Micargi Falcon GT Stretch Chopper Project

GoldenMotor.com

4you2eat

Member
Oct 27, 2012
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Spring Texas
Here ya go. Micargi Falcon GT. Stretched out the chain stays 17". I will beef up the rear end for safety. I extended forks 6", added brass filler cap from hw store the petcock fitting from kit tank, sealed tank w/ Caswell epoxy sealer. 49cc Skyhawk. I will make exhaust from 3/4" emt. Might do a springer front end. I see I will have issues w/ chain rubbing on chain stays. I shall have to engineer it. Mebbe a jackshaft or frame mods to allow clearance for drive chain. I shall cut off seat post top and add a pivot for a solo seat.. I have a mountain bike shock I might play w/ for the seat spring setup on the solo seat. I shall prolly get some leather and some thin foam on the seat pan, need 12ga metal for pan. Need front disc laced into hub. We shall see what happens. I need to stare at it more and scheme. Don't have a lot of $$ but plenty of time to play w/ it.

 
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2door

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Sep 15, 2008
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Littleton, Colorado
Looks like the bike in Venice Motorbike's logo :)

Good start. You might explore off-setting the engine to the left. My Nirve Switchblades required a 9/16" offset. That means custom mounts but it worked for me.
Keep us informed on your progress. Very interesting build. Thanks for sharing.

Tom
 

4you2eat

Member
Oct 27, 2012
101
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Spring Texas
Main issue w chain is the gap between chain stays and tire. I brazed a mount onto the frame for front mount. I shall put drive sprocket on and see what I can see
 

4you2eat

Member
Oct 27, 2012
101
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Spring Texas
Here are some pics of what I shall have to deal with. I installed a rag joint sprocket and the chain is rubbing the tire and the frame. I'm thinking a Piratecycles sprocket adapter will push the chain away from the tire and some bending on the chainstay arms along with tensioner / idler sprockets will give me chainstay clearance and if I put washers / shims on the drive sprocket side of the axle stud between the dropout and the sprocket to spread the chainstays. I see I caused the issue by brazing the dropouts centered on the chainstay tubes. I should have placed them inside the chainstay tubes. Ohh well, live and learn or die stupid.


Yes, I still have some grinding to do on the chainstays where I brazed extensions. I did insert some 3" long steel rods inside the joints for strength. I shall also do some gusseting and add some support on the rear end so a catastophic failure shall not happen. the setup is asking for failure if not properly suppported.

pic above - Top view w/ chain on top of sprocket. 415 chain rubs both the tire and chainstays closer to seat post

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pic above - Top view w/ chain on bottom of sprocket chain rubs tire and lower chainstay arm.

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pic above - Chain rubs against tire view w/ chain on top of sprocket. Chain is above chainstay arm but it does rub chainsaty arm closer to seatpost.
 
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2door

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Sep 15, 2008
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Littleton, Colorado
Hindsight is always 20/20. It would have really simplified things had you designed the extended chain stays around the chain instead of the other way around.

How about a longer axle and spreading the frame? You only need a little clearance as long as the chain tension is good. Just a thought.
I never want the tensioner to pull/giude the chain off track. The chain should be a straight line between the sprockets for best performance of a roller chain and to reduce the possibility of derailing it.
Although the sprocket adapter is a good product, it's not going to change your clearance problem.

Tom
 

4you2eat

Member
Oct 27, 2012
101
12
18
Spring Texas
Hindsight is always 20/20. It would have really simplified things had you designed the extended chain stays around the chain instead of the other way around...How about a longer axle and spreading the frame? ............Although the sprocket adapter is a good product, it's not going to change your clearance problem.

Tom
I'm impulsive sometime..leap, then look. I copied the mounting of the dropouts to original placement on the bike before mods. The extensions made it worse. Looking back I should have mounted motor, drive sprocket, checked chain alignment then added extensions building w/ all that in mind.

I shall try and spread the frame a bit, might not need a new axle, might just be able to use existing. I have a little room to play w/ on existing axle, but it is an option to go w/ longer axle and some washers will space things out. I'm thinking the sprocket adapter will allow me to pull chain away from tire some as it has more leeway as it can allow sprocket to move away from hub more than rag joint. Im looking for mebbe .250" . I think that will not mess up alignment from engine sprocket to drive sprocket.. Thanxx for the input
 
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4you2eat

Member
Oct 27, 2012
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Spring Texas
I got out the car jack and spread out the frame enough to allow room for chain to clear frame.. Now just need to cure tire rub issue. Now onto building solo seat w mountain bike shock and custom seat pan.



