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Post by beebo on Nov 21, 2013 19:54:47 GMT -6
I own a couple of motorcycles, a couple of scooters, and they all have a different "feel" to them, and I enjoy riding them all. But this Jonway has always had quite a bit of vibration in it, and it has taken a while to figure out the source(s) of the vibration. The first thing I suspected was the tires that came on it, very soft rubber and kinda lumpy looking, and howled like mud grips on a 4-wheeler. They were worn out at 2300 miles, put on some shinkos that now have almost 4000 miles on them with little wear, and that did help some. Then I started noticing a sound, like a bell ringing, when I was idling at a light, kinda sounded like a biker bell or something, so when I got home, I found that the rubber bushing at the motor mount was loose, so I tightened it some, and that made things a little smoother yet.
At the same time I was wondering why this thing was such a dog--both my 150's will easily run off and leave this 250 in the dust! It takes off at 4000 rpm, then settles in at 3500 rpm and stays there until it eventually climbs with increasing speed. My 150 launches at 6000 and settles in at 5500 rpms! So I decided to pull the cover off the transmission and see how much trouble it would be to pull the variator or clutch. I was pleased to see a gates belt from the factory in there, but it was hanging there limp with no pulley tension on it. Also, there were wear marks on the inside or the cover, so I was thinking that the belt was running loose at speed, too. I had it on the stand, so I fired it up and watched the pulley action as I revved the motor, and the belt was flapping around, with about 2" of deflection as it ran! I did a little reading here on site, and got to looking at the torque spring. I was easily able to pull the driven pulley apart to get enought slack to remove the belt. This didn't look right so I ordered a new spring from MPS Racing(a white one) and after finally getting that nut off, put the new spring in. It was about an inch longer than the stock one, but much stronger at compressed(installed) height. I like to never got that pulley to open up enough to get the belt back on! I could barely pull it apart enough to get a screwdriver in the gap and lever ihe pulley apart enough to get the belt in there. No slack in there now! Now the difference a new spring made was enormous! The bike launches at 4500 rpm now, settling in at 4000 rpm, and is so much smoother, It feels like a whole new bike! Very smooth, and the top end went up from barely reaching 70mph to barely reaching 80mph! I don't run at that speed, but it does 70-75 with ease, making it much easier to drive on the interstate, something I do daily now that I can.
I might try fiddling with the weights now, to get just a little better performance on takeoff. It seems like the weights are full out by 30mph(too heavy?) and it is like taking off in first gear and shifting straight into 5th gear at 30. I want something more in between there. I'm thinking around 5000-5500 rpm. I'm not real sure where the power band is on these 250's- Jonway's website says peak torque@5500rpm, peak hp@7500 rpm, but it is the same specs for all their motors. It seems like this longer stroke motor might be lower than that. It certainly isn't tuned for that powerband from the factory. Anyone have some better info on that? Anyone ever dyno'ed this motor?
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Clinician
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Post by beebo on Nov 21, 2013 18:46:24 GMT -6
I used to live in KC years ago, and I know just what you mean. I've seen it at 100 deg. at midnight, and I've seen it stay in the single digits for days in the winter. I always threatened to move south, and I finally did. Now I am getting to where I can't take the heat. At least I have a long riding season here in Texas. I rode to work 3 days this week, but tonight it is going to get down to the 20s here, with some ice and sleet coming. Cold doesn't stay long here, tho. It will probably be back in the 70s next week.
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Wheelie
by: beebo - Nov 21, 2013 18:15:12 GMT -6
Post by beebo on Nov 21, 2013 18:15:12 GMT -6
That vid brings back some memories...we recently sold a SunL 150cc scoot that was a wheelie bike! It had the little 10" wheels and a short wheelbase, more like a 50cc frame, and was a real quick bike. All you had to do was crank the throttle wide and the front wheel would come up-didn't have to jerk it up. Always had to lean into it if I was doing a hard launch or it felt like it was going to take off out from under me. The wife sold it after I fell over on the dang thing-I was leaning a little to the left when I romped on it and laid it over. I sure miss that little scoot. I can't seem to be able to get any of these others up on one wheel. Anyway, like the wife said, I'm getting to old for that shtuff.
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Post by beebo on Nov 19, 2013 18:39:24 GMT -6
Yes when it warms up and I've driven it a few minutes, everything settles down to normal.
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Post by beebo on Nov 19, 2013 18:30:16 GMT -6
I'd be looking for the source of that whistling sound, Might be an air leak. There's usually only one vacuum port on the intake, but it will tee off to supply vacuum to emissions stuff, fuel pump, etc. At 5 yrs old, they need to be replaced. I would be checking the fuel system, too-pump, filter. Check for a cracked intake manifold, too.
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Post by beebo on Nov 19, 2013 18:14:55 GMT -6
I've noticed the same thing with both my scooters. I don't know if it is because cold air is more dense, if you are running stock rollers packed in heavy grease, cold transmission oil, cold tires, or all of these. Mine seems to run stronger when it is cold than when it is fully warmed up, and pulls at 300 to 500 rpms higher range.
