Dong Fang DF 250 RTB Bobber Information

[barnone]

I appreciate the help. Still talking to the wife, you know how that's goes. Haha. Probably going to order one in the next week. I know these china bikes have some issues, I've been a mechanic for a few years though so no worries. Any heads up on issues with these?

Gear,
I've only had my 2012 DF for a week or so I have limited experience with it. Had the previous model back in 2010 and sold it.
Issues so far are minor.
Lack of clearance between rear tire and tail light wiring under fender. Some don't seem to have this problem.

Valves adjustment and oil change were necessary before starting bike.

Click on my photos at https://picasaweb.google.com/1091387...FangDF250RTBA#
for changes to my DF.

Probably will up the jet sizes, add some saddle bags, etc.
Very easy bike to modify and maintain but you do need some DIY skills which you appear to have.
I'd go back 20 pages or so in this thread and read forward. So sense in going back to day one.

[chruk bashre]

Don't pay any attention to these jokers. It is a good bike. It runs..

yeah just ride it.

[ghost1133]

yeah just ride it.

If it ant' broke, don't fix it,

Living the life I am living.
Hell yea !

[birdmove]

This should be a good motorcycle for someone to learn about working on them too. For instance, on the CCW Tha Heist Facebook page, there are several owners trying to adjust the valves and having problems. There is nothing easier to get your feet wet than on a pushrod single like these two motorcycles. One guy was obviously trying to do the valve adjust while on the wrong stroke. He kept backing off the adjuster at the rocker arm and couldn't get any clearance. Good thing he stopped and asked. On the Royal Enfield 500 Bullet (2007) I used to have, they never even gave valve clearance measurements. You got it at TDC on the firing stroke so both valves were closed, grabbed the pushrods and tried to turn them (spin them round). If they turned pretty easily, and had no up and down play, then you were good.

[barnone]

This should be a good motorcycle for someone to learn about working on them too. For instance, on the CCW Tha Heist Facebook page, there are several owners trying to adjust the valves and having problems. There is nothing easier to get your feet wet than on a pushrod single like these two motorcycles. One guy was obviously trying to do the valve adjust while on the wrong stroke. He kept backing off the adjuster at the rocker arm and couldn't get any clearance. Good thing he stopped and asked. On the Royal Enfield 500 Bullet (2007) I used to have, they never even gave valve clearance measurements. You got it at TDC on the firing stroke so both valves were closed, grabbed the pushrods and tried to turn them (spin them round). If they turned pretty easily, and had no up and down play, then you were good.

Is that RE technique with a cold or a hot engine?
I'd like to try that on my DF with a hot engine and then measure the clearances when cold.

[birdmove]

Cold. Though some owners said they did it hot, and said it worked too. The point being, on the Enfield, once you got the feel of the proper valve adjustment, it was something you would remember. I bet that would work just fine on these bikes too. I tried to get across to the Heist owner, that, if he goes to TDC, then checks both valves for looseness and finds one tight. DON't adjust it. Rotate the engine once around, and recheck for looseness. He would have then found that, after rotating once, he was now at TDC on the firing stroke, the correct position to make the valve adjustments. There are two top dead center's. But only one TDC with both valves closed (the firing stroke). He didn't do any harm, because he didn't try to start it. He would have spit a pushrod out and possibly caused damage, if it would have even started. With as much excessive valve clearance as he had, the valve may not even come open.

[barnone]

Since it is still raining here I'm gonna try the RE method hot and then check the cold clearance.
Makes sense that you want almost zero clearance (able to spin the push rods) when hot, right?

EDIT: No room to spin the push rods for my fingers and didn't want to use needle nose pliers.

Installed the mini tachometer and it works. Took off the tank to get some slack for the ignition switch and then mounted it right side up.

[ghost1133]

Cold. Though some owners said they did it hot, and said it worked too. The point being, on the Enfield, once you got the feel of the proper valve adjustment, it was something you would remember. I bet that would work just fine on these bikes too. I tried to get across to the Heist owner, that, if he goes to TDC, then checks both valves for looseness and finds one tight. DON't adjust it. Rotate the engine once around, and recheck for looseness. He would have then found that, after rotating once, he was now at TDC on the firing stroke, the correct position to make the valve adjustments. There are two top dead center's. But only one TDC with both valves closed (the firing stroke). He didn't do any harm, because he didn't try to start it. He would have spit a pushrod out and possibly caused damage, if it would have even started. With as much excessive valve clearance as he had, the valve may not even come open.

Birdmove. you are right on.
Always worked for me and that's with 36 years of road underneath my feet. But at the same time, I would of been lost without you guys. Go figure.

Thanks.

[axa]

I wouldn't think you have gone to small. If I remember right they come with a 12 or 13 on the front. That being said, I have a 15 on the front and a 38 out back. You are only 3 teeth less than I have for rear. And 2 to 3 teeth less in the front. If I remember the old rough formula was 1 tooth up front is equivalent to 4 in the rear. Skip all that mumbo jumbo, Bottom line, I still have taller gearing than you do even with your 35 and mine is spot on for my 250 lbs., 6"3 butt. My guess is you'll want to go with a 14 tooth up front to go even taller once you test it out. Unless you like it quick instead of higher top end.

Mumbo jumbo alright
How can you arbitrarily equate x amount of teeth on one gear to x amount on its coupled gear?
As the number of teeth in the system change, the number of teeth on one gear that relate to the coupled gear changes in kind.
In the end its all the ratio.

so as an example, 36 on the back 12 on the front, while exactly the same as 45 on the back 15 on the front, both 3:1,
if you do as you say take 1 tooth from the front and 4 from the back on both of these systems.
You end up with 32 to 11 a ratio of 2.9090, where 41 and 14 now results in a slightly differnt ratio of 2.92...
increase these numbers and grater the difference will be.

[4950cycle]

You can sound as smart as you would like axa. And yes, I know all about ratio math and numbers. I've built home made multi ratio power transmissions from scratch with belts and pulleys successfully ( I could send you pictures of my two speed belt driven motored bicycle that works like a charm). But the number of teeth on any said sprocket directly correlate to the circumference of same sprocket hence dictating what final ratio you end up with. All I was saying is, We noticed and was told by our local motorcycle mechanic when we were kids " you can add one tooth to your front (drive) sprocket or lose 4 on your rear to get the same (or very close to) end final ratio result. That's how we did it and it worked is all I can tell you. Now when you build a transmission from scratch , you have a lot more variables than what sprocket to use. Try having to figure out how much distance your drive tire OD covers per revolution and the list goes on. And I never said take 4 from the back "AND" add one to the front. I said do either or ! Not both !