Interesting 961 History Info

Triumph saw fit to put 2 balancer shafts in the 1200 , which also has a 270 crank.
Even the Daytona 955i Triple has a balancer. You can lay your hand on the tank at idle or 12,000 rpm/ 161 bhp with negligible vibration felt.
If the balancer shafts are hurting power output in those two, engines, it's not noticed.
I think the balancer shaft is a wonderful thing. We can have an engine run at 12 or 14 thousand rpm, make insane power and without the need to build half the bike out of rubber ( 750/850 Commando) trying to get away from the vibration. I love my old Commandos, but the rubber mounting is kind of a hokey way to utilize a tremendously out of balance engine. At that we still suffer some annoying shaking below 3000 rpm. A 270 crank could help a bit, but with the higher revs used now in most modern engines to get at higher power, ugly vibrations would likely remain.
It makes sense that someone decided to fix the engine to solve the problem. I suspect balancer shafts are here to stay. If they are made correctly, they are brilliant!

Glen
 
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We seem to have gone a tad off track...

How dya know it doesn’t hurt power Glen? You haven’t tried without!

I wasn’t saying balance shafts don’t work, or shouldn’t be fitted, especially to modern high rpm smooth engines !

But does a track focused 961 need one? In which, the crank and balance shaft are both out of balance as supplied by the factory!

And ref the 180, a 270 crank is inherently smoother than a 180. Phil Irving worked this out in the 1950s.

TonyA, ref the dummy shaft, it wouldn’t be needed if the noisy horrid gear primary and fragile clutch were binned and replaced with a belt drive and better ‘off the shelf’ clutch...

But alas, it would take greater skill, more motivation, and much deeper pockets than I posses to try any of this out !
 
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Even the Daytona 955i Triple has a balancer. You can lay your hand on the tank at idle or 12,000 rpm/ 161 bhp with negligible vibration felt.


Glen
I hope folks don't think that only twins gave balancer shafts.
Because several multis do as well, like the Yamaha R1, YZR, Kawasaki ZX-14, etc.......
Once twins grow larger than 500cc they produce significant vibes that must be addressed.
When 4 bangers grow above 1000cc or so their vibes become annoying too.
 
You’re right there, many big 4 cylinder motors have them these days.

But those motors aren’t as well balanced as us Nortoners might think. I read a quote from APE racing on this:

“None of these cranks are well balanced from the factory. They are, after all, street bikes that spend most of their time under 4000 RPM. If a crank is heavy where the factory can not drill holes, they are done, it goes in a motor. Yamahas are the best with Honda being worse overall. We have seen stock busas out 8 grams”.

And also from APE on the balance shaft topic:

“Any motor that is going to be raced should be race balanced. We get then to less than 1/3 gram end for end. We always recommend this if the balancer is removed. We get many reports that the cranks we have balanced and the balancer removed are smoother than stock”.

So I gotta say, I’m still thinking that a 961 with a well balanced crank and rod assembly may well turn out as smooth or smoother than stock, and certainly smooth enough for a track day hot rod!

Its all pie in the sky though. I’ll let you know how it turns out when I’m done, just don’t hold your breath waiting...!
 
How dya know it doesn’t hurt power Glen? You haven’t tried without!
I don't know if there is power lost by the balancer, however my comment was, if it's hurting power on those two engines, (955i, &1200) it's not noticed. Meaning I'm having enough trouble hanging on as it is! When the Daytona hits 8,000 rpm it's all I can do to keep up with it . You have to stay forward to keep the front end reasonably close to the ground thru 1st and 2nd. Second tops out at 105 mph at which point the front wheel settles down to the pavement then lifts briefly again in 3rd
No traction control or wheelie control on that old bike means full throttle is full power.

It could be that with the balance shafts removed, there might be a couple of extra horsepower. I sure wouldn't notice it.
Some racers have tried removing the balancer with the 955i, but all I have read about eventually failed.
The engines blew up or vibrated so badly that rad mounts and other things broke.
Jim ( Bushman) found that the balance shaft in his 961 was wonky and making things worse. He corrected that as well as the crank problems and now the engine runs quite smoothly.


Glen
 
So I gotta say, I’m still thinking that a 961 with a well balanced crank and rod assembly may well turn out as smooth or smoother than stock, and certainly smooth enough for a track day hot rod!