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Post by beebo on Nov 17, 2013 17:26:26 GMT -6
I've been digging around my bookmarks, trying to find a carb adjustment screw that might fit in the place of the one on my scoot. I came across it once while looking for CV carb info when I bought my old Harley. It had a knurled knob on the end of it that you can adjust easily with your fingers-would be ideal if it fits. It fits the Keihin CV carb used on Harleys just prior to switching to fuel injection, also some Japanese bikes. It is 6mm x .75 pitch. There is a picture of it on this page: www.nightrider.com/biketech/hdcvcarbappendix.htm#adjustable_idle_screwJohn's Motorcycle Parts site is down, so I am looking for another. I am going to order one--I can use it on the Harley if it doesn't fit the Jonway. Should be cheaper than a fancy wrench and easier, too! |
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Post by beebo on Nov 16, 2013 13:15:25 GMT -6
When I read your first post, I was thinking valves, or valve timing. Since you have gone in and re-done the top end, if the valve timing was off, you probably corrected that. Noting that you seem to have better compression and it will idle smoothly, I think you have it together right. I was wondering if you still have your original carb--you might try it out to see if your new carb is the culprit or not. If your old carb works, I would be looking at that new one-the jetting, main jet needle, diaphragm spring tension, etc.
Some of the members here mentioned restricting the intake/exhaust systems. I agree that on a stock system, there is a certain amount of restriction in the intake as well as the exhaust systems, not so much for efficiency as an effect of emissions requirements. Not just organic but for sound control. The carb has been tuned with these requirements taken into consideration. Seeing as you have put a high-flow head with big valves in it, I assume that more flow is what you are after, not less. The bike really should run with your stock carb, although probably not at its best. In my experience, 2 or 3 jet sizes is usually all you might have to move up. If you changed to a race type cam, you might need it to be a little richer on the low speed jet. Big valves+big cam+big carb= low vacum signal at the venturi, especially on a one-carb-per-cylinder setup. That problem usually goes away as rpm goes up.
If you have problems with either carb, you might look for one with an accelerator pump. Most of these CV carbs don't have one, because they meter fuel so well they don't need one. Some do, though- the CV carb(Keihin) on my Harley has a pump on it, and I have seen some others that did.
Anyway, these carbs are very tuneable, it might take some trial and error.
I hope you have mure fun than frustration!
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Post by beebo on Nov 9, 2013 22:58:26 GMT -6
I don't think valve problems come and go with the weather. My experiences have been wiring problems. Try to get your hand up in there while it is running and do a wiggle test. Just fiddle with the wires and see if it cuts out or dies. Might give you an idea where in the wiring to look first. I had to tie everything up tight with zip ties and crimp all the connectors to get mine to run right. No problems since.
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Post by beebo on Nov 9, 2013 22:49:44 GMT -6
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Mufflers!
by: beebo - Nov 9, 2013 22:20:57 GMT -6
Post by beebo on Nov 9, 2013 22:20:57 GMT -6
I had the same problem with my YY250T. Parts falling off the muffler, welds cracking, etc., so I did what you did- made me a drag pipe!. Plenty loud, but made a very noticeable difference in power/top speed. Somehow, it didn't have the same "cool factor" as my Harley with drag pipes, so I made a bottle-type muffler of my own design that is only a little louder than stock but flows like a straight pipe.
I was looking for slip-ons for my sporty and came across some at JC Whitney that were relatively cheap($50-$75) and one in particular that might work on my Jonway. It is a megaphone style, universal fit, with adapters for pipe from 1-3/8 to 1-3/4" so it might be fairly easy to adapt to these bikes. I saved a link to it on my computer at work, so if I get to the office Monday, I will post it here.
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Post by beebo on Nov 9, 2013 20:53:21 GMT -6
My YY250-T is the third scooter I have owned, but the first to give me any problems of any kind. My wife bought this scooter, wanting something a little bigger than our 150cc Super Scooter. Had problems keeping the battery charged, until I figured out that the remote starter was running the battery down. When you start the bike with the remote, you must kill it with the remote. If you don't, it is just like leaving the key on, and the battery will drain down. Also, I had problems with loose wiring. Every time my wife went to town, the bike would die and leave her stranded. It turned out to be loose wiring. So I bought a pack of zip ties and spent a Saturday tying up all the wiring I could get to without removing any plastic, until it would finally pass the "wiggle test". And I went over all connections, crimping connectors with a pair of pliers, especially at the cheesy little fuse box(at least it had one) and the CDI box. It took about 3 months to put the first 99 miles on it, working out all the electrical issues, and haven't had any more problems since. I have put 6000 miles on it in the last 3 months! How's that for reliable!
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Post by beebo on Nov 3, 2013 11:21:31 GMT -6
I've been looking at sidecars, too-- the wife wants one for her Lifan 250cc, although I wonder how it will do with a relatively small motor. I guess a 150cc scooter would pull one around ok in an urban setting. A Rowdy with its exposed frame would be a good candidate for a simple sidecar. Scoots like mine, shrouded in plastic, might be too much a pain to try it with. Anyway, take a look at the link I have here: www.saferwholesale.com/category-s/1987.htmThey have several custom and universal fit sidecars at the best prices I have found so far. |
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Post by beebo on Nov 3, 2013 11:03:24 GMT -6
I notice they don't seem to include Chinese bikes or scooters in their survey. Perhaps more people in the scooter market are buying Chinese bikes since the whole dealer/parts/support network seems to be getting better.
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Post by beebo on Nov 3, 2013 10:27:09 GMT -6
I stand on the left side of the bike, left foot on the ground, right foot on the lever, left hand on the handlebar, right hand on the rack, give the bike a tug backwards while standing on the lever. Pops up with ease. I just showed my wife how to do it-she weighs half as much as me and does it with no problem.
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