Bronco evolution

LincolnMercury · Nov 27, 2011

Did some work over the holidays. Welded a rear mount and engine carrier. Mocked up the mount and carrier using a slant head engine. The billet head did not clear the seat post. Notched the seatpost instead of making new mounts. The welds are not pretty; but they are solid and strong.

LincolnMercury · Nov 27, 2011

Cut off the end of the drive gear housing to accomodate the angle of the chain. Threw some paint on the raw metal parts.

LincolnMercury · Nov 27, 2011

Cut up an old muffler for a header pipe; tack welded a kidney expansion pipe (from bicycle-engines i think) and cked it for fitment. Ground down the welds and smoothed everything out. The thicker metal is SO much EASIER to weld.

LincolnMercury · Nov 28, 2011

Got the rear end assembled. Had to add the "heater hose" tail pipe extension. I had to gently bend the clutch arm up to clear the drive chain. Still have to shave the fender mount to clear the carburator. Mount full fenders and fab fender mounts out of 1/4" rod.

DaveC · Nov 28, 2011

LincolnMercury said:
Did some work over the holidays. Welded a rear mount and engine carrier. Mocked up the mount and carrier using a slant head engine. The billet head did not clear the seat post. Notched the seatpost instead of making new mounts. The welds are not pretty; but they are solid and strong.

Well...I have seen better welds...and worse...but the only one I'd really worry about is the notch. Just inspect it often and fix if you have to. If there's any problem with what you've done it will most likely be there.

LincolnMercury · Nov 28, 2011

The welding is getting better as I go. Trying to get the wire speed down per material. The thin wall tubing is a B***h to weld... blow throughs alot! I am not worried about the structural integrity of the seat tube. I also inserted, then and notched the seat post before welding in the 18 gauge sheet metal.

thegnu · Nov 29, 2011

LincolnMercury said:
The welding is getting better as I go. Trying to get the wire speed down per material. The thin wall tubing is a B***h to weld... blow throughs alot! I am not worried about the structural integrity of the seat tube. I also inserted, then and notched the seat post before welding in the 18 gauge sheet metal.

good thinking effectually you removed half its strength but unless those 2 peices are welded to one another it can still be weak I offer a simple lil fix if your afraid of it at all an you should be at least a bit concerned , just drill in to but not through the inner tube an drop in some nice hot spot welds above an below the notch front an back of that tube .
Gary

Venice Motor Bikes · Nov 29, 2011

Those Broncos are awesome looking frames!
It looks like you might have some problems with the engine chain dragging on the top of the engine case right above the engine sprocket. (I've had that same problem on a few stretch cruiser builds).
If it does?, you might want to angle the front of the engine down a lot more.

LincolnMercury · Nov 30, 2011

@thegnu; "great minds"... did just that! @venice; I chopped the end off of the drive gear housing to clear the chain. Caught that during mock-up. I could not tilt the engine anymore than I did without removing the seatpost. As it is, I used a slant head to setup the mounts, not with the billet head. Hence, the seat tube notch. You, RedB, Crazyhorse, Gaucho, Azbill, Norman and countless others on this forum keep me motivated, INSPIRED and excited about this hobby/addiction. Thank you to you ALL!

LincolnMercury · Nov 30, 2011

Ran the bronco with stock carb and Manic Mechanic billet intake. Pipe is quiet and rolls in around 2000 rpm (an "ear" guesstimation). Today, I welded up an offset intake for a "speed carb" (thank you Pirate Cycles!); tweaked the chain lengths and added a tensioner to the bike side chain. Just got in from the test ride... OMG!!! Very smooth throttle response, begins to accelerate IMMEDIATELY! To dark to see my speedo. A long ride is in my future, tomorrow morning!

thegnu · Nov 30, 2011

that bike is looking like a real racer nice job !

LincolnMercury · Jan 11, 2012

After 30 miles of riding everything was pretty smooth. Cruised @ 34mph; wot 44mph according to speedo and android gps. After a bump start the welds on the motor mount let loose. Long pedal home. Looking at the mounts, I had marginal weld penetration. I tossed the HF spool of .03 flux wire and got some Lincoln .035 wire. And redesigned the mount. I welded up the motor carrier and the bashed it apart with hammer and cutoff wheel to check the weld joint. Much BETTER!

LincolnMercury · Jan 11, 2012

And I redid the intake manifold so I could mount the bike side chain guard. Now, I am having problems keeping the engine running. It refuses to idle. I am not familiar with this carb enough to know what to adjust. It is the "speed carb" with the remote choke adjustment. The only change I make was increasing the intake length by 2 1/2 inches. I went back to the shorter intake and still no idle. I would take this thing apart if I had some idea what to look for i.e. clogged idle jets etc. Is there a manual or exploded view for this carb? I am already welding up an extended intake for the stock carb (there is something to be said for keeping things simple...). Any help or comments are welcome! Thanx in advance!

thegnu · Jan 11, 2012

after you get it running does it display any other symptoms aside from no idle ?
my only clue would be a pinhole or 2 in a weld letting in just enough air to keep it from idling , an the added length of your other intake really shouldnt affect much at all, although I have heard of those being too long (only in race gocarts from a freind of mine) in rare circumstances the fuel an oil could be condensing on the inside of it , an I may be wrong just taking a shot in the dark .
Gary

LincolnMercury · Jan 11, 2012

Thanx for the tip... I did find 3 tiny (ok, one was not so tiny) pinholes. I bathed it in solder flux and sweat some 60/40 solder ALL OVER the intake. Pinholes closed. It is now raining cats and frogs here in central FL, so I will have to wait for a test ride.

Ok... while prepping the intake for paint, I noticed the carb end of the intake was not cut squarely; so it was not sealing against the carb grommet. OOPS!

LincolnMercury · Jan 12, 2012

Went for a test ride today. Still can not get it to idle. Ok, thats not exactly true, I cannot get it to idle under 1-2k rpm. Fuel spews out of one of the upper vents and the throttle opening. I did get the full fenders off of my former Micargi Mustang mounted on the Bronco, so it is not a total loss. If I cannot get this carb sorted out I will go back to the stock carb.

thegnu · Jan 12, 2012

Fuel pumping out of the carb is usually a sure sign of a stuck float or needle in the float bowl, could also be a float that has become fuel soaked or filled somehow , check those out .

LincolnMercury · Jan 12, 2012

Thanx for the tip Gary. I found tips on Spooky toothes site and another (the other) forum about tuning/trouble shooting the CNS racing carb. Apparently, you need to crimp off and close a vacumn line that is looped to the bowl balancing vent. Also, I moved the needle e-clip to the center notch (I moved it to the top position late one night and forgot about that change), after all of the above, it runs like a top. Of course, before I could get any miles on it, the front fender mount popped (you've all heard the horror stories). Fortunately, I was idling, not doing a speed run. Now I know how to tune it, I cannot wait to start tweeking it... after I fix all of my fenders on all of my bikes.

thegnu · Jan 12, 2012

Cool , I just want to see it complete , you should try making your own fender struts from steel rod about 3/16 diam. an fender washers , weld a washer to the end of the rod an bolt it to the axel then smaller washer at the top an bolt to the fender , if made right I have never seen one fail .

Bronco evolution

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