1967/1969 Bonnie Rebuild Desert Sled Project

[speedrattle]

if youve got 0.060-over pistons at 77.5mm, then the original was 76, and so you would have had the standard routt kit at 745cc. to get 800cc, you would need a bore diameter of 79mm. the pistons are 0.060 over and are higher compression, so the cylinders may have been worn out twice before the last rebor, or they may be newer and the rebore just corrected some earlier damage.

here's some information on the original routt kits. there are several other manufacturers making routt-type kits.

https://burtonbikebits.net/big-bore-kits/
youve got options now. im thinking your cylinders probably cant be re-bored, even if 0.080-over pistons are available. so you can go back to a stock 649cc motor with stock size barrels and pistons, or do another big bore. heres some in the states

https://www.thebonnevilleshop.com/p...-routt-type-big-bore-kit-1963-72-pn-tbs-0150/
ive run a morgo for many years. an excellent product

https://www.morgo.co.uk/product/750cc-big-bore-complete-kit/
lots of ways to go

 

[Sundance]

if youve got 0.060-over pistons at 77.5mm, then the original was 76, and so you would have had the standard routt kit at 745cc. to get 800cc, you would need a bore diameter of 79mm. the pistons are 0.060 over and are higher compression, so the cylinders may have been worn out twice before the last rebor, or they may be newer and the rebore just corrected some earlier damage.

here's some information on the original routt kits. there are several other manufacturers making routt-type kits.

https://burtonbikebits.net/big-bore-kits/
youve got options now. im thinking your cylinders probably cant be re-bored, even if 0.080-over pistons are available. so you can go back to a stock 649cc motor with stock size barrels and pistons, or do another big bore. heres some in the states

https://www.thebonnevilleshop.com/p...-routt-type-big-bore-kit-1963-72-pn-tbs-0150/
ive run a morgo for many years. an excellent product

https://www.morgo.co.uk/product/750cc-big-bore-complete-kit/
lots of ways to go

OK, thanks for this info. I have heard with the big bore kits there can be some problems with overheating - perhaps that is what happened to this bike. If I am going to need an entire top end I will probably go back to stock. Thanks for the links to some kits for this. I suppose I'd better get the rest of the internals out first, like the rods and crank to make sure they will be serviceable or not, before I make any purchases. Cheers.

 

[speedrattle]

well, youre better off for lstening to the knowledge available here, because you can figure out what you want to be doing with some basic information that used not be available. theres shi tloads of experience on this forum that in the past you might have had to do without.

in my opinion, the best thing you can do to a 650 triumph is make it into a 750 triumph, as your routt installer thought back whenever he put that kit into your motor.. i think the long rod motors are better at 750 than the short rod motors, but i am prejudiced,

look at costs, and run the numbers. a new set of jugs for a 650 in america will run you $400, if you buy a new aerco casting, and then you need pistons and rings. a morgo 750 kit is comparable in cost, and its a bolt-on replacement, and you don't need to mess with balance. in my experience. you can buy used jugs and start out at 0.040 over, but you may start out with other problems.

the 750 kit will give you more additional low and midrange. not top end, unless you mess with the head. if you mess with ports and cams and valves someday, the morgo will not be left behind. i have run one in my T120 for over 30 years on th eoriginal rings, and it still pulls 150/155 psi and 117 mph.

the overheating issue is hisorically due to people just not paying attention to what they install. you already know better than that, and following the advice of people already on this thread will keep you out of trouble. back in the old days we had no support network. that has changed, and life is easier.

on the other hand, theres nothing wrong with the stock 650 long-rod motor. i like them a lot, and i race one that goes like stink and am building another. theyre traditional, and they work very well.

the money is more or less a wash. do some reading, and see which direction you want to go, you can't go wrong, because whichever you choose is a winning pathway. just give it some thought.

