Two speeder will not hold high gear and air leaks

[Deleted User]

Hi all,

Besides a few other things my two speeder has one snag that I dislike the most. It will not hold high gear on it’s own unless I tighten the band around the quickthread drum to such a degree that it is really tight. And this makes no pleasant gearchange as I like the drum to be a lot less tight on low gear (gives a lot more feel while riding off).

I have fitted one of Lauries excellent made new quickthread drums. The two speed gear has been converted to needle/roller bearings and has no play. I also played around with different size rollers (the ones that wedge the rings apart) etc. The two speed gear is snag free and works fine. It is just that when I adjust the band a little less tight it will not hold high gear or just for a while before “jumping” out.

While at Abbotsholme last year I tried a few gear pedals and those all were a lot lighter in action than mine. Of course the gear has by design no positive means of keeping it locked other than the band on the drum. Maybe the travel of my pedal is to great or wrongly adjusted. I figure in low gear, even when fully heeled down, the drum should not run on the high spots of the thread? But I wonder if I could adjust the pedal in such a way while in high gear it would still “grab” enough of the high spot to keep it locked.

Any experience or ideas on this one? I cannot imagine to be the first one with this question… Hope my description is clear…

Cheers,
Erik

[Deleted User]

Hi Erik,

When Ken Lack had my gearbox I posed the same question. He thought that the tangs that make up the outer quick thread drum could be made less stiff by filing away at their inner corners. He did this for me while the mechanism was with him and it has made as big difference. I am trying to load a picture….

Are you going to Abbotsholme this year?

Best wishes,

James

[Deleted User]

Hi James,

Thanks for your picture

But, by making the drum less stiff you would still need to apply the same pressure with the band as before to lock it on the drum? Or am I thinking wrong here?

I regret to say that I most probably will not be able to make it to Abbotsholme this year. It simply is too expensive with the ferry and all. On the other hand I should go as I still have to collect my award from last year 😉

Cheers,
Erik

[Deleted User]

Mmmm…. should have posted this before… 😕 Did some adjusting before even posting this and took the bike out today for the first time after that. The pedal is now very light which makes riding off a lot easier. I holds high gear pretty well, did not jump out over 15 miles. Must be magic 😀

The new gaskets I made for the doors also hold well but the bike is still coughing through the carb while idling. I do not find it easy to get all the joints air tight. The fixture of the carb is hard to get tight. The Binks weighs a ton and despite supporting it with an extra bolt it works loose every few rides, the bracket slowly travelling upwards on de frame downtube.
And of course the engine leaks a bit at the cylinder holding down bolts. Last week I altered those by turning a groove and fitting an O-ring in that to seal on the inside of the bolt holes. This has improved the air tightness a fair bit but there is still a seep of oil here and there. Difficulty is that it is hard to see where precisely as the whole engine is a bit sticky (I am more of a rider than a polisher). But I know it is leaking somewhere as my LH boot must be very watertight now as it is constantly being coated with a mist of oil 😉

At least it does not leak at the glands, grinding those in really worked.

Ever since I got the bike I have been strugling with carburation. It now is quite ridable but coughs at idle speed, then pulls pretty good but is too rich at full throttle. The two jet Binks has very little room for adjusting. I am sure the bike will ride a lot better on a more modern AMAL but that would spoil the look..
But that is a whole different story 😉

Cheers,
Erik

[Anonymous]

Hi Erik,

There are 2 ways I use to search out leaks.

First is to clean the outside of the engine, take off the exhaust and blank out the ports in the barrel, put both pistons at mid stroke then fill the engine with petrol from the carb or plug holes, and it will seep out of any leak points.

The other way is to spray the running engine with soapy water and it will blow bubbles at any leak points.

Cheers,
Rich

[Deleted User]

Mmm, those are new methods to me. I knew of a variant of the second one but than spraying with petrol. When the motor picks up revs you have found the spot. But soapy water is a lot safer as petrol vapor is…. well we all know what could happen if not carefull ;o)

I will try one of the methods soon but I think I know the answer already: cylinder holding down bolts and carb fixture…

But thanks!

Cheers,
Erik

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