1971 Bonneville 2.0

Skip Newsom · 09:52 AM

Six years ago tomorrow my Son brought home this Triumph from his buddy's uncles place in Oregon.
The original motor had been pulled and placed in a Rickman frame and pressed into a life of Vintage off road racing, it's still there, doing that.

Arrival 5-23-15

She sat and waited for attention for a couple years. My son came across a '72 750 motor that we went and got, wrestled into the frame and got running for a glorious hour or so until it seized up- still not sure why, plenty of oil, timed correctly and working on carburetor adjustments when it quit.

750 motor going in

After that motor died, she sat a while longer until I came across a recently rebuilt 1966 650 motor... for $500 we couldn't pass it up, the brief rides with the 750 motor were very very fun. Even with one of the least favorite years of Triumph production ('71 was the intro of the oil in frame design, done by aeronautical engineers, should have stuck with the motorcycle chaps!) the handling and feel were wonderful in a 7/10s way.
Not so much a racer as a fun cruiser. With routes of there and back again on the same roads so you can pick up whatever shook off 1st time through.

Aaron came home from LA for Mother's day weekend this year (such a good guy!) and he managed to get the new repop OEM stye fenders fitted and drilled.

I dropped off the tank, side covers, chain guard and new fenders off to paint yesterday, so maybe it's really Bonnie 2.1 or something...

Bonnie striped of her furnishings:

While she's apart this time she gets a new wire harness as the OEM harness is very hacked up, a new solid state voltage regulator and switch her from Positive Earth to negative earth like the rest of the world did a while ago.
I do understand electrons don't care which way they flow, but the positive ground to negative ground system is an easy change and feels more normal, no more wiring the charger in a backwards way.

More details and photos to come...

asphaltgambler · 05-22-2021, 10:09 AM

Luv all that

fanaudical · fanaudical's Garage

Great project!

Bill Douglas · 05-22-2021, 08:29 PM

Congrat's. Great engineering skills.

Hehe, reminds me of my '66 I had when I was at school.

Skip Newsom · 05-22-2021, 08:30 PM

Thanks!
It's been a great father/son adventure. I've let him drive the project as time/inclination allow and that's a rewarding approach in many ways.
We have enjoyed the parade of motorcycles, (mostly Hondas) but this old bike with it's new rear shocks, long geared 4 speed transmission, wrong sided shifter/Brake arrangement is a joy to ride. Handling is predictable and pretty sublime considering it's age. Just don't push more than 7/10's and she's a peach.

Also makes me appreciate similar time frame German engineering much, much more.

Bill Douglas · 05-22-2021, 08:50 PM

Quote:

Originally Posted by Skip Newsom

Ha, a bike like this makes you pretty good at understanding autoelectrics.

Skip Newsom · 05-23-2021, 07:49 AM

The electrical has been a challenge for sure, dead ended wires, new/different wires.
The voltage and continuity tester was put to use again and again and...

Sure been a fun journey!

More from along the way:

Skip Newsom · 09:43 AM

Rectifier Axis of evil, Lucas version

Funky fiberglass fender was not nearly long enough to protect this area, resulting in the dreaded rear tire to wire chaffing when you land after jumps

New harness time, this needs sorting.

Takes two segments, main and "headlight" harnesseses

Solid state version

Lucas (POD) still sells new guts for the old switch, I went with a "universal" one for the time being

LakeCleElum · 05-23-2021, 09:37 AM

A lot of those motors seized due to oil lines being reversed during engine out service work. Might double check that?

Skip Newsom · 05-23-2021, 11:33 AM

Thanks!
Will do.
The 2nd motor is a '66 650 rebuilt locally by a reputable mechanic, she's got over 500 miles of running.

The 2nd engine install took half the time of the first and the 750 motor has a nice spot to hang out and wait for rebuilding.

'66

Also beefed up the frame guided by some peeps with much more experience, the OIF had some weak points show up over time

Seahawk · 05-23-2021, 11:46 AM

The pictures are great because they give a sense of perspective on the size of the bike.

Well done, Gents. Wonderful project.