Its all pie in the sky though. I’ll let you know how it turns out when I’m done, just don’t hold your breath waiting...!
Well, I think this whole vibes issue has been done to death on the Classic forum already.
A parallel twin with a 270 degree crank will surely have less vibes due to primary imbalance than a 360 degree twin.
But it will have additional vibes from a rocking moment, where the 360 engine will not.
An unbalanced 1000cc - 270 degree twin engine, is bound to have significant vibes, even if the crank/rods/pistons are carefully dynamically balanced.
The pistons and rods counteract the flywheel mass in the vertical plane.
The villain is the crankshaft flywheel mass moving forward and back each engine revolution that has no counteracting mass.
It would be interesting though to see what an unbalanced 961 is like.
Especially if it were to be instrumented to measure vibes.
 
Vibration is a strange topic. Different frequencies , acting differently at different revs, etc. And, of course, different rider perceptions. The only vibration that really matters on a track bike is the vibration that breaks things. If it’s below that threshold, it generally doesn’t matter. And, that is the context in which the notion was put forward.

Nevertheless, FWIW, it is most certainly not clear that a 180 crank vibrates any less than a 360, they do vibrate differently, but which is better or worse ain’t easy to say. I know this from personal experience riding otherwise very similar bikes back to back. A 270 is definitely a better start point in the quest for a low vibe twin.

No question at all that there’s no such thing as an optimally smooth unbalanced twin.... But anyone looking for optimum smoothness ain’t gonna be riding a bloody 961... at least not for long...!
 
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In fairness, how many of those vibes are due to the " All hand built in the UK! "assembly job?
From what Jim tells me, these engines are smoothies once everything is properly lined up.
With a balancer shaft that is balanced and crank mainshafts not running in an ellipse, smoothness is possible, maybe even probable.
 
In fairness, how many of those vibes are due to the " All hand built in the UK! "assembly job?
From what Jim tells me, these engines are smoothies once everything is properly lined up.
With a balancer shaft that is balanced and crank mainshafts not running in an ellipse, smoothness is possible, maybe even probable.
Absolutely, as already discussed (#16), TonyA already reported this, much smoothness can be discovered this way. Still wouldn’t expect it to match your Thrux tho...
 
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One of the many Triumph engineers named Simon claimed that they felt that the new motor was too smooth initially, so they added some engine texture via fuel mapping.
It does have a strong pulse when accelerating in Sport mode, but that is quite a different thing from vibration, isn't it?

Glen
 
One of the many Triumph engineers named Simon claimed that they felt that the new motor was too smooth initially, so they added some engine texture via fuel mapping.
It does have a strong pulse when accelerating in Sport mode, but that is quite a different thing from vibration, isn't it?
When I rode a Thruxton I was amazed at how smooth it was. But I didn’t like that! As I said earlier, in my opinion vibration is a multi faceted thing that’s often difficult to be precise about. The pulsing you describe is still a type of vibration to me. But a good one! High frequency buzzing through the bars is a bad one. This is the type that ‘smooth’ multi cylinder engines can produce.

Perception of the rider is key too of course. I’m one of those that need a visceral riding experience, so need some vibration or pulsing to add to the experience. The idea of a turbine smooth and quiet electric bike does NOT appeal to me at all. But some would consider it the holy grail.

To each his own. Again.
 
The 961 is no way as smooth as the Triumph. FE , I like the idea of a full on 961 racer eliminating the balance shaft and going with a belt or chain drive with a crankshaft rebalance ! BUT , just letting you know guys know that It won't be me . If I could see a clear path to getting the parts and the expertise it could be viable. But right now I just don't see it .
 
As already mentioned, as well as in other threads, a lot of this is subjective and unfortunately we are thinly spread with few dealers so cannot compare machines. As I seem to have to escaped a lot of common issues I would be most interested for other owners to try my bike to see if it feels any different. Maybe once this is all over we can have a nice big meet-up one warm and sunny weekend! (for our more climatologically blessed cousins outside the UK this means rain a few degrees away from horizontal and to be able to turn our heated grips to Low).

