Carb jetting question or please help this idiot.

sickopsycho · April 9th, 2017, 04:58 PM

Hey guys- bike has been running beautifully so I haven't been around here on the forum...

Lol- since it was running so well I decided to mess it up. I still have my 2012 250- it was bone stock. I bought an Area P full exhaust for it and tossed in a K&N filter in the stock airbox (removed the snorkel per Area P instructions). I also got a jet kit with the exhaust- I wanted to put in a larger jet so as not to run too lean. Area P reccomended for my Mods to put in a 98 Main jet with the clip on the 3rd ring down from the top of the needle. I decided to buck the system and put in a 100, since the stock jet was a 98 and I occasionally heard pops when I pulled the clutch at high rpm (backfire). So the bike now has a 100 main in it, clip is on the 3rd down.
Before I did anything, I noticed the bike didnt idle right. Sounded almost as if, only at idle, it was running MOSTLY on 1 cylinder. Found that problem- one of the air/fuel screws was only backed out 3/4 of a turn, the other was about 2.25. Thought that was crazy since I had to remove the EPA plugs... don't think this carb has been touched since Kawasaki tuned it. As per Area Ps instruction- I backed them both out 3 turns. It idles beautifully! Starts right up no choke (i had to choke it until it warmed up before). Thats it, though. Runs like hell other than that. It backfires quite a bit more on decel now. Acceleration is great, but a little sluggish until 3krpms. Rpms seem to kind of hang when they should be dropping... that's a sign of a lean mixture, right? If I have it at 9k rmps and pull the clutch, it's slow to rev down. Doesnt make sense that a larger main would create a leaner mixture at high rpms... unless the needle taper is that much different. Any advice? I have an entire jet kit, but I think the next size up is a big jump... 106 maybe? Can I put the stock needles back in with this main? Wonder if that's a good idea...

ducatiman · April 9th, 2017, 05:43 PM

Sicko, what brand is your jet kit?

read this guide.....with full credit acknowledged to Factory Pro...

http://www.factorypro.com/tech/carbtun.html

Triple Jim · April 9th, 2017, 05:47 PM

Bookmarked, thanks.

sickopsycho · April 10th, 2017, 06:32 AM

Quote:

Originally Posted by ducatiman

Sicko, what brand is your jet kit?

read this guide.....with full credit acknowledged to Factory Pro...

http://www.factorypro.com/tech/carbtun.html

Its a dynajet kit. While I was riding to work this morning, I had the bright idea to slightly apply the choke. My logic being I'd rather she run rich then lean. By slightly, I mean i just baaaaaaarely applied it until there was a noticeable difference in idle. I ran all the way to work like that and she ran beautifully. I know this isn't a fix, but it's a band aid until I can get the carbs back off tonight. Also, I figured it confirmed my lean mixture theory. I'll check out the link right now, thanks!

sickopsycho · April 10th, 2017, 07:20 AM

I am reading another thread on this forum (jetting database) and everyone keeps referring to popping being cause by the Kleen Air system. I wonder if this is what I'm thinking is a backfire? So, upon further review- it is indeed confirmed that I am an idiot. I forgot that dynajet sizes do not reflect the same number as Keihin sizes. A 98 dynajet would be 1 step up from a 98 Keihin. When I get home, the carbs are coming back out and a 98 is going in. The Kleen Air system is being removed and I will tune the air/fuel with the engine running, starting from the suggested 3 turns out. I will keep you all in the loop of the results.
One thing I wanted to add here that I havent read anywhere. These carbs are a real PITA to get out and in. My 2007 was easier because I did the battery box mod and the airbox would move back further. No such luck here and the airbox can't be disassembled in place. In order to get my carbs back in place... the last parts I put in were the runner boots to the intake. I used clean motor oil liberally along both ends- inside and on the lip. This allows the boots to easily slide onto the heads and carbs. I then replaced the stock clamps with hose clamps that I could completely open and place around the runners. I couldnt get the runners in with the stock clamps on, and if I removed them and put them on after install, it was too hard to line up the screw. Hope that helps somebody...

