Another speedway

#21
Here is the pipe now primary section is way long around 20 inches to pipe is now tuned much lower. Was the only way to get it to fit. My other dragbike has only a single section loop pipe around 28 inches long and it runs real strong


My other dragbike pipe also a speedway frame.
 

delray

Well-Known Member
#22
ole4
The motor has a black mamba, 1.3 ratio rockers, ported 32/25 head, 37lb springs and 16cc chamber with a flat top piston. Carb is a 26mm flat slide.
more like a 9000rpm motor,yep you will need little more gearing.....:rolleyes:
 
#23
Made a curved intake to keep carb from sticking out, just about done with mockup, now have to disassemble and prep frame for paint. I blasted it with my pressure washer sandblast attachment and while clean of any paint and original rust has a patina of surface rust from the water. Gonna take some time to remove it.
 
#25
Made a curved intake to keep carb from sticking out, just about done with mockup, now have to disassemble and prep frame for paint. I blasted it with my pressure washer sandblast attachment and while clean of any paint and original rust has a patina of surface rust from the water. Gonna take some time to remove it.
Orlando the manifold looks great , although long as shit though . I had one almost that long on my track bike , this last race in Mississippi it broke at the flange while on the track . Tracks kinda bumpy and it needed a brace . But I end up borrowing at short aluminum one from Angelo, one of those that everyone gets with their Mikuni kit . But the thing is that motor ran so much better with that short intake , it was night and day difference.

Just wondering if you have tested to see hat works better ?
 
#26
no I am using pipemax simulator and for the cam timing I have and the peak rpm I put in the program (7500 rpm) the length from center of valve to inlet needs to be 11.3 inches. It would not work well for a flat track bike as when it is off at certain rpm it can cause severe reversion and blow out fuel then bring it back in and result in such a rich mixture it will hardly pull a load. This is a drag bike and I have the salsbury set to 3800 more or less.
I saw your broken manifold and the curved part is a cheap casting but I won't be hitting any bumps and if it does not work well I'll cut it. The length with carb hanging off will put a lot of leverage on it. Did yours break at the weld or did the casting itself fail?
 
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#27
The best I could tell the weld broke , it looked real grainy kinda like a casting . The flanges were from a billet manifold and the tube was some sch 40 aluminum tubing I had . After that I'am sticking to steel manifolds, haven't had one break yet . Lol
 
#28
Gentlemen,
We have had some success in making more durable weld connections in exhaust tubing of various materials. I chucked some scrap rigid copper 3/4" in the lathe and ground a HHS tool bit and didn't grind a chip breaker ledge on the bit. After some fussing, I was able to make some "copper wool" from the long strands of copper. We packed a bunch into a coupling point on an exhaust project after we tacked the joint in a couple of places. Then we finished the weld, and removed the copper heat sink. The exhaust repair is still in operation after three years of fairly hard use. We are talking about trying additional heat sink methods like wrapping the outside of the tubing with bare copper ground wire on either side of the joint to absorb even more heat.
Hope this helps some of your applications,
Happy Holidays and safe travels,
SAT
 
#29
What material are you using. On my exhausts I use stainless .063 wall tube. I use tig so heat affected zone is small. Only problem is you have to backpurge inside of tube and it uses a lot of argon. My intake curved section is a cheap eBay aluminum casting welded to a billet straight section. With the long length of the intake I would not be surprised if it breaks on the casting side.
 
#30
Can't you just put a brace on the carb to the head to avoid a break?
I made a similar manifold out of steel and made a brace that went from carb bolt to head boss.
You can't really see it here though. I'll see if I have a better picture of it.

Danford1

 
#32
Can't you just put a brace on the carb to the head to avoid a break?
I made a similar manifold out of steel and made a brace that went from carb bolt to head boss.
You can't really see it here though. I'll see if I have a better picture of it.

Danford1

Wow, nice engine to frame configuration Danford, I wouldn't mind seeing the rest of that bike.
 
#35
Ole4,
Sorry about the delay in responding to your post, Mother Mature brought cold weather to Northern Michigan. I use half and three-quarter black pipe with braces for most engine exhaust pipes. DOM tubing to suit the application for the rest. They have to stand the test of parade days on Thanksgiving day-Woodward ave. and St. Patrick’s day-Michigan ave. in Corktown. And not interfere with any rider’s clown pants.
Our little Millermatic 141 further restricts our exhaust system choices. It looks like we might have a TIG in our future.
Thanks to you and all in this thread,
Steve
 
#37
Ya, -24 degrees F at night, -2 for a daytime high... I’m not bragging or hijacking this thread.
Nice work on your Speedway project, I learn a bunch every time I visit this Forum.
Again, thanks,
Steve
 
#39
They are pitbike in inverted forks. They feel great but are very heavy for a minibike. Between their weight and the long swingarm I hope to not need wheeliebars
 
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