The KHA restoration starts (slowly)

[paul.jameson]

The bike today successfully completed the run for the Gloucester Branch barbecue so it is completed, as far as I am concerned. That said, there are a number of oil leaks to sort out including (probably inevitably) one from the left side hydraulic rear damper. The right side one seems ok so my plan is to fill the left side one with oil before a run, the same as the original trials riders did, for the rest of the year and have a closer look next winter. The carb is a problem, probably due to distortion in the body making it run very rich just above tickover. With any reasonable throttle opening the bike runs fine and the plug colour isn't bad but just off tickover we get black smoke. The (chronometric) speedo saw fit to go to 120mph on the way home so it needs an overhaul. I can only cope with the PA type so do we have a recommendation of someone good with chronometrics?

[robjameson]

Remind me about the speedo restoration when I see you. I had my KH speedo done by a guy who received it on the Monday and I collected it from the post office the same Saturday, having missed the scheduled delivery Thursday. Was only £80 too.

[david.anderson]

Paul
The speedo skipping up to 120 and staying there can be a speedo cable problem if the inner does not engage correctly in the speedo. A lose speedo cable ferule can be the culprit. It has happened to me on two separate occasions over the years.
David

[charles.bulloch]

A. E. Pople is very good, http://www.speedorepairs.co.uk/

[keith.mettam]

Hi Paul,
Not wishing to teach such an experienced Arielist as yourself to suck eggs but just a thought about your carburetion issue. If you are happy that the fuel level and Pilot Jet are both fine then perhaps try a slide with more cutaway ? I had the same problem, albeit with a monobloc carb, on my late NH single after fitting a high comp piston and HS Mk1 cam. A little research revealed that the slide cutaway was likely to be the issue if the fuel level and Pilot Jet were ok. Not wanting to pay for a new slide without proving it first (and wishing to keep the old one) and having checked the fuel level was correct and finding I couldn't successfully adjust it out with the Pilot Air Screw (also dropped the needle a notch to no avail), I had a spare 3.5 monbloc slide which I carefully modified into a number 4 cutaway. Each full step on an Amal slide is 1/16" with a half step being 1/32" etc. so a 3.5 slide has a cutaway height of 7/32" and a no.4 would have a cutaway height of 1/4". With a bit of careful measuring, scribing and removing metal with a half round file then finishing with fine wet and dry paper I was happy with the end result. Thoroughly washed it off in petrol then lubricated it with some WD40 and fitted it to the carb. Tested it to find that it had cured that puff of black smoke as the carb goes off tickover making me a very happy bunny. Note I did find that, presumably, due to manufacturing differences when comparing both slides and cutaway measurements they are not 100% accurate but I don't think this really matters very much in the greater scheme of things when you are looking to increase the cutaway to weaken that area off a bit. I did make sure that I ended up with 1/4" cutaway height carefully curving each side down to the starting point of the original cutaway each side. Very pleased it cured my problem and the bike runs really well.

No. 3.5 Monobloc slide.

No 3.5 slide modified to a no. 4 cutaway.

As can be seen from the first image, a 3.5 cutaway is 7/32" which in metric should be 5.55mm not the 5.8mm it actually measured ( manufacturing difference ?).

[paul.jameson]

Thanks for that Keith. I will try it if the current attempt at a cure doesn't work. This works on the idea that the jet block is not a tight fit in the somewhat distorted carb body so I have swopped it into a better one but not yet been able to try it out. The thought is that petrol may well have been leaking round the jet block to richen the mixture. The bore of the old carb body measures 1/16 " difference between vertical and horizontal !

[paul.jameson]

First trip out on the KHA this year. The leak on the left side rear damper is reducing which is good. David Anderson's trick with the speedo cable worked really well so that is sorted. One new problem is poor fuel flow. I have cleaned out the breather hole in the filler cap since I got back home and it wasn't that so either the tap isn't opening far enough or there is some sort of blockage somewhere. The new carb body has improved matters no end but I may well be trying Keith's modifications if the fuel flow problem cure doesn't solve the rough low revs running. But it is an awful lot better then it was.

Photo taken at the top of Ankerdine Hill with the Malvern Hills (home) in the background.

[chris.shearwood]

Both the bike and the countryside look very appealing!

[david.anderson]

Paul
Warping of amal carbs is always a problem, sometimes resulting in sticking slides or sucking air and altering the tune. John Healey cam up with a way to straighten them which is quite simple. See this link and click on the youtube video which will show the process as well as the tool to do the job which is pictured 2 posts further down the thread . It works for side bowl, monoblock and concentric carbs. as you press the distortion from the flanges it also removes distortion from other parts of the carb.
https://www.accessnorton.com/NortonComm ... mal.31089/
Also as you ride the bike a ride report on the hydraulic rear damping compared to normal anstey would be appreciated.
Your bike looks great
David

[Ian.Taylor]

WOW Nice job on the KHA Paul.