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Discussion Starter · #1 ·
I’ve been lurking around here for a few months after purchasing an unmolested, matching numbers 77 Bonnie. I enjoy taking old vintage bikes and bringing them back to life. This will be the first Triumph I have ever attempted and I’m wondering whether or not to go ahead with this project after reading here about how undesirable the OIF bikes are.

Are these OIF bikes just a ticking time bomb? So what do you guys think? Is it worth the trouble with this OIF machine or would I be wiser to find a Bonnie that doesn’t use the OIF method? -Steve
 

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Keep in mind that opinions are like belly-buttons. Everyone has one.

Here's mine. I have a '76 that I purchased last year and a '66 that I purchased last month.

It is my understanding that the early OIF bikes are not very desireable from a collector POV. But I also understand that the post-strike bikes, like yours are more desireable than the pre-strike OIF bikes.

The OIF bikes do not possess the lines and grace of the 60's bikes, but are still handsome. But I think most if not all will agree that the OIF bikes are more rigid, and hence a better handling bike. The later bikes have front disc brakes which although not equivalent to todays brakes, are better than mechanical drum brakes. That's always a consideration if you are going to ride the bike hard.

OIF engines have real valve covers that stay on instead of bottle caps. I've had at least two people tell me to keep a spare cap under the seat of my '66 or Locktite my caps because they fall off.

Although some may argue that the OIF was just a bad idea, I do not necessarily agree. It may have been executed poorly, but the idea is sound. Seat height is a complaint by many, but I have a 32 inseam and both my feet sit flat on the ground when astride my '76. My understanding is the early OIF seat heights were higher than mine.

I'd say it's your call. If you are doing this to turn a profit, that probably won't happen unless you do everything yourself and got it cheap. If you are doing this because you enjoy the process and it's a passion of yours, then any bike that puts a smile on your face is a good candidate.

Others with more experience on the details of the various model years may have better input regarding engine details, ignitions, carbs, exhaust ports, etc.

Regardless, when you are done and take the bike for a spin, you are going to get a lot of thumbs ups everywhere you go. And plan on having more than one casual conversation everytime you park it.
regards,
Rob
 

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Oh dear, what have you done . . . of course I'll do you a favour and take it off your hands.
;0
I've been riding one of these from new ( 30 years ) as my main transport; been rebuilt once after a long break, 30000 miles and apart from the odd nut falling off still going strong. Plenty of spares available, some sensible mods too, like boyer ignition, proper oil filters, etc like any old vehicle, needs a bit more TLC than a modern one, but I wouldn't get rid of mine for anything.
 

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In terms of overall function the OIF bikes were probably the best of the lot. Some traditionalists weren't happy with the appearance and oil capacity was a little down compared to the earlier bikes. If needed you can add extra capacity with an oil filter or cooler.

Stick with the bike and don't pay attention to the uninformed.

Bruce
 

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I remember when I bought my '76 new, the disk brakes were considered state of the art.
I was warned during orientation to use "one finger" on the brake levers or suffer the consequences.
If you've ever gone back to a drum braked vehicle after having disks, you'd be scared to ride it.

For that one feature alone I think the OIF is a good bike to have.

As far as the oil storage, I never gave it a second thought, but storing stuff in the frame is a novel idea.
My brother uses the downtube as a fuel tank and the swingarm for compressed air in his drag bikes (not Trumpets).

Investmentwise, the 70's bikes haven't caught up, but give them time. I think they'll come around when they get more scarce.
 

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Ohio-Rider - I have owned two OIF Triumphs, '72 Bonneville and '77 Tiger, and rode them many years. The motors, I understand, are improved over the pre OIF models, although I am not sure exactly in what regard.
I have met "purists" who said OIF's are all wrong and a hot oil tank burning your leg is the way to go. And I have met others, although fewer, who mock the unit construction models and enjoyed aligning the transmission. I wonder how'd they view my 2007 Bonneville, LOL!
The only OIF model of which I have ever heard any supportable criticism may be the 1971's.
There, some bugs needed to be worked out.
1977 Triumphs are pretty good machines!
 

