spark plug pics,lean or OK ?

[jambo]

I know almost nothing about tuning a motor for lean / rich running. However, according to a site I've referenced in the past, Mikuni 152s are not a very big step up from Dynojet 140s:
http://roadstarclinic.com/content/view/61/96/

You may need to go further if you were running more than a very little lean.

HTH

Jambo

i was running this lean

attached this time

[embee]

If that graph is to be believed then I'd say you're still too lean. I'd be looking for lambda 0.9 or about 13:1 A/F at the leanest personally for max output.

As for plugs, visually it can be tricky as others have described, and to a large extent it can be a reflection of the plug grade suitability. What grade are you using? If this is a track only use, there'll be little problem in going one grade colder than stock, the only risk is some cold fouling which you can avoid simply be careful start-up procedures, but once up to race speeds it won't be an issue.

Yeah. This graph is from when i was running 140 dynojets. I've now gone up to 152.5 mikunis. It seems to be fueling a lot better but I don't want to spend another £60 to dyno it and find out for sure. The whole idea of racing in minitwins was to keep the cost down. I havn't even got a set of wets !!