Plug chop test results...

[Shuriken]

02 model. UNI air filter. OEM exhaust. 5700ft elevation. 150 main jets.

I have this color at idle, mid, and full.

Are we going for the light tan or the light gray?

 

[Fire-medic]

I think you may get an improvement in operation with 147.5 Mikuni mains.

 

[Shuriken]

I think you may get an improvement in operation with 147.5 Mikuni mains.

Funny you mention that. I put 147.5s in my 85 many years ago....

I have some 147.5s on the way. It will be nice to have 152.5, 150, and 147.5 to experiment with.

 

[Aquamax]

To me, that's not a bad color. I think you may find the 150's will be golden to your altitude...especially with OE exhaust. Is it a single UNI filter in the stock air box? If you had a Kerker system, I would definitely say you need to get into the 147.5 range.

 

[maleko89]

I agree. I'd be ok with the look of those plugs.

Mark

 

[Shuriken]

To me, that's not a bad color. I think you may find the 150's will be golden to your altitude...especially with OE exhaust. Is it a single UNI filter in the stock air box? If you had a Kerker system, I would definitely say you need to get into the 147.5 range.

It is a single filter. I've used K&N before and have one of those in my 85. This UNI came installed in the bike.

I might be splitting hairs.... but my 85 feels slightly stronger. It has the same OEM configuration, but uses a single K&N with the OEM exhaust, and 147.5 main jets.

I have some 147.5s coming. I do need to remove the carbs one more time to replace the right rear carb body. The PO effed up the idle mix screw threads. I tapped out the body to m7x1 and made my own bolt, which works, but it looks hokey and isn't as easily adjustable. So I need to decide if I want to keep these 150s installed or try the leaner mains.

The difficulty is that I sometimes ride at lower elevation (around 2800) and sometimes ride at higher elevation (over 8500). But in the current state of tune, which looks and feels pretty decent, I have to have my mix screws out beyond 5 turns. I have not gone a step down on pilot fuel jets.

I really wish I could find my Colortune plug that I bought 20 years ago. They are like $200 now. I used it on my old XS1100s to really see what was going on. I use the "ear method" in general but the XS1100s preferred a slightly rich idle. For example, bunson blue flame at idle on my XS1100s just wouldn't quite hold the idle, while slight orange flame would; but it was real easy to get all 4 pretty close with the Colortune plug, combined with the ear method.

 

[gentsvmax]

Funny you mention that. I put 147.5s in my 85 many years ago....

I have some 147.5s on the way. It will be nice to have 152.5, 150, and 147.5 to experiment with.

Search and READ this post,

Carb Tuning at altitude​

 

[Shuriken]

Search and READ this post,

Carb Tuning at altitude​

Wow... thanks for that! I had never seen that thread before now. Super helpful.

It looks to me that there are some mentioning in that thread to go up on the pilot fuel and down on the mains.

If so, I can see why I have to go 5-7 turns out on the a/f screws...

Alright... unfortunately I am on the last dregs of riding and testing season but there is a ton of info in that thread and new tests for me to perform.

I think it's worth getting it right. I can't imagine what this engine would do, properly tuned at sea level.... I haven't really found a tire that will withstand a clutch drop in 1st though...