fast ariel 500

[wetdog]

im board so have decided to see how fast I can get a iron 500 ariel to go (I have a lot of spares) any one experience of the best way to go , which they have tried , I have read tuning for speed so looking for other information , the frame is ridged with girder forks alloy rims etc and I want to keep it on petrol for now

[Bomber]

Is it a twin or a single?...

I'm doing the same with an ES2 motor. I have managed to get a cast alloy barrel and I picked up a new off the shelf Alfin alloy head from the good old US of A for peanuts. I've opened up the throat from 28mm to 34mm and fitted Goldie valves which are much larger than original. Fitted a liner and bored the barrel to take an Alpha Romeo piston which takes it up to about 620cc and lightened all the tappet gear. I need to make a new steel crank or buy one as the standard flies apart if over revved and I also need some better cams, not sure which way to progress as of yet.

Good luck with the Ariel, it will be interesting to see!

[wink]

Hartley ariel parts, eg cams were also made at De Havillands. I didnīt say that either.

[wetdog]

its a single , steel flywheel and all iron single lobe cam (scrambles i think) bigger valves , polished rocker gear etc Ariel must be one of the simpler british singles but some people made them go very well , but i still want it rideable on the road .

[R]

im board so have decided to see how fast I can get a iron 500 ariel to go (I have a lot of spares) any one experience of the best way to go , which they have tried , I have read tuning for speed so looking for other information , the frame is ridged with girder forks alloy rims etc and I want to keep it on petrol for now

Best way to go for speed = down !
Bigger engine sprocket, and down a long steep hill ?!

Didn't someone say that Ariels were very similar to JAP speedway engines in the top end ?
JAP cam timing, maybe ?
You already have a lumpy top piston in it ?
No substitute for compression - although the iron will limit that somewhat.  E10 helps ?

[33d6]

It's all about the power/weight ratio. You can either add power or reduce weight for the same performance increase. Reducing weight is by far the cheaper option and makes for a more agile, responsive and better handling bike.
Before I even thought about engine modifications I'd be making sure the frame and forks were straight and working how they should plus the wheels balanced, brakes not binding, chain sprockets in line, etc so rolling resistance is absolutely at a minimum. After that comes the weight reduction program.
About the only thing I'd automatically do to the engine of a girder fork Ariel is fit a big bore oil pump. Ariels slowly increased the oil pump bore over the life of their singles and I'd make sure I had the last and biggest size fitted. Its a standard part and just replaces the earlier ones. No drama.
Cheers,

[R]

Weight reduction makes it quicker, not faster ?
Useful advice though.
Not eating breakfast helps - a little... !

What spec is this Ariel ? 
The Red Hunters were quite strong in the performance dept ?

[wetdog]

"Ariels slowly increased the oil pump bore over the life of their singles" .............. I did notice this as I have a few pumps , why did they feel the need ? on another ariel I have I have fitted a smaller delivery side pump as to much oil was getting to the top end and no standard way of regulating , the engine was a standard RH , I will be trying to shave the weight by throwing most parts off but it will still need lights . comp is about 8to1 which I will leave for now , and running 32mm amal with inlet opened to suit , cam is one piece all iron single lobe and I have never tried this cam , but its the most tuned ariel cam I have

[Bomber]

Yes I agree, probably the best and cheapest way for me to make any bike faster is to lose 4 stones

[wetdog]

ive give up on that idea as I like real ale to much , I do have faster more powerful bikes but find I have ariel parts everywhere , the front end ive used is military nos Bsa , did fit webs but took out for a velo , frame is good and straight have several tanks but may make one to fit between top tubes (like a wedge of cheese ) I have seen this done before and told it held about 1and half gallon , we will see

[wetdog]

im told these do fast ariel cams , are they still trading ?, the number i have is constant answer phone
Joy Engineering Motorcycle Camshaft Specialist - Motorbike Parts in Bishop's Stortford CM22 7BS
also been told to drop the cam follower spindle by 1/16 (new one for me) not sure why so may just turn a ofset spindle up for now

[33d6]

I'm not sure what you mean by a standard RH model. Ariel made a VH,NH & LH but no RH that I know of.
The single lobe cam was standard fitment to all the old single cylinder range from 1950. Various grinds were available of course but there's nothing exotic about it being a single lobe. Its major virtue is that it allows for much wider and thus slower wearing cam followers than did the previous two cam arrangement with narrow followers.
Ariel provided various methods over the years of regulating the oil flow to the rockers. In the past I've come across owners trying to run a mixture of parts and having bother. It could be difficult convincing them that buying a manual and following the instructions is a wise way to go.
Finally, of course Ariel found a need to fit bigger bore oil pumps over the years. As roads and suspension systems were improved bikes were cruised at faster speeds and for longer distances without a stop. Oil both lubricates and cools and the extra cooling from the greater flow rate became more and more necessary. Ariel were not alone in this, other makes did exactly the same thing. Matchless/AJS are the most obvious example. They doubled the speed of the oil pump on their singles around 1946/7. Norton did much the same.
Cheers,

[Rex]

RH....Red Hunter?

[wetdog]

"but no RH that I know of".............. theres two lyeing here ........... I have removed the twin lobe A7 cam so I am now using the forked follower and single lobe cam , but this one has a very high and steep lift , its one piece (unlike most which are two) and I understand it to be a scrambles cam , inlet and exh valves are 1and 13/16 which I shall leave for now , the engine will be finished today and im going to put it in my ariel rat for now just to see if its any good (for me the chassis will take the time) on this engine I can see no way of regulating the flow to the top end which is via external pipe off front of cam chest , I have fitted valve seals as think the more oil goes up there the better as it lubricates the cam and followers

[33d6]

As far as I'm aware for a time prewar Ariel used the letters RH on the timing case to show a particular model was from the sporting VH, LH or NH Red Hunter range. The numbers 250 and 500 refer to engine size.  As you can imagine swapping the standard timing case for an RH one was a sneaky way of claiming you had a top of the range bike and not the bread and butter version or impressing everyone with your really fast 250 which was really a 350.
You get the picture. Having an RH outer timing case fitted is no guarantee as to what the engine is. Given the easy interchangeability of Ariel parts the only way you can do that is to strip it down and check. For example you can't see what type of main bearings are fitted without pulling the flywheels out and Ariel made a point of specifying a heavier duty bearing for the Red Hunter than they did for the standard engine.
All of the above makes discussing your engine rather vague as we don't really know what it is. Not that this matters much as I'm sure you'll have fun with the finished article and as it won't be ridden fast and far it should hang together okay.