jetting help needed

[WNARACE]

Hey guys I have recently got my quad together, the mods are as follows t-5 pipes, boysen reeds, and pkw 28mm carbs with open lid and uni filter.

 

The bike seems to be running a little rich on the top end with 170 mains, and seems extremely sluggish in the low and mid before hitting the pipe in comparison to my buddies shee with similar mods and dg pipes. Could this be my jetting or is the differance in the two pipe combinations what I am fighting.

 

I'm at approx 500' and outside air temps im the mid 40's.

 

Thanks for your help and info.

[MonoxideChild420]

Sound's like you need to bump up the main to a 300,or possibly 310. is your needle on the 4th clip.....?try adjusting your air screw also, 2.0 turns out from fully seated....do you have a clean filter and good plugs.....?

[ogre03]

where is you needle at? also what pilots are you running?

[bigboybanshee]

Sound's like you need to bump up the main to a 300,or possibly 310.

454099[/snapback]

 

He's running Keihin carbs, not Mikuni.

 

I would try dropping the main jet one size, run it, see if it gets better. You may have to go down more than one size on the main, but would start by going one size at a time. Once you get the main right, you may not need to adjust the needle...just ride it and see. If it's still sluggish in the midrange, I would try going one notch leaner on your needle.

 

DG's hit the powerband sooner and have more mid range than toomeys do (from my experiences). That could very well be the reason why yours seems a little sluggish while his is running "smoother".

[WNARACE]

My needle is on the fourth position, but i cant remember which pilot im running, I will have to check to day. Thanks for the info I have never been around or ridden a bike with dg's, they seem to have lots of snap right off idle and it made me wonder if there was something wrong.

 

I later found out that my buddy also has his head milled 40thousands, could the added compression make the bottom end that much better?

[bigboybanshee]

I later found out that my buddy also has his head milled 40thousands, could the added compression make the bottom end that much better?

454210[/snapback]

 

Yep, it does add a decent low end gain...on top of the fact that DG's are more of a midrange pipe I'll bet it does have quite a punch. I ran DG's before I switched to Toomeys and there was definitely a difference in where the powerband hits.

 

With his head milled that much, he might risk his pistons slapping the head. I think the farthest you want to "safely" mill your head is .035...I'm no expert on milling heads though, I took the easy way out and bought a NOSS head.

[Banchetta]

The toomey is more of a top end pipe, but not being there, your jetting can play a large effect also...Higher compression will make a huge difference. I would buy a noss head over milling the stock head. I wouldn't go over .025 on the stock head. I've seen others deto w/ .030....although a lot of others on here never had a problem....so.........your call. As for the jetting, keihin carbs have more overlap than mikunis....I'd think your mains should be very close, but eliminate that w/ a wide open test in 6th gear for 5-10 seconds, shut it down, coast to a stop and check the plugs...black is rich tan is lean and chocalate brown is perfect...next what size are your pilots. How does it start when cold? Warm? Will it idle? What does it do if you cruise at ONLY 1/4 throttle, try to maintain 1/4 throttle for as long as you can, does it rev clean or choke up?

[WNARACE]

Thanks for all the info guys i didnt get a chance to check my pilots today, however im certain that they are stock for the carbs. As far as starting in the cold it takes approx. 5-10 kicks with the choke on, and maybe a few if it dies while warming up. Once it is warmed up it starts first kick every time. I did make a few wide open pulls today on new plugs and they look tan to darker brown the deeper you go into the plug. I think im pretty close on the main, but may be a little off on the pilot or the mixture screws. Havent checked the mixture screw position either, making a checklist of things to do this week.

 

 

Thanks again.

[Banchetta]

Your pilots sounds close and maybe a size too lean...You might want to try a larger pilot and see what happens. I'd also go out this weekend and try different clip positions on the needles, I'd raise the needles by moving the clip towards the pointy end of the needle...as for the plugs, you want to read the "finger" or ground strap. New plugs won't work so well, put some ride time on them to get some color on them, then do a wot run. You want the outer circle to be black and the tip of the Finger to be chocalate brown. The transition of color should be on the bend of the finger or ground strap....