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Post by motorhead on Feb 2, 2011 15:00:27 GMT -5
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Post by 90GTVert on Feb 2, 2011 15:08:36 GMT -5
I installed a longer duration cam by NCY (from Enviromoto) in my 139QMB. It definitely improved upper RPM performance, but not a lot of gain. A lot of peopel think it's not necessary, but I advise checking piston to valve clearance with new cams. Not only lift, but duration as well, can affect this. I have bent valves to prove it. lol
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Post by motorhead on Feb 2, 2011 15:30:38 GMT -5
That's what I thought, not much improvement. When you go to a parts site you get sold a lot of hype and not a lot of truth. and thanks again my man for informing me.
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Post by 90GTVert on Feb 2, 2011 16:16:59 GMT -5
Yeah, unfortunately info is scarce on a lot of stuff in the scooter world.
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Post by Goosey on Feb 2, 2011 18:25:22 GMT -5
The A8 cam gave me a 2mph extra, and the A9 3-4...this was in my stock 150cc. It was not a real big improvement, just what I personaly wanted, with another 2mph improvement with clutch/variator improvements. So it does improve top end some? just not a major upgrade.
Also, that listing, "performance" is pretty vague. It may be the same as a stock cam, it doesn't say anything about what size it is in the description.
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Post by rocketdog on Feb 3, 2011 8:01:00 GMT -5
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Post by motorhead on Feb 6, 2011 8:38:45 GMT -5
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Post by lshigham on Feb 6, 2011 8:51:39 GMT -5
I put one on my 139QMB, with no noticeable difference.
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Post by 90GTVert on Feb 6, 2011 9:13:38 GMT -5
Considering you have a concern for fuel mileage, I would stick with one of the cams that doesn't have a whole lot of valve overlap. The charts RD posted will show you that. If you are trying to make it comparable to a certain engine, look over their peak power RPM and tty to adjust accordingly. For example, 3 of the engines in your chart are 7,500RPM peak HP, including the GY6. One is 8,250RPM peak. If you truly wanted to try and simulate the powerband of the Metro that peaks at the same RPM as the GY6, you'd wanna keep about the same duration, but perhaps increase lift to gain more power. If you want to shoot for 8,250RPM, you may want to increase duration a little. Again remembering, the more overlap (which tends to come with longer duration cams), the less engine vacuum and the more emissions and fuel economy tend to suffer.
I'm no cam expert though, so maybe someone can tell you better than I can. It's also harder to read the specs on these. I'm more accustomed to cam cards telling lift in inches, duration in degrees, and lobe separation angle. The best I can tell you is to try and find a cam to the A-series specs that fits the bill, since you at least have a chart showing what they should do. I dunno how well manufacturers even stick to those specs though?
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Post by reveeen on Feb 6, 2011 11:40:22 GMT -5
I'm wondering if the 4 cycle Dio stuff, specifically the camshaft, would fit these engines?
I like the removable chain sprocket that you can "dial in".
KITACO: KTC-300-1128000
Intake open: 10° BTDC
Intake close: 35° ABDC
Exhaust open: 40° BBDC
Exhaust close: 2° ATDC
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Post by motorhead on Feb 6, 2011 12:55:33 GMT -5
I'm wondering if the 4 cycle Dio stuff, specifically the camshaft, would fit these engines? I like the removable chain sprocket that you can "dial in". KITACO: KTC-300-1128000 Intake open: 10° BTDC Intake close: 35° ABDC Exhaust open: 40° BBDC Exhaust close: 2° ATDC Not a bad idea. I've done some radical things in the past to make parts from 1 scooter fit another. I'm going to explore using that Dio cam, I could make it fit as long as the sprocket it the same gearing. |
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Post by reveeen on Feb 6, 2011 21:18:25 GMT -5
Ok, that cam, while it physically might fit, is a roller cam for a 4 valve head, so, unless you snag at least a head and associated hardware (from Hero Honda of India for a 4 cycle Dio) that isn't going to work for you.
Those are fairly good numbers though, the duration is a bit long, I would look towards tightening up the valve overlap (less).
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Post by stepthrutuner on Feb 6, 2011 21:50:16 GMT -5
Be sure to find some stiffer springs to deal with the steeper ramps and allow higher revs. You could have to cut reliefs in the piston crowns too.
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