What's the highest speed for a VH

[Les H]

Slightly difficult, perhaps, to answer this one but what would you say is a "natural-easy going" best top speed for a VH? I mean there is always a speed that a motorbike feels happy at, top speed-wise and a point that it seems to start getting harsher and vibrates to a point that seems you are stressing it too much. last night I took my recently acquired VH out on the deserted roads and gave it some "stick". It gets to 60MPH very easily but 70MPH sitting upright seems to be thrashing it a little. I feel it would get into the low eighties if in the crouch position but I can't imagine it would last long at those revs. Then again maybe it was just my nervousness of an unknown engine staying together, What do others feel regarding a VH's ability to hold high speed, commensurate with not too much vibration?

[dave.owen]

Les, while a VH is a fast bike,top speed doesn't matter. On my 52 plunger VH comfortable speed 2 up is 60-65mph, it will go faster but not as enjoyable.

Dave

[Les H]

Hi Dave, that's the info I was after. I was wondering at what speed the engine was letting you know it was working hard even though in reality it might produce more power if you held the throttle open and just waited to see what it topped out at. As said, it's not an easy answer, but some bikes can whistle up to say 70MPH and you feel you have plenty more and the engine will oblige. Yesterday evening I let it get up to just under 70 at about half to 2/3 throttle, but pushing it more I thought I would damage the engine due to the fact it sounded very busy and the vibes were getting quite strong. I suppose that's the limiting factor. If it was really smooth I would have pressed on with adding more gas, but I had the impression there was a heavier than standard, slug of a piston, whacking up and down out of balance and creating too many vibes. I suppose only a direct comparison with a perfect VH is going to let me know the answer to my question, but anyway, I'm still interested to enjoy what other owners say as regards their bikes performance. Cheers Dave

[nevhunter]

Your top speed depends on the engine's power and having the suitable gearing. The frontal area of you and the bike matter too and to a lesser extent the weight. A good VH should do about 84 MPH with about 25 horsepower. I had a Rudge Ulster 1937 that would do the ton as well as a Velo Venom that would do the same. Mates international Nortons did a genuine 100 with 33 HP'. Vibration feels bad and may be wrong balance factor and /or poor crankshaft alignment. Lighter pistons and conrods make a better result likely and shorter stroke also helps.. Hope that's relevant to your question. Nev

[Dave.Barkshire]

My VH doesn't have a speedo so I don't know. I would guess most cruising might be in the 50-55mph zone.

Engines all vibrate differently and there are happy and unhappy zones in the rev range. Rev the nuts off an antique bike and you might damage it, best buy a Honda for that sort of thing and keep the Ariel for more relaxed duties.

[Les H]

Thanks for your replies. Yes, not really a good question as its difficult to really put over what I meant. If I think more of what I was trying to say, it was really more like: At what speed do you think the vibrations of the engine start to manifest themselves as becoming excessive making you feel the engine is starting to get "thrashed"? Perhaps in reality it isn't. Hopefully you can see what I mean. Say the engine was totally vibration free but identical to what you have power-wise. You could just open the throttle and let the speed build up to its end point which obviously is going to vary depending on road gradient and wind resistance. ..Whatever the top speed, you would feel you weren't doing the engine much harm. However if the very same engine had a lot of vibration at say 5000 RPM of its 6000 RPM limit, you would feel that getting to the top speed was pushing the engine very much harder, and of course vibration IS stressing the engine more. So, what I was asking was: Does the VH run up to its terminal top speed fuss free or do you have a little too much vibration that's somehow saying "enough is enough... don't push me anymore, even though I can go faster" (yes I know engines can't speak) but you know what I mean. Boiling it down even more, perhaps I should be asking "Is the engine relatively vibration free at top speed"...Yes that's easier and clearer. So in my case, my engine, I would say, IS NOT that smooth. ..probably because it has a heavy replacement piston and not re-balanced. Then again, it MIGHT vibrate no more than an engine as sold from new?
Only direct comparisons would reveal this. Thanks for reading

