You may find that the parts are very reasonably priced to fix your engine. If you can get the cylinder off without dropping shrapnel into the bottom end.
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You may find that the parts are very reasonably priced to fix your engine. If you can get the cylinder off without dropping shrapnel into the bottom end.
Attachment 13335Attachment 13336
She hit 300 miles today. Time for an oil change.
ive been thinking about "cheating" and putting a 200cc 2 stroke in it :p , get these things doing 110 :O
u know keep the 4 stroke for inspection time , then swap to 2 stroke for a year , rinse and repeat
Ive just found a 2 stroke 250 online for 450 bucks , that many horsepower may buckle the frame ? although my little dong I love sitting on so much seems pretty sturdy .....
how do they inspect bikes in tx?Quote:
Originally Posted by DanDaMan
i mean, cant you find a garage that will just say whatever... this thing's a toy.
thats basically how they inspected my bike...
Well guys, the cush bushings arrived as well as the new wheel studs. here is a pick of the correct part number and the new bushings in place.
http://img.photobucket.com/albums/v6...ps2f5deae2.jpg
They came out easy peasy and went in just the same. Haven't remounted the wheel just yet. I started to clean it when I got the bushings in, and the grime and slime came off pretty easy with a can of wd40. wheel actually looks almost new again, then I started to look at the rest of the bike, and figured since I have the wheel off, I could repair the saddle bags, so I took them off, had to go buy a new needle and some leather repair thread,( seam splitting at the bottom of one bag) , gonna do that tonight, and then start from the back forward and clean and tighten the whole bike up. Figured it would be a good 10,000 mile makeover.
Does anyone have a tach on them, and can tell me on average how many RPMs the engine does at what speed? (and what their sprocket setup is)
EG: they have a 13/38T setup, and get 5k RPM @ 50MPH, or 4K RPM @ 60MPH, or something?
afaik, only barone and i have tachs.Quote:
Originally Posted by ProDigit
regardless of gear ratios its pretty well observed that max rpm with unrestricted air flow, no filter no cat, is about 7.5k
I have a reverse air ram and am able to top just about 7k if going down any sort of decline.
if you know your rpm, gear ratio, wheel size, you will be able to calculate possible speeds. But lack of power will keep some gear ratios from easily attaining those top speeds/rpm (unless as i say you are headed down a hill or something) then the ceiling is when your valves float, again unlikely more than 7.5k
knowing what you do at a certain speed will let you closely and calculate your speed with differnt gear ratio.
I have a new filter that allows me to reach 7k RPM without the sputtering and cutting out. Attachment 13361
http://www.ebay.com/itm/181180637913...84.m1439.l2649
I wonder if a larger 28mm to 30mm would gain any increase in power on top end?
Are you talking about the DF carb? It is a Deni PZ30 so is already 30 mm.Quote:
Originally Posted by ben2go
Quote:
Originally Posted by barnone
hm, easy to wash, reasonably priced. though that material looks like its the type that will just crumble after a few weeks... (or after the first wash) let us know
I just wanted to see how much RPM you get per MPH, and how that works on your sprocket setup.
Meaning a 229cc engine, doing 7k RPM doing 70MPH, with a 15/41 setup could easily be lowered to a 35T sprocket, doing 6k RPM instead. Lower RPM, means better fuel economy.
Some people happily trade torque in for fuel economy, to gain engine life.
If my top speed would not exceed 60MPH anyway, I could calculate a good sprocket change.
For instance, If I would change the 15T front sprocket to a 17T, and the 41T to a 31T, I would be able to lower RPM from 7k RPM @70MPH, to 4k RPM @60MPH; which makes this bike quite the ECO bike!
If MPG was 75MPG before, now with the sprocket changes, it should be ~112MPG. This makes easy riders like me, extra happy, knowing they can go cross state with one tank of fuel!
The gears will be very tall, but the torque/acceleration not necessarily less.
Instead of 5th gear, you'll be running the same speed and RPM in 4th gear.
Acceleration will just be less at initial departure (the point where the clutch needs to grip is a bit harder to achieve), and final gear is basically a cruising gear, or an overdrive gear; where there will be little torque (no one is preventing you from upshifting one or two gears, and WOT the cr@p out of that bike, to overtake traffic).
