750 crank balance factors

redax5 said:
Quentin, it is not too difficult to build up the OD on a set of bearings to take up any slack in the crankcase journals, I had to do one when I rebuilt Maxene's Monty
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Hi Red. I marvel at the benefit a World Bank of engineering knowledge can bring to a curly one! Not something I would ever have thought feasible (how DO you get the copper on there, BTW?!).
I?ve completely lost rack of the mileage on my motor (hasn?t had a speedo since I fitted that TZ 4LS in 1976), but I know I tired of seeing spin marks in my cases and alu picked up on my mains outers. In desperation a few decades ago I pinned the cases and put a small nick in the external housing of the outer mains that they fit into (had seen how Kwakka roller cranks always had pinned bearings). Stopped the rot, but didn?t restore the tight fit.
I recently finished a total motor rebuild on a ?totally rebuilt? SF1. A friend had bought it, complete with receipts for thousands of dollars worth of engine work, most of which was probably done quite well. They?d also cleverly and expertly overbored the mains journals and fitted sleeves over the outer mains and half sleeves to top and bottom of inner mains journals to suit. A tiny oversight was that they covered the slotted oil-feeder holes that supply the slingers, big-ends  ???? cylinders, pistons, small end, etc etc ! I started with a motor with a disintegrated piston and a rod with a lovely U-turn in it! Nice work, just not quite finished.
My journals really need to be totally cleaned up ? do you think a hone would suffice, then copper the bearings? It?s not imperative, as I have a set of cases in perfect nick that were given to me in exchange for expertise. And I?ll probably pin those as well (never seen a used SF that hasn?t shown signs of spun mains). But I will need to restore my original eng#13,000 cases at some stage (thinking of a 2nd, less radically modded roadster ? probably with 18 inch wheels on it!).
I?m getting inspired to get back out in the workshop and play with some of my poor neglected bits & pieces ? maybe the kids can watch and learn how to dial in a cam  :D.
ps Is it possible to successfully sleeve a conrod big-end? Vee Two in Perth were doing it a while back and I wondered if it was a viable resto for otherwise perfect SFC rods (not for racing, of course).
QF
 
Hi Quentin,
Is just a copper build process, bit of solution, few chunks of copper, electricity, time, seal the bearings properly first, not difficult, Cam will explain the process a lot better then me.

wholeunit_zpsa749777f.jpg


I doubt you will need to hone the case journals, once measured you will probably find they are within 0.01mm of round, be surprised if they are too far out, wear should be even.
Would be difficult to hone the journals anyway, you would need to use a Sunnen CR mandrel or an AN mandrel and then adapt it to a low speed heavy duty drill, even with that set up I doubt you would get a true finish, would be very hard to hone the journals on a horizontal Sunnen hone machine.
I also have a Comec Vertical Hone machine (made in Italy) but I doubt it would do the job either.

Nearly every Laverda engine I have worked on has had signs of the bearings rotating, triples and twins except for the 120 engines and the 500 engines which have pinned middle main bearings in them.
Very few need building up as we did to Maxene's Monty, most you can hold in place by using a good Loctite retaining fluid when installing the top case.

One piece Carrillo conrods have a sleeved big end from new, I believe they do that so they can retain the toughness in the parent metal of the conrod and then use a hardened sleeve for the bearing surface.
I have sleeved standard Laverda triple conrods in the past and both the cranks I have done are still running which has surprised me somewhat but yes, it is possible, but in reality, now I just change the conrods out for Carrillo's, is so much easier and works out at nearly the same price, most often cheaper.

I heard the sleeved Vee Two conrods did not work out so well. ?
Quite a few spun their sleeves, is the story I heard and no back up or support from BH ?

HTH
Red


 
Looks like an electroplating process to me.

The next question would be...why copper, rather than some other metal?

bazzee
 
bazzee said:
Looks like an electroplating process to me.

The next question would be...why copper, rather than some other metal?
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'cos it's cheap and easily accessable.  Could even do it at home with a little patience.  Amount of copper deposit depends on time and power going through the electrolyte.

piet
 
redax5 said:
I heard the sleeved Vee Two conrods did not work out so well. ?
Quite a few spun their sleeves, is the story I heard
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The people at Falicon Crankshafts reckoned they could sleeve conrods when I first asked them about it. But when I went back to firm up a price and maybe get some done they had stopped doing it. They didn't want to talk about it so I assume they were having the same luck. I guess some things are just not meant to happen.

Ken
 
Shaeze! It's been well over a year since this lively topic on twin-twisting and crank balance has seen any action.

Red, I hear rumours you'll be back from safari (how did the pith helmet sit?) quite soon. Back when we were discussing all this everyone was keen to get some feedback on how the three crank twisting projects would turn out re balance and vibes. I'm still super keen to hear from any of the three owners.

