WR jetting?


10 replies to this topic
  • wrwest

Posted January 21, 2011 - 04:09 AM

#1

My bike is used at 4000-5500ft alt. Mods: AIS removed ,baffle out, snorkel intact ,grey wire not removed and was jetted with a NFLR needle 48 pilot and 152 main .

Bike ran fine with this jetting.

I replaced the main jet with a 158 main as I felt the bike was a bit lean on the top . It's a bit harder to start now??? Makes a bushhhhh sound almost as if backfiring if kicked when cold , when hot and kicked it starts 1 st kick . E start spinns twice and then the backfire sound and imediately starts after that .

This Bhwissssss sound was not present with the 152 main jet ?

Anyone got an idea?

  • William1

Posted January 21, 2011 - 06:54 AM

#2

Main has nothing to do with starting. You could have the main missing and the bike would start fine. You problem is a coincidence. To prove it, put the 152 back in.

Did you touch the hot start?
Did you leave the vacuum port to the AIS uncovered?
Was any other work done to the bike?


Once you get this issue resolved, pull that snorkle an jet accordingly, let it breath, there is a bunch of power you are missing out on.

  • wrwest

Posted January 22, 2011 - 03:50 AM

#3

Thanks W1 I knew you would post! I set the fuel screw (GYTR) to one turn out and the sneezing is gone! . When I had the lid off the airbox with the 152 main the bike was bogging at quick throttle openings and felt sluggish at WOT. My bike starts cold first kick ,no choke and e starts constant on the 3 rd cycle .

The bike has enough power for me at this stage.

  • William1

Posted January 22, 2011 - 04:56 AM

#4

Hmmmm the fact your bike does not need the choke is not correct. That makes me think your pilot jet is too large. Humor me and do this:

Fuel Screw/Pilot Jet
Fuel screw settings in the 'book' are recommended starting points. Every bike is different, as is the temp and altitude. Set the screw according to this method. Do it with the bike fully heated up.
Gently turn the screw all the way in. Now back it out two turns. Start the bike and fully warm it up, go for a 10 minute ride. Set the idle to speed to 1,500~1,800 RPM as best you can (I know, without a tach this is tough, just set it to were it idles relatively smoothly). Once warmed, slow the idle to the lowest possible speed.
*** When turning the fuel screw, keep an accurate 'count' of the amount you are turning it and record it in case you have to reset it for some reason. Makes life easier when you can just set it from notes Vs. going through the procedure again.***
Turn the screw in until the idle becomes rough or the bike stalls.
if it stalled, open the screw about 1/4 more turn. Restart it and slowly screw it in till you can just perceive a change.
If the screw can be turned all the way in and the bike still idles perfectly and does not stall, then you need to go down a size in pilot jet.
Now very slowly, open the fuel screw till the idle is smooth. Blip the throttle, let the bike return to an idle, wait say ten seconds. Confirm it is the same smooth idle.
If the screw has to be opened more than 3 turns to get a smooth idle, you need to go up a size in pilot jet.
If you find it does not stall with the larger jet but has to be open more than three turns with the smaller pilot jet, put the larger one in and set the fuel screw at 1/2 turn.
If the idle speed increased, adjust the idle speed knob to return the bike to a real slow idle speed. You must then re-visit the fuel screw. Keep doing this till the fuel screw is opened just enough to provide a nice steady idle at the lowest possible RPM. Once this is done, increase the idle speed to the normal one for your bike, typically about 1,800 rpm, but go by the spec in your manual.

  • wrwest

Posted January 22, 2011 - 10:42 AM

#5

You are right W1 the pilot is a #48 from the AIS GYTR kit and replaced the #45 standard pilot. When my bike is started with the Choke it starts to run rough and wants to die, so yes it seems it is realy a bit rich.

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  • wrwest

Posted January 22, 2011 - 11:08 AM

#6

I trailride my bike only no competition or WOT rides . After the first plug change at 200 km the plug was black and after the 1000 km plug change it was black too so even riding with a main of #152 it ran rich in the bottom range ? correct? #48 pilot to a#45 or #42 maybe? Would this affect the bog? runing a stock 60 leak jet.

  • wrwest

Posted January 22, 2011 - 11:09 AM

#7

Is it wise to remove the clear plastick sealed pipe from the airbox bottom?

  • William1

Posted January 22, 2011 - 11:57 AM

#8

I trailride my bike only no competition or WOT rides . After the first plug change at 200 km the plug was black and after the 1000 km plug change it was black too so even riding with a main of #152 it ran rich in the bottom range ? correct? #48 pilot to a#45 or #42 maybe? Would this affect the bog? runing a stock 60 leak jet.

I'd ignore the plug color, todays fuels makes trying to read a plug (unless it is racing fuel)pointless. So you have to go by feel or a stop watch or with wideband A/F sensor and logger.
I'd pop the #45 pilot back in and do the test I provided. That will resolve cold start/no choke and hot start difficulties.
Regarding the bog, have you done the oring mod or a stiffer AP spring yet? If not, do it. The bog may get slightly worse when you get the correct pilot in and the fuel screw set right, do not fret. But you must get the pilot and fuel screw right before you and tweak the AP.
After you have teh oring or spring done, if there is still a bog, you'll want to tur the AP timing screw 1/2 turn and retest ride. Ride normally. If the bog is still there, turn the AP timing screw again and retest, then report back. Keep good notes of any adjustments you do, that is important.

Is it wise to remove the clear plastick sealed pipe from the airbox bottom?

I keep it on. If I go through deep water, it is one less opening to let water in. I look at it during a wet ride and if I see water in it, I pop is off, drain the water and put it back on.

  • wrwest

Posted January 22, 2011 - 09:58 PM

#9

Cool thanks for the info!

What is the best way to get to the pilot jet? carb off or on the bike? tilted sideways left or right etc?

  • William1

Posted January 23, 2011 - 02:48 AM

#10

Depends on the tools you hav and how good you are with them,. I use a Motion Pro 90 degree tool. Pop the cap, insert the tool, out the jet comes. Some use a stubby screw driver. The carb really does not rotate with all the cables attached. Pulling the carb to swap a pilot is not needed. Get a mirror and you can easily see what you are dealing with. Be gentle when you fit a screw driver to the pilot, a small well fitting one is important, do not force a wide blade up there or you may crack the housing. Gunsmith drivers are great.

  • wrwest

Posted January 23, 2011 - 10:01 AM

#11

W1 thank's for all the info! will do it that way from the bottom.

Great to have all this info available on TT !




 
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