April 9th, 2017, 04:58 PM	#1
sickopsycho One ugly son of a gun. Name: Andrew Location: Raleigh, NC Join Date: Sep 2016 Motorcycle(s): 2012 250 Posts: 167	Carb jetting question or please help this idiot. Hey guys- bike has been running beautifully so I haven't been around here on the forum... Lol- since it was running so well I decided to mess it up. I still have my 2012 250- it was bone stock. I bought an Area P full exhaust for it and tossed in a K&N filter in the stock airbox (removed the snorkel per Area P instructions). I also got a jet kit with the exhaust- I wanted to put in a larger jet so as not to run too lean. Area P reccomended for my Mods to put in a 98 Main jet with the clip on the 3rd ring down from the top of the needle. I decided to buck the system and put in a 100, since the stock jet was a 98 and I occasionally heard pops when I pulled the clutch at high rpm (backfire). So the bike now has a 100 main in it, clip is on the 3rd down. Before I did anything, I noticed the bike didnt idle right. Sounded almost as if, only at idle, it was running MOSTLY on 1 cylinder. Found that problem- one of the air/fuel screws was only backed out 3/4 of a turn, the other was about 2.25. Thought that was crazy since I had to remove the EPA plugs... don't think this carb has been touched since Kawasaki tuned it. As per Area Ps instruction- I backed them both out 3 turns. It idles beautifully! Starts right up no choke (i had to choke it until it warmed up before). Thats it, though. Runs like hell other than that. It backfires quite a bit more on decel now. Acceleration is great, but a little sluggish until 3krpms. Rpms seem to kind of hang when they should be dropping... that's a sign of a lean mixture, right? If I have it at 9k rmps and pull the clutch, it's slow to rev down. Doesnt make sense that a larger main would create a leaner mixture at high rpms... unless the needle taper is that much different. Any advice? I have an entire jet kit, but I think the next size up is a big jump... 106 maybe? Can I put the stock needles back in with this main? Wonder if that's a good idea...

April 9th, 2017, 05:43 PM	#2
ducatiman ninjette.org certified postwhore Name: Gordon Location: new york Join Date: Sep 2009 Motorcycle(s): '95 DUCATI 900SS/SP '07 DUCATI SS800 '19 HONDA CBR650R Posts: A lot. MOTM - Nov '18, Mar '17	Sicko, what brand is your jet kit? read this guide.....with full credit acknowledged to Factory Pro... http://www.factorypro.com/tech/carbtun.html __________________________________________________ gordon@customcarbservices.com Custom Carb Service www.customcarbservices.com
	1 out of 1 members found this post helpful.

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April 9th, 2017, 05:47 PM	#3
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April 10th, 2017, 07:20 AM	#5
sickopsycho One ugly son of a gun. Name: Andrew Location: Raleigh, NC Join Date: Sep 2016 Motorcycle(s): 2012 250 Posts: 167	I am reading another thread on this forum (jetting database) and everyone keeps referring to popping being cause by the Kleen Air system. I wonder if this is what I'm thinking is a backfire? So, upon further review- it is indeed confirmed that I am an idiot. I forgot that dynajet sizes do not reflect the same number as Keihin sizes. A 98 dynajet would be 1 step up from a 98 Keihin. When I get home, the carbs are coming back out and a 98 is going in. The Kleen Air system is being removed and I will tune the air/fuel with the engine running, starting from the suggested 3 turns out. I will keep you all in the loop of the results. One thing I wanted to add here that I havent read anywhere. These carbs are a real PITA to get out and in. My 2007 was easier because I did the battery box mod and the airbox would move back further. No such luck here and the airbox can't be disassembled in place. In order to get my carbs back in place... the last parts I put in were the runner boots to the intake. I used clean motor oil liberally along both ends- inside and on the lip. This allows the boots to easily slide onto the heads and carbs. I then replaced the stock clamps with hose clamps that I could completely open and place around the runners. I couldnt get the runners in with the stock clamps on, and if I removed them and put them on after install, it was too hard to line up the screw. Hope that helps somebody...