lean looking plugs-what fi?

[oldyam80sg]

No matter how good the bike runs,the plugs always look lean.If i turn the screws out and ride the bike shouldn't the plugs darken up?I put the brand new plugs under a load and they still look white.The bike ran fine under a load but still they look white.

[bikerphil]

Ride for a couple hundred miles and then check them. If they color quickly, you are running too rich. If it runs fine, don't be too concerned.

[oldyam80sg]

It runs fine but does pop when slowing down.

[ManagerMike]

My personal experience with popping on decel is that it is too lean on the idle mix (pilot mix). Your plug color is not dependent solely on the mixture screw adjustment. It only affects closed throttle (idle) up to part throttle fuel delivery. Additionally, if your plugs always read 'lean' this also lends credence to the 'being too lean on the pilot mix' theory.

[WMarshy]

Might be worth checking the tips are not broken off of the idle screws, if you havent already.

By the way, your pilot circuit has very little affect to F/A ratio under higher load/rpm. And, how many miles does the plugs have on them?

[BA80]

My personal experience with popping on decel is that it is too lean on the idle mix (pilot mix). Your plug color is not dependent solely on the mixture screw adjustment. It only affects closed throttle (idle) up to part throttle fuel delivery. Additionally, if your plugs always read 'lean' this also lends credence to the 'being too lean on the pilot mix' theory.

Thank you Mike. That is ABSOLUTELY TRUE and I have been arguing that fact with many for YEARS.

@ Oldyam; an occasional pop ain't bad, constant is lean on closed throttle condition. If you can tell which side it's coming from try backing the idle mix screws out 1/4 turn at a time on each carb on that side and riding to check.

There is a good way of adjusting the idle mix with the vacuum gauges but it's a little complicated if your not really technically inclined.

[jjz28]

Thank you Mike. That is ABSOLUTELY TRUE and I have been arguing that fact with many for YEARS.

@ Oldyam; an occasional pop ain't bad, constant is lean on closed throttle condition. If you can tell which side it's coming from try backing the idle mix screws out 1/4 turn at a time on each carb on that side and riding to check.

There is a good way of adjusting the idle mix with the vacuum gauges but it's a little complicated if your not really technically inclined.

I just fixed mine by turning out the mixture screws. It was worse on the right side so it took more to get it right. Now the plugs are nice and does pop on decal.

[oldyam80sg]

I will try that and report back.I replaced the vacuum caps yesterday and at least it will idle now.

[skids]

The float level also has an affect on richness. There are a lot of variables. You have a Kerker 4 into 1? I have a Jardine 4 into 1 and at the best adjustment I could do (so far), I get a bit of a rumble with light popping on decel. The plugs are good on that bike. I think I do need to raise the float fuel level a little because it loses torque and the speed levels off at just under 100 mph. The next bigger main jet makes it worse, and raising the main needle is really bad. This is a 78E with K&N individual filter cans and I am at mile-high elevations (minimum). I am a bit reluctant to do anything more with it because the bike runs so well at normal speeds and has real good torque at low to mid rpms (all the way to 6000).

[BA80]

The float level also has an affect on richness. There are a lot of variables. You have a Kerker 4 into 1? I have a Jardine 4 into 1 and at the best adjustment I could do (so far), I get a bit of a rumble with light popping on decel. The plugs are good on that bike. I think I do need to raise the float fuel level a little because it loses torque and the speed levels off at just under 100 mph. The next bigger main jet makes it worse, and raising the main needle is really bad. This is a 78E with K&N individual filter cans and I am at mile-high elevations (minimum). I am a bit reluctant to do anything more with it because the bike runs so well at normal speeds and has real good torque at low to mid rpms (all the way to 6000).

Your never going to get ALL the ranges perfect skids. you can either have good low and mid range response or you can have good mid and high range.

You need to chose where you want it.

Mine with the stock air box and UNI filter with the MAC 4 into 2 hits a wall at about 97 MPH but will go to 120 if I shift down to 4th. I guess I should mention I have an 850 FD also.

Those pods will affect the top end. There will be a vacuum effect in that area at higher speeds I would think. That might be why the air box snorkel is up under the seat.

Just thinkin'.

[oldyam80sg]

I have no issue going 100 mph + with this bike.Will do some more riding less fussing with it.

[TopCatGr58]

I will try that and report back.I replaced the vacuum caps yesterday and at least it will idle now.

This note right here points to your vacuum leak and partly why it was running LEAN! Like you said later, ride it and then check the plugs after a few hundred miles and you may get pleasantly surprised at some light tan color!?

T.C.

[oldyam80sg]

I will have a lot of riding to do-still have 3 more vacation weeks this year.Spent 2 weeks already at the beach and camping,time for more riding.

[oldyam80sg]

Took a ride today-no issues at idle,lightly pops though but runs good.A question though,when you spritz the pipes to see if they are hot, should they keep sizzling? Just curious,the water does evaporate though.

[Diskman01]

Another thing to look at is what type of GAS are you using. I HATE ethanol and it really messes with our bikes.

Sounds like you are getting it to run a bit better. Now try some different gas. Higher octane will burn slower and sometimes will backfire in the exhaust if enough unburned fuel is present. Try lower octanes, higher octanes, different brands etc.

I settled on a name-brand gasoline and ONLY fill at those stations. Makes tuning the XS much easier. When I *DO* go out of town, I look for comparable gas ratings. So far so good.