Oldboy
Well-Known Member
This is my first attempt at a new thread, so I hope it goes well!
Why would someone build a full race Bonneville 750 long rod engine and stuff it in a chopper frame? Someone should've asked Rob (that's me)from Oldboyracing that very same question. But what's done is done(or may be done someday).
Well, it seemed like a good idea at the time, so I just did it. Sounds like a catchy phrase, but to me it has developed into a life plan.
The engine started out as a 1973 Triumph Bonneville 750 five speed, which was still attached to its original frame (gasp)! It was low miles, and ran good. But that wasn't good enough for the Oldboy. A master of disaster, Oldboy tore the 750 apart and scattered the pieces about his Bloomington Illinois based shop, known as the Auto Clinic. "I then bought an alloy 750 cylinder from a guy in the Hemming's motor news catalog (eBay for old people). He told me it was for a 750 Triumph, and you shouldn't question the validity of any statement made over the phone from several hundred miles away. When it arrived I promptly installed it on the engine, only to find out the pistons at TDC were about 1/2" too far down into the barrels. That probably calculated out to roughly 5:1 compression, not too impressive sounding on a build sheet. So I conspired with Dion Warner from Oreana Illinois to purchase a set of NOS JRC rods. Not sensible enough to quit while I was ahead, I then called in a favor from another friend, John Caplinger from nearby Towanda Illinois. I purchased an old drag bike engine core which I also dismantled and mixed all the parts together. For pistons I contacted Big D Cycle from the great Country of Texas. The core engine donated a set of Harman Collins cams, which the guys at British Only informed me the numbers on them were not in the Harmon Collins catalog. Added then was a Boyer Bransden ignition fired by an Accel Super Stock H/D coil. From the ashes I then constructed this engine which I cleverly named "750 Bonneville".
Since then I have ran into a couple speed bumps. The cylinder(a Dunstall 750) seized in storage and broke both liners. I have a Routt 800 kit for the 650 that I am installing on it until I find a set of liners large enough to run the Arias forged 800cc pistons, at which point I will probably sell the Routt cylinder with a set of Routt 800cc pistons I am planning to purchase.
The carbs are a matched set of 38mm Electrons from the Woodstock (Illinois) swap meet that were cleaned up and modified by Oldboy so that the fuel lines were both to the center of the engine, and mounted on Mikuni manifolds. I used 1-1/2" automotive fuel neck hose wrapped in decorative aluminum sheet removed from plumbing no-hubs. To mount the air cleaners required 3" radiator hose from a Cummins Diesel, courtesy of the local Cummins repair center, and more no hub covers.
"I used the filler neck hose because of an incident with a set of Mikuni carbs on the stock engine a couple years earlier. One of the rubber manifolds, although NOS, broke unexpectedly and I attempted to hold up the right carb while operating the throttle with my left hand. Not the best idea I ever had, as you can only imagine. I flipped the bike in a construction zone, but thanks to the circus blood in my family (my grandfather, Henry Robbins, was a catcher with the Ringling Bros and Barnum and Bailey circus. My grandmother, Rose Whitsell Robbins, rode bareback horses and elephants with the same circus), I stopped, dropped and rolled, ending up in a handstand facing traffic. Luckily the full size Buick wagon, of which I only saw the oil pan barreling at me, was piloted by another good friend, Joe Houchins (hope I got that right, it's been a lot of years Joe). He stopped and offered assistance, and we uprighted the bike with almost no discernible damage. Oldboy wasn't as lucky, as I received numerous bruises and road rash on my arms and knees. This was the day before my 34th birthday, so the pain reliever from the pre birthday party was still able to help with dulling my senses (and the rest of my brain as well)."
Now back to the build.
This is the primary side. The cool red plate, also from the donor drag bike motor, which I thought was made by MCM houses a sealed bearing in place of the output shaft seal, and supplies outboard shaft support. Not in the photos is a Tony Hayward alloy belt drive overstuffed with a Barnett alloy drive and driven clutch pack. Power is transferred by a 32mm wide, 10mm pitch drive belt. I will be running an open belt primary with a custom cut chrome cover I purchased on eBay. Also being installed on the new improved version is a Wassell 16 amp alternator kit. I am planning to use titanium alternator studs and rotor retaining nut, as well as titanium clutch studs, cylinder studs, and oil pump studs to hold down the Morgo oil pump.
Polished cases provide the glare to blind oncoming traffic. Those looking closely will notice that the case studs look odd. I drilled the holes to 13/64" and installed 3/8" case studs handmade from grade 8 threaded rod. Also in the photo are the JRC rods mentioned earlier
I built the frame from an unknown custom B*A chopper front section onto which I welded a Honda 450 hard tail so I could stretch the frame about 8 inches. I then created the unique rear fender by plasma cutting the edges off two trailer fenders and welding them to another fender, then cutting and welding sheet metal to the sides to strengthen it since it doesn't use a fender strut.
This is the finished (yeah right) frame. I will be taking it out further for the 21" over springer fork below
I am missing the top plate and rockers, but I have found a 2"-3" over fork for parts and am in the process of arranging the shipping from Washington state. Thanks to James Ialleggio for working with me on this purchase. This saves me fabricating the missing parts, which moves my estimated finish date to somewhere in mid 2060. Don't laugh too hard, my grandmother from the earlier part of this post died in 2016 at the age of 99! On the other hand, my grandfather died in 1959, a year before I was born. Toss of a coin.
If you made it this far and are still alive, I will end this post. But rest assured I will make a hearty attempt to bore the life out of you again by posting what I like to call a progress report, which to normal people means more pictures and inane babbling about my next batch of ideas on how to never complete a project bike.Thanks for listening.
