Author Topic: 66 Bonneville  (Read 288 times)

Offline Oggers

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66 Bonneville
« on: September 11, 2018, 10:49:29 AM »
Chaps

New to this forum so please be gentle.... I am fortunate enough to have acquired a 66 Bonneville and would very much appreciate the advice of those who know better on a few points outlined below.

The bike has been fitted with a T140 head. Is this a retrograde step or is it advantageous in some way? Larger valves perhaps?

PCC has the breather tube fitted. I understand these were not fitted until 1970 - could this therefore be a retrofit? Engine/frame number is 400025 - which is a 66.

Gearbox is somewhat "crunchy" but then the bike has only done 500 miles since a full rebuild of the engine and box. Is it worth changing the gearbox oil, and adjusting the clutch rod end via the PCC. Any other tips to achieve a smoother change appreciated.

Carbs. are Amal concentrics - should be monoblocs I think for a 66. Again is this a big deal?

Very many thanks

Mark



   
« Last Edit: September 11, 2018, 10:51:47 AM by Oggers »

Offline mini-me

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Re: 66 Bonneville
« Reply #1 on: September 11, 2018, 02:40:24 PM »
Your bike will behave best as Triumph made it; I have no experience of T140 isn't that a 750?, in which case it will be pointless.
Just larger valves will do NOTHING for your performance.
Don't worry about the breather tube,if ts ben done properly there should be 3 x 1/16 holes behind the engine sprocket at about 5o/c.

Clutch cable adjustment need to be done correctly, see on a Triumph site 'cos I can't be asred to write it out right now.

Your crappy gear change will 99% be the pressure plate not lifting properly causing drag; when the engine is running with cover off and lever held in, the pressure plate should stop spinning. Adjust with the spring nuts to get an even lift.

Unless I knew the person who built the engine I'd never trust the rebuild; cruel but learnt from experience.


Carbs; I prefer monoblocs but it don't really matter. You can get new monoblocs from Burlen,Salisbury,don't expect then to hold your hand.

Took me 20mins to figure out what pcc was.

Good luck, a cracking bike when properly set up.

Offline Rex

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Re: 66 Bonneville
« Reply #2 on: September 11, 2018, 03:51:59 PM »
The original was a nine-stud head and the T140 was a ten-stud so someone's taken big boy's tools to it. Don't really know why anyone would do that. Set up properly the T120 from 1966-70 are cracking bikes and IMO one of the best Triumph ever made. As M-M says there's an Internet full of stuff re setting up Triumph clutches...it ain't hard.
Your engine number has one digit too many and no prefix...is that correct? Do the engine numbers have the "Triumph" stampings behind them?

Offline Oggers

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Re: 66 Bonneville
« Reply #3 on: September 11, 2018, 04:11:30 PM »
Quite right,  typo by me  - number is DU40025 which corresponds to 1966. No stampings - too early for those. The question about the head was more of a concern than an argument for increased power. I believe it was like that when the engine was rebuilt - meticulously rebuilt from what I read in the extensive report.

I'll check out if the pressure plate is still spinning when clutch is in through the cover in the PCC - thanks for that tip. I guess if it is spinning I adjust at the bars or at the rod threaded end c/w lock nut.

Rest of the bike appears spot on - Boyer, Devon rims, fresh pistons, new paint job etc. Handles very well, engine still a wee bit tight perhaps.

Only other issue is the rear brake rod is fully wound in - with the actuating lever at vertical, and about 6 inches of threaded rod protruding - which seems odd. Either shoes are well worn or the hub has been over-skimmed....thoughts welcome.       

Offline Rex

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Re: 66 Bonneville
« Reply #4 on: September 11, 2018, 07:01:32 PM »
Reason I said about the stampings was because I was wondering whether you had a T120 with a T140 engine over-stamped.
Excessively skimmed drum or worn out shoes?  Go for the obvious first...worn shoes.

