Safe max revs between gears...

[Nige W]

Hi all.

Got in a quick run on the Arrow this afternoon and, now I've put over 100 miles on it since buying, started to wind it up a bit more. The thing is that without a tacho, I really don't know how many revs it's doing.

Looking at the gear ratios, and gleaning from the original handbook that each 1000rpm = 11mph in top, I've kind of worked out that 6,500rpm (where it's supposed to produce max bhp) equates to 22, 38 and 52mph in 1st, 2nd and 3rd gears respectively.

Can anyone please advise safe rev limit on this engine in standard tune and (if significantly different to my figures) max speed in gears before changing up.

I'm presuming that the engine will rev higher as, according to period tuning articles, the bike can run to 100mph on standard gearing when tuned.

Thanks,

Nige

Attached pic of the bike this afternoon on one of my favourite back roads near Harewood House.

[Michael.Brown]

Hi Nige,

I believe the maximum safe limit for revs for a std Leader or Arrow would be 7000 rpm.

As to when you should change up, I prefer to listen to the engine note, rather than try and calculate what the max would be.

Is yours a 200, or 250? I can see it has high compression heads which will give it a little more power.

There is an old saying that says when riding older machines, 2/3 of the maximum speed it would have been capable of when new is plenty and safest if you want to avoid mechanical failures, but you are right when tuned they can be very quick.

I am sure there will be more knowledgeable replies in due course.

Mike

[Nige W]

Hi Mike - thanks for the info. The bike is a 250.

7000 would sound a reasonable max revs figure for a standard road engine, as max power is at 6500. I wonder what revs a tuned one would be running at then?

Though I have (much!) faster bikes in the garage, I do enjoy getting the most out of smaller bikes and so would be looking to get at least three-thirds out of this one, lol.

[Michael.Brown]

Hi Nige,

Good luck with that one, let us know how you get on.

Mike

[bh.sprint]

Hello,

Most of the literature on the Arrow and Leader say the engine with the 10-1 heads revs to 7000 rpm. I have rev counters on both the Leaders and the Arrow and 7000 seems the max the engine will go to but out of respect for the engines I normally set 6000 ish as a max figure.
The tuned bike belonging to one of the two stroke tuners at Mallory was reaching near to 100 mph on the straight and reving near to 10,000 rpm.

Brian H.

[Nige W]

Thanks for the info Brian. 10,000!

[bh.sprint]

Hello,

Re the fast Ariel Arrow, from a distance it looks like a normal Sports Arrow with a slightly larger carb but in front of the rider is a large rev counter going up to 10,000 revs. The charges to the ports are all hidden inside the engine but Ron really knows what he is doing with two stroke tuning.

Brian H.