 

[Sundance]

well, youre better off for lstening to the knowledge available here, because you can figure out what you want to be doing with some basic information that used not be available. theres shi tloads of experience on this forum that in the past you might have had to do without.

in my opinion, the best thing you can do to a 650 triumph is make it into a 750 triumph, as your routt installer thought back whenever he put that kit into your motor.. i think the long rod motors are better at 750 than the short rod motors, but i am prejudiced,

look at costs, and run the numbers. a new set of jugs for a 650 in america will run you $400, if you buy a new aerco casting, and then you need pistons and rings. a morgo 750 kit is comparable in cost, and its a bolt-on replacement, and you don't need to mess with balance. in my experience. you can buy used jugs and start out at 0.040 over, but you may start out with other problems.

the 750 kit will give you more additional low and midrange. not top end, unless you mess with the head. if you mess with ports and cams and valves someday, the morgo will not be left behind. i have run one in my T120 for over 30 years on th eoriginal rings, and it still pulls 150/155 psi and 117 mph.

the overheating issue is hisorically due to people just not paying attention to what they install. you already know better than that, and following the advice of people already on this thread will keep you out of trouble. back in the old days we had no support network. that has changed, and life is easier.

on the other hand, theres nothing wrong with the stock 650 long-rod motor. i like them a lot, and i race one that goes like stink and am building another. theyre traditional, and they work very well.

the money is more or less a wash. do some reading, and see which direction you want to go, you can't go wrong, because whichever you choose is a winning pathway. just give it some thought.

So . . . I've been looking at a lot of the kits. I think I'll go with a new one rather than something used since I have so little experience and I'd like to avoid pitfalls of which I know nothing. I get the idea that this motor is fine at 750 and much better too. I've looked at some of the more expensive kits, like the Alloy Billet kits from MAP, which run around $1700 and have some extra items. I've also looked at the Morgo kits, and apart from finding something else it seems like the best way to go and there are some good reports on these on this and other forums. I will need to get the rest of the motor apart to assess the rods, crank, etc., in case I will be needing to replace some of these other substantial items. I'm sure as I go ahead I will be making good use of this forum and the advice from you and others. When I started this it was my idea that I wanted to do as much as I could do on my own. So I am thinking of the heads and valves and such - and if tackling a rebuild of the heads is something that I can do on my own. Thanks again!

 

[speedrattle]

i love the morgos, and wouldn't do anything else if i wanted a 750. i have a trackbike that i might buy another one for that im building right now.

but on your stuff, post lots of pictures as you go.

i am a believer in letting specialists i trust do specialist work, so i do no headwork myself. but thats because i have a very competent machinist close by. basic head work is within your reach, if you get a few special tools and take your time in measuring and doing the work.

much of the rest of the motor is accessible with simple measuring tools. you don't need crank journal micrometers if you buy plastigauge. you don't bore gauges if you have feeler gauges and advice on using them.

some things you will farm out, and be better off for doing so. but every bit of the disassembly, inspection, and reassembly is within your reach.

 

[Sundance]

i love the morgos, and wouldn't do anything else if i wanted a 750. i have a trackbike that i might buy another one for that im building right now.

but on your stuff, post lots of pictures as you go.

i am a believer in letting specialists i trust do specialist work, so i do no headwork myself. but thats because i have a very competent machinist close by. basic head work is within your reach, if you get a few special tools and take your time in measuring and doing the work.

much of the rest of the motor is accessible with simple measuring tools. you don't need crank journal micrometers if you buy plastigauge. you don't bore gauges if you have feeler gauges and advice on using them.

some things you will farm out, and be better off for doing so. but every bit of the disassembly, inspection, and reassembly is within your reach.

I appreciate this advice. I was thinking I might try fitting valves, etc., but now am thinking I may want this done by a "professional." Perhaps I can do the rest myself, like fitting the new bearings and bushings as needed. I'd like to have a good understanding of how the bike operates when I'm done. By the way do you have any suggestion on where to purchase a Margo kit, or is there only one vendor for this? Thanks.

 

[speedrattle]

i bought mine from MAP, back when they were the sole US distributors.

looks like sealy cycles in texas is a distributor now. maybe not.

send an email to morgo in britain, too. or burton bike bits, also in britain. they may be cheaper to buy from directly.

 

[Sundance]

i bought mine from MAP, back when they were the sole US distributors.

looks like sealy cycles in texas is a distributor now. maybe not.

send an email to morgo in britain, too. or burton bike bits, also in britain. they may be cheaper to buy from directly.

OK. I looked on line and saw the morgo kit from sealy cycles (Unit - Nine (9) Stud MORGO 750cc Big Bore Kit. | sealycycleservice) costing $999.95 and what looks like the same kit from burton bike bits ( Morgo 750cc Big Bore Kit Triumph T120/TR6/6T 650cc) for 402 pounds or $550, as well as directly from Morgo for 327 pounds or $448. I suppose shipping would add at least $100 or so. It seems like quite a mark up for sealy if this is the same kit. I will have to contact Morgo directly.

