35mm left between valves) and the cams with the highest lift are made asymmetrical (shortest side on exhaust closure / inlet opening) fir this I think. Fbartolo has measured also deck height : 4mm (!) pour each kit and associated to heads volume it conduct to very CR : 125 ~ 7.75:1 155 ~ 7.0:1 A 2Hp lost for the 155cc ! GY6-motor.de is selling kits with cylinder 1mm milled and really no problem to be expected with valves. We still need to acquire ignition timing of several CDI and we would have a complete view of our GY6. Fbartolo asked Akunar for a GY6 piston with hight head height but they answered having nothing available. Could you tell where you buy your 13.5:1 piston ? Major problem remain inner springer too high fully compressed that cause valve retainers and "eat" cam inlet lobes ( a lot of dispersion in Chineese head / springs) Regards   |
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Post by autox4fun on Sept 21, 2009 19:37:36 GMT -5
I want to thank you guys for your research.. I was looking for this via the search function - but some how, some way, it only would pull up 364 days back.
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Post by crdscooter on Sept 21, 2009 22:14:42 GMT -5
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Post by skyetone on Sept 28, 2009 13:35:30 GMT -5
so I'll have to chase on roketa but my block says 157QMJ-III any ideas? The first links are broken on the first post BTW.
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Post by medman1952 on Sept 29, 2009 13:07:43 GMT -5
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Post by skyetone on Sept 29, 2009 13:28:17 GMT -5
um yea I'm blonde so i go in circles for a while.... but WTF
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goose
New Puppy Dawg
Posts: 1
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Post by goose on Nov 27, 2009 19:46:44 GMT -5
whatabout decking the p head to fit without changing the t-chane
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Post by chrish on Nov 27, 2009 23:27:09 GMT -5
anyone heard of BN157QMJ? I know that BN157QMJ-3 is the extra longcase for the 16" wheel, but I have't been able to find anything about BN157QMJ. I have one, in every way it looks like a normal longcase, the only abnormality is that it came with a strange 12 pole stator that I have never seen anywhere.
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Post by richardhill on Aug 4, 2010 10:30:11 GMT -5
I have a 157QMJ and the CVT belt failed I think it is the long case style 18" on the gasket side from end to end, and about 19" on the outside. I think it takes the 842 20 30 belt. Can soimeone help me with this?
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Post by sprocket on Aug 4, 2010 18:07:55 GMT -5
Could be a 835-20-30 or a 842-20-30
Measure the old belt and it will put you in the ball park
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Post by therealld on Apr 13, 2012 0:24:08 GMT -5
Great thread ! I am just now getting into this G6 scooter stuff, since buying my Znen 150 Rowdy (BN157QMJ engine), and when surfing most scooter sites, this sort of talk is non-existent.
Keep it up guys!
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