Ariel Owners Motorcycle Club

And of course…. Still have to resolve this….

Ah! That's beautiful.
MikeN.

Am I correct in thinking that the drive side pipe is much more
discoloured than the timing side?

If I'm correct the first thought is that the drive side is running
significantly hotter than the timing side. Quite why is more of
a challenge.

Another thought is that some chromium plate isn't as good as
others when it comes to exhaust pipes.

Hi Will

Your right - drive side is more blue, timing side is getting there, but less so. Exhausts are from Armours - so I’d hope they’re ok, but there is a blue patch of poor chrome on the timing side too (further down the pipe) which has blued and is clearly just that- poor.

Anyhow / to the ‘why?’, I did wonder if valve clearance has any bearing on it. Maybe exhaust valve set too tight. Must check.

I don’t think it’s induction bias from the carb out of line or whatever, nothings changed from when it was all stripped down,L (he old exhausts were original (!) and unblued, just rusted through…

Plugs are a nice grey/brown so I think the mixture is right now, it runs beautifully in top at 50mph, accelerates nicely, and ideal well. Just that odd spitting (once in (say) 15/20minutes at lights or junction),

However, having already blued the pipes, obviously I can’t now tell if all is well since they don’t go back to chrome and I can start again! They don’t seem to be getting any worse, so maybe the tweaking so far has helped it stabilise?

Need to strobe the timing to be sure that’s set fine. Then I am out of ideas!

Hi Martin

My exhausts, (Armours too), began to colour when I first started my FH post restoration, that was down to me setting the timing too far retarded I'm still using magneto ignition so the purchase and use of an AO Services timing light sorted that.

I believe you've converted to electronic ignition but I don't know the specifics of how it is triggered, the cam effect in a KF2 can be non symmetrical and a compromise has to be adopted to get the best position for timing of the two cylinders, could this be why your timing side is cooler than the drive side?

As for 'seeing' if future changes have any effect, I use an infra red thermometer before and after to gauge what's happening - for info, the head adjacent to the exhaust clamps on my FH currently runs at 240 C and the pipe discolouration has stopped.

Regards Mick

Morning Mick

Yes you’re right - converted to electronic (Wassell unit - seems good). I set the trigger at fully advanced and 34degrees BTDC. I did read that depending on the electronics, the trigger may do it’s things bang on time, but the minuscule differences in electronic bits may mean the spark appears a nanosecond later - hence a bit retarded - so strobing is the only real way to get the spark at exactly the right degree etc. I’ve added a pic of both pipes (drive side is bluer - but not much, and you can also see the small patch of poorer chrome on the timing side that indicated ‘variable’ chrome…

If/when I get it all sorted (your temperature guide is brilliant thanks!), I may see about rechroming the headers.

Evening Mick. Mr Amazon brought me an infrared thermometer - and the head by the exhaust after about a 10mile roll was 193c. Temp between the cylinders just under the rocker box was 230. The rocker box over the exhaust valves was 220deg c and the rear was 195. Just for fun - the carb was 48deg and the oil tank was a mere 32. Timing cover was 29deg. My boot was 21.

Can you tell I’ve been enjoying the new toy?

Importantly though - looks like yours and mine are about same temp so maybe another indicator that the timing/mixture etc is all there or thereabouts. Cheers as always for all the guidance.

The discolouring of chrome is unaffected by the quality of the application, if chrome gets above a certain temperature it will alter in colour, chemical stuff. The main advantage of electronic ignition is that the 2 sparks will be 180 degrees apart, so this is unlikely to be your problem.

Martin K wrote: ↑Tue Jun 06, 2023 7:08 pm Evening Mick. Mr Amazon brought me an infrared thermometer - and the head by the exhaust after about a 10mile roll was 193c. Temp between the cylinders just under the rocker box was 230. The rocker box over the exhaust valves was 220deg c and the rear was 195. Just for fun - the carb was 48deg and the oil tank was a mere 32. Timing cover was 29deg. My boot was 21.

Can you tell I’ve been enjoying the new toy?

Importantly though - looks like yours and mine are about same temp so maybe another indicator that the timing/mixture etc is all there or thereabouts. Cheers as always for all the guidance.

Try the same tests, but on each cylinder - see if the results are similar. I made some tests on my SQ4 and the results were interesting!

Roger Gwynn wrote: ↑Wed Jun 07, 2023 9:26 am The discolouring of chrome is unaffected by the quality of the application, if chrome gets above a certain temperature it will alter in colour, chemical stuff. The main advantage of electronic ignition is that the 2 sparks will be 180 degrees apart, so this is unlikely to be your problem.

Evening Roger. Do you know the Wassell system then? You’re right about the redundant spark - I have a different question about the advance /retard (and whether it’s still needed due to the ECU thingy now controlling advance?) so if I still have the A/R unit working normally - advancing the ignition as revs increase, is the ECU fighting against it - causing the timing to be ‘off’?

The fitting instructions are silent about removing/disabling the AR (I wouldn’t know what to do in any case!), so as it stands, I fully advanced the unit, set the degrees at 34 BTDC and then connected up the trigger at that point. Starts first kick, revs nicely and whops along at 50/60 very smoothly - so I guess it’s doing OK. Just wondering if as revs rise the ECU mapping doesn’t realise the AR is also working and so the pipes go blue?

Your ideas very welcome