Slow Jets
Thread Starter
Junior Member
Squid
Joined: May 2007
Posts: 17
Slow Jets
Hi all, I am new to the forum but have already found it very valuable. Hope someone answer a jet question.
I have been doing some carb tuning and last night I went from 48 slow jets to 50 slow jets. It was WAAAY too rich. Didnt want to start or idle and threw flames out the exhaust when cruising ~4k. I tried riding it to warm it up, but that didnt change anything.
So I went back and took the carbs off...again...
Found the 48 jets are labelled "48S" but the 50 jets have no "S" after the number just "50".
What's the diff? I wouldnt expect such a dramatic change from 48 to 50. Does the S designation mean something?
I have been doing some carb tuning and last night I went from 48 slow jets to 50 slow jets. It was WAAAY too rich. Didnt want to start or idle and threw flames out the exhaust when cruising ~4k. I tried riding it to warm it up, but that didnt change anything.
So I went back and took the carbs off...again...
Found the 48 jets are labelled "48S" but the 50 jets have no "S" after the number just "50".
What's the diff? I wouldnt expect such a dramatic change from 48 to 50. Does the S designation mean something?
Senior Member
SuperBike
Joined: Jul 2005
Posts: 1,548
From: MN
You referring to the pilot jets? do they still have the keihin insignia on them? Or is that what you are seeing? Stock is 45 I believe, so 48 is already larger than stock. What problem are you trying to correct by going even richer on the pilot jet?
Senior Member
Superstock
Joined: Jun 2006
Posts: 358
the S means the emulsion holes on the jet are smaller.... it doesnt allow as much ari to mix with the fuel.. i always dump S variants. occasionally i run across them in dirtbike and even ATV carbs. they do that to help with emisions. also when you swapped the jets did u mess with the air screw? i went from 45's air screw all the way out to 48's with air screw about 1/3 the way out.
Thread Starter
Junior Member
Squid
Joined: May 2007
Posts: 17
The jets are pilot jets and came in a box with the bike when I got it. They were in a Honda bubble wrap package. I went to Keihin website and noticed lots of variants that look similar, Im guessing it was the wrong style.
The reason I was going up to 50 was the chugging and vibration I get when cruising 75 and up.
btw, what are the jet increments above 185? Is there an 187? I want to go to 185front main. What would I put in rear? Do you have to go to 190?
The reason I was going up to 50 was the chugging and vibration I get when cruising 75 and up.
btw, what are the jet increments above 185? Is there an 187? I want to go to 185front main. What would I put in rear? Do you have to go to 190?
Senior Member
SuperBike
Joined: Jul 2005
Posts: 1,548
From: MN
There are some good sites for jetting procedures out there. I think there is something on the factory pro website. I don't think the pilots are going to affect the 4K cruising range that much. And it wouldn't make the most sense to go richer on the idle low speed and at the same time going richer on the mains in that order. Most people start with getting the right mains first, since they affect the whole rpm range. Once those are perfect then get the needle right then finally the low speed circuits. I can't tell what mods you have to your bike but there is probably someone here with the same mods and you could get some reliable jetting recommendations to start with.
Thread Starter
Junior Member
Squid
Joined: May 2007
Posts: 17
I have 180f/185r now and I'd like to go richer, but don't have the jets so I will need to buy them somewhere. (anyone have leftovers from a factory kit? I just need jets...) I'm pulling a Dr. Moreau with two sets of carbs I have, but I've maxed out the jets I have.
The engine has been warmed up with 11.5 pistons, milled head, polished ports, K&N and D&D exhaust after a CCT failure but hasnt been properly jetted since the internal work was done.
The engine has been warmed up with 11.5 pistons, milled head, polished ports, K&N and D&D exhaust after a CCT failure but hasnt been properly jetted since the internal work was done.
Senior Member
SuperSport
SuperSport
Joined: Dec 2006
Posts: 880
From: Victoriaville, Quebec, Canada
Wow 12:1, damn this is big for a wide combustion chamber like a twin. I hope you are running high octane fuel, did you retard the timing at all ?? No wonder why you want to go richer, if detonation gets in there, you may be shitting rod chunks tomorrow 
.
Well I'd like to hear more from your setup, sounds like a very nice and unusual mod on the VTR.
.Well I'd like to hear more from your setup, sounds like a very nice and unusual mod on the VTR.
Junior Member
Squid
Joined: Jun 2006
Posts: 2
I'm looking for a 182 main jet. Anyone have one they'd be willing to drop in an envelope? Obviously I'd pay going rate plus postage.
--Terry
konatkp@hotmail.com
--Terry
konatkp@hotmail.com
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