Timing tool for narrowcase

[new kid on the block]

Hello once again!

Work's been continuing on the monza for a while now and everything's come together to getting it started now.

My ignition circuit seems to be working spot on, a very strong spark. The carb is in place (although mine's a UB22 but it's had a blanking screw where i believe the choke cable should go in).The fuel lines are hooked up to a dummy tank. Compression is very strong.

All in all, key components all there. Anyway, when i kick it over all I'm getting is a backfire through the carb. This leads me to believe that my ignition is too advanced so it's firing before the intake valves are closed. I have a workshop manual and it shows a potractor like tool to mount on the end of the crank to setup the points.

I've looked on most of the usual sites and couldn't find one, somone on bevelheads pointed me to one on australian ebay but it was about £80 which i think is a bit steep. Anyone know anywhere that stocks them that dosen't cost so much? I was considering trying to make one from a plastic drawing protractor and machinig up something that'll get it to fit in that tang on the crank.

Sorry for the long post but cheers for any help

[crm114]

Race spares

Bevel Heaven - Detail

[new kid on the block]

Thanks for the links there, after looking into it I think my valve timing's out by a tooth or two. I think the previous owner must have had it apart and assembled it incorrectly. I'll need to correct this before I get onto ignition timing again.

[DesmoDog]

Confirm that it's wrong before you reset it... on the roundcase engines anyway it wasn't uncommon for improvements to be had by timing the cams with a degre wheel rather than blindly trusting the timing marks.

[new kid on the block]

Originally Posted by DesmoDog

Confirm that it's wrong before you reset it... on the roundcase engines anyway it wasn't uncommon for improvements to be had by timing the cams with a degre wheel rather than blindly trusting the timing marks.

How would I confirm this? Basically the issue is, i've been attempting to start it and the bike's just backfiring through the carb. Fuel's getting in because the sparkplug gets wet. The spark is strong, my initial though was that the ignition timing was too advanced.

After speaking to a few people they suggested that the valve timing was out, this lead me to look at the timing marks. The timing marks on the top bevels line up once (every 6 turns i think?), but when the teeth on the top bevels engage(I am yet to check the lower pair) the piston is still a good few milimeters from the top of it's travel.

When the piston is at TDC the teeth with the marks are disengaged.

My next path of investigation is to get the points/oil pump cover off and see if the lower bevel pair are correctly aligned.

[machten]

My next path of investigation is to get the points/oil pump cover off and see if the lower bevel pair are correctly aligned.

That's the right course of action. If they don't line up as they should, then either it is an assembly error, or as DesmoDog mentions, maybe someone has been seeking to improve the cam timing. A few of us are soon to experiment with this on a 750 Sport by at least taking some measurements. There is an excellent article by Peter Shearman on this for bevel twins here (not sure of the direct relevance to singles, but I would think the theory is applicable) :

Cam timing - Ducati Up North

It took me a bit of time and some pencil and paper to get my head around, but I found it pretty interesting stuff.

Kev

[DesmoDog]

Are you on the bevelheads list? This was just discussed there... or maybe I"m just haveing a case of deja vu!

The dots don't line up at TDC. At least they didn't on the last bevel I rebuilt.

To check everything requires a degree wheel and in the case of timing the cam, a dial indicator.

In thinking about it... checking the cam timing is probably overkill for where you're at. Just making sure the dots line up is probably good enough for now? Setting everythign to factory specs may not be optimum but it should get it running.

Unless the cam has been switched with one that has different indexing on the keyway, but for a single that's unlikely. (On a roundcase it is much more likely, as sqyuarecase cams fit but don't have the same indexing)

This is the site I used for info on cam timing when I did my roundcase:
http://www.docv.org/index.php/techni...vels-and-older

I think the articles are mostly written for twins but he same ideas apply to the singles.

[new kid on the block]

Cheers for the info DD, yeah, that was my post on the bevelheads list too.

Basically, I spoke to a guy who works in a ducati shop not far from me on the matter because I was concerned about it and he seemed to think that the dots should line up when the piston is at TDC.

I'm fairly sure that the cam timing is out because it just backfires out of the intake every time. Surley this means that the intake valves are still open when it's firing, well that or it's sparking early?

[new kid on the block]

She runs!!!!

I spent half the day with the inspection covers off, got all the dots lining up, put it all back together. I started kicking it over but was to no avail, so i tried some easy start spray, started straight up. This week i'm going to be rebuilding the carb as it's full of rubbish then hopfully it'll run propely.