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General => Douglas Motorcycles - General Discussion => Topic started by: PhilEW on 09 Apr 2021 at 11:52

Title: Valve timing EW 1926
Post by: PhilEW on 09 Apr 2021 at 11:52
Hello,

Can someone confirm that this arrangement is good, the key faces the rear cylinder (dot on the gear).

(https://nsa40.casimages.com/img/2021/04/09/210409015919944524.jpg) (https://www.casimages.com/i/210409015919944524.jpg.html)
Title: Re: Valve timing EW 1926
Post by: Doug on 09 Apr 2021 at 12:45
According to the handbook, with the key to the rear cylinder the cam lobes should be on the tappets for the front cylinder.
See this post:

https://www.douglasmotorcycles.net/index.php?topic=6035.msg22233#msg22233 (https://www.douglasmotorcycles.net/index.php?topic=6035.msg22233#msg22233)

-Doug
Title: Re: Valve timing EW 1926
Post by: Paul H on 09 Apr 2021 at 14:27
Hi PhilEW,
I have just retimed my cams after regrinding them. The valves are timed at top dead centre. On my EW600 the pistons are at top dead centre when the key is facing forward but some models may have the key reward at TDC. This is the place to set the timing when the valves are rocking from exhaust to inlet on the front cylinder.
Paul.
Title: Re: Valve timing EW 1926
Post by: cardan on 09 Apr 2021 at 22:20
Can someone confirm that this arrangement is good, the key faces the rear cylinder (dot on the gear).

Hi Phil,

Keys and timing marks are good things to talk about on a new - or nearly new - engine, but one something pushing 100 years old it's best to ignore them entirely. If they line up where they should, excellent, if not parts have possibly been changed or altered.

Your photo at the top looks good is the rear cylinder is at top dead centre, but no promises about the mag!

My suggestion would be to put a pointer at the top of the flywheel, and put a mark with a texta pen at TDC. Then, for each cylinder, check where each valve opens and closes: the chart Doug links to says inlet opens 15 degrees before TDC, exhaust closes 15 degrees after. In your pic, the exhaust is just closing and the inlet just opening - in an old engine this is usually roughly symmetric about TDC. (Amazingly, in some old engines the inlet didn't open until maybe 10 or 15 degrees after TDC!) If you rotate the engine forwards through one complete turn you should have much the same opening/closing pattern of valves at TDC on the other cylinder.

If the inlet opens/exhaust closes is OK for both cylinders you should be right. You can check where inlet closes and exhaust opens, but there's not too much you can do if they'e wrong due to wear/old age/wrong parts.

Looks like there is some vernier adjustment with the three keyways on the half time pinion? You might be able to get better valve timing, even if your marks no longer align.

Leon
Title: Re: Valve timing EW 1926
Post by: PhilEW on 10 Apr 2021 at 15:44
Thank you for your helpfull replies, i will look at this carefully as soon as possible.

Philippe
Title: Re: Valve timing EW 1926
Post by: PhilEW on 31 May 2021 at 09:28
Finally, the timing of the camshafts was right, but the ignition timing wrong, too much advance. As i did not want to remove the magneto gear, I removed the upper camshaft axle, the gear on crankshaft and could turn the magneto gear. One tooth of difference and it was right.

The bike now starts and runs well.

Thank you for your help.