 

[speedrattle]

on picking out a machine shop, do some asking around. the old british stuff has peculiarities that some modern engine shops arent aware of. if possible, get a recommendation from someone in your area. i found my machinist by going to the local harley shop and asking who did their head work. turns out he was superb, fixing anything from gravely tillers to 800 horsepower mudtrucks to flathead harleys and so on. ive had him do cylinder work, valve seats and springs, weird one-off tasks, and he's been a gem.

a bit of research here will be fruitful

 

[Sundance]

on picking out a machine shop, do some asking around. the old british stuff has peculiarities that some modern engine shops arent aware of. if possible, get a recommendation from someone in your area. i found my machinist by going to the local harley shop and asking who did their head work. turns out he was superb, fixing anything from gravely tillers to 800 horsepower mudtrucks to flathead harleys and so on. ive had him do cylinder work, valve seats and springs, weird one-off tasks, and he's been a gem.

a bit of research here will be fruitful

Good idea. I've a friend I can check with who had a 1957 bonneville restored. However I think he has a long waitlist. Have you ever sent items away for rebuilding like using fagengine.com in California? Thanks

 

[speedrattle]

dan at fagengine has an excellent reputation. ive not had him do work for me but i buy parts from him regularly. he's super busy now and usually cant answer the telephone, but if you can get him to do the work it will be first rate.

there is another first-rate shop in asheville north carolina-- rob hall of halls custom vintage. he's done a head for me and for two or three other people running high performance motors. his stuff is excellent. definitiely worth a telephone call.

https://www.facebook.com/pages/category/Motorcycle-Repair-Shop/Halls-Custom-Vintage-304306866256343/
theres also keith martin at Big D in dallas. lots of history there.

https://www.facebook.com/bigdcycle/
these are just three. there are other shops with competent people here and there, but we're running dinosaurs and so any specialized knowledge is getting spread pretty thin. im lucky to have such a good shop near me.

 

[Sundance]

dan at fagengine has an excellent reputation. ive not had him do work for me but i buy parts from him regularly. he's super busy now and usually cant answer the telephone, but if you can get him to do the work it will be first rate.

there is another first-rate shop in asheville north carolina-- rob hall of halls custom vintage. he's done a head for me and for two or three other people running high performance motors. his stuff is excellent. definitiely worth a telephone call.

https://www.facebook.com/pages/category/Motorcycle-Repair-Shop/Halls-Custom-Vintage-304306866256343/
theres also keith martin at Big D in dallas. lots of history there.

https://www.facebook.com/bigdcycle/
these are just three. there are other shops with competent people here and there, but we're running dinosaurs and so any specialized knowledge is getting spread pretty thin. im lucky to have such a good shop near me.

OK, thanks. I often get down near Asheville since my wife’s mom lives nearby in TN. I’m up in the Washington DC area. I thank you for the references and will start by making a few phone calls. By the way, have you ever replaced valve guides, honed them and fit new valves yourself? I imagine so. I’m just wondering if it is something that can be easily screwed up. I’m not making a race engine, but one that I’d like to be durable. Thanks.

 

[speedrattle]

no, i take my cylinder heads to my machinist. he has tools and equipment i dont have and lots more experience.

but its not hard and people do it at home all the time. pull the guides in and out rather than hammering them, if you have the tools. if the wear is substantial you will have to recut the seats and you want to remove as little as you can. some people get by just lapping the valves. measuring the valve guide clearances can be tricky. and yes, its something that can be screwed up if you have poor tools or little experience.

im a believer in taking advsntage of other peoples skills and experience whrn i can. i do all my own work except the actual machining and flow bench. for me its a good balance, as i cant be an expert at everything

 

[Sundance]

no, i take my cylinder heads to my machinist. he has tools and equipment i dont have and lots more experience.

but its not hard and people do it at home all the time. pull the guides in and out rather than hammering them, if you have the tools. if the wear is substantial you will have to recut the seats and you want to remove as little as you can. some people get by just lapping the valves. measuring the valve guide clearances can be tricky. and yes, its something that can be screwed up if you have poor tools or little experience.

im a believer in taking advsntage of other peoples skills and experience whrn i can. i do all my own work except the actual machining and flow bench. for me its a good balance, as i cant be an expert at everything

Thanks. Good advice for me right now. I think I’ll find an expert for this more critical stuff. And I’m barely an expert at anything. Cheers.

