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| Motorcycle Message Board - Motorcycle USA > MotorcycleUSA.com! > Ask Motoman! > Carb tuning | Forum Quick Jump
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skyhawk04kilo
Registered Member
      
Date Joined Jun 2009
Total Posts : 180
| Posted 11/6/2009 8:33 PM (GMT -8) |   | CaddmannQ said...
Carb tuning is specific to the altitude where you live, as air pressure varies with altitude.
Does he offfer different kits depending on whether you live at various altitudes?
Does it consider intake system mods?
Does he mention fuel grades?
Operator weight?
Sprocket ratios?
There's a reason they say their kits are a good "starting point."
They are made to sell to people who cannot possibly do this on their own but must have something 'cause it's better than having nothing.
If I was wrong about all this, your bike would run fine by now.
The kit includes 3 sizes of main jets, and the one you start with varies depending on altitude and average temperature that you ride in. You have to mod the air box in a specific manner described in the instructions, and fuel grade is still 87 octane after the kit is installed. I did tell Dale how much I weighed over the phone and he assured me the kit would still work despite me violating his "no fat chicks" principle on two fronts (not a chick, and not skinny). Sprockets are stock.
I'm not trying to argue with you Cadd, as I think you have a lot of knowledge to share, I just think that Dale Walker has worked through this enough to know whether or not the bike would need new needles. The kit itself isn't a "starting point", the kit is supposed to be all-inclusive, but they give you starting point settings and from there you fine tune it with the stuff provided in the kit. If there was a chance I needed new needles, they would have been in the kit, or at the very least it would have been mentioned in the instructions.
So anyway, starting point is 5 shims on each needle, and they gave me about 20 extra shims, and instructions say to add more shims if needed. I guess that's what I'll do...
2001 Suzuki Bandit 1200S | | Back to Top | | |
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fr4nk
Registered Member
Date Joined Nov 2009
Total Posts : 1
| Posted 11/13/2009 4:02 PM (GMT -8) | | | Someone know where is located the carbs of 1999 suzuki GSXR600 ? | | Back to Top | | |
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CaddmannQ
Random Moto-geek
Date Joined Jul 2003
Total Posts : 17141
| Posted 11/13/2009 9:14 PM (GMT -8) | |
skyhawk04kilo said...
I've tinkered a bit and want to see what you guys think. Just to review, I installed a jet kit and when riding at normal RPM range (3000 to 6000), opening the throttle past 3/4 would cause the bike to pull less hard than if you just held the throttle at 3/4. After riding at 1/2 throttle in 1st gear for 1 mile at 10,000 RPM, each spark plug was white. Using this info, we had decided that the needle jets were too lean.
I added 1 shim to each jet needle (started with 5). Now the bike starts to fall off on power when opening the throttle past 1/2 instead of 3/4. Now I'm thinking the needle jets were fine all along and it's the main jets that are off. I'm going to remove 1 shim from each jet needle, back to 5, and install the next bigger size main jet. Does this sound right to you guys? OK, I'm starting to think that the springs may have been cut too short and the slides open up too quickly. The main jet really shouldn't be the deciding factor at 1/2 throttle IMO.
We know how the bike runs with 5 shims and 6 shims, so I might consider seeing how it runs with 4 before I pull the main jets.
An alternative might be to add weight inside the slides so they don't rise as quickly. That will richen the mid-range mix just like lowering the needles would, except that making the slides heavier also slows their response time when opening the throttle and quickens it when closing. (Assuming the vacuum remains equal of course.)
See, there's more than just the mixture you get at any given throttle opening. The mixture must be correct while the throttle is moving too. That typically means you want to richen it slightly above the correct running mixture at any particular RPM, if you want to accelerate from that RPM to higher RPM quickly. This is why some carbs have accelerator pumps. When you open the throttle faster than the the carb can richen the mix, the pump adds fuel so the engine won't bog.
A CV carb is the opposite.
If you open the throttle faster than the the carb can richen the mix, the slides lag behind, cutting out some air to richen the mix.
So, absent a pump, you can make the slide rise slower, or open the jets. Either can make the mix right at a static RPM, but one or the other will likely provide better acceleration depending on whether the engine can use more air at any particular point in the fuel curve.
"When in doubt, ride."
Cadd................................Clovis CA
2004 Nomad 1500............"Baggins"
caddmannq at yahoo dot com
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