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Yamaha XS vs Triumph vs Norton (650-850)

Discussion in 'The Garage' started by xs650-4-me, Dec 5, 2018.

  1. xs650-4-me

    xs650-4-me XS650 Member

    Anyone here ever have the privaledge to ride all of these (vintage only) to compare power (and more) ?

    I'm curious how much more 'engine' the Bonneville 750 or Norton 850 might have. Especially since the Norton 750 and 850 have a undersquare (meaning smaller bore than stroke) stroke of 89mm. The Bonn 750 also has a stroker motor. The XS is slightly oversquare at 75x74.

    My lust these days seems to be for a Norton 850 Commando :)

    Sure wish I knew someone in TN that had one - that I could take for a low rpm spin :) I'm really only interested in torque, not speed or rpm's. If I really wanted to go fast, I'd buy an R1.
    Marlin72xs likes this.
  2. Rasputin

    Rasputin XS650 Addict

    I have a 75 XS and a 68 Triumph Trophy, both 650. The Triumph would in my opinion beat the XS. But the XS is smoother. The problem with the XS is it’s wieght, the Trophy is like pushing a push bike compared to the XS.
    Both nice to ride in their own way, I rode a 750 Comando belonging to a friend in 1972, any comparison with that ride would be useless, it’s so long ago, but as I recall that was a lovely engine.
    Wulfbyte likes this.
  3. xs650-4-me

    xs650-4-me XS650 Member

    The Trophy is a single carb right ?

    What about pulling power, not a real race ? Power characteristics...
  4. gggGary

    gggGary Stop that! Top Contributor XS650.com Supporter

    You can get what you want with careful carburation. Madness a 750 kitted XS650 is cammed and carbed for high RPM power but with bit of tweaking it pulls extremely well from rod rattling RPM. And THAT is the rub, You CAN make an XS or any 650-750 twin pull from the bottom but it will have engine life consequences if you routinely use the very low RPM torque. Honda shadows and other twins often use a ramp clutch to reduce the drivetrain punishment those individual power pulses can cause. That does not protect rod ends or crank alignment.
    Wulfbyte, YamadudeXS650C and MaxPete like this.
  5. Mailman

    Mailman Hardly a Guru Top Contributor

    I had a ‘76 Bonneville with a fresh engine and new carbs. That bike ran beautifully , and in my opinion was snappier than the XS. I’ve always dreamed of Nortons but so far have not had the opportunity to ride one. They’re pretty rare in my part of the world.
    Wulfbyte, GLJ, MaxPete and 1 other person like this.
  6. Rasputin

    Rasputin XS650 Addict

    The Triumph pulls like a train, really strong, and I don’t use too much revs beyond 4000 rpm.
    XS needs more throttle to make it pull, needs revving, that could be down to the CV carbs.
    These days though a lot of speed has gone out of me, I am quite happy around 50/55 mph.
    Wulfbyte, Mailman and GLJ like this.
  7. MaxPete

    MaxPete Life with Lucille...I suggest, she decides. Top Contributor XS650.com Supporter

    I've done a couple of same-gear roll-ons with some vintage Brit-bikes and I can normally take a Triumph 500 or 650 with my Lucille (a '76 XS650C), but a 750cc Bonneville had me and Norton 750 and 850's had me for lunch. BSAs were similar. In a roll-on, if they started in their power band, they did well but ran out of breath at higher speeds and if they started below their powerband - I had them off the line and they often couldn't catch up. The XS650 seems to be able to rev higher and still make good power (but of course, that is a matter of individual bike tuning and overall condition).

    I just checked and a 1970 Bonneville weighs 423 lb while later model XS650s weigh around 455-460 lbs (around 30-35 lb more) and so I guess the extra weight of the XS650 is a factor, but in my experience, the weight of riders can vary as much or more than the 25-30 lbs difference between a Triumph and a Yamaha - and so that effect is a bit of a wash unless the riders are about the same size.

    The Bonneville produced about 49 HP @ 7200 RPM versus a rated 53 HP @ 7000 RPM for the Yamaha - so the power-to-weight ratio is very similar (8.53 lb/HP for the Triumph vs 8.58 lb/HP for the Yamaha).
    NOTE: the difference of 0.05 lb/HP is less than 1 ounce or 25% of the weight of a McDonald's Quarter Pounder burger - so NOT a big deal.

