Author Topic: Neraly there....  (Read 245 times)

Offline PHILIP2908

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Neraly there....
« on: April 05, 2021, 03:37:49 PM »
Hello all,
The DK/DS Special is still fighting me like its done for the past 5 years.
I'm almost there, got insured (Motorcycle Direct of Bristol - £79 for an old fogey), its off SORN, new helmet but it still doesn't run properly.
Start up is instant but it pops and bangs through the 1-4 cylinder silencer and when revving it actually spits flame. Me thinking I've got the valve timing wrong and that the engine has to come out again. But a bit more investigation revealed that all the valve clearances had gone down to not very much; and on some there is no play at al.I remember that I set the clearances when it was on the bench and just a few start ups has settled the valves back in the seats and eliminating the gap - exhaust valve stays open and that's why I get flames... at least I hope that is what it is.
The question is: it is difficult, even when I had one in the 1980s, to get a feeler gauge in there, with a ring spanner and my fat fingers and a torch, so I was wondering if at least to get it running I could set the clearances by counting the number of turns on the screw?
I seem to remember a post, but can't find it, that one turn of the screw = 0.1mm or 40 thou. So from that perspective you should be able to set a gap fairly accurately even if not exactly.
A good idea or not?
1988 Mercedes Benz 300SL - Red - if you think Jap OEM parts are expensive, try a Merc
1974 Honda XL250 K0 - Silver - owned for 32 years. Not running at the moment
1972 Honda CB750 K2 - Flake Sunrise Orange - Ex USA, a DK special - needs a lot more work than I thought - very quickly becoming a DS special...
Previous Hondas: C100; C102; 2 x CD175 (slopers); CB175; 2 x C72; 3 x XL250; CB250 K2; CB250 G5; CX500; 2 x CB750

Offline K2-K6

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Re: Neraly there....
« Reply #1 on: April 05, 2021, 03:43:07 PM »
Yep, that would work to get it verified as having clearance on all valves.  Better than having any tight and staying open.

Variation is to set the touching and back out about 10 degrees with the engine hot to make sure there's absolutely a slight hot clearance.

Offline adespin

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Re: Neraly there....
« Reply #2 on: April 06, 2021, 08:56:08 PM »
 Popping and banging on 1 and 4 cylinders sounds like a duff capacitor, try swapping with 2-3 capacitor to see if the problem moves to those cylinders.
« Last Edit: April 07, 2021, 02:48:14 PM by adespin »
1971 cb750 K1


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