I'm trying to figure out what setup you're running, so I could determine what sprockets to install...
MPG and CC's is directly related to torque. At 110+MPG, final gear should have very low torque, but if it's just to cruise around, high torque is not necessary.
In lower gears, even with the insane eco-sprocket change, the acceleration should be somewhat similar to a short geared bike.
Perhaps even better, since I'd have to shift less, thus less time lost in shifting.
you not will find the drivability as simple a comparison as that but if considering only sub 60 mhp indicated perhaps it's close enough for you.Quote:
Originally Posted by ProDigit
first consider if investing in a front sprocket, rear sproket and new chain is really what you want to do cuz you will not be able to fit the 520 around a larger front.
if your like me and look to budget my bike mods , then you will find the Jtr279.30 tooth on amazon for only 17.50$ shipped to your door. that will give you a 30/13 ratio, the tallest possible with least possible work.
barone has and likes it. even in the depths of the Appalachians.
that said with my ratio, as I stated near 7k max rpm I best get about ~62 indicated in 5th. roughly about 50 in 4th, 38 in 3rd, 27 2nd, 18 1st.
not sure what that will tell you, you can do the same math using your current ratio and speeds
Yes.I was thinking it was a 26mm.Quote:
Originally Posted by barnone
Thank you!Quote:
Originally Posted by axa
For sure, the 13T in the front is WAY too small!
Don't know if it's possible on the DongFang, but I've seen bikes that only needed a smile lid to be filed off for a larger sprocket to fit.
For comparison, I have a current bike, 127cc, running at 55MPH sustained, and 60MPH tops. I'm sure you can still optimize something to go faster on that bike, as 60MPH seems too low IMHO for a 200+cc bike!
Most 200cc scooters with CVT go 70MPH. That's a 10% loss that the CVT usually brings with itself.
The 127 I have is a MC-05-127 cc carbureted manually geared bike, comes stock with a 15/41 setup, and way too small gearing. I changed it to a 15/31T (too tall), but get 115MPG out of it, and it goes 50MPH easily all day long!
Recommended on that bike would be 15/34T setup, for better torque than 15/31, and would still get 105MPG with that sprocket.
I've tested out that bike with a couple of sprockets, and just like the DF, this 127cc engine is a Big Bore 110cc engine, with peak torque in the 6,5k RPM range (though I don't know if it's a push rod engine).
Changing sprockets from 41 to 31T (testing 36 and 34T sprockets too) does not increase top speed, but does lower RPM (and torque too).
Changing downto 34T or 31T does make top speed more susceptible to winds, while with 41T I'm running at max revs, and with a 36T I guess I'm in the torque band, and it sustains speeds much easier, even with heavy wind gusts;
When tailgating a truck, top speed could possibly exceed 60MPH (GPS verified), with a 34T sprocket.
Since I use that bike mainly in the suburbs, with 35-45MPH roads, (50MPH max speed on 45MPH roads here), I geared it really high with that 31T rear sprocket; as the bike is not good enough to go on highways or interstate (though I've done it before).
I don't mind going on the interstate with a bike that can maintain a sustained 70MPH, but 62MPH seems off...
I'm not getting identically the same bike. I'm getting the naked bike, RTC-B which is more aerodynamic.
They say the RTC and RTB use the same engine.
The RTB is the Bobber,
The RTC is the racing bike
The RTC-B is the naked bike, new for 2013 I believe.
But from what I'm hearing, that 13T sprocket is WAY too small!
And a top speed of 62MPH on the 229cc engine is VERY disappointing! Something must be wrong on your readouts!
I can't believe I would add 100cc, and still go just as fast as on my 127cc; although the 127cc is jetted a bit too lean, but it does have a manual choke on the handlebars. That manual choke can be opened slightly, to tune the a/f ratio (as the bike is jetted a tad too lean, opening the choke will cut a bit of airflow, and makes it run less lean), and when doing so, the bike increases in performance.
Strange but true, sometimes cutting airflow with the choke (by 10-25%) improves performance.
Sometimes increasing a jet size from say 100 to 105 might not improve performance at all; if the case is that the perfect jet size would be 102 or 103. I notice on my choke that the bike is very sensitive to that 'perfect' af setting. When you hit that perfect setting just right, the bike has noticeably a few HP extra from jetted too lean or too rich. Sometimes one millimeter off on the choke lever can mean 1-3 MPH slower top speed. And that perfect setting always changes, depending on the engine heat, fuel type, and throttle position.