    As I see it, in real-world road riding, the older British bikes - being 4-speeds - were also often compromised in the gear ratio department. With a 5 speed twirler, I can usually keep the Yamaha on the boil more easily. Also, when it came time to start up after a coffee break - I could be away much faster (albeit with some exciting and euphonious gear gnashing sound effects) and without the eye-crossing pain of a kick start (we're all old guys in my riding group).

  8. xs650-4-me

    xs650-4-me XS650 Member

    Yes, I spend almost all of my time below 55 too, and below 4000rpm also. If I'm looking for anything, it's 2500-3500rpm torque, so I could cruise at lower rpm. My XS's have never seen 6k, maybe even 5k rpm. I never see the need. I run it, shift, run, shift, until I run out of gears. I may end up going a tooth or 2 smaller in the rear on an XS to see how she likes it. I sure would like to ride a Bonn 750 or Norton. My Uncle had a Bonn but I was maybe 12 when I rode on the back and don't remember much. I have a Suzuki GT750 to compare my XS's to. When my GY is warm, and on a center stand, I can start it with my hand, carefully that is. Nothing to turn over but pistons mostly.
    Wulfbyte and MaxPete like this.
  9. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    I worked at a Honda shop that also sold Triumph, Harley, Bultaco, CZ, and we'd work on just about anything else. In '75, I had built my XS1B into a 375 lb 750cc chopper (with some tweaks). One of our mechanics had a new 750cc Triumph T-140, and wanted to compare tall-gear roll-on against mine. My bike had a bit of a weak torque zone around 3,500rpm, near 60mph, and I was curious as well.

    We went out to a quiet section of highway, evened-up at about 50mph, and opened them up. We stayed pretty much even, up to about 85mph, at which point he started falling behind. At about 2 bike lengths behind me, I heard him downshift. Looked back over my shoulder expecting him to catch up, but he continued to drop back. Ok, so I'll drop into 4th. Finally, the engine's coming on the cam and taking off. Kinda like Bert Munro's test run, where he pulls away from the evaluation team.

    Chatting with the mechanic later, he said that his T-140 had nothing left, and was hoping I would drop to 4th, just to see it run.

    If my XS1B was stock, I doubt it could've kept up with him.

    Have you looked into the new 1200cc Triumph T-120?


    1,200cc, Bore 97.6mm, Stroke 80mm.
    Yes, over square, but reportedly pulls strong at low rpms.
    6-speed, Weighs less than 500lbs.

    Member Michaelo acquired one last year, and is quite pleased with it.


    Last edited: Dec 5, 2018
    Wulfbyte, YamadudeXS650C, GLJ and 2 others like this.
  10. X77S

    X77S Unmotivated..... HELP!

    I'd love to be able to experience the old brit bikes. And the new 1200 Thruxton looks like a total blast. But I'm dreaming now. Still need to get motivated and get mine rolling.
  11. fredintoon

    fredintoon Fred Hill, S'toon. Top Contributor

    You can't buy the ultimate British vertical twin, you have to mix'n'match build it yourself.
    Norton Featherbed frame, Triumph engine & tranny and swap in actual working brakes.
    delagem and MaxPete like this.
  12. motormike

    motormike XS650 Addict

    I have both a 650 Brit and the XS. The Brit has a bit more snap go'n for it. I think the XS add'd weight and diaphragm carb's contribute to this. The 70' and 71' XS units had a better cam and was much snappier then later XS units. Why Yamaha neutered them, I don't know.
    I have a little time in the Snort'n saddle. Major grin factor.. pulls like a freight train. Not my first choice for Dragons Tail but great for more open back roads. Perhaps it's the slow rev and longer wheelbase.
    I also have a Triton (3 yr Minnesota winter build) It goes very well … :) and handles very :) Dur'n the build I wanted to keep it old school.... so, I vetoed modern carbs... vetoed a side stand and vetoed disc stoppers. Afterwards... I should have second thought the stoppers.
    Triton tail.JPG Triton shiney.jpg

