Help tuning...

[1st Shirt Maxer]

My 2001 just got running, I did the valve adjustment, tore down, cleaned and rebuilt my carbs installing a dynojet stage 1 kit. I have a k & n filter, stock air box with cobra slip-ons. I synced the carbs but they still seem to run a little rough. I haven't been able to put a lot of miles on the bike but will be riding after I get my registration done. When it is time to tune the carbs, my question is when do I adjust the fuel flow via the adjustable needles vs adjusting the fuel air mixture screw?

 

[NHVmaxpower]

:ummm: fuel flow?

 

[1st Shirt Maxer]

You'll have to forgive my verbiage I've never had to tune a carb from scratch. The bike runs at the moment but sounds like some popping going on at slow speeds. I'm just trying to figure out what would tell me I need to adjust the needles and when to adjust the fuel air mixture?

 

[sdt354]

There are some good thread here on Cobra slip on tuning. They aren't a performance upgrade over the OEM exhaust. The carb kit isn't recomended with your exxhaust. I'd put the OEM needles back in. A wet fuel level check is the first thing that needs to be done. A smaller main jet will get you running better. 147's-150's. A/F adjust? 2 1/2 turns out from seated is a good starting point.
Steve-o

 

[naughtyG]

I think because the Cobras are so open (and lack backpressure compared to OEM) you will always tend to hear some popping with them.

That said, the only way to tune the A/F ratio properly, regardless of whether it fuel bowl level, A/F screw, jet sizes or needles, to to get the bike on a dyno with an exhaust sniffer to read the A/F ratio accurately.

Anything else is guess work.

 

[1st Shirt Maxer]

Thanks for the info, I guess I'll have to save up for some supertrapp's from Sean. In the mean time, ill just make sure I'm not running lean and deal with the popping.

 

[naughtyG]

As a rule of thumb, we usually set the A/F screws at 2,5 turns out as a start, then out more 1/4 to 1/2 turn at a time if you feel it's lean, or back in if rich.

You gotta make sure your float levels are set right tho - it's really easy to check the wet level. You just need a length of transparent hose that fits over the drain hoses that come out either side of the carbs, make some marks on the test hose and hold it up against the marks on the carbs with the bike on its center stand on level ground.
If the floats are too high you'll run rich, too low you'll be lean.

Another good way to tell is look at your spark plugs: black = rich, white = lean, should be light tan on the electrodes.

 

[donnelly317]

Always start from the top end. Find a spot you can go WOT. go WOT for like 2 minutes.... if you can lol Pull clutch in shut engine off right away. Get to the side of the road and check plugs. The ceramic part of plug is what your gonna be reading the most inside part..
Reference this http://www.jetsrus.com/FAQs/FAQ_spark_plugs.htm

Black - rich
Brown - perrrrrrfect
White - lean

This is your main jet.. adjust accordingly. To lean install next bigger jet

Do the stam for mid RPM say 5000 ish. This is needle adjustment. Adjust accordingly lowering clip on needle makes it richer (raising needle away from jet allowing more fuel to flow)

Idle is a lot of A/F MIXTURE and pilot jet.. I still have stock pilots even with muscle kit in it.

And yes check your float levels play a big part in how rich or lean your running

Sent from my SCH-I535 using Tapatalk 2

 

[1st Shirt Maxer]

Re: Help tuning...thanks for all the help

So, after getting some parts in the mails from Sean Morley and working on the bike I found the following, I had a small slit in the fuel line behind the filter. It was sucking air and after replacing it, my fuel pump no longer runs as long as it did when turning the bike on. I also checked all my float levels using the wet float thred on this forum and all of the carbs read 17mm. Next I'm going to install a washer on the stock needles between the clip and the plastic spacer to see if this helps. The plugs are reading slightly lean but not to bad. Ill be able to ride it this weekend to see how all of this has changed it's running mannerisms. More to come...

 

[tugla]

the stg 1 isnt the best with stock headpipes.... a/f sceews will help the popping go away along with clip position.. but ya will be beter with stock nedles for sure...