New style frame doodlebug db30r exhaust

#3
Looks like putting gas in is a royal PITA. :D

You need a measurement that indicates how far the pipe needs to come out to clear the frame and the fender. The engine looks really tucked in there.

The only exhaust pipe fabricators (on ebay) consistently providing dimensions are andrei-x and jtwfabrication.

https://www.ebay.com/usr/jtwfabrication I've bought from him before and while he is open to adding a threaded 3/4" NPT coupler, he hasn't done it yet. These straight pipes need a muffler as they are LOUD.

This one might fit: http://rover.ebay.com/rover/1/711-5...0001&campid=5335845805&icep_item=283207826829
 
#4
Looks like putting gas in is a royal PITA. :D

You need a measurement that indicates how far the pipe needs to come out to clear the frame and the fender. The engine looks really tucked in there.

The only exhaust pipe fabricators (on ebay) consistently providing dimensions are andrei-x and jtwfabrication.

https://www.ebay.com/usr/jtwfabrication I've bought from him before and while he is open to adding a threaded 3/4" NPT coupler, he hasn't done it yet. These straight pipes need a muffler as they are LOUD.

This one might fit: http://rover.ebay.com/rover/1/711-5...0001&campid=5335845805&icep_item=283207826829
Well, I went with a pipe from HRM. It fits, but the grey goat pointed out a flaw I didn't think of.....it is rigidly mounted to frame. I am gonna make a different mount set up for it so it can flex with the engine if needed. Makes sense. I don't know why HRM wants it hard mounted to frame like that. It is tapped and came with a soda can muffler. My kid wants it off. I'm ok with that. Noise is good. No noise worries me. And yeah, fueling isn't easy, but it ain't too hard either. He filled it without making a mess. I know we can get a different tank for it with a side fill. We will see. image.jpeg image.jpeg image.jpeg image.jpeg image.jpeg
 
#5
If you have no neighbors within a couple of miles you probably can get away with a straight pipe, otherwise don't be too surprised when the police show up due to noise complaints.

FYI: That's a front tire on the rear, tread designed for steering rather than driving. It will work but won't provide the driving traction in soft stuff that a rear tire tread would.
 
#6
What's HRM?
Looks good and I like the length. Thanks too for the plentiful & HQ picts.

I wanna use a sausage (soda can?) muffler but drill out the center with several holes or one big one to see how it works.

The engine's going to vibrate but not exactly flex since it's rigidly mounted (it's not rubber mounted is it?), but having the pipe rigid-mounted to the frame bothers me. A brace that's mounted to the engine a la the kind used in kart racing (Briggs Raptor, etc) would be better because those support but also 'give' a little if I understand correctly.

Otherwise, use something like a flexible exhaust hanger like those used on automobiles but smaller.
 
#7
If you have no neighbors within a couple of miles you probably can get away with a straight pipe, otherwise don't be too surprised when the police show up due to noise complaints.

FYI: That's a front tire on the rear, tread designed for steering rather than driving. It will work but won't provide the driving traction in soft stuff that a rear tire tread would.
Noise not a problem where we are. Very rural area. Not much around besides orchards and all the farmers ride some crazy stuff. The tire......had no idea about that. Are you talking about the tread only or the shape? Seems everytime I get tires for it, the shape is different. Sometimes they will be rounded and sometimes they are flat. Well, he'll run these till they wear out and I'll make sure to get correct next time. thanks for the heads up.
 
#8
What's HRM?
Looks good and I like the length. Thanks too for the plentiful & HQ picts.

I wanna use a sausage (soda can?) muffler but drill out the center with several holes or one big one to see how it works.

The engine's going to vibrate but not exactly flex since it's rigidly mounted (it's not rubber mounted is it?), but having the pipe rigid-mounted to the frame bothers me. A brace that's mounted to the engine a la the kind used in kart racing (Briggs Raptor, etc) would be better because those support but also 'give' a little if I understand correctly.

Otherwise, use something like a flexible exhaust hanger like those used on automobiles but smaller.
HRM.....HOT ROD MINIBIKE.COM. The muffler, I called a soda can because that is what it looks like. Since he doesn't want it on, I guess we can drill it out to see what it does also. Otherwise, it is going in the trash. The engine is not rubber mounted. Just mounted on an adjustable plate. I disconnected the clamp on the frame and yeah, the vibration can be seen on the header. Glad I took the clamp off. It would eventually break. Today I will go to the hardware store and see what I come up with for a mount.
 
#9
Noise not a problem where we are. Very rural area. Not much around besides orchards and all the farmers ride some crazy stuff. The tire......had no idea about that. Are you talking about the tread only or the shape? Seems everytime I get tires for it, the shape is different. Sometimes they will be rounded and sometimes they are flat. Well, he'll run these till they wear out and I'll make sure to get correct next time. thanks for the heads up.
I was referring to the tread, it's basically a modified rib tread. Think of a farm tractor (an older one, anyway) with rib tread front tires for steering and chevron tread (AKA: bar tread) tires on the rear for driving, or a modern sport type ATV (not utility type). Both of those examples, being rear wheel (only) drive, use front tires with tread optimized for steering and rear tires optimized for driving, front tires having more longitudinal tread elements and rear tires having more transverse (often angled to reduce plugging) tread elements. Not a huge deal on a minibike, it just won't have as much "bite" for driving as some other tires might have; it's much better than the squared profile turf saver type (lawn mower) tires that many people use. Any single-track wheeled vehicle should have rounded profile tires.

https://en.wikipedia.org/wiki/Single-track_vehicle

https://en.wikipedia.org/wiki/Bicycle_and_motorcycle_dynamics

I found a couple pictures of Coleman bikes with that tread pattern on the front and a different tread on the rear.

Coleman BT200X.jpeg
Coleman CT200U tread.jpeg

Some tires are directional, so always check the sidewall for rotation markings.
 
#10
I was referring to the tread, it's basically a modified rib tread. Think of a farm tractor (an older one, anyway) with rib tread front tires for steering and chevron tread (AKA: bar tread) tires on the rear for driving, or a modern sport type ATV (not utility type). Both of those examples, being rear wheel (only) drive, use front tires with tread optimized for steering and rear tires optimized for driving, front tires having more longitudinal tread elements and rear tires having more transverse (often angled to reduce plugging) tread elements. Not a huge deal on a minibike, it just won't have as much "bite" for driving as some other tires might have; it's much better than the squared profile turf saver type (lawn mower) tires that many people use. Any single-track wheeled vehicle should have rounded profile tires.

https://en.wikipedia.org/wiki/Single-track_vehicle

https://en.wikipedia.org/wiki/Bicycle_and_motorcycle_dynamics

I found a couple pictures of Coleman bikes with that tread pattern on the front and a different tread on the rear.

View attachment 244709
View attachment 244710

Some tires are directional, so always check the sidewall for rotation markings.
For now, I mounted his old doodlebug tire back on the rear. I now see the difference! Thanks for letting me know.
 

Top