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OIF's

I'm having my first experiences with Unit engine stuff. They seem not too different from the early 40's speed twins. same two pistons going up and down eh?

the early twins had an interesting crankshaft set up and babbit bearings so we've had some major improvements in terms of easy repairs since then, though finding someone to repair them in the 60's when I started riding them was no biggie, mainly what we did was swap to a later crank and the insert bearing rods.

the early 70's had some factory main bearing problems from the factory, a bit less oil storage, and a too tall frame. On the other hand that twin down tube frame is significantly stiffer than the earlier single front down tube frames, so not a bad trade off eh?

I rode no front brake rigids for years so having any front brake is a joy and the front disc is significantly better than the old drums usually. There is always the actual condition of your ride that determines much of that comparison.

So... any of the design problems are fixable including the height issue although NIB shorter rear shocks are rare on ebay. the engine is pretty much an easy rebuild if you're willing to learn the tricks to doing it and invest in the pulling tools to get it apart gently and that fixes any main bearing problems that were factory.

There are many good tips here in the blog archives that make a superb rebuild possible along with a good crew of experienced riders and builders so that's a plus.

I'd say it being an undervalued model lets a lot of us indulge in having one and if you enjoy riding it, well that about sums it up eh?
 

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Discussion Starter · #9 ·
Thanks everyone for the input. Glad to hear that the OIF units are nothing to fear. It will be a few weeks before I will have time to begin this project but now I am much more excited to get moving on it. They really are great looking motorcycles and should be quite an exciting rider. I'm sure to have plenty of questions for all of you along this journey. -Steve
 

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Discussion Starter · #11 ·
When I purchased this bike I wasn’t even looking for a new project but I just couldn’t let the previous/original owner chop it just for fun because he was bored this past winter. Can you imagine having a bike for thirty plus years and then deciding to chop it? There are plenty of Yamaha’s out there screaming to be chopped so why pick on a classic?
 

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why pick on a classic?
I agree. However, I have been lambasted in another section of the forum for looking for a donor to bob. In reality, I'm looking for a pre-unit powerplant, and not a whole bike. So if it's repairable and restorable, keep it original.
 

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As has already been said, you`ll be glad you`ve got a OIF unit construction bike, when you need to do any maintenance.
I hear the forks on the pre-units, are a good game.:)
 

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Well You Are Ready Have The Bike So Might As Well Enjoy It!

If Your Worried About The Frame Do What I Do And Use Newer 750, 5 Speed Motor And Put In Pre Oif( Older Frame).
 

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Discussion Starter · #15 ·
It's not the soundness of the frame I am concerned about as so much as the seemingly inability to clean 30+ yrs of gunk from the oil tank. I would hate to spend time and money on preserving something just to have a chunck of something come loose in that oil tank and possibibly destory all my efforts.

Hey RICHO, Nothing wrong with bobbers. I've had several bikes which began life as a bobber. I'm the kind of guy who likes to ride em as soon as I got the wheels and an engine. Then bolt the parts back on as I find them. Theres lots of ways to skin a cat so they say.
 

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cleaning is easy, you can use chemicals (i wouldn't) they can destroy more than help. i use plan old hot water or take to local cleaner shop and have them soak frame in boiling water for hour or two and presto your done
 

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Discussion Starter · #17 ·
Thanks for that Stewdog68. I obviously misunderstood the topic of another thread I remember following here awhile back. I’m sure glad to have found such a friendly place as this to find this kind of stuff out.

By the way. Here’s a photo of the bike I’m talking about. I think it is pretty much all there. Of course the seat has been trimmed, mufflers trimmed, Honda rear axle adjusters, and of course those knee pads don’t belong on a 77 either. My half hearted attempts to get it started have resulted in the kicker arm locking up. Oh.. and the clutches are frozen as well. This is going to be a fun one. –Steve


 

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Discussion Starter · #20 ·
Thanks David, Sprucing up is a good description of my plans for this bike. Hopefully it runs as well as previous owner says it does, but I have yet to hear it cough.

Stewdog.... Hey man we're like neighbors. I'm just east of Warren. Thats the kind of ride I'm looking forward to with this Bonnie. First ones on me. :D
 
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