Dong Fang DF 250 RTB Bobber Information

[Roadkill]

I wish I knew , I geared for 90 , rear tire size + ratio to determin speed at 6000 rpm's

I wish 1 single person was in Austin so we could go ride together

and yes I have been tailed and verified - although had the smaller front tire , so speedo read 10% faster then = have since added a slightly taller tire to make speedo more accurate , when drafting I can run center lane without slowing traffic

Lived in Austin for a year or so. I really miss it. In that year, I don't think I hit 60 any place in town. That city has the most messed up drivers in TX except for Laredo. Rode a Honda Valk in Laredo for a while. That's some crazy stuff for a biker.

[DanDaMan]

no engine mods only added bigger mainjet and removed air inject

maybe it is as simple as that , gearing for 90 , so your 4h gear will be AT LEAST as fast as 5th was stock

let me break it down , when I got it top of 5th did about 60 screaming , I got the 13 tooth front (10% speed increase every front tooth = 20 %) that got me near 72 screaming , then I dropped in the 35 rear (2% per tooth) nuther 20% about 86 mph for screaming valve float rpm's

- but actually 5h only does like an overdrive gear holds highway speed at low rpm's , unless I can get rpm's up a bit (catching a short draft backwind or downhill stretch) , then baring an uphill stretch or stiff headwind it will hold the higher speeds unaided to about mid 70's

=now 4th reaches slightly taller than 5th did stock about 60-65 when shift to 5th

I also have the lower mass 428 HD chain , which allows for more drastic front sprocket change

[DanDaMan]

and im not yanking chains , I wish someone wer near to verfy , what im able to get from her , simply by making it basically a 4 speed (to 65mph) then a overdrive gear (5th) that has very little power other than to HOLD SPEED that 4th gear attained , at low nice sounding rpm


haha - shoot I even have a 2X8" speaker cabinet that tops my sissy bar and acts as my backrest , with plug play quick disconnects for lighter outlet to power mp3 player , phone recharger and amp power - working but still a work in progress

[Tedub]

Does anyone know how to tell when I need a valve job? My bobber is getting a tinging pinging noise and seems to have more vibration than normal. It has almost 3k. And if it does, is there a tutorial to learn how to do a valve job? Thanks!

[Roadkill]

Does anyone know how to tell when I need a valve job? My bobber is getting a tinging pinging noise and seems to have more vibration than normal. It has almost 3k. And if it does, is there a tutorial to learn how to do a valve job? Thanks!

Check link 5067 posted by Barnone. Compression testors are pretty cheap.

[axa]

no engine mods only added bigger mainjet and removed air inject

maybe it is as simple as that , gearing for 90 , so your 4h gear will be AT LEAST as fast as 5th was stock

let me break it down , when I got it top of 5th did about 60 screaming , I got the 13 tooth front (10% speed increase every front tooth = 20 %) that got me near 72 screaming , then I dropped in the 35 rear (2% per tooth) nuther 20% about 86 mph for screaming valve float rpm's

- but actually 5h only does like an overdrive gear holds highway speed at low rpm's , unless I can get rpm's up a bit (catching a short draft backwind or downhill stretch) , then baring an uphill stretch or stiff headwind it will hold the higher speeds unaided to about mid 70's

=now 4th reaches slightly taller than 5th did stock about 60-65 when shift to 5th

I also have the lower mass 428 HD chain , which allows for more drastic front sprocket change

If u say so, I can't have all the facts to say otherwise, but I do think I have most of the facts.

As for the chain discrepancy, I understand there is justification:
http://www.superstreetbike.com/how-t...er-mythbusters

But the benefits are so miniscule I just don't see it... And ones that I would think surely eaten by a FAT car tire!
I'm more inclined to consider an improvement in chain quality over stock a more significant factor.

So has anyone seen a performance increase when ditching the stock chain for something better? Let alone performance increase with any chain swap at all?

[Roadkill]

If u say so, I can't have all the facts to say otherwise, but I do think I have most of the facts.

As for the chain discrepancy, I understand there is justification:
http://www.superstreetbike.com/how-t...er-mythbusters

But the benefits are so miniscule I just don't see it... And ones that I would think surely eaten by a FAT car tire!
I'm more inclined to consider an improvement in chain quality over stock a more significant factor.

So has anyone seen a performance increase when ditching the stock chain for something better? Let alone performance increase with any chain swap at all?

I did see a post where someone had switched to larger front sprocket and 35T rear. They did the chain swap because of clearance problems with the larger sprocket. There is a kit being sold for Tha Heist. I think it's about $100.

[DanDaMan]

I didnr realize there was proof to smaller chain - better hp+torq , I thought it mearly the fact I was gearing 20% higher that any o u could was the issue :p

[Roadkill]

I didnr realize there was proof to smaller chain - better hp+torq , I thought it mearly the fact I was gearing 20% higher that any o u could was the issue :p

Didn't say that. Smaller chain from what I read was only for fit. I think it was to clear the front cover with the larger sprocket. Seemed like to much work for me so I stayed with the 35T rear sprocket mod. I'm pretty sure that you could gear a bicycle to go 150 mph if you could pedal it. I don't think I would like the acceleration of this machine if the ratio went any higher.

[axa]

I didnr realize there was proof to smaller chain - better hp+torq , I thought it mearly the fact I was gearing 20% higher that any o u could was the issue :p

Yes the lower ratio would in theory allow a higher speed of travel, by moving ceiling created by float at around 7.5k
But one needs the engine power to overcome all resistances (primarily wind at highway speeds) to attain these higher speeds.
And if one considers a flat road with windless conditions as a benchmark, none of us other 167fmm riders have seen enough power to "cruise" at the speeds that you claim to...

Thus the search for what is so unique about your bike goes on...