Post by br4inl3ss on Jun 6, 2023 23:47:39 GMT -5
I suggest that you do some comparisons and get the right belt. If the new one is tight, the same conclusion will be had.
I think that if you to get the belt over the rear driven pulley and then over the drive boss, you 'have to' pull the rear pulley in and compress the spring to get the belt even over the drive boss, or if the belt doesn't just fit like a glove then the belt is too tight.
Maybe you can measure the distance between the center bolt of the crankshaft over to the center bolt of the rear pulley at the ends, and be consistent, and get a measurement then ask if anybody else would measure theirs and see if you find a match and ask them what belt it is that they use. I would suggest from what you've said so far that the belts are too tight and to be looking at a larger belt.
I had a chinese scooter that used an offsize belt and I broke variator and belts and driven pulleys and never found the right belt until years later when I discovered some other sizes. and this was the problem I had. Ive found heat issues with my new belt and its a bando made in japan for my scooter precisely. its tight, doesnt fit 'like a glove' and I had engine overheating issues. even tried to rejet the carburetor but it just ran worse.
some chinese scooters are made like that, one off. and since you dont know what the original size of your belt was, it may be an e-ton belt, or a jog belt. or some other offsized belts that they make for some odd european bike.
is your bike a 4-stroke? I thought this was a 2-stroke but I just seen that video you posted on your previous post. 50cc? theres no telling what it would match.
shoot, so idk i mean besides measing the center drive shaft to center driven shaft, theres the angle between the 2, one sticking out further than the other. you will have to be consistent, like both do it in a straight line, making sure to measure center of shaft to center. someone with your belt could tell you if your measurements is longer and then that would give you, a place to start with what belt size you need.
but to me looking at yoru video, the belt looks a bit deep in the rear pulley at idle.
well this become complicated lol.
first, yes its a 4 stroke gy6 50cc 139qmb.
the 1PZ belt ( a bit shorter ) fit a bit better than on the photo with shims ( for a "glove fit " i need to use 3mm of shims with the Glixal variator, and i guess 1mm max with old stock resurfaced variator ). but with 3mm of shims, bendix shred itself on the drive face when electric starting... so i probably need shims, but that much with a decentlly made variator. oh lord i miss my Naraku sport variator
gonna test the Naraku belt tomorrow. but even on the weirdo Glixal variator, unshimmed, that belt was fitting better than the 1PZ belt. the Naraku seemed like a good fit. but who know too many things to do at the same time. tomorrow will tells.
i boiled some water and put my suspicious contra spring in it. and surprise, it soffen alot in boiling water. my brother white Malossi spring for his 2009 Yamaha Vino 50 4t doesnt soften as much. not at all id say.
cheap spring at fault i guess ? duno. maybe... but had this problem with 2 "stock" type spring ( one used came on it , the other came with a Goofit complete clutch assy )... or maybe overheating destroyed them all ?...
anyway. one told me that a 72cc bbk 139qmb shouldnt even upgrade the spring at all. lol.
i ordered a malossi white spring ( +5% of original iirc ) for now... ill need them all anyway so gotta start somewhere while others are out of stock temporarly.
shaft to shaft is 25cm. the usual long case 139qmb with 12 and 13 inch wheel ( mine is 13 inch, 5 spoke weirdo wheels ). also widely known to use 729 belt. i found a site selling replacement parts for my weirdo model ( HT50QT-36 ), all list 729.
youa re right, ive seen some VERY rare scooter using weird belt size. but those have weird lenght between shafts. mine is standard widespread 25cm.
belt fitment is a thing... but this rpm / slipping feel issue is another thing.
last test i did today was 6.5g rollers, old resurfaced variator, NCY rear pulley, 1PZ belt, no shims, glixal blue 1000 rpm contera spring, and old Goofit clutch with glixal red 2000 rpm clutch springs. 6é5g is too light for this 2k rpm spring so i still had the issue. gonna retest with 7 and 7.5g rollers ( i got the Jasil kit with shitloard of rollers ).