Spark Plugs, what do you guys think?

Triton Thrasher said:

Then the side with the hot looking plug might appreciate a bigger main jet, if you are sure there’s plenty fuel flow from the tank.

Don’t raise the needle and change the jet. Test one change at a time.

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Yes plenty of flow, both peacocks open and give good flow and about 7L in the tank.

I am just wondering why that side runs so hot? Maybe am over thinking it but...

gortnipper said:

I am just wondering why that side runs so hot? Maybe am over thinking it but...

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Probably weak mixture, easily fixed.

gortnipper said:

Yes plenty of flow, both peacocks open and give good flow and about 7L in the tank.

I am just wondering why that side runs so hot? Maybe am over thinking it but...

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Yep, probably just a little leaner than the other side.

Just because the carbs and jets are the same size, don't assume they are going to give you the same mixture.
Even a single carb seldom [never] gives the same mixture on both cylinders.

comnoz said:

Yep, probably just a little leaner than the other side.

Just because the carbs and jets are the same size, don't assume they are going to give you the same mixture.
Even a single carb seldom [never] gives the same mixture on both cylinders.

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When I first started out mechanic-ing, I would laugh when I found different jets/settings on carburetors in a multi-carbed engine, thinking what an idiot the previous owner/mechanic was to have not checked to ensure the same jets/etc were in each carb. Fortunately, an experienced mech took me under his wing and informed me (and demonstrated on a dyno) that it may well have been intentional to get the best performance from the engine. Of course, it's still possible that finding different jets/settings could be a mistake by the previous owner/mech...but maybe not!

All runs done on a private road as I would never go over the speed limit on public roads

Recap: new barrels & 880 pistons + head worked on by Jim C. running on unleaded petrol.

Did a number of 'high speed' runs today.

Pushed the revs up to 5K which works out at 100mph indicated on the speedo.

Did a plug chop, just above 5K, throttle just above 3/4 turn, here's the plugs:





Seems OK to me, heat change point on strap seems, to my eyes, to be where it should be..

Full ring of carbon, 2-3 threads with colour.

Porcelane is white, which I believe is OK for unleaded.

I'll look a bit closer later today & see if I can see a ring of black at the base of the porcelain.

Bike pulling like a train, tickover like a clock, could have gone over the 100mph but rider was getting too much wind blast! I also noticed when I snapped the throttle at 5K I got clutch slip, which is fair enough!!

What do you guys think of the plugs?

Just had a look at the plugs again, I've all manner of magnification devices but can't really see the base of the porcelain or at least I don't seem to be seeing a ring of carbon around the base of the porcelain.

Did a compression test while the engine was still warm, throttle fully open, approx. 6-7 secs on starter, 190psi both left & right. I'll take that as an indication that the rings are bedded in!

looks very good. Jim

Nice one Click, looks like you’re sorted !

Just gotta beef your clutch up now eh?

Thanks lads, setup for the summer season

Starting to research all things clutch related!!!

Sit down, pour a whisky and contemplate a job well done.

Sláinte

cliffa said:

Sit down, pour a whisky and contemplate a job well done.

Sláinte

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Thanks but the praise really needs to go to Jim C. and everybody on this forum. I was just the grease monkey tightening nuts & bolts!
For the likes of me this forum is a fantastic resource & support, I've had lots of 'advice' in the past from 'experts' who I've met along the way & it's taken me many years to realise that most of it was hogwash & just information they had heard & just passed it on without any 'real' life experience.

Now, where did I put that bottle of whisky Sláinte

click said:

Thanks but the praise really needs to go to Jim C. and everybody on this forum. I was just the grease monkey tightening nuts & bolts!
For the likes of me this forum is a fantastic resource & support, I've had lots of 'advice' in the past from 'experts' who I've met along the way & it's taken me many years to realise that most of it was hogwash & just information they had heard & just passed it on without any 'real' life experience.

Now, where did I put that bottle of whisky Sláinte

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Well, obviously have one for Jim too