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carburator adjustment with jet kit stage 1 and a hypercharger
Hi Folks,
I owned a shadow aero 1100 2001 and last year I did install a Kuryakyn hypercharger. The bike was acting not so great, it would run fine but if I would to asked more (crank the throttle opened), it would stall. Furthermore, my friends told me that the bike was not burning all its fuel. They also said that my alternative was to install a jet kit.
So last week, I did install a stage 1 dynojet kit. I did the job exactly as prescribe in the instruction. The bike is not at all better, I'll say that it even worst, even with the pre-set of 2 and 3/4 turns. So after this setup, I felt that too much gas was going into carbs and I did take the needle from a 3 position to a 2 position. As I was opening the throttle, the engine would stall and produce black smoke with no power.
The machine is equipped with its original pipes that have been pierced through but still have the baffles, a K @ N filter in the hypercharger and the spark plugs are totally carbonated (very black). Then asking around at work, a good body said that with a set of carburetor synchroniser I should be able to adjust the carbs. I did as he had explained to me very patiently but I had very little change in the adjustment. The deflection of the mercury was less than a haft an inch (1/2"), except when I totally closed the air idle mixture screw.
Now what should I do? A - should I go back to the 3 position on the needle and performed another cars synchro? B - should I reinstalled the original needles and resync? or C - should I reposition the needles to the 4 position on the needle and resync? At this time I am wandering what should I do as lots of people with many ideas, some good some bad, are influencing my de-snagging, I need some more advise in this matter. Thanks for your assistance and help.
Yves Roy
Some Ideas..
There are a number of things that can cause that. Need more details to make an accurate guess. Black smoke and lots of carbon on the plugs certainly indicates it's running rich. Was the bike running ok before the hypercharger? I would think the hypercharger by itself should cause it to run lean.. but maybe something broke by coincidence? Does the bike idle ok? Syncing the carbs mainly affects the idle... and really only helps smooth out the idle. If it idles ok and will idle for a while without shutting off or running rich.. black smoke for example.. then chances are you can rule out a bad float and or needle and seat. Usually if those are bad it'll run rich at low throttle conditions but get better the more throtte you give it.. It sounds like something is choking off the intake. Changing the needle position only makes minor changes in jetting.. moving one position to another will hardly ever make enough difference in jetting to make an engine stall completely.
The hypercharger has a butterfly valve on it right? I believe it's vacuum operated. Does your bike run ok without the filter charger installed? It's ok to fire it up for a short time without any filter on it. Just make sure there's not a lot of dust and dirt flying around when you start it. If it runs ok then, you can be pretty sure the hypercharger is the culprit. If it runs ok without the hypercharger.. then install it again and prop open the butterfly valves.. does it run ok? I think the butterfly valves are vacuum operated.. are they moving(opening) when you give it throttle? If they are moving.. and it does run better when you prop them open, they aren't moving enough. Personally.. I see no need to have the butterfly valves on the hypercharger.. it's just something extra to go wrong and is pretty much for show on the hypercharger. On drag engines with blowers, valves on the intake are a necessary thing and usually use mechanical linkage instead of vacuum. If it does run better with the butterfly valves propped open, you may want to consider modifying them to just stay open. Again, I'm refering to the butterfly valves on the hypercharger.. not the ones inside the carbs.
There are some other things that can cause a bike to run rich and blow black smoke and stall. There could be a massive fuel leak in the carb.. but if that were the case, I don't think it would even start. The spark could be weak at the spark plug. This would cause part of the fuel mixture to not burn.. usually it'll idle ok, but then when you rev it, it will run poorly and produce black smoke and sooty plugs. This could be caused by a bad coil, bad plug wires.. or bad plugs.. chances are I'd go with a bad coil. You can check the plugs by yanking them, ground them against the bike while they're plugged into the wires and observing the color of the spark. The spark should be a hot white/blue color and not a dull orange.
Dynojets settings are usually spot on.. so I'd say jetting isn't your problem.
I'm think though, that if the problem started after you installed the hypercharger.. it's the hypercharger and I'm thinking that by it's design, it could be the butterfly's aren't opening quick enough.. if at all. I'd yank it and see how the bike runs with nothing on it first.