cvt vs manual trans and clutch and mileage By cyborg (Read 1,415 times)

[cyborg]

With all the talk about mileage lately i've had my doubts about the "auto" trans in the scooter,,,,mine gets 65-70 mpg is a 150cc with a cvt,,,a stella has a touted 140 mpg (100-110 is reality) 4 speed manual 150cc,,,,the sym wolf classic also a 150cc,,,gets 90mpg,,,also a manual 5 speed ,,,,are the cvt so inefficient that they don't get good mileage??

[kz1000st]

It's the belt slip. A belt drive at it's best is only about 80% efficient. My 50cc gets 135 mpg with gears and a chain. The best belt drive 50cc I've ever heard of hits around 100 mpg.

[randy]

My two stroke Stella will get 110mpg around town but if you take it out and run 50~55 it goes down quite a bit.

[jct842]

Belts are super efficient until you start changing gears with them. Besides harleys there are a few other bikes using belts for final drive and they get as good or better miles per gallon as a chain drive. In a cvt when you let off the gas the pulleys instantly start shifting down. No coast. That one thing that is going to cut miles per.

[richardv]

Are the scooter engines as efficient as those in motorcycles? And what about tire size, that can't help.

[kz1000st]

No, because the belts on bikes are cog tooth belts. They engage in sprocket pulleys like cam belts in an overhead cam engine. Scooter belts are like the V belts on an alternator and slip all the time. In theory motorcycle belts are even more efficient than chains because of less internal friction.

[jvino]

Good to know thanks kz.

[cyborg]

Oh i get the whole gilmer belt thing,,had a harley,,,final drive changes were a fright,,,,,i didn't think the cvt was so inefficient ,,, i thought about it before i bought anything and had settled on the bms bi metro,,,then second guessed myself because i thought the wife would use it and then thought again that she would be intimidated by the shifting,,,,,there i go thinking again,,,,i don't want to be a doomsdayer,,, i think $6 a gallon of gas is in our very near future,and it's going to stay there,,,, i want something to top 100mpg but still have enough snap to hit 70mph,,,a tall order but,i think it can be done,,without being too radical,i built a little honda sl into a buzzbomb but it was short lived

[jct842]

With a cvt 100mpg and 70 is a tall order. Manual will do it now if you ride conservatively. Efficiency is why car makers went to the flat serpentine belts for accessories as alternators, power steering pumps, and air. Belts that ride on their sides just ain't going to do it for good gas mileage. john

[cyborg]

yes i agree a manual trans small engine combo can do it,,,,KZ is a prime example with his 50cc manual trans bike getting better than 100mpg,,,i was leaning a bigger version of his combo in the bms bi-metro,,,it's a coin toss for me for the bms or the wolf classic 150,,,either one will be in my garage within the month

[johnvino]

Cyborg getting another bike nice. I heard YOU TALK ABOUT YOU HAVE A DR STREET AND TRAIL ALSO. How do you like it I am in the market for one and think I will be looking at a klr 250 tomarrow at some point and Saturday a ktm 620 94. The klr is a 2000 I believe you heard anything good about these bikes.

[cyborg]

Yes i have a mildly built dr350,,,carb/full custom made pipe,high energy coil and new cdi recurved with a better advance and slightly higher rev limit full suspension work front and back,,,and much more ,,,i read good things about the kawi klx 250,,,went to see and test ride one,,,then got the shock of my life $8000+ out the door,,,ouch,,,but it needs a 300 kit to be right cause it's weak,,,i rode the klx it was ok ,,i like my modded dr350 way better,,,got it with 1200 miles for a grand,,,put a grand in it and BAM!!!!! instant great dirt bike that i can ride on the street,,,i really like the beta 350 dualsport but not for $9000+so ill hang with the dr right now,,,great bike,,, parts are everywhere,,,,and cheap,,,,it's a winner,,,,and i'm sold on the sym wolf classic,,,,,

[Bashan]

This is just an observation with watching CVT transmissions for hours (I know, I know...help me). You have to squeeze the crap out of the belt to make it work. The variator weights are constantly pushing out against the belt and the clutch torque spring is pushing against that. That's a huge difference from a notched belt sitting down in a cogged pulley. If you're mashing in against a belt there has to be friction. However, that is offset somewhat by the beauty of a CVT always trying to find the sweet spot for the engine. Who knows....keep your hand off the go handle and your mileage will be great. Fun vs mileage...I'll take fun.