Petro
Scoot Enthusiast
Posts: 149
Location: Gothenburg, Sweden.
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Post by Petro on May 25, 2020 13:30:47 GMT -5
About to change the belt, the one that's on there now is 723mm, 729 is the factory recomendation. No wonder the bike locks and screams like a pig at 55km/h... The 723 has aprox. 6-8mm left to the clutch rim and instead of the recomended 729 I am going for a 740 to fill up that gap but I'd like to hear if I'm going to far or if there is any disadvantages with my "plot"  . Danke! |
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Post by Zino on May 25, 2020 14:48:45 GMT -5
That old formula for pie is 3.14 x diameter to et the didtance around. Multiplying 3.14 x 6 equals 18.84 Adding 723 plus 18 is 741 The only wild card is the belt manufactures all measure belts different . Stay with the same Brand so there is some consistency for measuring belts . One more thing make sure you have at least 6mm at rest on the back pulley or you could have trouble . Here is a thread that has Ryan working through a belt sizing challenge as he goes up on the torque driver. 49ccscoot.proboards.com/thread/24543/top-performance-td-belt-length |
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Post by GrumpyUnk on May 26, 2020 11:09:02 GMT -5
My limited experience with a 10" wheel machine... the installed belt was a bit worn, I thought install a new belt, and it would grip better, and work well. Umhhh. no. The belt was stiff, and shorter. Dunno if it was out of spec, but cleaning up the old belt, and using a plastic(?) sandpaper to buff the side of the belt, and installing it added a lot of seat-of-the-pants performance, and brought the rpms back to reality.
I think I would use the magic-marker(felt tip) procedure to know where the belt was riding when at its max, and go from there. If you use a slightly wider, slightly longer than stock belt, you can(*may*) get the belt to ride just a bit above the outer diameter of the variator. That would give max gear ratio for highest speed. OTOH if you go too far, the belt may decide to wander around inside the CVT case, such as if it got any sideload potentially caused my mis-alignment. (or other... I dunno)
tom
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Petro
Scoot Enthusiast
Posts: 149
Location: Gothenburg, Sweden.
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Post by Petro on May 26, 2020 20:44:57 GMT -5
Bought a Dayco (made in Italy) today and installed it. Had an 723mm installed on the bike, 729 is factory recomendation. I went with a 743mm though and it's night and day in difference.
The bike is now silent as I want it with lower RPM's across the whole range. Bike made (GPS) 52 km/h before and screaming, now it does 55km/h silent. The 49cc cylinder doesn't have the power to get me going faster but that's the last thing I am going to upgrade, probably to a 47mm since 50 or 52.4mm make the bike "shake about" too much...
Tomorrow my new tyres should arrive, 110/100-12 instead of 100/70-12 which will ad another 15% of length to the range. I'm sure that's to much for the poor 49cc but nothing a good quality (naraku?) bigger bore cylinder can't fix...
Next time I'm taking apart the belt cover again I'll have a look if I could use an even longer belt, installing this one made me believe so... I'll report back if so!
Thank you!
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Post by Zino on May 27, 2020 7:43:05 GMT -5
Good to hear The Belt worked .
You May be able to shim for extra travel and it will help fix any belt slap if the width of the belt is slightly different then stock.
I see a bbk in your future and from 2strokd experience the Naraku 70 is a good bang for buck upgrade.
pLea throw a sig Line so we vcan keep helping you as you build and your results can help others you could also start a build thread .
To post your signature line
click on "profile" at the top of the screen it is under the S in 49ccScoot
Then on the next screen in the right corner click on "edit profile"
Next screen click on "personal"
scroll down to "signature "
and post your mods and save
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Petro
Scoot Enthusiast
Posts: 149
Location: Gothenburg, Sweden.
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Post by Petro on Aug 2, 2020 2:11:02 GMT -5
743mm is the longest belt that works properly, I try'd a 758mm, too long, it doesn't reach deep enough on the rear pulley when it's on the rim of the front one. all this with the stock pulleys of course. For all you that need's speed I try'd a worn belt, 743x16mm and this one was the best for high speed since it went all the way down the rear pulley. It how ever makes the enging rev too much for my liking at take off... See pics: photos.app.goo.gl/xHvtq4vp4w9amMs97Belts width is 18, 16.5 and 16mm. EDIT: Correction, the long belt I try'd was 765mm (Dayco 7191K), not 758. Sorry. |
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Post by bullybike on Aug 2, 2020 20:04:26 GMT -5
THE BELT MIGHT RUB ON THE STARTER BENDIX
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Petro
Scoot Enthusiast
Posts: 149
Location: Gothenburg, Sweden.
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Post by Petro on Aug 3, 2020 0:32:39 GMT -5
THE BELT MIGHT RUB ON THE STARTER BENDIX No, no it doesn't. |
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Post by Steve B on Aug 3, 2020 1:19:46 GMT -5
743mm is the longest belt that works properly, I try'd a 758mm, too long, it doesn't reach deep enough on the rear pulley when it's on the rim of the front one. all this with the stock pulleys of course. For all you that need's speed I try'd a worn belt, 743x16mm and this one was the best for high speed since it went all the way down the rear pulley. It how ever makes the enging rev too much for my liking at take off... See pics: photos.app.goo.gl/xHvtq4vp4w9amMs97Belts width is 18, 16.5 and 16mm. Great job with the belt work. I like the way you took photos of how the belt rides on rear pulley.  |
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Post by GrumpyUnk on Aug 3, 2020 11:38:41 GMT -5
Can you post an image of the redneck oil cooling effort? I had some ideas about drilling and tapping to route the oil coming back from the rocker arms outside through a finned tube and then back to the sump. Normal flow is back via the timing chain chamber, which offers essentially no cooling.
The other alternative was to do some drilling and tapping on the filter retainer plug, but have not thought that one through at all.
Who makes the Baotian? Sure is similar to a GMW M2 of several years ago, or a Znen 'globle hawk' I have. The Globle Hawk(they can't spell) has a second spring/shock on the right side of the rear axle. If you want to see, look for ZN50-QT62 or go to znenmotors dot com and take a gander at the HAWK. Look closely and you'll see a spring/shock on the right side. Only one I've seen in the 50CC category.
tom
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Petro
Scoot Enthusiast
Posts: 149
Location: Gothenburg, Sweden.
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Post by Petro on Aug 4, 2020 0:57:20 GMT -5
Can you post an image of the redneck oil cooling effort? I had some ideas about drilling and tapping to route the oil coming back from the rocker arms outside through a finned tube and then back to the sump. Normal flow is back via the timing chain chamber, which offers essentially no cooling. The other alternative was to do some drilling and tapping on the filter retainer plug, but have not thought that one through at all. Who makes the Baotian? Sure is similar to a GMW M2 of several years ago, or a Znen 'globle hawk' I have. The Globle Hawk(they can't spell) has a second spring/shock on the right side of the rear axle. If you want to see, look for ZN50-QT62 or go to znenmotors dot com and take a gander at the HAWK. Look closely and you'll see a spring/shock on the right side. Only one I've seen in the 50CC category. tom I can do that but there is nothing revolutionary to see... I don't think You can make new oil channels in the head to route the oil to a radiator, the whole pressure needs to go to the top of the head in my opinion... What this oil adapter I have does, it's (still) sucking from the crank, it's just the routing between the crank and the pump that changed. I'll make a post in the performance section later. Here: 49ccscoot.proboards.com/thread/27396/redneck-oil-coolingEDIT: I missread Your post on the routing I think, sorry. |
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