Thread: timing question
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Old 12-16-2009, 04:30 PM
Athedra Athedra is offline
XStremely XSive
Join Date: Oct 2009
Location: Benoni, South Africa
Posts: 221
Hear what you are saying, but have you considered fuel starvation?

Have a look at your petcocks and tank filters. Once you are happy with your fuel supply, then check you vacuum advance.

I am working on my knowledge of the 2H9 here, where you should have a 39 degree on 5000 rpm. I found the big bore motor to be the same. Just put your bike on an electronic tach/dwell tester. (About R200 at Midas (about $20)) and test it like that. If you are happy with you idling dwell (Think it was 10 degrees, but not sure) then have a look at your Coils and HT leads. The tach/dwell I got hold of tests everything from ohms (to test your coils) right up to volts. I paid R200 for mine, and can test eveything from Volt supply to my coils to my actual revs and dwell angle).

You might even have the wrong heat range plugs in there. Over here we use NGK BP6ES, but saw a few guys mistakenly putting in BP6ERS which is a higher resistance plug used for Racing (as far as I understand it). If I am not mistaken, it is shorter, resulting in your sparkplug not reaching into the actual chamber.

The other possibility is a stuck choke. See if your choke isn't stuck. Had that on my previous set of carbs where the holding screws was loose, and the choke lever closed, but not the actual chokes on the carbs. This will however result in over fueling, giving you a similar result. While we are on the over fueling part, what filters do you have on there? A while ago, we discussed cones (pods) with a broad inner lip closing the jets. It will be as if you close the carbs at the back with your hand (Choking it).

Just a thought...........
'79 XS1100 (2H9) named Bones
1196 Big Bore
4-1 Cowley exhaust
750FD Conversion
Echlin 54mm Racing Cones (Americanese = pods)
Black Ebony Bottled glazed Tank (To be redone now)
BMX footpegs
Tank internally lined (Professionally this time)
GSX400 Throttle bodies (Under serious investigation)
Anti Sticky float bowl system
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