Monday, 11 October 2010

Ariel HS Engine build up #1.

I have been working on a Ariel HS engine this weekend. Been meaning to do it for a long time........and now I have some plans for it.........

Ariel HS, made from 1954 to 1958. HS stand for Hunter Scramble, Ariels moto cross model. It`s a 500 cc push rod single with aluminum head and cylinder.

This is howe a HS engine look like.......

Now I need a fast engine.........Well, they where fast fifty years ago....
Some of the work was done years ago.....


The crank needed a good wash and polish....The big end bearing and small end bush had to be replaced.

This engine had only ball main bearings (3). I use two rollers and one ball bearing. Takes some time to shim up the crankshaft.

I have got an new liner in the cylinder so it`s back to standard (81,8 mm).

The pistons from left to right: HT (trail), VH standard, HS high comp.

I used the high comp one.....

                               NOS Hepolite piston rings, comes with warranty slip.

                               Filed the gaps to racing spec......

The important cam shaft. Ariel singles use only one single lobe (from 1951) for both valves.

The left one are HS MK1 the right are VH standard.

The difference:
Apart from the grinding the HS cam have a hole down the centre of the shaft and a smaller hole through the base of the cam.

You can use the HS cam with standard cam followers, but I will use the HS type for more performance.

A good start..........Have to order some bits from Dragonfly motorcycles.


Anonymous said...


Could you please provide valve lifts and timings for HS MK1 cams?

Many thanks,

Beveldrive said...

HI Karol, I have the info somewhere....You want the BTDC etc?
Regards, Stig

Anonymous said...

hi your hs build up is great,im picking up a bitsa hs this weekend ill be checking the cam,to make shore it looks like your one.will you be posting more photos, on your hs engine build,what you have done is grate regards greg.