Skip Newsom · 05-23-2021, 06:30 PM

One of Aaron's CV19 projects was a short movie of Bonnie 1.0.
I may have driven a video chase vehicle, and may have shot a small bit of the footage...

speeder · speeder's Garage

Nice work and as for the engine, any Unit Twin Triumph motor is pretty much the same as another with small differences over the years. I'm rebuilding my 1970 engine with a 750 kit, I should have some photos this week for my thread. I've been busy with life but this week should have progress.

The new wiring harness you are doing should be a great improvement, my bike got one when it was restored 20 years ago and it's still like new. I discovered a great YouTube channel for rebuilding my engine, it would be helpful for you if you rebuild the 750. Probably videos for other operations as well, these guys are super thorough and great videos:

There are several chapters adding up to many hours, this just happens to new the one I'm on now.

speeder · speeder's Garage

Just watched your video and it's great...that motor sounded fantastic...I'd be really curious as to what happened?

There are very few things in life more enjoyable than riding a good Triumph Bonneville from the golden age, IMO. It's like driving a 1970 Porsche 911S, just a sweet spot in time when engineers had no constraints other than maximum performance using old technology. Engineering over design but the design wasn't bad, either.

Skip Newsom · 07:37 AM

Thanks Denis for the video link!
I've found a few online that have helped along the way, one series featured a gent with serious fingernails that I'm sure could tighten slot head screws up to an impressive torque with. His accent is very thick, certainly knows what he's doing even if I can't always figure out what he's saying.

To clarify, the 750 motor did not run long enough to get much footage, the video was with the 650 engine.

I too am curious what killed the 750, it was sold as "running when removed" and the story was that a decade ago the owner of the 72 Bonneville pulled it, cut up the frame to make a chopper but then never built a frame.
It came with a couple boxes of parts and the frame head with the 72's original serial number stamped in.

With the 650 running well I am impressed with it's performance and some day the 750 may get rebuilt and shoved back in. Bonnie 3.0?

Boxes of goodies showed up regularly for a while, new seat, new Amal carbs, tires... and so on.

New rocker box oil line, some bending required

Previous owner cut off the center stand mount- I knew early on this will not do, same guy that welded up the frame stiffening bits fabricated new mounts and attached a center stand for us. I believe some of the concern for frame cracking was directed at how the center stand mounted so owners were just cutting em off.

I found these to be a helpful addition to my workbench

Rot 911 · 05-24-2021, 08:32 AM

I too own a 1971 Triumph . Mine is a Tiger 650. A bit of advice on your new carburetors. A number of people, including me, had trouble both starting and idling after installing the new Amals. Turns out a bit of manufacturing swarf can get caught in the pilot jet hole. They make a pilot jet drill bit for cleaning it out. You might want to do that before you install your carburetors.

Skip Newsom · 05-24-2021, 10:17 AM

Sweet Tiger!!
My Son and I both want this one to look much more like yours, one color instead of 4-5 with all the mods/tragedies shes gone through.

On the carbs- I bought these:
"Amal Premier 930 30mm Carburettor Set for Dual Carb T120 T140 A65L PN# 930Lp and 930Rp" and have over 500 miles on them with good results.

Although the right side does run richer than the left at the same settings...
I'll get that tool and some misc British bullet syle electrical connectors to wire up the LED lighting turn signals and Taillight.

Test fitment in MancaveShop

Skip Newsom · 08:07 AM

More headway.
Pulled all the old wiring except the handlebar switch and headlight harnesses, dissembled the coil/electrical mounting plate, straightened it, sanded and painted it.

Also pulled and refinished the battery box, ordered more rubber bits since the originals are changing shape after 50 years.

New harnesses patiently waiting

John Walker recently posted to Instagram that this is great stuff, giving it a go.
I trust JW!

New rubber bits to mount the tank after it comes back from the paint shop- the old ones had also reshaped themselves after several decades

Skip Newsom · 05-27-2021, 08:13 AM

Battery box area before

New harnesses provided with a helpful diagram and "trust Lucas" printed to give you hope?

Bill Douglas · 05-27-2021, 11:50 AM

Another great thing about these bikes is there are so many less bits to them.

While speaking of Triumphs, here's me as a 16 year high school kid old back in 1976 on my '66 Bonneville Saint.