How about a few owners putting dyno run results of their bikes on the forum? Although I know someone who visited several dynos with his his car and found huge variations to big-up their tuning work but the curves should still be useful.
 
A large displacement twin other than a 180 degree opposed, definitely needs counter balancing for smooth operation. Otherwise, you will have a modern version of the classic British paint mixer twin vibrator.

A counterbalancer shaft is not necessary, BMW uses a reciprocating counterbalancer mass. This would require a different crankcase/crankshaft design though.

View attachment 78092Hosted on Fotki

Dave, Richard Coote, and Bushman have shown that the precision alignment for the 961’s crank and balancer shaft is lacking. Better alignment will have a positive effect on vibration reduction.
Now this idea was drawn up back in the 1960s by burt hopwood along with the singel sided swing arm and the V5 Nortons porjects all in the book what ever happend to the British motorcycle industery By Burt Hopwood well worth a read if you can still get hold of this book
 
Now this idea was drawn up back in the 1960s by burt hopwood along with the singel sided swing arm and the V5 Nortons porjects all in the book what ever happend to the British motorcycle industery By Burt Hopwood well worth a read if you can still get hold of this book
 
I ran across these postings on a 961 Sport up for auction on BAT. I recognize that some of the comments might be controversial, but thought some of you might find them interesting.


