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Post by Fox on Feb 4, 2011 21:01:58 GMT -5
The bottom line is:
Not all 139QMB's are created equal nor are they all made in the same factory so the QC and specs will differ as well as worker moral and pay
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Post by erictheviking666 on Feb 4, 2011 21:13:52 GMT -5
LOL, yeah maybe or mine was built first thing Monday morning when everybody was fresh and ready to go.
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Post by shakerdriver on Feb 4, 2011 21:14:29 GMT -5
If thats the case, everyone i've been on and worked on were built close to quitting time on payday. lol
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Post by erictheviking666 on Feb 4, 2011 21:20:45 GMT -5
Also I bought mine from ATVDiscounters who at the time were the worst sellers on the internet. Apparently I was one of the few satisfied customers they ever had.
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Post by motorhead on Feb 4, 2011 23:07:47 GMT -5
:lol: :rofl: You guys are cracking me up. AhMen shakedriver. I feel like my bike was a factory prank on a new guy and they gave him the spec sheet for a rotary tiller. Wow, that bike was bad. I broke the potmetal tranny-cover trying to kickstart it up on day 1, And on its best day it did 26mph. I wonder what it's really like in those factories. >:(I want the Okay... Back on topic. I have updated the comparison chart to include the Vespa. This is interesting because compared to the metropolitan you would think, add compression and stroke to the QMB. But then the vespa engine is nearly square to the QMB. What I can see is that the Vespa and the Metro both have higher compression ratios even with the vespa being aircooled. Attachments:
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Post by 90GTVert on Feb 4, 2011 23:58:10 GMT -5
Yamaha Vino 50
Bore : 38mm
Stroke : 43.5
Compression : 12:1
HP/RPM :
TQ/RPM : 3.4/6000
Top Speed :
MPG : 110
Cooling : Liquid
Valves : 3
I can't find the HP rating. Other things to point out on this scoot that gives it advantages over the cheap Chinese scoots... TPS sensor and 2D mapping CDI, ceramic coated bore
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Post by erictheviking666 on Feb 5, 2011 12:42:09 GMT -5
Good read!
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Post by scooterguy863 on Feb 5, 2011 17:16:05 GMT -5
i owned a 2006 honda metro and now have a 2006 yamaha vino 4t the vino seems to be rated by yamaha at 3.5 hp on paperwork given to me at time of purchase
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Post by motorhead on Feb 5, 2011 19:50:23 GMT -5
Okay here is my final chart. We have four bikes with a combination of liquid and air cooling. 2 & 3 and 4 valves. Fuel injected and carburated. The verdict is in. The only remaining question now is... Can you push the questionable craftsmanship of a QMB to bring it up to the specs of the other 3 scoots  I'm still searching for a cheap guinea pig scoot to find out. To be continued... Attachments:
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Post by reveeen on Feb 5, 2011 20:38:44 GMT -5
If you read through this link (stolen from the posting on camshafts) you soon realize that no two engines, or their parts, are the same. translate.google.com/translate?js=n&prev=_t&hl=fr&ie=UTF-8&layout=2&eotf=1&sl=fr&tl=en&u=http%3A%2F%2Fwww.scooterchinois.fr%2Fmodules%2Fnewbb%2Fviewtopic.php%3Ftopic_id%3D6455%26forum%3D71While if you inspect any Honda, Vespa, or Yamaha, engine, the first one made in one model year, is the same as the last one made. Just the idea of a mis-cut keyway, for the flywheel, on a crankshaft, makes you wonder about the camshaft driver sprocket placement accuracy. (or the welded on camshaft sprocket placement) In an overhead camshaft engine cylinder deck height is vital to controlling engine timing, without strict quality control you will end up in the current situation, some being "dogs", some being "excellent". Quality control manufacturing meets "good enough" manufacturing. "Good enough" being: it starts and runs, we can sell this! Honda learned this lesson in the 80's when they partnered with an an Indian firm ( Kinetic Honda in India) to manufacture Honda products in the hope of export...... they (Honda) walked away having wasted a whole bunch of money and time. I *think* if your goal is to achieve something out of a 139QMB you must assume nothing. A complete disassembly is in order, in reassembly EVERY part must be treated as suspect, with checks, and rechecks, every step of the way, and at the end of it you will have more "in" than if you had installed a "fresh" 150 GY6 motor (and likely less performance). |
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Post by motorhead on Feb 22, 2011 10:39:48 GMT -5
I still have yet to acquire a donor bike to do this project. But I did think of something to factor in in this experiment. I have come across 2 types oh heads for the QMB. Some have an EGR system and most just have the standard head cover on the right with the single vent hose as seen in the picture. Would a QMB engine with the egr system necessarily outlast a similar bike with the standard head cover? Attachments:
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Post by Fox on Feb 22, 2011 16:12:56 GMT -5
I say no. I always plug off the EGR port on the head and remove all the EGR system whenever I see one.
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Post by motorhead on Feb 22, 2011 17:10:10 GMT -5
I say no. I always plug off the EGR port on the head and remove all the EGR system whenever I see one. How come??? EGR is standard on all cars, how come its no good on QMBs. I think the system is also called PAIR, pulsed air injection reed. |
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Post by Fox on Feb 22, 2011 17:51:43 GMT -5
Because in my opinion removing anything that isn't necessary tends to make a scooter more reliable due to having less stuff to go wrong for one thing and for seconds I don't like the thought of recirculating anything through the carb and intake cause it will eventually gunk up the works. I even run the crankcase vent up and over the frame and straight out the back so it doesn't get oily water spray on/in the air filter. Less is more when it comes to intake connections.
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Post by rocketdog on Feb 23, 2011 8:00:13 GMT -5
You can hand port the QMB head and make it flow a bit better. Not as well as the Vespa's V4, I wouldn't think. One thing on the side of the Vespa is that the four valve head probably has a Pent Roof combustion chamber. More efficient than the QMBs.
And finding a piston to increase the compression of the QMB is a task in itself. I have a collection of pistons to prove it. I've been trying. If you find one that will increase it to 12ish to 1 the valve pockets aren't large enough and the valves hit the piston. If you enlarge the pockets you lose compression. A vicious cycle. I may have finally found the answer, though.
RD
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