Lurker's V-twin build

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cobrafreak

New Member
Feb 16, 2011
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sacramento ca
For the Frame I used my buddies Miller mig welder because the tubing is too thick for my little Harbor Freight welder to penetrate well enough. I will be using the HF welder for the tank and other things on the bike. One of the major jobs I have been procrastinating on is cleaning up the welds.

I only have a rear drum brake at the moment but I will add a front drum if necessary. I really want to keep this as authentic as I can but I think I will have to make some sacrifices pretty soon.
If you spray anti-splatter on the steel before you weld it really aids in the clean -up. The splatter is almost non existent.
 

Lurker

New Member
Jan 29, 2010
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Pittsburgh
I'm starting to think about what I am going to do for the exhaust and while walking through the hardware store I found this little gem. It is a reducer for gas pipe that goes from about 1 inch to 1 1/4 inch with a tight radius 90 degree bend. The tight bend will keep the width of the bike down and the cast look will help with the vintage look of the engine.
 

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harry76

Well-Known Member
Apr 16, 2011
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Brisbane, Australia
I concur. The tires are a joy to mount on Worksman rims but a total Devil to put on bike rims, at least the bike rims I used to run. They were so tight that I broke a whole set of bicycle tire irons. They just snapped in half. I had to go with steel motorcycle irons. But with the Worksman rims I almost don't need them at all. I really appreciate these Simplex tires. They wear so well and the with the fear of a blowout of a bicycle tire gone, they are worth their weight in gold. Good Job on the bike Lurker. I'm digging it.
I regularly break the cheaper bicycle tyre levers when using Maxxis Hookworm tyres with downhill rims, because the sidewall is so much stiffer or maybe it has a wire bead??????
 

Lurker

New Member
Jan 29, 2010
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Pittsburgh
Thanks for the tip cobra, where can I get some of that stuff?

taylorv those pieces are steel, I know better than to weld galvanized. But thanks for the concern.
 

IreBo

New Member
Jul 22, 2011
156
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Monterey,CA
I think this is the largest displacement on this site. Topspeed might be close to 100 mph
I really like the vintage style you are trying to stick with!!


Yea 100 mph may be a bit of a stretch!!! the motor isnt spinning at 17000rpm is it?? i dont think so. gears....no.....granted it has gobs of torque but not 100 mph worth...imo! ill guess at 65 to 73mph... but am going to lean tward higher 60's... cause the rotating mass is alot!
 

Mr.B.

Well-Known Member
Oct 21, 2008
1,329
559
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Upper Mississippi River valley
I'm starting to think about what I am going to do for the exhaust and while walking through the hardware store I found this little gem. It is a reducer for gas pipe that goes from about 1 inch to 1 1/4 inch with a tight radius 90 degree bend. The tight bend will keep the width of the bike down and the cast look will help with the vintage look of the engine.
I’ve been planning on using one of those for carb intake.

TaylorV, it’s a black gas pipe fitting, check your favorite hardware store.
 

taylorv817

New Member
Nov 30, 2011
19
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arlington, tx
I really like the vintage style you are trying to stick with!!


Yea 100 mph may be a bit of a stretch!!! the motor isnt spinning at 17000rpm is it?? i dont think so. gears....no.....granted it has gobs of torque but not 100 mph worth...imo! ill guess at 65 to 73mph... but am going to lean tward higher 60's... cause the rotating mass is alot!
Let me remind u he has a 630cc not 110cc. if he plays around with sprocket size he can reach close to 100 mph considering how much hp he has.
 

harry76

Well-Known Member
Apr 16, 2011
2,557
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Brisbane, Australia
I think he can hit 200mph if he closely trails semi-trailers to block the wind and injects his legs with roids so he can get the extremely highly geared bike off the line
 

IreBo

New Member
Jul 22, 2011
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Monterey,CA
Let me remind u he has a 630cc not 110cc. if he plays around with sprocket size he can reach close to 100 mph considering how much hp he has.
ok well im still sticking with my gut! the hp is nice but the rpm's still wont be too high, and what, is he going to the salt flats to run a 4 mile stretch and finally get to 100 mph? if its geared so high it seems it will take forever to get up to speed... and on a track like the short honda track it will be burning the clutch through the turns?? i dont have a boardie with a 600cc 4 stroke but seems like that may need a infanite v planetary gearbox...
 

harry76

Well-Known Member
Apr 16, 2011
2,557
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Brisbane, Australia
ok well im still sticking with my gut! the hp is nice but the rpm's still wont be too high, and what, is he going to the salt flats to run a 4 mile stretch and finally get to 100 mph? if its geared so high it seems it will take forever to get up to speed... and on a track like the short honda track it will be burning the clutch through the turns?? i dont have a boardie with a 600cc 4 stroke but seems like that may need a infanite v planetary gearbox...
I don't doubt lurker could get this going 100mph if he really wanted. I believe he got his last bike to 65mph..... I don't think top speed is his goal however.

I think a trip to the salt flats would be a great idea? How about it lurker? You could be the modern day motorized bike Burt Munroe, he built machines in his shed while you build them in your kitchen :)
 

Lurker

New Member
Jan 29, 2010
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Pittsburgh
A trip to the slat flats! I would love that.
Seriously tho, harry is right the last bike I made did upwards of 60mph and that was just a little 200cc with a 3600rpm limit. Any thing is possible with the proper gearing, and I highly doubt that the real btr did 100mph on there first lap. I'm sure it took at least 3-4 laps to reach top speed. Have you seen some of the old videos? Some of them had to have another street motorcycle to get them going because they were geared so high.

I was talking to a guy who put a 18hp Vanguard in a Cushman scooter and he said his top speed was about 70. Now that is with a 10inch tall rear tire and a 50-60t rear sprocket with a comet 44 cvt. So if he can do that, I don't see why I wouldn't be close to 100mph with a 27inch tire and a 38t sprocket.

But in a reality will I ever do 100mph on this bike? I doubt it, but I want the bike to have the spirit and feel of the real deal.

p.s. Burt Monroe was a rad dude!
 

curtisfox

Well-Known Member
Dec 29, 2008
6,077
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minesota
I am realy love this build totaly AWESOME. I takes a little backbone to do something like this. Thats what Burt had. But to go a 100 mph its just to high for that needs to be built lower. Sure would be fun to go to the flats and try...............Curt
 

cobrafreak

New Member
Feb 16, 2011
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sacramento ca
A lot of the old board tracks were two mile ovals. I thought this was ridiculously long but it makes sense. By the end of the first lap they were probably at top speed. I was looking at the gearing on an old BT bike and the rear sprocket was tiny. Probably 20-25 teeth and the jack shaft gear on the other end of the chain was the same size. Engine pulley was typical small and the reduction gear was around 30-35 teeth. These things were only made for triple digit speeds for sure. It would be an exciting sport to watch. No wonder it was popular. No wonder it was deadly too. Can you imagine getting a blow out and sliding on the wood only to get 8 inch splinters in your flesh? Yikes! A sport made up of ex solders from WWi that got hooked on the adrenaline rush of combat and needed to do something to get a fix.
 

Ibedayank

New Member
Oct 29, 2011
1,171
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Columbia Tennessee
I'm starting to think about what I am going to do for the exhaust and while walking through the hardware store I found this little gem. It is a reducer for gas pipe that goes from about 1 inch to 1 1/4 inch with a tight radius 90 degree bend. The tight bend will keep the width of the bike down and the cast look will help with the vintage look of the engine.
might as well just slap a restrictor plate on it as well...... NEVER use a tight 90 on intake or exaust chokes the life right out of it that why you dont see them used on headers