Airbox/Carb Configurations
12-09-2007 | 10:42 AM
#1
Thread Starter
Junior Member
Squid
Joined: Nov 2007
Posts: 8
Airbox/Carb Configurations
Sorry guys, but it's another carb/jetting question.
Currently on 190 mains, with K&N filter, an DynoJet needles on the #5 clip, mixture screws about 3 turns out with 45 pilot jets, and Scorpian cans with the baffles removed.
I'm having trouble with lack of power (Compared to what other people describe), a second of lag/stutter between going off the throttle to back on the throttle and surging at constant speeds.
I've tried running 180 main jets and 190 neither of which seemed to make any difference on these symptoms, and I have had the mixture screws at two, two and a half, and three turns out, none of which seemed to solve anything.
I took the snorkels out of the airbox, and the surging and stutter/lag stopped, but left the bike sluggish throughout the midrange and top end. Any ideas why this might be?
Should I be looking at timiing maybe instead of jetting?
Cheers guys.
Currently on 190 mains, with K&N filter, an DynoJet needles on the #5 clip, mixture screws about 3 turns out with 45 pilot jets, and Scorpian cans with the baffles removed.
I'm having trouble with lack of power (Compared to what other people describe), a second of lag/stutter between going off the throttle to back on the throttle and surging at constant speeds.
I've tried running 180 main jets and 190 neither of which seemed to make any difference on these symptoms, and I have had the mixture screws at two, two and a half, and three turns out, none of which seemed to solve anything.
I took the snorkels out of the airbox, and the surging and stutter/lag stopped, but left the bike sluggish throughout the midrange and top end. Any ideas why this might be?
Should I be looking at timiing maybe instead of jetting?
Cheers guys.
12-09-2007 | 11:16 AM
#2
Senior Member
SuperSport
Joined: Mar 2005
Posts: 758
From: Laurel, MD
My guess is that the jetting is fat in the midrange causing the loading your experiencing. Rich reveals itself as a bog, lean as a choke or cough, if that helps.
Put in 182F-185R mains, for starters and leave them in until you sort out the proper needle settings. Put the velocity stacks back in if that's what you're talking about, the (1) snorkel if that's what you mean.
Sort out the midrange, then do some plug cuts to sort out the mains. But you'll find they're spot on or within one size.
Put in 182F-185R mains, for starters and leave them in until you sort out the proper needle settings. Put the velocity stacks back in if that's what you're talking about, the (1) snorkel if that's what you mean.
Sort out the midrange, then do some plug cuts to sort out the mains. But you'll find they're spot on or within one size.
12-09-2007 | 11:27 AM
#4
Thread Starter
Junior Member
Squid
Joined: Nov 2007
Posts: 8
Put in 182F-185R mains, for starters and leave them in until you sort out the proper needle settings. Put the velocity stacks back in if that's what you're talking about, the (1) snorkel if that's what you mean.
Sort out the midrange, then do some plug cuts to sort out the mains. But you'll find they're spot on or within one size.
Also, with previous experimentation, the bike seemed to surge and have less lag with the choke on, but I'm already running everything pretty rich, so maybe I'm drawing air from somewhere?
12-10-2007 | 11:24 AM
#7
Junior Member
Squid
Joined: Aug 2007
Posts: 19
From: Toronto
Here are my two cents after having fiddled around with a set up like this as well...Your mains should be fine with that setup in the 180 -185 range Dynojet provides. Go for the 48s as suggested, fuel screws 2 1/2 to 3 turns out. Leave the stock intake tracts in place. Best and cheapest way to trouble shoot is to put a new stock airfilter back in and set everything up for that and see how it works. I've gone through all these scenarios too and to be honest with you the K and N on a VTR as proven by dyno gets you barely anything on top end but takes away a bit down low and results in alot of surging up to 5-6k like it sounds you're having and which is very hard to rejet for. The hit the K &N provides later on is just the lost hp catching up. Honestly, the stock filter works very well and especially in low to mid range roll-ons which is what makes this bike such a delight. Good luck!