A bike that's jetted too lean, can be compensated with a choke (if it's a manual, non step, choke, meaning where one can slide on or off the choke, and it does not have steps, but like a throttle can be slid open to any position).
If the bike is jetted too rich, there's nothing you can do with the choke to compensate. All you can do, other than jet it leaner, is play with the AF screw to let it run a bit leaner at idle, so that at WOT it might run a bit leaner too. But the AF screw only impacts the fuel mixture in a minimal way; and it could give problems idling on a cold day when you do.
I'm also very skinny (160LBS), and top speed (60MPH) is only gotten when sitting ducked forward, or tailgating a truck. When sitting upright, my 127cc only goes 55MPH.
I don't know how you can say the size of the 13 tooth front sprocket is way too small when the size of the front sprocket by it self means nothing. It is the combination of the two sprockets that matters.Quote:
Originally Posted by ProDigit
I'm running a 13/30 right now on my 2012 DF with a top speed of about 65 MPH indicated at about 7k RPM now that I have an air filter that flows enough air to stop the cutting out. BTW, I am sitting upright and not tucked under.
Maybe you should start a different thread for the DF250RTC-B which looks like a neat bike. Also send an email to the seller to correct the 250cc to 229cc in their ad.
That is a two stage filter with the outer sleeve being a courser material to act as a prefilter. I have had similar filters in the past and they last just fine. Don't use too much filter oil (inner sleeve only) after a wash.Quote:
Originally Posted by axa
It's a common error for those engines...Quote:
Originally Posted by barnone
I guess they're meeting the emission standards for a 250cc engine, but not for the 229cc.
Concerning the gear ratio, you're still 1000RPM above the optimal setting, meaning for every 200-300cc bike, there's an optimal 100:1 RPM over MPH ratio, meaning at 60MPH you should be doing 6k RPM, not 7K. That way you can go another 5MPH faster.
Your gear ratio is about the same as my 150cc scooter with CVT, and that one accelerates like a beast, and also tops out at 62MPH. I can only imagine with 1/3rd more cc's! (CVT eats upto 10% of power compared to geared bike).
I'm saying the front sprocket is too small, because it is. You can't go much lower on the rear without having the chain eat up the rear fork. You need to increase the front if you want to make your ratio a bit higher.
From the numbers you told me, optimal gear setting for your bike (best acceleration/MPG/top speed) would be a 15/31 sprocket setup. 15/30 is bad because of the rear sprocket teeth being a multiplier of the front sprocket teeth, causing uneven tooth wear.
It would drop RPM from 7k to 6k, which is a lot better for the engine.
If I would have geared your bike, from the numbers I see, I would have equipped it with a 17/30 setup. It would not be a dragster, but it would be rideable in traffic, accelerate just fine, do 5,5k RPM at top speed, perhaps suffer some top speed, but it would be in the 110-125MPG range.
But should I sell that bike as a dealer, I would equip it with a 17/36T setup, which is about the same as a 15/31 or a 13/27.5T (yeah, just between 27 and 28T on the rear)
With that sprocket you'll not only lower RPM, and increase MPG, but you hit top speed right in the torque band, allowing you to go even faster (at least 5MPH faster, perhaps 70-72MPH tops).
No wonder top speed figures didn't make sense to me!
I can't believe they actually equipped those bikes with a 13/41 (or 13/43 for the RTD, which is a rebel type) stock.
I don't know what front sprocket the RTC series have, but the RTC racing bike has a 46-48T rear sprocket, which is just insane, but at least it has a lot of room for improvement on the rear!
http://www.mychinamoto.com/forums/im.../confused1.gif Is it just me or can everyone else make heads or tails of this?Quote:
Originally Posted by ProDigit
maybe you should start that RTC thread...
Why? The info seems straight forward, it's aimed towards the RTB, not the RTC.Quote:
Originally Posted by axa
It's just a calculation on an optimal sprocket/gearing setup for best top speed.