 
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2door

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Sep 15, 2008
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Good work. As far as spacing the sprocket on the rag joint, I've seen some guys add a few washers but I don't like that idea. A full face spacer would be better. You could make one from an old, smaller sprocket. Grind off the teeth if they interfer with your chain and current sprocket. Just a thought.

Tom
 

2door

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Sep 15, 2008
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It will be interesting to hear how the suspended seat works out for you. It's a very unique and innovative idea. Have you given any thought to fabricating a custom seat pan with foam padding and upholstery? Something akin to a banana seat shape?
Keep us informed.

Tom
 

4you2eat

Member
Oct 27, 2012
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Spring Texas
Im looking at it now and I see I need to redo the front pivot. I made it w a 1/4 pipe nipple and I think it might be prone to failure. Im afraid to hang my junk on it without some additional stuff. I have already brazed a stub of seatpost on the bar. I decided against a pan seat or banana cuz I just grabbed what I had on hand. Mebbe next build
 
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4you2eat

Member
Oct 27, 2012
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Spring Texas
One more pic still sorting out. I shall add a piece from the chainstays to the seat tube to strengthen up the rear end. Just took it for a pedal drive. Might work. The seat is comfy. Need to figger out what happens when shock bottoms out to make sure I have clearances and safety. Might keep the seat setup as is, need to burn grey matter and figger it out.

 
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2door

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Sep 15, 2008
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That is a long 'moment arm' to support. The stress is going to be on your brazed areas.
If you're confident about them you might consider some 'bridging' between the two trailing arms. That would stiffen them considerably but it won't take the stress off of the brazed joints. What material are the extensions made from?

Tom
 

4you2eat

Member
Oct 27, 2012
101
12
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Spring Texas
The extenstions are gas pipes. Nice and thick. I sleeved the joints 3" inside the connections for strength using some all thread. I ground off the threads to fit inside the gas pipe and chamfered the mating surfaces of the 2 pipes, err tubes were joined. I'm sure I got a good join where the brazing worked into both tubes and the sleeve. Im planning on adding an arm from the chainstay arms to the seat post just behind the brazed joint. The shock's lower mount is connected to a U shaped piece that wraps from R side chainstay to Rside seatstay and "bridges" across to L side seatstay to Lside chainstay as it were.
 
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4you2eat

Member
Oct 27, 2012
101
12
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Spring Texas
She lives !!! almost there. i was going to go for a ride today and the seat bar bent / broke. Good thing I was just rolling it as at 30mph, it would have been catastophic. pics coming. Must engineer the seat / shock setup more. now I'm thinking of mebbe a banana seat or tractor seat setup. I have it painted to a finished level... but a little more work 2 do
 

4you2eat

Member
Oct 27, 2012
101
12
18
Spring Texas
Ok getting close. I'm now left w/ the seat covering, fenders?, some ignition wiring cleanup w/ shrink tubing and touchups. This has been a tough project but well worth it. I just rode it and she rides fine. I had to redo the seat / shock arrangement because it had a major failure. The shock was angled forward and the pivot bar bent because of the seat post being behind the shock. The shock fell forward and the seat buckled behind the shock hitting the tire. The bar bent upwards. Luckily I was only scooting it down the driveway when it happened. If it was going 20mph, I might have been converted into a eunuch. The fix was to angle the shock backwards some and place my fat butt forward of the shock making the shock travel just a bit forward as it compressed, keeping the shock angled back enough to keep it from tipping frontwards if it bottoms out. It seems stiffer now.

I used Krylon High Temp radiator paint topped w/ VHT clear Hi-Temp sprayed well away to give it a powder-coated look for the finish. The Krylon paint has worked well on my Nirve B-1 build and looks tough enough to last.


Not bad for a $220 bike and $150 motor kit, $50 for the tank sealer, $80 for the sprocket adapter LOTS of welding and some found pieces. I guess I have $500+ into the bike and I hope to sell it for some good profit. Let's see what happens. I did go through 2 chains getting the chain to ride right without coming off. The bearing was loose in the rear wheel allowing the wheel to wobble some and the rag joint sprocket had some runout which made the chain come off too. I fixed that w/ the chain tensioners, adjusting the bearing and the hub / sprocket adapter.









 
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4you2eat

Member
Oct 27, 2012
101
12
18
Spring Texas
Detail of chain tensioner. A flat washer brazed onto a threaded rod and a simple bracket w/ a hole for adjustment. I'm thinking of adding this to all my future builds.





Now for the seat, Im thinking of a dark leather seat or red or black or red & black. Hmmmmm, mebbe red tires too ? Paint the motor black too ??

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