Jetting help

[nick20555]

I got some time today to plug chop so I did another half throttle chop before I removed the throttle stop screw. It is on the right. Then I removed the throttle screw and did a full throttle plug chop on the left. I think the half throttle is a little rich but I like that for cruising. I would like your opinions on the full throttle plug on the left and the close up below. Is that too lean? We are in the heat of summer so I don't want to be lean because cooler weather will only make it leaner.

half and full plug chops

• nick20555
• Jun 12, 2015

Half throttle plug chop on bottom clip position (right) full throttle plug chop with 160 main (left)

full throttle plug chop 160

• nick20555
• Jun 12, 2015

Full throttle plug chop with 160 main

 

[Blaaster]

The needle looks good but the full throttle needs at least one size larger jet!

 

[nick20555]

The needle looks good but the full throttle needs at least one size larger jet!

Thanks for the reply I think I might go 2 sizes larger because like I said, this is the heat of the summer so it's only gonna lean out from now. So I think I'll try 2 sizes up in hopes that I can be a little rich so if I ride on a cooler day I won't have to worry about being lean.

That was with a 160 main, you think a 165 would put me either perfect or a little rich? I have a 162 but I'll have to swing by a shop to get a 165

 

[nick20555]

The biggest main I had was only one size bigger (162) and no shop around here had what I needed so I have 165-170 on there way but it will probably take a week.

But here is a plug chop at 162. Is this too lean as well?

full throttle plug chop 162

• nick20555
• Jun 13, 2015

Full throttle plug chop with 162 main jet

 

[MercMenace]

I would step that up 1 more. I'd call that plug right on the line.

 

[Blaaster]

Up 1 more and call it correct!

 

[nick20555]

I would step that up 1 more. I'd call that plug right on the line.

Up 1 more and call it correct!

Alright, thanks to the both of you. I thought I would probably want a 165 in it. Unfortunately I have to order that across the country because no one around here has one and all these places I find on the Internet with genuine keihin are located in California. So it will probably be next week before I get it in

 

[dirtysquared]

Did you try jetsrus? They usually have everything, and will get back to you fast if you email.

 

[Larry's Shee]

Carb Parts Warehouse Cleveland, O
http://www.carbparts.com/

 

[nick20555]

I ordered from jets r us yesterday. I wish I would have seen carb parts warehouse was in Cleveland because that probably would have gotten here very fast.

 

[nick20555]

Not sure if I'm being overly paranoid but I'm still doing plug chops to verify jetting. I just for some reason can't get my motor to respond to set my air screw and pilot jet no matter what jet I throw in it. It's leak free, I have checked multiple times. I did a plug chop at around 1/3 throttle and 2/3 throttle just to check a fairly wide range to see if I'm good. Look at them and see what you think. I think my 2/3 throttle one looks perfect so I'm guessing my needle and main are perfect or close to it. I can do a full throttle plug chop later to verify the main. The 1/3 looks a little light and I think it might have to do with my pilot jet and air screw being off. Any suggestions? 1/3 throttle is on left and 2/3 on right

plug chops

• nick20555
• Mar 8, 2016

Plug chops
1/3 throttle (left)
2/3 throttle (right)

 

[jbuckster07]

maybe turn the screw and blip the throttle? maybe the slide is sticking?

 

[nick20555]

maybe turn the screw and blip the throttle? maybe the slide is sticking?

I've done that. It's really starting to bug me. I've had this problem since I built the damn thing over a year ago. I have taken the carb apart so many times that I've worn out and replaced all the hose clamps on the intake and reed side. Everything is within spec and motor is leak free. I've gone as high as a 52 and as low as a 40 pilot and cannot get it to respond like it should. At one point I found a spot where is was really responsive but probably too lean with the 50 in and about 4 turns out so I put a 48 in and now I've lost it again. Only reason why I haven't made a big deal about it is because I know I got the needle and main set pretty good and that's the throttle ranges I typically use so I just turn the air screw in to the point where I know I'm not lean on idle.

 

[nick20555]

I turn the air screw in a half turn and did about a 1/4 throttle plug chop (left) since it looked a little lean on that 1/3 throttle chop I did last time. Also did a WOT plug chop (right). 1/4 looks good I think. What do you guys think on WOT? Up a size?

1/4 throttle (left) WOT (right)

• nick20555
• Mar 11, 2016