    Attached Files:

  13. Mailman

    Mailman Hardly a Guru Top Contributor

    Beautiful Triton Mike!
  14. I have owned and rode BSA TRIUMPH NORTON and XS650
    Norton was built to go fast and the one I had was a low 13 second quarter mile bike 750cc with head work
    My 67 triumph was a dual carb. bonney and had a 850 cc Routts kit on it and went high 12's 1/4 mile
    My BSA was a chopper used it for 4 years every day and even rode it from Phila to Canada single carb two kicks and you went where you wanted too.
    I bought the Triumph to do street racing in the 60's because I lost $500 to a CB350 in a 1/8 mile race with my car.
    True story when I was in partner with my buddy at the Honda dealer . We bought a 305 6 speed factory racer from Honda in Japan. Bike had delortho carbs and I took it to the track and went 13:30 1/4 mile and though that was great. Until I came back to shop and my partner told me I had the CHOKE on.
    The Honda you want to ride and buy toilet paper was the mad MR250 dirt bike. You had to sit on the tank to keep it on the ground. Back then they built bikes to hurt you so you had respect LOL . Had guys break ankles feet just kicking some of these bikes. No push button start HAHA . Anyone as old as me could tell you that. One of the fastest old bikes I drag raced was a KAW H2 750. Not only was it quick but you didn't hear for weeks after a race LOL
  15. 5twins

    5twins XS650 Guru Top Contributor

    Gear the bike too high and you'll be killing the low speed/low RPM power you seek. For an 18" rear wheel, I feel a 33T sprocket works best. I have a couple wheels and put a 32T on one, a 33T on the other. I can really feel the difference and the "hit" the low end performance takes when I swap that 32T equipped wheel in. If I rode on the interstate constantly, it would be fine, but I don't do that. I do mostly local in town and back road riding. I want good performance in the lower gears and in the low to middle RPM range. That one tooth reduction still gives me that but also reduces the RPMs at cruising speeds by 3 to 400. My bike seems happiest cruising along between 3500 and 4K. Anything lower than that I would consider lugging it. It's relatively smooth in that RPM range and just into the lower end of the power band. If I whack the throttle open, it will still take off smartly and get out of it's own way, lol.

    The way you say you ride, maybe you shouldn't be gearing up at all. Maybe you should stick with the stock 34T or even go to a 36T. Even with a 36T sprocket, I still wouldn't cruise around at 3K. I think that's lugging the motor and no good for it.
  16. perki48

    perki48 XS650 Enthusiast

    Owned a 69' Bonneville and a 72' XS2. Rode a friends 750 Commando. Commando was the fastest followed by the Bonneville. Bonneville was the best handler and the XS2 the most reliable.
    gggGary and MaxPete like this.
  17. xs650-4-me

    xs650-4-me XS650 Member

    Thx for all the replies...
    I don't want a new bike...
    I may go down a tooth in the rear then again I might not and just ride.
    I'm not familiar with the MR250, but I've been racing/riding MX bikes for 50 years. My favorite for excitement was my 81 Maico 490. It was an ankle breaker, but I retarded the timing a few degrees to get a better powerband, and starting was a tad easier. I still have a like-new rebuilt 83 490. I also have 5-6 96 CR250's, McGrath's last year with Honda, last steel frame 250. On that 81 490 i also took off the adapter between the carb and cyl, and bolted the carb right to the cyl. WOW. What low end, and not much of a loss on top. Remind me again, who needs tiop end on a 490 ? I also modified the forks, as those were the days of negative travel. I moved the springs around and went from 9" or travel back to 12 like it was supposed to have. Maico really screwed up those forks. I was told my 490 was better than the factory units. I should have got Ohlins rear shocks but had Works instead. Oh yea, and I went down one size on the pilot jet to get rid of the small uncontrolable low range hit. Too many open bikes were overjetted and too hard to ride. My 490 was a pussycat to ride, but coudl also be a tiger. "The easiest open bike I've ever ridden" I was told a few times.
    In any case, I'll keep an eye out for a Bonne or Norton test ride here in TN.

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