"Sluggo503 This author's likes: 457

Nice bike & good price. I might be able to offer some clarification on a few issues. First, the frames for these bikes is the same as the prototypes that came from here in Oregon-Norton America. Kenny Dreer worked with Jeff Cole of the famous C&J frames to create these, Jeff is now retired but still does small batches of frames for all kinds of bikes, Of note, He has made a number of custom frames for Matt @ CNW but I have spoke to Jeff and while I have several prototype Nortons and the original CAD files, new frames are not inexpensive. I have spoke to many of the Norton UK vendors and many are operating on rev1 CAD prints so, the claim that Stuart Garner made of revamping the entire bikes is not entirely true.
For clarification, When Garner bought Norton from Norton America the chassis was 100% production, Shovel ready. The motor was at 90% and while they knew what it needed, lacked the funds to go into production, Hence the venture capitalist who funded Norton Americas decision to sell. Garner employed a well known midlands company to refine the motors and build all the early ones. Based on this bikes date, This bike SHOULD have one of those motors. However there was a dispute over funds and eventually that company severed ties with Garner/Norton. When they had them built by a new vendor and some inhouse, they had some issues. All of which if you search on the net you can read about. I have several of these early motors and they are excellent.
As to Spondon, thats a different topic, and post liquidation seems there was some issues with the purchase of Spondon and its assets. Again well chronicled on many sites, including AccessNorton. If true, & the reports are credible, Its an unfortunate outcome for what was once a reputable company.
TVS has allegedly targeted another 40 bikes of the 961 series, But after that the future of this model is uncertain as well as spares, But most are hopeful that they support the owners and hopefully continue making them. But fear not… other than crankcases and cyls and heads, ALL components can be sourced. I dont want to go too far into that topic, but many of the parts on these are also in production for other applications.
For example, The trans is the same as a Harley Sportster or Buell. In fact, wishing a 6 speed you can buy them from Baker drivetrain and Norton America had some and planned to offer them as an option.
The Alternator and clutch can be found on some Suzuki models. And the Starter? Thats history repeating itself from the days of the Norton 850 when Norton bought rejected starters for Harley ironheads and fitted to 850s. Norton owners refuse to acknowledge this and pay 2x too much for starter upgrades from Norton suppliers, while the same upgrade from a Harley source is a fraction of the cost. The Starters on the 961 series bikes are a common starter, again found on Sportsters, Buells and even some cars. My Kubota and Yanmar tractors with the 3 cyl diesels also use this starter.
I have discussed this with 961 owners and even the forum admin at In-AccessableNorton and they dont believe it but, yes, you CAN fix your Norton from parts at the local Lawn-Garden & tractor shop.
As for TVS, TATA and the others,, I can confirm they were looking at Norton for purchase for many years. At one point even Harley considered a purchase as well as some Chinese manufacturers. There was a matrix for buyers, Some, Dreer called “All hat, No cattle”
But they ranked the buyers based on several factors and one was preserving the brand identity and legacy.
Later, after Garner bought the brand it was on shaky ground for some time and many entities were looking at it should the opportunity arise. I took a friend over to meet Dreer as he lived a short distance from me, (Now retired and out of state). In discussion Kenny revealed that at that time he had been contacted and asked about his interest if a sale happened, WOULD he be interested in returning to a role in the new Norton company? My friend Dave, who has spent a lot of time in Asia and India immediately knew who he was talking about and Kenny was shocked, We kept it quiet at the time, But yes,, for many years Norton was being looked at. I have not spoken to Kenny for some time and no idea if he is in contact with the current owner, but last we spoke, he said,,, “Im happy to talk boats or fishing but dont want to discuss motorcycles anymore”.
I am a big Norton enthusiast and confident that Norton has a bright future, I can 100% say this bike is a future collectible bike and a good investment. Should you have any issues, questions or need tech help there is a lot of passionate people to support you and assist.
As to this model, actual production numbers are fuzzy and hard to figure out but not many were built in this configuration, those forks and wheels are IMHO the nicest set up, most used USD forks and the spoked rims just connect it to the heritage of the bike.
There is so much wrong in this, that it almost reads as though ai wrote it 😂
Frames were very different, even the R1 Donington frame when compared to the only running Dreer bike that the factory had. By the end of production, they were up to R8 of the Commando and I think (I'd need to check) R5 of the Dominator. A lot of changes were brought in by Xtreme Motorsport, down in Leighton Buzzard, who also produced the frames for around 18mnths. Their frames are easy to identify, as they stamped each one with XM- followed by the production number....run your finger under the plate that the rear tank mount bolts to, and you feel it. They were very nicely made frames, lots of zinc plated parts prior to assembly, properly primered and nicely welded. One of their modifications was the vastly improved lock stops, away from the very weak tig welded on pegs that fall off at the slightest hint of a drop...to the nicely welded in triangular shaped section. Lots of other mods were seen over the years, oil pipe heights within the tank, oil pipe outlet orientation to clear the fuel rail, twin seat reinforcing, alterations to the swingarm mounting section to clear the chain, oil cooler mounting....these are just the big things, there was many minor tweaks. The Xtreme Motorsport jigs I have...along with all their remaining production stock after parting ways with Norton. Frames thereafter were produced inhouse and powdercoated by Protech Coatings in Wolverhampton.
Engines assembled by MCT had problems, nothing to do with the workmanship...just some issues that were highlighted over time. First one to spring to mind...who remembers rocker towers coming adrift early on? There has been a HUGE amount of revisions to components and procedures over the years...even today the 961 is still evolving, it's been a very drawn out R&D process, quite a public one too. Most engine parts were later moved to production in Taiwan. We had very little in the way of problems with anything produced over there, excellent standards...I'm sorry to say, it was usually the British involvement that caused problems 🤦🏻‍♂️ Also wheel hubs produced by the same company, never seen one of those crack, whereas the UK made Talon hubs have to be inspected closely, and regularly, especially the front.
Starter motors, yes same as a sportster. I'm really struggling to get silver now.....the chrome ones rust faster than a Lancia Beta, so that just leaves the black starters. I'm still looking for silver though. No it's not the same as a car or a forklift etc etc....comes from the same family of starters ie they share some components, but castings are different for mounting points for starters (pun).
Clutch is not Suzuki. The clutch plates are Yamaha. It was a boring job unpacking those, as they came individually packaged ie each plate, which you had to put together into kits....and it was always a big order from Yamaha. But that's all it shared with another manufacturer.
Gearboxes, not the same as a HD....but similar. I believe this has been covered on here quite a lot already.
I honestly can't think of a 270° parallel twin Ducati? Or am I misreading that? The TRX850 was done as a 270° to give a V-Twin sound and feel (absolutely stonking engine tbh)..seeing as they were pitching to compete with the Ducati 900ss. But that's the only other bike I can think of.

(I'll check for typos etc later when I've properly woken up)
 
Now this idea was drawn up back in the 1960s by burt hopwood along with the singel sided swing arm and the V5 Nortons porjects all in the book what ever happend to the British motorcycle industery By Burt Hopwood well worth a read if you can still get hold of this book
It's taken me more time than I care to admit to decide if youre actually a real human or not.
 
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