I would use premium fuel and your air cleaners. Needle in middle position and 180 or 190 main jets, depending on how noisy your "silencer" is.
289 carb settings
- Thread starter Hump3
- Start date
The premium fuel, at least in Australia, seems to burn cooler. That is what I've been told by the best Vincent engineer in the country. May not apply in the Untied States!
Even on the premium fuels now available, no more than about 8:1 compression ratio, otherwise you will have to back off the ignition timing to stop the engine pinging ( detonating ) Unless you run fuel additives to offset this. Unfortunately this is a trade off on all the older air cooled engines running hemispherical combustion chaimbers, so common years ago, but not combatable with the modern fuels of today......Cheers.....Greg.
If you experience a lot of spitting back through the carbs when cold ( not sure if you are running the original choke slides or not...??) and even if your slides have been sleeved or whatever.... you can still easily put the slides in the lathe and machine from say 20 to 30 thou off the bottom, then refit as per normal, and this will help fix the problem. I made up a soft alloy mandrel to slide neatly inside the slide so as not to crush the sides in the lathe chuck, and i generally take off 30 thou and refit.....air filters will always create some form of drag no matter how free breathing they "Look" and normally if you run them you may need to lean off the idle mixture a bit ( on 276/289 ) carbs, screw in is RICH and out is LEAN, and maybe drop the needle by one or two notches......Just do some spark plug colour checks after a good run.....let it cool off first though....!!!.......Greg.
[/QUOTE]I would be interested in hearing what other members run also. I assume we are talking about a standard motor, not big bore, hot cams etc..
Would not generally recommend running without filters though if you are going to use it regularly[/QUOTE]
Yes, it's a standard spec Shadow motor and the silencer is not of the spiral baffle variety.
Would not generally recommend running without filters though if you are going to use it regularly[/QUOTE]
Yes, it's a standard spec Shadow motor and the silencer is not of the spiral baffle variety.
Matthews Black Shadow with 8 to 1 pistons and. burgess straight thro muffler its only deviations from std except for D type coil ign continues to run beautifully on its original carbs , these fitted with 210 main jets . Usually a one kick starter with amazingly stable idling . Like Big Ben ticking over , never drops a beat . Strong running and very smooth . Used to belong to Ed Leksa , built by Allen Rennie who took me around the Works production stations and to the 1953 Rally in Coventry . Sid .
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289 jetblock fit to body
Another thing to look for on 289 type carbs is the fit of the jetblock in the body. It should be tight.
The idle circuit goes via the tickover adjust screw and through the body into the jetblock. If the jetblock is not round and a good fit into the body especially where the idle circuit holes are, air or fuel can leak around this area inside the body and cause starting / tickover problems. If your engine does not respond very well to tickover mixture adjustment setup and is not a easy starter (assuming everything else is ok) this is usually where the problem is.
I have a front carb which suffered this problem and in the end I replaced it. It was very difficult to measure if it was the body or jetblock that was the problem.
The only solution to this problem I can see is to replace the jetblock with a slightly oversize one to get the tight fit back or to sleeve the body to a tight fit with the jetblock. Unfortunately such jetblocks are not available so its make your own which is not easy. Sleeving the body to fit the jetblock could cause problems with the throttle slide.
Has anybody come up with a solution to this problem? (apart from buy a new carb).
Cheers
Simon
Another thing to look for on 289 type carbs is the fit of the jetblock in the body. It should be tight.
The idle circuit goes via the tickover adjust screw and through the body into the jetblock. If the jetblock is not round and a good fit into the body especially where the idle circuit holes are, air or fuel can leak around this area inside the body and cause starting / tickover problems. If your engine does not respond very well to tickover mixture adjustment setup and is not a easy starter (assuming everything else is ok) this is usually where the problem is.
I have a front carb which suffered this problem and in the end I replaced it. It was very difficult to measure if it was the body or jetblock that was the problem.
The only solution to this problem I can see is to replace the jetblock with a slightly oversize one to get the tight fit back or to sleeve the body to a tight fit with the jetblock. Unfortunately such jetblocks are not available so its make your own which is not easy. Sleeving the body to fit the jetblock could cause problems with the throttle slide.
Has anybody come up with a solution to this problem? (apart from buy a new carb).
Cheers
Simon
Simon,
Interesting observation that. I always use std carbs on my Vins and haven't personally been aware of any slack jet-blocks. That's not to say it can't happen of course. The only simple remedy I can think of is electroplating the brass jet-block exterior with fine jiggle wires through those pesky little holes to keep things clear.
Peter B
Bristol, UK.
Interesting observation that. I always use std carbs on my Vins and haven't personally been aware of any slack jet-blocks. That's not to say it can't happen of course. The only simple remedy I can think of is electroplating the brass jet-block exterior with fine jiggle wires through those pesky little holes to keep things clear.
Peter B
Bristol, UK.
Would it be remotely possible to machine a small groove around the hole and fit a small section fuel proof "O" ring in the groove and then reassemble using some lubricant to help stop the o ring from grabbing. The outer face of the o ring would only need to protrude a tiny bit, to help in sealing........Greg.