[nevhunter]

Balance feel is not a good indication of how the engine will "kill" itself to any great extent. I used to do a lot of balancing professionally and one rider who was brought up on Honda farm bikes, I had to tell him he was going to wreck his old bike if he didn't get it into top gear earlier and stop revving the guts out of it. He said but it's smooth and feels like it can take it..WRONG!
I've never been an engine revver. er..well lets say I realised early that it would be costly if I kept doing it when the valves on my ZA7 BSA kept getting bent. and the timing side main didn't last long.. I have NEVER blown an engine up because firstly the engines are not run hard IF they are not fully overhauled and checked over. Secondly REVS are what kills them. I've seen riders who ruin a VH big end in less than 10,000 miles and another who inherited his fathers 39 VH and it did 100,000 miles before the bottom end had to be done. A good average life in their day was above 30,000 miles, BUT people rode them to work on poor roads and were a lot easier on them back then than many rallyists are today on more modern roads. I hope this is more help. A VH gets it's full power at 6,000 revs.dynamic forces increase as the square of the Revs so if you only do 4,000 rpm it's 16 units against 6x6= 36 at 6.000 RPM. Well under 1/2 the load. Another factor is old parts are somewhat fatigued often and are more likely to break than "Younger " motors. Nev

[john.nash]

According to the 1950 roadtest , by Motorcycling, the top speed is a whopping 86mph.

Blimey.

[Les H]

Thanks very much Nev, very interesting. I suppose I still have that teenage urge to find out what any motorbike I own will get to, top speed wise. I don't do that on a regular basis (it would be illegal anyway apart from my smaller engine bikes) You have to remember though, you can get into top gear by not revving the bike very much and top gear is usually over-geared by quite a bit so even testing for top speed wouldn't mean you were really thrashing the engine to valve bounce at any time. I consider any GOOD engine should have a big end size and strength commensurate with being able to hold it's top gear speed for a decent amount of time (note I'm not saying maximum power revs). Take the Velocette Venom that did 100MPH for 24 hours, as far as I know it wasn't shredded at the end of it, but obviously more worn than doing 24 hours at 60MPH. I would say taking a VH to its top speed occasionally (conditions permitting) is OK once in a while and to repeat, it would not be screaming the engine at its maximum rated RPM of 6000RPM . I find it amusing that owners put in sportier cams, higher compression pistons if the bike can reach 77MPH (max legal limit) in standard form. It will simply mean they reach that speed with less of a throttle opening, but they had that speed capability anyway, it just needed a bigger throttle setting. I would concede that the maximum legal speed can be obtained more quickly though which is obviously very nice and hill climbing ability improved too, but did they ever attempt that hill with full throttle anyway? Having spurned that tuning passion, I'll admit to doing the same thing too, hoping that my VH has a high comp piston and Mk3 HS cams already fitted. Maybe its just fun or maybe its just nice to have that extra urge at hand. It is surely a male psychological thing I'll answer my own question now (maybe I did already earlier?) but 70MPH seems the highest continuous speed I would ever let my bike cruise at, its just too busy and vibrates too much to exceed that.

[nevhunter]

One of the real issues is, can the engine get rid of the heat at continuous high power outputs? With an all cast iron motor this becomes debateable unless running on alcohol. A good alloy head helps when fitted but many are too soft, stripping threads and having Valve Guides and sometimes inserts, come loose. The Velocette has a narrow crankcase and a good oil pump and is a fairly "quality" engine. Bottom end rigidity is essential for high revs and low vibration. Crankshaft runout under deflection of high rev loads will vibrate and maybe fail. Built up cranks are generally not as strong as solid ones can be but permit rollers to be used in the big end. A traditional lay out for singles and Vee Twins..I like my engines to be smooth and not peaky. To want to go and not be nasty at low speeds and starting and have torque over a good range and fairly heavy flywheels . I'd only lighten for out and out acceleration through the gears.. Nortons tend to get this right in their road singles, both OHV and SV. Nev