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Rob's WD16H and Big4 Forum

Dutch army, Johan Herman Fuhler, somewhere between 1945 and 1950

Rob's WD16H and Big4 Forum
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16H over heating

Hi i have just finished rebuilding a WD16H however the engine seems to be running very hot. I just wondered if anyone has had this problem or if any one could point me in the right direction so I could investigate the problem. Thanks AJB

Re: 16H over heating

What sort of machines are you used to Alan ? Side-valves do run hot and the 16H is no exception.

What are the symptoms ? Has it been re-bored ?

Re: 16H over heating

Alan,
Good to hear there is one more 16H back on the road.
Sidevalves do run very hot around the exhaust valve - to do with the tortuous gas flow.
As long as you have the cam timing, ignition timing and carb settings sorted then it may just be normal?
I found that the pin marks on my cams were wrong so it does pay to check the cam timing when assembling.
Do you have any specific symptoms that the mechanics on here can work with? Plus info like new carb or old etc.
Iain.
oops two at once

Re: 16H over heating

Hi Rik, It is the first side valve I have restored, its just that it seems exceptionaly hot. I thought may be the ignition timming was running retarded but I have checked it and it is 7/16 BTDC fully advanced. I set the timing with a cigaret paper.

Re: 16H over heating

Hi IainB. There are no pin markings on the timing gears so I have set them as you explained on my earlier posting, both valves about 2mm open at TDC. The ignition timing is set at7/16" fully advanced BTDC. I set it with a cigaret paper, I was wondering if it is running to retarded? The carb is old but I have fitted new jets and needles. It has not been rebored but I have fitted a new piston, the bore is OK.

Re: 16H over heating

All these engines are different but I find that if I time mine as per the book (to the best of my ability with a fag-paper), it runs best with the timing backed off slightly from the full advance position.

I've also tried the alternative technique of timing on full retard at TDC and this gave similar but more extreme results.

If yours runs best with the wire fully tight (assuming it's all standard) then I'd suspect that you may be able to advance the timing a little.

You have presumably got new rings so it will be a little tight and new paint burning makes things smell worse than they are. There is also the aspect that modern fuel can burn hotter but we have to live with that.

If it's not blistering the spark plug or losing power then there probably isn't a problem (which is all very easy to say over the internet ! )

Re: 16H over heating

My cams had no marks and I didn't mark them when I took them out. I think we can be a bit more precise with the valve timing. The inlet should open at 5/16" or 27-30 deg BEFORE TDC and the Exhaust closes at 5/16" or 27-30 deg AFTER TDC making them at equal positions at TDC. This was easy to do with a dergree disc or I'm sure just as easy with a measuring rod in the bore with TDC and 5/16" positions marked.

It's right to the book and the pictures I took before stripping although I haven't run the engine yet. Here's a picture with the piston at TDC making the keyway of the timing pinion on the botton.

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Re: 16H over heating

Thanks Rik I think I will run the bike ie down to the MOT station then see what its like. Mag is standard and has been rewound and new bearings, if it still appears to run hot after a couple of days I may try advancing it a bit. JB

Re: 16H over heating

Hi Horror

I originaly set mine to the book using a disk and dial indicator on the push rods. However it depends on how you interperate the book, is it 27/30 degrees at start of opening on the cam or valve, it makes a big difference, starting to open - just open or open, and the reverse on the exhaust.JB

Re: 16H over heating

Hi Alan,

I know what you mean, but there would be no point in having those reference points if the valve was already open or closed. They are the degrees when the inlet valve is just about to open and the exhaust valve has finished closing. If they are in any other position you get the exhaust valve open on the down stroke which would be sucking in and the inlet valve still open when the piston is on the up stroke, which would be blowing back through the carb, probably blowing petrol out.

At TDC on the compression stroke both cams are in the same position without being under load and it may be possible to set the valve timing in this position with the barrels on if the tappet guide rods can move high enough to remove the cam. This is also the position show in the WD manual.

I hope this helps


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