JONWAY 250 FULL POTENTIAL By trvstlh (Read 2,561 times)

[trvstlh]

WHAT ADJUSTMENTS CAN BE MADE IN ORDER TO GET FULL M.P.H. OUT OF MY SCOOTER? WOULD THAT BE CARB.,THROTTLE,MUFFLER. ETC. PLEASE HELP

[yoster]

Assuming your roller weights are pushing to their maximum position, then ultimately what limits top speed is max RPM.

It's like in a car, in your top gear. If you're going 90mph at 5k rpm and you need to go 100mph, you need to increase your max RPM. You need to first find out what's preventing your RPM's from climbing.

Could be a simple lack of horsepower, or it could be something like a rev limiter.

For our scooters, I'd start with your RPM band i.e., power.

The first and easiest place to start is with variator tuning. Go with some Slider weights, about 2-4 grams lighter than stock. Now what this is going to do is give you more pull off the line. It also inherintly gives you slightly higher top-end because of the slider design - they're said to 'push out' the variator a tad more than roller weights (effectively causing a slightly higher final gear ratio.)

Now, in my opinion, the next place to start is with air and fuel. If you go to "kidnmeparts" they have some kits that come with larger carb jets, a fancy CDI (automatically adjusts engine timing,) and a better air breather.

Upjetting and the airbreather - you're going to see a good improvement there. It's going to allow you to make more power at top speed, pushing you higher in the RPM band, resulting in a few more MPH's. CDI will also help out there.

No matter what you do, exhaust or intake-wise, you need to rejet. This is important. You could potentially get LESS performance if you simply change intake or exhaust without doing that. These are not fuel injected machines, so there's no computer to automatically compensate for more or less air - you need to do that yourself.

Have fun! I think if you start with those slider-weights, you'll already see enough of an impact to put a smile on your face.

And remember.. these are not speed machines. If you're looking to really get some serious speed, you might be better off looking for a different scooter.

[trvstlh]

thanks for info Yoster, i looked at some slider weights and would like to know, how do i know which set to purchase?, i see they come in different weights

[yoster]

Remind me which engine you have. The 244cc honda clone or the 257cc yamaha clone?

[trvstlh]

Thanks, i have the 244cc honda clone

[yoster]

Ok - And next question, if you don't mind me asking, about what do you weigh?

Regardless, the size you want is either 24x18 or 23x18. Either will work, but according to Honda, 24x18 is the OEM size, so that's what I personally went with. The 20g rollers I had before were 23x18 and they did fine, so like I said, don't worry about that too much. I'd say whichever's cheaper.

Now you just need to decide on a weight. If you're like me.. 220-235 depending on the season (lol), and occasionally ride 2-up, then 19g sliders would suit you well. Especially if you ever go up hills. If you're mostly 1-up, then I would (personally) recommend 20g or 21g. At the end of the day though, anywhere in the 19g-21g range will work just fine. If you're primarily interested in top-end, than I'd lean towards 21g. I don't recommend going any lighter than 19g.. you'll start losing top-end at that point.

Be sure to pick up an electric impact wrench (can get it for $40ish from harbor freight) and some threadlocker. Will come in handy when you change these out. Trust me, you don't want that variator nut coming off when you're going down the road (happened to me.) I have a lockwasher put on now as well, just for good measure.

[cruiser]

All good advise from yoster, especially when working on the variator. I also have the 244cc clone. The electric impact wrench is a necessity and I use a torque wrench along with a strap wrench to tighten the variator nut to specs. Here's the strap wrench I use:



I also use threadlock, a lock washer, and a self locking nut. Make sure you are not pinching the belt between the variator halves when tightening the variator nut.

[nulldevice]

A simple setup for more power that worked for me.

1. Put 8000 miles on the scooter using regular motor oil for a complete break-in

2. Remove the carburettor main jet. start gently poking number size drills through it, flutes first, until you find the largest that will go through the hole. Go up one size and drill the jet out.

3. Take a 3/8 inch drill and drill a dozen or more holes in the air box near the air inlet. Use the stock air filter.

4. Change over to your choice of synthetic oil.

5. If your scooter has a square-ish like the Helix muffler, replace it with the cylindrical muffler with the hemispherical ends like the Reflex muffler.

Enjoy the 10 to 15 MPH gain in top speed from when it was new.

Edit:
One other trick, get good tires that are round and can be balanced. The stock ones that came with my scooter were awful.

[ihrugby]

Null//////sounds like adjustments made to a SS Carb on a harley.......what setting or how many turns out did you make to your plugged Fuel/Air mixture screw on the bottom side of the carb? and what are your RPMs set to at your new idle settings after these adjustments are made or do you just tune by ear and rear wheel rotation as before?..........Thinking about making similar adjustments to my 2008 Jonway 244cc......TIA

[nulldevice]

I started out with 2 1/2 turns out on the idle mixture screw, adjusted to the fastest idle, then back out 1/4 turn from there. I set the RPM as low as it will reliably idle, which is quite a bit slower than the wheel rotation method.

I left the needle setting alone.

I've been out riding since I posted before and realized I exaggerated the gain. It is more like a five to ten MPH gain in speed. The mods were still worthwhile for me. That was enough to let me ride moderate distances on the Interstates and keep up with traffic running the 65MPH speed limit.

[prodigit]

I'd say wind optimization; make sure you have the aerodynamic plastic plating in good order.

Also reduce the load on the alternator by putting a switch between the radiator fan. Turning it off when driving high speed.

Get rid of a wind shield, and duck forward when driving.
Get rid of any passenger backrests, or back storage bin.

Use premium gasoline, it will make a small difference (93 octane on gas station)

Enlarge the air filter, if possible make it so, that air gets forced in the air filter by wind movement caused by driving.

Tires fully inflated
Gasoline tank full (reduces drag on fuel pump).

Clean/replace filters (air/fuel/oil)

Perhaps put a slightly larger exhaust pipe; most of these bikes have an exhaust that is optimized for little sound, but have some back pressure in them, that does not allow the cylinders to get completely empty of their burned gasses.
A bigger exhaust (with larger airflow) should improve bits.

Put SAE 10W30 in the motor, it gives a performance gain over 15W40.

That's about it