I saw the pics of the unfortunate off-circuit sojourn of House's 284 deg - very glad injury was to inanimate objects (including pride) only and no humans were harmed in the telling. If either you (Housey) or the other two beneficiaries of Red's tireless toil in rephasing and balancing works read this, please post and tell us what you reckon.

The way talk was going, by now there must be another 100 or so twisted sisters on the streets of the planet!

Cheers, Quentin
 
Years ago I fitted a disc brake late model Bonnie fork to an earlier model,the steering head bearing were close but 3mm too small on the OD.I had them hard chromed and ground to fit.Worked out great.Probably more shock loads on steering heads than main bearing.
 
Delayed reply, just returned to the city after 6 days in the wilds of Madagascar chasing Lemurs, place we stayed at had power 5hrs per day, no net and very suspect food, apparently I am having a good time, off to South Africa today.

Quentin, to your question as to the smoothness of the Twisted Twins, it would be easier pulling toenails out of a Lioness then getting information out of House, I pretty well gave up, he has his own Crew Chief now which has allowed me to move on to working on peoples bikes that I actually get paid for.

Greg's 270 degree twin has only just been registered, he was at Broadford as you may have seen here on the forum, he sent me an email last week saying it was running great, makes good power, wants to change to higher lift cams, never said anything about how smooth or not it is, told him we would talk when we get home mid June

3rd Twisted Twin engine is stillbolted to the side of my main work bench, finished except for loading the cams into the head, waiting to be paid for that engine so stopped working on it, owner having personal issues so not all his fault.

Have orders for 3 more 880cc x 270 degree engines, most likely do them next year but more keen to do a 597cc x 270 degree 500 twin first just to see how it goes and fit it into the 500 Spaceframe that we own

Cheers
Red
 
but more keen to do a 597cc x 270 degree 500 twin first just to see how it goes and fit it into the 500 Spaceframe that we own
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That, I think, is the best use for the 270 set-up as it could well save rods smashing through crankcases - even more possibilities with the Zane bikes to try and make them useable for more than their (expected) short life. - Regards - Phil
 
The Zane bikes used a 668cc DOHC twin air cooled motor and a 750cc twin water cooled motor -  based on the original Alpino motor. - Regards - Phil
 
Ultimately Anything can be fitted to anything - but not seen a Breganze twin motor in a Zane chassis. I think someone - (Maybe Dutch) has fitted a triple motor?? - Regards - Phil
 
Bruce is in the process of doing one at present in fact, using a Diamante frame (steel trellis).  Motor seems a pretty good fit from the pix I've seen.  Look forward to seeing it finished. 
 
redax5 said:
Delayed reply, just returned to the city after 6 days in the wilds of Madagascar chasing Lemurs, place we stayed at had power 5hrs per day, no net and very suspect food, apparently I am having a good time, off to South Africa today.

Quentin, to your question as to the smoothness of the Twisted Twins, it would be easier pulling toenails out of a Lioness then getting information out of House, I pretty well gave up, he has his own Crew Chief now which has allowed me to move on to working on peoples bikes that I actually get paid for.

Greg's 270 degree twin has only just been registered, he was at Broadford as you may have seen here on the forum, he sent me an email last week saying it was running great, makes good power, wants to change to higher lift cams, never said anything about how smooth or not it is, told him we would talk when we get home mid June

3rd Twisted Twin engine is stillbolted to the side of my main work bench, finished except for loading the cams into the head, waiting to be paid for that engine so stopped working on it, owner having personal issues so not all his fault.

Have orders for 3 more 880cc x 270 degree engines, most likely do them next year but more keen to do a 597cc x 270 degree 500 twin first just to see how it goes and fit it into the 500 Spaceframe that we own

Cheers
Red
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Thanks for the reply, Red. Yeah, the toil of the workshop has often of a high gratis factor (is that like balance factor?  :D) Enjoy your break.

Hopefully Greg will see my post and report on the findings - for a start, loads of your time, a lot of bloody debate and hours of studious ponderings went into the subject - and we'll never get any idea of where we should be heading if noone can report back on the results of the early work: road-going vs race?, 270 vs 254? 60% vs 65% etc etc. And you did such a beautiful job setting them up and having them dynamically balanced that we are right in the sweet spot with regard to eliminating other factors and finding answers to these questions.

I have to toss up whether to experiment with a stock SF crank (after you do a number on it by machining and fitting the big dia centre) or building up my new lightweight 'SFC' unit with triple webs.

Best feedback so far seems to be from Phil's 270 balanced at 65%. I'm sure my SFC crank at 50% is far from where it could be.

Hopefully be in touch with you when you're back on duty.
Quentino
 
Type of motor in the smaller twins is 180deg cranks to start with.
I can?t understand why no other manufacturers than Yamaha did 270, it takes a simple design twin into a new dimension. I thought BMW had done it with their parallel twin but it seems not.
 
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