New build, very tight fit, intake fabrication.

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mapbike

Well-Known Member
Mar 14, 2010
5,502
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Central Area of Texas
Well, I've had a new schwinn link city series bike for a while and I finally got around to motoring it up with a pull start 66cc slant head that I've had for a while also, wow if I would have known that it would have been such a tight fit I'd just went with another bike but I'm gonna get it done and it will be a much more comfortable bike than my old mountain bike, below is a pic of the intake I had ti make because there isn;t enough room after the engine is mounted to fi the carb. it doesnt look like much but it's the best I could do for a quick fix for now, my pie bender is not for the thin wall tubing and crimps it at the bend point so this makes it look a little rigged, now I just need to drill my carb jet a little more becuase the long tube has made it run just a little on the lean side, havent rode it yet but when it idles it will surge up and then slowly back down in RPM's. but I'll get it tuned and then I'm gonna put a 39 or 40 sprocket and hub adapter from Jim " manic Mechanic ", I'll post some good pics of it when it is all done, I'm kinda excited about this one, this will likely be my ride to work this summer which is 16 miles one way.

.wee.
 

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Nashville Kat

Well-Known Member
Apr 20, 2009
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Jacksonville, Florida
Good luck- BUT

I personally feel that it's probably not that good to get the carb so far away from the motor-

I got immediate excellent results with the same NT stock carb when I went with a straight billet intake- The Maniic Mechanic shortened the billet intake even further after that-
for more frame clearance and performance-
I also got one of those but not sure that made any performance difference
They have become less available now- except I see the tapped boost bottle on a couple of sites, and they seem to more have the CNS billet, which I guess is more needed for clearance
The larger Speed carb also upped the performance a bit, but not as much as the intake itself
A lot of guys have complained about the CNS the last several years, and I always had a notion that the extra-long offset intake may have had a lot to do with that

http://www.pistonbikes.com/category-s/49.htm
Just by using a crude guesstimate and adding about another inch or inch and a quarter for the billet intake to the carb assembly- it looks like one of those may fit the frame, if you can't get your own intake to work

You surely do have excellent mechanical skills for building that intake though- while I can speculate and offer my own experiences- I could not build one of those myself! The aluminum billet seems harder to get- maybe you could go into business selling short intakes...
 
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klapool

New Member
Aug 29, 2011
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Wisconsin
I had fitment issues also attempting to get the engine into a Jamis Explorer.

I ended up cutting the intake and welding it at an angle.



 

mapbike

Well-Known Member
Mar 14, 2010
5,502
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Central Area of Texas
fellas if you will look at the date you will see that my post was made in April 2010, that bike no longer had an engine on it just a couple weeks after that post, lower bearing in that ngine gave up the ghost so I rebuilt it with new crank...ect.... ran good for another 450 mile and then crankshaft shifted toward clutch side of engine causing mag flywhel to eat into case and crank seal on that side creating a severe air leak, engine is layed up waiting for a tare down in the future to see what caused the crank to get so much end play and shift over like it did.

I have the Manic intakes for all my engines now and have descovered that the RT carbs that Duane at Thatsdax sells are performing even better thus for than the NT carbs which I like by the way, the RT carb seems to give better torque and the top end speed is just as good or amybe a bit better.

Anyway, disreguard my above post from here on out..........it's a dead duck.....! LOL

Peace, map
 

killercanuck

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Dec 17, 2009
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Wallaceburg ON
Sorry mapbike, didn't realize how old the thread was. I found it using the search. That's really weird the rotor chewed into the case, wow. Is the RT about the same size as the NT? I know the CNS is a monster compared to the NT... :)

That's a good way to do it klapool, I wish I had a welder handy. Kat, I'm still using the shorty intake as a base, can't beat the port match, for sure. I did try an offset intake too, but the angle of the carb came out worse than with the shorty, and too close to the frame for the filter I wanted. Now I know, heh heh.

I may as well post a couple pics too.
Even with a Shorty Intake I had no room at all for an air cleaner. Ran great, but don't need gravel dust or something getting into the carb :p


This is what I threw on to get a filter on, and have the carb level, but the idles pretty wonky. Pulsing and whatnot. As long as it runs I should be happy.
 

vincent713

New Member
Jun 2, 2010
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Dallas
Killercanuck,

I like the short intake u had on but seems like it was at a steep angle, did you have an issues at idle when u had it on? What you could have done for the air filter was take some pantyhose and wrap it around the plastic that holds the origin filter in place. Then just screw it onto the carb. I did that on my pocket bike and it works great!
 

PatTheThird

New Member
Apr 24, 2011
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Southern Maryland
This was my solution. Its a cheap offset intake with the last joint cut and rewelded. The carb is a ThatsCax.com knock off Delorto r15. It is a rediculous awesome carb. Throttle response is perfect through the band. I think its like 20 something bucks. Comes with different jets too. Oh and it took all the slop out of my throttle cable.
 

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vincent713

New Member
Jun 2, 2010
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Dallas
I've seen those offset intake, they are good solution to small frame bike. What is that shield u have on the side?
 

Stinky Finger

Member
Jul 26, 2010
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Leicester, New York
More than one way to skin a cat, M.B. Filling the tubing to be bent with sand will force the pipe to retain its round shape as it is being bent. The outside of the bend is stretching while the inside is constricting. The forces bear against the ends, to a point, but following the path of least resistance exit outward at the apex of the arch forming a kink. This is easily demonstrated with a simple coffee stir stick, on of those little red plastic straws. Place it between the index finger and thumb and squeeze. Of course it bends but soon kinks in the center. Repeat with the straw now filled with sand and you will see it can be bent father before it fails.

http://www.youtube.com/watch?v=vUrHBIYLzG0
 

killercanuck

New Member
Dec 17, 2009
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Nice shields Pat, they're good for "stealth" too, I'd imagine.

That's a good idea with the 'hose Vinny.

At the original angle, it ran pretty good actually. Idled great, and the top end screamed. It runs a lot worse with the extension. But that could be my fault. The 3/4" elbow is clamped over the shorty, so there's like a ledge there. When going down to idle, it'll rev like crazy and I have to let the clutch out a little to help it settle. There's no air leak, so I think a puddle builds up at(and under) the ledge and won't let it idle for a good 5 seconds after going off throttle.

On the other end of the scale, it won't rev up half as fast, or near as far either. Going to rethink the 3/4" and figure out a more streamlined internal profile. You'd think that going from the 3/4" to the 1/2" would create a 'venturi' effect. But nope, no luck with this set up. Back to the plumbing section ^^)

Stinky, that's a good tip. I've also read about filling a tube with water and freezing it for the same effect, to keep it from 'pinching'.