 

[Sundance]

So I made some progress on my engine tear down on the primary side. I got stopped when I tried to take the rotor off the crankshaft. I don’t have a 2-jaw puller and it did not come off on its own - so I’ll have to get the 2-jaw puller soon to get the primary chain off. I found some parts of very tiny springs in the oily bottom of the primary case. I’m wondering if any of you might know what these could be and what kinds of problems this might indicate with the engine? Thanks.

 

[speedrattle]

often the rotor can be gently pushed off the crank by sticking two large smooth screwdrivers behind it and prying alternately against the sprocket

dont take the gearbox apart until you undo the clutch nut. you can hold the mainshaft still by wrapping an old chain around the gearbox sprocket and clampng on a pair of vise grips

 

[Sundance]

often the rotor can be gently pushed off the crank by sticking two large blunt screwdtrvers behind it and prying alternate sides against the sprocket

Thanks for the tip. I will give this a try, gently that is. Perhaps I will need a puller later on in the rebuild?

 

[grandpaul]

I can't think of what that spring could have come from, don't thing it's within the original parts specs.

Use a 3-jaw puller on the rotor, SNUG it up tight, then rap the center bolt on the puller to break it free. Too much futzing with puller will loosen the alloy body off the steel hub of the rotor, ruining it. Hopefully, as you're snugging up the puller, it pops free on it's own...

 

[Rudie]

rotor off the crankshaft. I don’t have a 2-jaw puller

3-jaw puller on the rotor, SNUG it up tight, then rap the center bolt on the puller to break it free.

You might have more difficulty than that. The centre bolt of any puller must bear on the end of the crankshaft in some way. Your picture of the alternator rotor does not show any of the crankshaft projecting outside the rotor for a puller centre to bear on.

The crankshaft picture in the 67 parts book shows a stud (part #7), one end of which screws into the end of the crankshaft, the other end projects outside the alternator rotor and takes the nut that secures the rotor. If you do not have this stud for some reason, either get one or you will need a spacer of some sort to replace it so any puller can work.

Too much futzing with puller will loosen the alloy body off the steel hub of the rotor, ruining it.

Lucas began supplying encapsulated stators in 67 so, if the "67" part of your engine includes the bottom end, the alternator stator indicates it is either early 67 (the number is near DU44394) or the stator is not original. I advise against considering reusing that stator.

If a group of three or four figures are not visible now stamped on the outside of the rotor, they should be on the other side when you get it off. The three or four figures are the week number and last two figures of the year of manufacture. Unless the year is very recent and you did not do much "futzing with puller", I also advise against considering reusing that rotor.

 

[Sundance]

You might have more difficulty than that. The centre bolt of any puller must bear on the end of the crankshaft in some way. Your picture of the alternator rotor does not show any of the crankshaft projecting outside the rotor for a puller centre to bear on.

The crankshaft picture in the 67 parts book shows a stud (part #7), one end of which screws into the end of the crankshaft, the other end projects outside the alternator rotor and takes the nut that secures the rotor. If you do not have this stud for some reason, either get one or you will need a spacer of some sort to replace it so any puller can work.


Lucas began supplying encapsulated stators in 67 so, if the "67" part of your engine includes the bottom end, the alternator stator indicates it is either early 67 (the number is near DU44394) or the stator is not original. I advise against considering reusing that stator.

If a group of three or four figures are not visible now stamped on the outside of the rotor, they should be on the other side when you get it off. The three or four figures are the week number and last two figures of the year of manufacture. Unless the year is very recent and you did not do much "futzing with puller", I also advise against considering reusing that rotor.

Rudie,

Now looking at the photo I see the problem in getting a puller to have a place to bear. I removed the long shouldered nut from the rotor and this is how it was. By the way, the engine is a 1969 engine (the 1967 on my thread refers to the frame, etc, being from 1967). So I'm not sure if this is why there is not a stud in this place.

The stator looks pretty rough so I was thinking it should be changed out. I'll take a look at the rotor once I get it off. In all, thank you for the comments as I am not wanting to re-use any parts that are compromised.

Here is a photo prior to removing the nut on the rotor.

Cheers.