12-10-2007 | 10:48 PM
#9
Senior Member
Superstock
Joined: Mar 2007
Posts: 268
From: San Diego
I have pretty much the same setup as you.
Went up mains, i'm now running 192f 195r, dynojet clips on 5th needle, and 48 pilots.
You gotta up your pilot sizes to 48. I had the low rpm surging issue, this cleared it up.
Clips also gotta go to 6th notch. I've tried 7-8 different combinations, i've tried increasing the mains size until it covered up the notchiness in the midrange.
IT'S NOT GONNA HAPPEN.
6th clip.
I still have to change mine to 6th clip.
Or go fuel injected.
Went up mains, i'm now running 192f 195r, dynojet clips on 5th needle, and 48 pilots.
You gotta up your pilot sizes to 48. I had the low rpm surging issue, this cleared it up.
Clips also gotta go to 6th notch. I've tried 7-8 different combinations, i've tried increasing the mains size until it covered up the notchiness in the midrange.
IT'S NOT GONNA HAPPEN.
6th clip.
I still have to change mine to 6th clip.
Or go fuel injected.
01-20-2008 | 04:41 AM
#10
Member
Squid
Joined: Oct 2007
Posts: 45
From: Newcastle, Australia
-1 on 48s. Not meaning to be rude here guys as you have all jetted your own bikes. But experience using wide band has shown afrs to be very rich with 48 pilots regardless of mixture screw settings. I learnt this the hard way! 45 gave me 13.5:1 afr at idle, giving me a smoothe idle and good economy.
I had the same drama as you. The factory 3/8" vacuum line that runs to the tank can be very easily kinked as its flimsy and poorly routed. If its partially blocked air wont enter the tank causing a vacuum lock and lean condition.
By all means please replace this vacuum line with some 3/8 fuel hose(tougher) and route it in a direction to prevent kinks.
Ditch the 190s it will be killing it. I have datalogged with 190s and had afrs of 10:1 at WOT when you should have 12.5-13:1 Air fuel ratio. I had to progressively drop down to 170 mains front and rear to obtain correct afr at WOT(13:1) here I had the most hp and very progressive hp curve.
VTRs like rich needles. Stock needles shimmed work a treat. DJ needles you need to run on clip 5 with 2 washers or clip 6 no washers. 48 pilots on clip 5 will give u terrible economy. And 48s on clip 4 will give u a lean hole on acceleration. Once I fitted 45s I had great afrs at idle and better economy.
All my jetting was done from datalogging in all conditions running unleaded 91RON petrol with K and N filter an pipes. I spent $600 on tuning equipment and lots of hours(plus datalogging at 240km/h!) to obtain these results.
Cheers
Joel
I had the same drama as you. The factory 3/8" vacuum line that runs to the tank can be very easily kinked as its flimsy and poorly routed. If its partially blocked air wont enter the tank causing a vacuum lock and lean condition.
By all means please replace this vacuum line with some 3/8 fuel hose(tougher) and route it in a direction to prevent kinks.
Ditch the 190s it will be killing it. I have datalogged with 190s and had afrs of 10:1 at WOT when you should have 12.5-13:1 Air fuel ratio. I had to progressively drop down to 170 mains front and rear to obtain correct afr at WOT(13:1) here I had the most hp and very progressive hp curve.
VTRs like rich needles. Stock needles shimmed work a treat. DJ needles you need to run on clip 5 with 2 washers or clip 6 no washers. 48 pilots on clip 5 will give u terrible economy. And 48s on clip 4 will give u a lean hole on acceleration. Once I fitted 45s I had great afrs at idle and better economy.
All my jetting was done from datalogging in all conditions running unleaded 91RON petrol with K and N filter an pipes. I spent $600 on tuning equipment and lots of hours(plus datalogging at 240km/h!) to obtain these results.
Cheers
Joel
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