This Carb is driving me Crazy!
Posted June 11, 2008 - 05:39 AM
Needle: JD red 4th position
Everything else stock
Results: No sputtering, no backfiring on deceleration but i did have an off idle bog in 4th.
After much review of the jetting database and research in general i decided to do the following:
1. Changed main jet to 168. this resulted in crisper throttle, exhaust sound.
2. installed GYTR fuel screw set at 1.5 turns out.
3. installed NGK cr9eix iridium spark plug. seems to wake the bike up a little.
4. installed R&D Power Pump with ALJ set at 40. installed stiffer spring on AP linkage and also did O Ring AP linkage mod.
Here are my concerns:
1. Bike doesnt run smooth at mid rpm, it kinda sputters.
2. Although not significant, i do have some backfiring on deceleration.
3. When i checked the plug it was kinda black. The plug has been in for a few months and i was adjusting the fuel screw during this time so i had been running at 2 turns out for a period of time that could have caused this.
4. with the bike running at idle, standing still, i adjust the fuel screw all the way in (closed) and the bike continues to run???
I am thinking, if the plug is dark, i am running rich so i dont need to go back to a main jet of 170. I have messed with the ALJ but i really dont feel anything significant so i keep it at the suggested 40 position. Should i go higher on the needle... to the 5th clip position? What about the bike running at idle with the fuel screw closed? do i need to change to a 45 pilot? Please help, i am beginning to go crazy trying to get everything dialed in. Thanx.
Posted June 11, 2008 - 07:16 AM
I would definitely drop to a 45 and readjust the fuel screw to optimum.
The only real way to see how your main jet is performing is to do a plug chop, anything else will skew the visual plug results, being rich on the pilot can certainly do this.
Posted June 11, 2008 - 09:02 AM
sounds like you've got a rich pilot jet. try one step down from the 48. since you're in the bahamas, the humidity may be a bit of a factor. maybe someone that lives in a humid place can help you out.
Posted June 11, 2008 - 09:10 AM
Use a clean or new plug.
Completely warm up the bike - ride for 10 minutes to do so.
Find an open stretch where you can open it up some under load - a gentle uphill is nice.
Accelerate aggressively through the gears until you get in a higher gear (4th or 5th) with your throttle wide open for 20 seconds, then pull clutch and hold the kill switch while chopping the throttle - doing this simultaneously stops the plug from firing (holding kill) and stops the tranny from turning engine over sucking more fuel in (pulling clutch). Now - probably in the middle of some field - you have to pull the plug (hope you brought tools and gloves) - the color of the plug insulator will tell you whether you're lean/rich/just right at that particular throttle opening - in this case full throttle - meaning only the main jet is being tested.
If you perform this at varying throttle intervals (easiest if marked on your throttle/handle grip) you can map where on the throttle your bike does what - essentially giving you a profile of your needle, thus allowing you to determine which needle profile may be more appropriate for your setup by using your current needle as a baseline.
The OP's plug is showing signs of being rich, because this likely was read after shutting it down from idle and not a WOT chop - it will indicate the pilot circuit's current state, NOT the main jet. Many make the mistake of thinking they have to adjust the main jet based on this reading.
Posted June 11, 2008 - 09:37 AM
The pilot and main jet are fun too.
Plug readings worked when there was leaded fuel. Now it only works if your really way off.
Posted June 11, 2008 - 11:09 AM
Sure - It's a bit of a pain, but once you're dialed in it's not exactly something you have to do every second week.
As for your main and pilot - yes the aluminum bikes leave a lot to be desired in the way of access, at least on mine (steel frame) I can get to them in 2 minutes.
You know, I think everyone here including the OP knows how hard it is to access stuff on these bikes, if he could wave a magic wand at it and fix it, I'm sure he would.
If I could tell him to wave a magic wand TO fix it, I'm sure I'd suggest it!
He's been at this for a while now, it's obvious he's trying to dial it in right, and although you may have a problem with pulling your tank, I haven't heard him complain about it.
TribalBC asked me to explain what a plug chop is - I did - including mentioning running uphill since this helps get a better reading with unleaded fuel.
Then there's always lead additives available at stores if you still have problems.
Posted June 11, 2008 - 05:36 PM
Yeah with the pain it is on a 07 I pretty much rely on seat of the pants jetting.
Posted June 15, 2008 - 10:39 AM