I understood it , I run VERY tall gearing , I hit 68 indicated in 4th as I change into 5th , gives me 80-90 mpg highway milage depending on which way winds blowing and ability to draft
the stock gearing , arg both 1st n second gear to low , shift twice into third to cross an intersection !! get out
ok so what your estimating is a ratio of 2.066666 would be ideal... who knows, could be, i think thats what dan has and he seems to like it.Quote:
Originally Posted by ProDigit
he has a differnt bike as well, and changed chain so he could use the larger front sprocket
aye I run 17 36 ? or a custom 35 I don't recall , with a 428 HD chain , but my back tires also about 5" shorter so needs to spin faster and increases my torq , for flatland I find it ideal
so your fella's gearing shouldn't be quite that tall or u never be able to use 5th gear
Enough with the gearing, do whatever you want.
I went riding with a load to the recycling center
Attachment 13411
and ran into my buddy Jim Tom Hedrick who is an ex moonshiner and now stars on the Discovery Channel's Moonshiner series.
Attachment 13412
Here he is on my DF in front of a still he made for Thunder Mountain General Store outside of Robbinsville,NC.
That's his liquor scooter (too many DUIs) with a trailer like mine that has seen many miles.
Beautiful day for riding the DF here in the mountains of Western North Carolina.
I can't find my damn Owners Manual. Does anyone have it online in a file format that they could email it to me by any chance? I'm goin crazy over here trying to find the damn thing.
Yeah, I guess the limiting factor in using 5th gear would be, how many MPH does your bike do at 2,5k RPM?Quote:
Originally Posted by DanDaMan
Ideally you will want to run between 2,5 and 3k RPM. With a 100:1 RPM/MPH ratio, you'll still be running only 25MPH to 30MPH, which is ridiculously slow for a final gear; but then again it's a small engine!
If you run it below 2-2,5k RPM the engine might start lugging, but at 2,5k to 3k RPM even my 127cc can pull the weight.
At 25MPH in final gear, you might as well depart from 2nd gear, and immediately shift in 5th gear, I mean...
Most roads in flat florida don't require torque, and I'm doing just about the same gear ratio on a 127 motorcycle, and a 150cc scooter.
The 127 is a bit on the slow side with these gearings, understandable, the engine is very small too.
Most roads in flat florida also allow you to ride between 35MPH and 40MPH. If you're cruising, you will want to do that in 5th gear. With that 100:1 ratio, that'll mean your RPMs will run 3500-4000 RPM, for just cruising at 35-40MPH.
Ideally you will want to reduce those RPMs when cruising, and upshift into 4th to reach top speed.
I know the math is a bit simplified, but it comes very close to the real thing.
If fast acceleration is not your thing, but comfort riding, and economy (good MPG) then you will want your engine to run at ~3k RPM when you're doing 35MPH.
The engine won't have no problem pulling that off, since there's not a lot of wind resistance below 40MPH, so not a lot of torque is needed to cruise around.
I know I'm castrating a perfectly great accelerating bike into something that's barely puffing along, but that's my aim, to maximize my fuel efficiency on bikes like these; and in the process extending engine life as well!
If you're into high revving engines, fast acceleration, this might not be your kind of pie. But to each his own!
Another thing, getting gas mileage on the highway of 80+MPG is extremely hard!
Those 100+MPG numbers you basically only get when taking it easy, going 35-40MPH, without too many stops.
Any slower, and you'll have to downshift, causing lower MPG; any faster and the wind drag increases so much that MPG automatically suffers from it.
On my 127 I get ~96MPG @ WOT 60MPH, ~104MPG doing 50MPH, and 118MPG doing 35-40MPH.
I guess if you're eco-cruising, it makes most sense to stay between 35 and 45MPH.
Jim is still riding that old liquor sickle.He's got some stories to share.Quote:
Originally Posted by barnone
Quote:
Originally Posted by ProDigit
and here we thought you had a question...
I work with this crazy guy, he is always talking about this thing called hypermiling.
you sound like him
Thanks for the comparison!
It helps me writing out my ideas.
It wouldn't surprise me, that very soon in order to meet EPA emissions, they'll look at, and optimize gearing as well as exhaust, and vehicles accelerating faster than a certain amount will not pass epa regulations (as acceleration torque is directly related to gearing, and gearing to the MPG you can get out of the bike)... They're always there to make our lives more and more miserable, so it wouldn't surprise me if I come to see that day; and where riding is all about transportation, instead of fun.