Cheers from Illinois, the frozen bung hole of America! thanks
Oldboy
Why would someone build a full race Bonneville 750 long rod engine and stuff it in a chopper frame? Someone should've asked Rob (that's me)from Oldboyracing that very same question. But what's done is done(or may be done someday).
Well, it seemed like a good idea at the time, so I just did it. Sounds like a catchy phrase, but to me it has developed into a life plan.
The engine started out as a 1973 Triumph Bonneville 750 five speed, which was still attached to its original frame (gasp)! It was low miles, and ran good. But that wasn't good enough for the Oldboy. A master of disaster, Oldboy tore the 750 apart and scattered the pieces about his Bloomington Illinois based shop, known as the Auto Clinic. "I then bought an alloy 750 cylinder from a guy in the Hemming's motor news catalog (eBay for old people). He told me it was for a 750 Triumph, and you shouldn't question the validity of any statement made over the phone from several hundred miles away. When it arrived I promptly installed it on the engine, only to find out the pistons at TDC were about 1/2" too far down into the barrels. That probably calculated out to roughly 5:1 compression, not too impressive sounding on a build sheet. So I conspired with Dion Warner from Oreana Illinois to purchase a set of NOS JRC rods. Not sensible enough to quit while I was ahead, I then called in a favor from another friend, John Caplinger from nearby Towanda Illinois. I purchased an old drag bike engine core which I also dismantled and mixed all the parts together. For pistons I contacted Big D Cycle from the great Country of Texas. The core engine donated a set of Harman Collins cams, which the guys at British Only informed me the numbers on them were not in the Harmon Collins catalog. Added then was a Boyer Bransden ignition fired by an Accel Super Stock H/D coil. From the ashes I then constructed this engine which I cleverly named "750 Bonneville".
Since then I have ran into a couple speed bumps. The cylinder(a Dunstall 750) seized in storage and broke both liners. I have a Routt 800 kit for the 650 that I am installing on it until I find a set of liners large enough to run the Arias forged 800cc pistons, at which point I will probably sell the Routt cylinder with a set of Routt 800cc pistons I am planning to purchase.
The carbs are a matched set of 38mm Electrons from the Woodstock (Illinois) swap meet that were cleaned up and modified by Oldboy so that the fuel lines were both to the center of the engine, and mounted on Mikuni manifolds. I used 1-1/2" automotive fuel neck hose wrapped in decorative aluminum sheet removed from plumbing no-hubs. To mount the air cleaners required 3" radiator hose from a Cummins Diesel, courtesy of the local Cummins repair center, and more no hub covers.
"I used the filler neck hose because of an incident with a set of Mikuni carbs on the stock engine a couple years earlier. One of the rubber manifolds, although NOS, broke unexpectedly and I attempted to hold up the right carb while operating the throttle with my left hand. Not the best idea I ever had, as you can only imagine. I flipped the bike in a construction zone, but thanks to the circus blood in my family (my grandfather, Henry Robbins, was a catcher with the Ringling Bros and Barnum and Bailey circus. My grandmother, Rose Whitsell Robbins, rode bareback horses and elephants with the same circus), I stopped, dropped and rolled, ending up in a handstand facing traffic. Luckily the full size Buick wagon, of which I only saw the oil pan barreling at me, was piloted by another good friend, Joe Houchins (hope I got that right, it's been a lot of years Joe). He stopped and offered assistance, and we uprighted the bike with almost no discernible damage. Oldboy wasn't as lucky, as I received numerous bruises and road rash on my arms and knees. This was the day before my 34th birthday, so the pain reliever from the pre birthday party was still able to help with dulling my senses (and the rest of my brain as well)."
Now back to the build.
This is the primary side. The cool red plate, also from the donor drag bike motor, which I thought was made by MCM houses a sealed bearing in place of the output shaft seal, and supplies outboard shaft support. Not in the photos is a Tony Hayward alloy belt drive overstuffed with a Barnett alloy drive and driven clutch pack. Power is transferred by a 32mm wide, 10mm pitch drive belt. I will be running an open belt primary with a custom cut chrome cover I purchased on eBay. Also being installed on the new improved version is a Wassell 16 amp alternator kit. I am planning to use titanium alternator studs and rotor retaining nut, as well as titanium clutch studs, cylinder studs, and oil pump studs to hold down the Morgo oil pump.
Polished cases provide the glare to blind oncoming traffic. Those looking closely will notice that the case studs look odd. I drilled the holes to 13/64" and installed 3/8" case studs handmade from grade 8 threaded rod. Also in the photo are the JRC rods mentioned earlier
I built the frame from an unknown custom B*A chopper front section onto which I welded a Honda 450 hard tail so I could stretch the frame about 8 inches. I then created the unique rear fender by plasma cutting the edges off two trailer fenders and welding them to another fender, then cutting and welding sheet metal to the sides to strengthen it since it doesn't use a fender strut.
This is the finished (yeah right) frame. I will be taking it out further for the 21" over springer fork below
I am missing the top plate and rockers, but I have found a 2"-3" over fork for parts and am in the process of arranging the shipping from Washington state. Thanks to James Ialleggio for working with me on this purchase. This saves me fabricating the missing parts, which moves my estimated finish date to somewhere in mid 2060. Don't laugh too hard, my grandmother from the earlier part of this post died in 2016 at the age of 99! On the other hand, my grandfather died in 1959, a year before I was born. Toss of a coin.
If you made it this far and are still alive, I will end this post. But rest assured I will make a hearty attempt to bore the life out of you again by posting what I like to call a progress report, which to normal people means more pictures and inane babbling about my next batch of ideas on how to never complete a project bike.Thanks for listening.
Cheers from Illinois, the frozen bung hole of America! thanks
Oldboy
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