8k @ 30 mph

[jstich]

As said Im turning 8000 rpms at 30 miles an hour. I have more throttle when Im at 8k rpm but don't wanna wreck it.I think they put super light rollers in it because the rpm and the speedo have red zones at 8k and 30 mph. Any thoughts? 4T 49cc Its a tao tao vip 50

[AtariGuy]

I redline the crap out of mine. If the valves aren't floating, i'm not goin fast enough.

Actually 8k isnt bad on a 4t scoot, but i'd consider heavier rollers so you can stretch its legs a bit more.

[jstich]

In all honestly it doesn't sound like its over reving really when I get 8k registered on the stock tach.

[AtariGuy]

You'd know valve float if you hit it, feels like a rev limiter but a little jerkier. I believe on single spring valves, you'd feel it closer to 9k rpms - dual coil about 9.5-9.7k.

Honestly it's not the best thing to subject your scooter to. Occasionally is fine, but it'd be in your best interests to retune your cvt so you dont float your valves. Consider it the engines way of telling you that you have more top speed somewhere in your cvt. And more speed (on a well maintained/built bike) is not a bad thing

[jstich]

I don't think Ive floated the valves.I   quit when it got 'clangy' sounding on the throttle.Around 9k. She pulls nice from 6 to 7k rpm. But yeah Im only at 30-35 mph indicated. Im still worried about the lean condition.

[90GTVert]

May need heavier rollers or sliders. Also check belt width.

[jstich]

The belt has 60 miles on it . What do I check?Maybe nose  around the cvt?

[90GTVert]

If the belt has 60 miles on it, it should be fine. Didn't realize it was new. Being new, you could make sure there's no restriction in the variator. I don't think they've been using them lately though.

[humanshield]

Are you sure your tach is reading properly?  If so I agree with the above.  Try heavier weights in the variator.  Is the clutch ok?  Do a good thorough inspection.

Just keep in mind you're dealing with VERY inexpensive innards in terms of bearings, tolerances, the metals used etc. These are NOT Yamaha or Honda motors. I'd bet they cost lest than $25 US to manufacture. On a 4t GY6 motor, 8k rpm is getting up there imo. everything I've ever read about them and just going by what they actually are, they aren't built for high rpms.

Sure, some folks will say they crank it to 1 million RPM every day and that's fine for them if it works for them. But, are they gonna fork out to help YOU get a new motor when it blows? If you don't care then sure, go for it.

Truth be told, most GY6 motors, even modified ones (except for the pros who put a LOT into them and know what they're doing) have a torque and HP curve that drops off sharply after about 7500rpm. So while you might have the motor screaming, you're already well past the sweet spot in terms of power. You're just stretching parts and spinning bearings.

Now this doesn't account for all motors of course. There are plenty of 2T motors that can run WAY more than 9K rpm. And my sport bikes can do 13000rpm......but they're designed for it. GY6 motors that come in TaoTaos and most common Chinese scooters simply ain't made for it. it might last, it might not. Roll of the dice.  Your motor has a specific RPM where it makes maximum power.  Try to tune your CVT so that that point coincides with your top speed.  I'd bet a wooden nickle it's around 7500-8000rpm (or slightly less)

Have fun!  Be safe and wear a lid. 

[GrumpyUnk]

I'd want a second opinion. Your tach may be optimistic. I would try to keep rpms at 8k or below. IF I were concerned with longevity. I am. In my whole life I have had one engine blow, and that was when my Dad was helping me learn about the lawnmower engine I had been given. They have a governor for a reason. He was used to radial engines and turbines, not 1.5 hp Continentals.
The manuals indicate an 8k redline, or less.
When you consider the selling price, after shipment, and what you get for that amount, you must realize these machines are not made of the 'finest, most pure, strongest or even the proper alloy of metals'. They use what they can get at the lowest cost that will do the job.
Watch a youtube where the connecting rod is replaced, or the crankshaft bearings. You can see the job being done in a back room shop. It appears to be 'bendable' by tapping with a hammer. Well, not bendable, but adjustable so the throws are parallel and in 'time'. A built-up crankshaft is by nature less robust than a cast or forged one-piece crankshaft. Of note is that racers are using 'plain bearings' instead of the formerly ubiquitous ball bearings. At least that's what I read.
Seriously, if you want to turn 9k or more, be sure to balance the rotating mass. A BBK will by nature be imbalanced if the crankshaft was balanced to a 39mm bore piston. Add high rpm, and you ventilate your crankcase. Maybe.
tom

[jstich]

Yes I was wondering if the stock tach is optimistic.Even at 8k it doesn't sound wound up very bad.I don't go over 8k just to be safe. Im still breaking it in, it only has about 60 miles on the odo.

[jwinn]

Now i'm even more curious as to the rpm's i'm running on my 4 week old peace sports 50.

I tried a tach from cycle gear, poc only read 3k or so rpm's at any position of the throttle so i took it back. Doing the stock top speed of 38mph rpm's sound good. It's when i hit 43 in a tuck it sounds like it kicks in and starts to whine getting me up around 48mph.

[jstich]

I now have it at 8200 rpm with max speed at 38 indicated @ wot. Should I get rollers that are a little heavier than current ones? Also should I dial my carb in before I do cvt work? Im gonna get an aftermarket carb.