Offline mini-me

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Re: 66 Bonneville
« Reply #5 on: September 11, 2018, 08:15:15 PM »
Quote
I'll check out if the pressure plate is still spinning when clutch is in through the cover in the PCC - thanks for that tip. I guess if it is spinning I adjust at the bars or at the rod threaded end c/w lock nut.

pay attention, as I said adjust the pressure plate  by the spring nuts; you will have to remove the cover, otherwise its pointless.

cable must be adjusted gearbox end first. read the manual.

As for the rear brake,all the other suggestions, but my cynical view inclines to a crap indian made replacement rear drum.

Offline john.k

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Re: 66 Bonneville
« Reply #6 on: September 12, 2018, 01:14:48 AM »
Will 750 cylinders fit a 66 crankcase.?..........cracking around the area between the cylinders was pretty common,IIRC.

Offline Grunt

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Re: 66 Bonneville
« Reply #7 on: September 12, 2018, 12:54:39 PM »
Whether 750 barrels will fit or not I donít know, going by local urban myths from the Ď70s the 750 T140V barrels will fit the 650 T120V crank cases though I never tried it. I do know that the 750 has an oil feed through the right hand side front flange to the exhaust tappet block. Without major work to the crank case the tappet block wouldnít get this extra oil. One check to see if they are 750 barrels is to look for this oilways blanking plug on the front right hand side of the barrel flange.

Offline Rex

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Re: 66 Bonneville
« Reply #8 on: September 12, 2018, 01:19:53 PM »
If it was relatively easy to up a 650 to a 750 then the old Morgo kits wouldn't have sold as many as they did. Don't know why they were so popular anyway as the 650 was a nicer engine than the 750.

Offline mini-me

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Re: 66 Bonneville
« Reply #9 on: September 12, 2018, 02:59:29 PM »
That oil feed was pre T140, from about 67/8 if I recall.

Offline Oggers

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Re: 66 Bonneville
« Reply #10 on: September 12, 2018, 03:16:17 PM »
Hmmmm....Forgive me for a supremely dim response, but is it feasible to fit a T140 head on a T120 barrel from a 66? Fairly sure I have a T140 head as I have the 2 siamesed rocker covers - Not sure what I now have for the barrel!


Offline Rex

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Re: 66 Bonneville
« Reply #11 on: September 12, 2018, 03:59:51 PM »
If you mean the two larger rocker covers (rather like BSA A10) then they were first used on the early 1970s OIF 650s.

Offline Grunt

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Re: 66 Bonneville
« Reply #12 on: September 12, 2018, 04:30:29 PM »
Quote
That oil feed was pre T140, from about 67/8 if I recall.
I donít remember it on my Ď72 T120V. But then just because I donít remember it, it doesnít necessarily mean that it wasnít there.

Quote
but is it feasible to fit a T140 head on a T120 barrel from a 66?
Fitting and fitting properly are two different things. As, I think some one has pointed out there will be too many holes in the T140 head, or not enough studs on the T120 barrels.
« Last Edit: September 12, 2018, 04:34:44 PM by Grunt »

Offline Oggers

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Re: 66 Bonneville
« Reply #13 on: September 12, 2018, 04:31:11 PM »
Well, all I can say is that I was told it was a T140 head....and from the rocker box covers, it looks like one.

Offline mini-me

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Re: 66 Bonneville
« Reply #14 on: September 12, 2018, 04:41:33 PM »
Quote
I donít remember it on my Ď72 T120V. But then just because I donít remember it, it doesnít necessarily mean that it wasnít there.

Give away is the square front RH corner on barrel flange that houses the dowel.


2nd give away is the oil leak where idiots have left out the dowel that feeds the oil through....

Others are correct about the first use of those oblong covers, never liked them, its not a Triumph if its got all four round ones left ;D

Only exhausts are siamesed;  thats an exhaust not a header or a muffler......... ::)