Idle Issues? Full exhaust and Jet kit.

[mikeyt073]

Heres the situation. Just bought a 97 Kat 600. It has a full yoshi pipe. Tore the bike down. Carbs seemed pretty clean. tank is spotless. only 4k on bike. 110 main jets. A/f screws were 3 turns out and the choke cable was seized and 1/3 of the way on. Replaced the cable, changed the A/F screws to 2.25 turns out as mentioned in a previous thread. Problem is i still can't get her to idle. Races a little or stalls out depending on idle adjustment screw. If i let it race, then once i take off i have cruise control and i need to back the idle adjustment screw out while i'm riding. Then i pull up to a stop sign and stall out. It is very frustrating. Besides all that she actually runs pretty decent at speed (even low speeds), smooths right out. What is the most probable cause of the above situation, and what steps should i take to resolve the problem and achieve a nice smooth low idle.

[Black_peter]

Defiantly the idle circuit.
Was the 2.25 turns based on the jet kit and pipe?
Why did you adjust them and how was it running before?

It sounds like once you get out of the idle circuit (based on vacuum not RPM) the bike runs fine. Try cleaning the FA jet holes again. Make sure the o-rings are good and you have the screw, spring and o-ring right.
If it wasn't running better at 3 turns maybe you need more that 3 turns..

[mikeyt073]

I adjusted to 2.25 turns based on a thread i read about carbs that said 1.5-2 stock and 2.25 with a jet kit. My bike has a stock airbox and filter. at 3 turns out i had the same problem, but i think it was worse. I feel like im closer now than it was. Isn't more than 3 turns a lot. How do i know if i need less than 2.25. The bike wasn't running right when i got it ($1000). So there is nothing saying 3 turns is right, or 2.25 for that matter. All Help is appreciated. Thanks.

[Black_peter]

Well if 2.25 is better than 3 keep going...
These are not really calibrated things. This is vacuum we are talking about so a lot of things can effect the result. Try 2 turns.. Better? Then for the hell of it try 3.5 turns.. If you can buy the motion pro screwdriver..

see:

http://www.katriders.com/forums/viewtopic.php?p=424354#424354

and

http://www.motionpro.com/motorcycle/tools/pilot_screw_adjusting_tool/

With a little fiddling (or make the changes I made) you can adjust the screws without pulling the carbs.

[mikeyt073]

Yeah I think your right. I couldnt even get it started today so I will try 3.5 That thread is very helpful. Thanks. I knew someone had this type of problem.

[Black_peter]

Mine gave me fits.. Mainly because getting to the screw sucks!! I bought that screwdriver from my local shop for $16!! What a steal! It was great to get those buggers tuned in without removing a thing!

[md86]

I dunno , it sure SOUNDS like there's cap in the carbs , not just that the screws ain't set right ......

[Black_peter]

Yeah, That's why I suggested another blast of carb cleaner.. And you need to be sure the screws are assembled right.

[md86]

Yeah , but "a blast of carb cleaner" probably ain't gonna get the stubborn dirt out . Need to get in there with some brake cleaner and can of compressed air , maybe a wire bristle , too ....

[mikeyt073]

Well some good news. Pulled the carbs again and removed the pilot screws. Sprayed carb cleaner in the orifices and followed with compressed air. reassembled with springs washers and orings. set them to 3.5 turns this time. got it all back together. It runs much better and smoother now. I actually got it to idle at 1000 rpm with out stalling. Big progress! But the symptoms now include rpms hanging real bad. It is to the point that it races a little and i can't get the rpms to knock back down. But if they do come back down it will idle. Took it for a ride and it just seems to have no power. It is dogging real bad and might even bog a little. But smoother than ever. Does the adjustment of that screw affect the power in anyway or it is only for low rpms. (i.e. is it running to rich or lean?) Will a goos sync fix these symptoms. I am much closer now than i was. Thanks again for all the input. ~Mike

[md86]

Well , you SHOULD synch them anyway . The pilots DO effect power at lower rpm's , and how the throttle responds . Wait , FULL exhaust , and you're running 110's ? 3X105's and 1X110 is what comes stock on the 750 , and I KNOW the 600 uses larger jets stock .....

[mikeyt073]

New issues? Exhaust, Jet kit. Experts please (discrepancies)

Ok so what you might be saying is that whoever put the exhaust on this bike probably had no idea how to jet a carb. What size jets, needle position and pilot screw settings do you think that i need? It's all new to me, but i want to learn. I read a post by donmega that i'm sure you're familiar with. It is called "Installing jet kit. How to...write up" this is what i think would most apply to my situation

" Aftermarket Muffler & Header Unrestricted stright through setup with a high free flowing muffler such as V&H & D&D - Now its true that you will find that your idle will most likely be a little eratic or funny. When I say funny I mean it will idle low but if you turn up the idle speed adjustment screw your idle will be too high, you just cant seem to find a nice idle @ say 1k. Sometimes your rpms will hang up as well, if they hang up badly this could be from an air leak as well or from the vent tube going into the valve cover being clogged which will usally cause oil to come out so you would know if that was the case. To fix this problem you can simply adjust the fuel mixture screws located @ the bottom of the carbs. At this time I would also install 1 step up in main jets. This would be a size 116 on a pre 98 750 and a size 108 on a pre 98 600. "

however he writes that in the same situation with a k&n use 110 main jets on a pre 600, but I don't have a k&n.

I have an adjustable needle which tells me the needle is aftermarket? and 110 main jets are not stock correct? so i know that a jet kit was at least attempted. I would really like to get this situation resolved. I have pulled the carbs at least 4 or 5 times now.

Do i need to re-jet the carbs? or should i be able to get this resolved by readjusting my mixture screws (currently 3.5) and a sync. I don't really want to pay the hefty bill of taking it to the dealer for a tune. Once i get it right i will have gained so much knowledge and experience that it will all be worth it. Thanks again.

[arsenic]

well, the question is how much money do you want to spend? If you want to spend little money then you will have to keep messing and adjusting. If your willing to spend some money, just buy a new jet kit, throw that in, and you know everything will be right.

[Black_peter]

Throttle hang is caused (most of the time) by the FA adjustment. Sounds like you are close but not quite there. My experience is that even a 1/4 turn will get rid of hang. I will also say that after a full tear down and clean I still needed to spray carb cleaner into each FA hole, replace all the tiny o-rings too. That was just to get it running. I know (believe me!! I know) what a PIA these adjustments are. Until I got the 90 degree adjusting tool mine were never right. While my gas mileage is not where it should be but my carbs were performing really well. I have to say that I know little about jetting. However I would put Md in my list of most knowledgeable carb people. I know that on a Pre 98 750 there are no clips on the needles and as far as I know neither did the 600s.. Lastly I will respectfully disagree with Md on the use of a wire bristle in cleaning carbs. I don't think it is a good idea. I use fishing line.. I don't recall donmega's post exactly but I do know there was a fairly long post about some hard and fast jetting/pipe dos and don'ts. I don't recall anyone disputing his facts. So if that was donmega's I guess it was the right one to follow. Carbs=frustration IMO.. Don't loose faith!
I would rather tear apart my top end then have to tear into my carbs again. But I fear it is eminent in 2008...

[steves]

I would rather tear apart my top end then have to tear into my carbs again. But I fear it is eminent in 2008...

FYI, Maple Syrup does not make a good fuel stabilizer when one stores the bike for an extended period of time. Did you get that tip from a canuk?