how to tune your bike?

[blackhawk9]

Iv read a lot about carbs and syncing. Also did a lot of carb work on my bike too. But what I don't get is how do you tune the air/fuel mixture just right? Does it go hand and hand when you sync the carbs? Or is it just a trial and error thing? I also have a motion pro syncpro if that helps me in anyway.

[phantasm]

After sync. turn a/f screws in till idle changes, then turn out till idle changes. count the # of turns and set a/f in the middle.

[arsenic]

What phantasm is saying is called the "drop down method". That needs to be done with the carbs on the bike, and the bike running. You need to use a special angled screw driver. The special tool sucks massive donkey balls. If you just set them to 2.5 turns out while the carbs are off the bike. Install the carbs and sync the carbs. You'll be good to go.

[blackhawk9]

That sounds like it does suck major d**k. Do you bottom out the screws or just till you hit resistants? I bottomed them out and it was 5 turns out. And I'm getting crazy backfire, I have a yoshi exhaust, stock air filter, no jet kit.

[arsenic]

just snug them up and back them out 2.5 turns. Why the **** would you turn them out 5 turns? For the record do not do that.

[blackhawk9]

just snug them up and back them out 2.5 turns. Why the **** would you turn them out 5 turns? For the record do not do that.

That's how many turns out they were before I touched them. Soooo I just assumed to put them back the same as before I opened it up. But since I'm getting crazy backfire and my mpg is way down. I'm assuming I'm getting to much fuel and need to turn the screw put more yes?

[arsenic]

dude, 2.5 turns out. That is 3 times I've told you that in this thread alone. What are you not understanding here?

[Bigyellowkat]

dude, 2.5 turns out. That is 3 times I've told you that in this thread alone. What are you not understanding here?

Arsenic knows Carbs. If he says its 2.5 then its 2.5. The carbs 101 and 102 docs both say the same things for a reason. Cause that's the correct amount for most applications especially stock or close to it. Start setting it anything other than that and your bike will run like crap.

[Wild-Bill]

Blackhawk, chances are that the screws were sitting at 5 turns out because the PO knew enough to adjust them but not enough to clean the carbs. They let the bike sit, it ran badly (too lean) and so they tried to fix that by adjusting the A/F screws. When they discovered they couldn't back the screws out far enough to get the bike running right they sold their problem to you. Now that you've cleared out those clogged idle passages and fuel is flowing again, 5 turns out is way too rich.

That clear it up?

[blackhawk9]

Blackhawk, chances are that the screws were sitting at 5 turns out because the PO knew enough to adjust them but not enough to clean the carbs. They let the bike sit, it ran badly (too lean) and so they tried to fix that by adjusting the A/F screws. When they discovered they couldn't back the screws out far enough to get the bike running right they sold their problem to you. Now that you've cleared out those clogged idle passages and fuel is flowing again, 5 turns out is way too rich.

That clear it up?

A bit but if a 1/4 of a turn can make a huge difference and mine are out 2 full turns then you would think the bike would be starving for gas and not run. BUT it runs with no problem. Backfiring and my mpg down a little would tell me its running to rich. Maybe I'm over thinking this.

Just telling me 3 turns doesn't really explain it. I know how many turns its suppose to be but I want to know why. Sorry I want to learn about my bike and understand why this is happening .

[05RedKat600]

Why? Because that's where it runs best. If you want to know more than that, google "How carbs work" and start reading.

If your bike runs like crap with the screws at 2.5 turns out, your carbs need cleaning or they need synced.

Backfiring? that's through the carbs....popping in the exhaust is afterfire, and it means you're lean. I'm betting your carbs are dirty and need a good cleaning.

I suppose it could mean you're rich, but that also means your float needles aren't seating or your floats are set wrong. Kat carbs are hardly ever rich. Well, pretty much never.

With my pipe, and no jet kit, it took 3 turns out to make it run well. but I plan on getting a jet kit for it because it's still not RIGHT, it's just OK.

[Kreylyn]

A bit but if a 1/4 of a turn can make a huge difference and mine are out 2 full turns then you would think the bike would be starving for gas and not run. BUT it runs with no problem. Backfiring and my mpg down a little would tell me its running to rich. Maybe I'm over thinking this.

Just telling me 3 turns doesn't really explain it. I know how many turns its suppose to be but I want to know why. Sorry I want to learn about my bike and understand why this is happening .

The bikes generally will run with the a/f screw at anything between 1.5 and 4 turns. Run WELL is a different matter. Add to this that it certainly is possible for each carb to need a slightly different exact setting makes it more complicated.

Ultimately... 2.5 is right about middle of the setting and generally works "well enough" for 99% of applications that are close to stock.

The drop down method lets the engine tell you specifically what it needs for your distinct setup.

Krey

[blackhawk9]

Ok thanks guys for all the input. Ill try and tinker with it tonight.

[Wild-Bill]

One thing nobody's pointed out is that you turn the screws in to lean the mix and out to richen it.