Plug colour

motoddrob

motoddrob

Hero member
Location
S/W Australia
After 225 track kms these are the colour of the plugs.
Centre looks slightly hotter than#1 and #3 is looking richer.
I've got the mix screw set at 1 turn out.
Mikuni RS carbs. 3/4 to 1 is based setting. Also noticed the revs hanging slightly when blipping the throttle.
Bike ran fantastic both days.
Some fine tuning needed.
Thoughts???
 

Attachments

  • 20250611_134109.jpg
    20250611_134109.jpg
    175.4 KB · Views: 71
motoddrob said:
After 225 track kms these are the colour of the plugs.
Centre looks slightly hotter than#1 and #3 is looking richer.
I've got the mix screw set at 1 turn out.
Mikuni RS carbs. 3/4 to 1 is based setting. Also noticed the revs hanging slightly when blipping the throttle.
Bike ran fantastic both days.
Some fine tuning needed.
Thoughts???
Click to expand...
Howdy Rob,

Havin a hoot over in WA.....
:cool:
My thoughts below
Maybe hangin up cause of an air leak??
Mixture screw should be no more than halfa turn out.
Try lifting needle a notch or two.
Whats ya main size?
 
Hi Hocksey
Mains 122 iirc
Pilot 117.5.
Raised the needle 1 notch when carbs first installed. Has been running like that for 15 years.
I had the carbs off last week to clean the pilots refitted and balanced.
Got them pretty damn close with the carbi tune. Pretty sure it's a fine tune with the air/fuel.
1/2 turn you say. Have set at 1 turn.
Red said 3/4 to 1.
I haven't touched these carbs in years.
Always ran good.
Remind me out to enrich?
 
motoddrob said:
After 225 track kms these are the colour of the plugs.
Centre looks slightly hotter than#1 and #3 is looking richer.
I've got the mix screw set at 1 turn out.
Mikuni RS carbs. 3/4 to 1 is based setting. Also noticed the revs hanging slightly when blipping the throttle.
Bike ran fantastic both days.
Some fine tuning needed.
Thoughts???
Click to expand...
Often a sign of lean-ness, same as your plug colours. Which plugs are you using? They look a little too light to me. Depends a bit on ambient temperature though. For colder temps, they'd be OK, borderline for higher temps, not much in reserve.

Guess you're not hanging around on the track, so those colours won't be caused by the idle circuit and mixture screw. Maybe hang the needle a notch higher or go for a slightly larger main? Drawing some oil on #3?

piet
 
B8ES Piet.
Have raised the needle one notch to solve a lean/popping issue when first installed. Also went from 115 to 117.5 pilots.
Main 122, worth going up a size main jet?
For general riding it seem to run fine. Done 8 track days in the last 18 month, = to well over 2000 track kays. Heap more kays than road miles. never missed a beat
Bouncing off the rev limiter so definitely main jet.
Whats the best way to set the mixture screws from base setting?
I'll start by raising the needle another notch and recheck balance. That'll keep me busy tomorrow.
Drawing oil via the guide??
 
I'd simply try some #9 or even #10 for track use, just to bring combustion temps down a bit. Won't have fouling either once the revs are up.

Imho, NGK 8s are generally a bit too hot for the triples. All the world uses them, but what the hell do I know... glad I've found a new source for the trusty Champions.:rolleyes: I've found Denso #24 to be a close alternative for the N3 Champs, #27 for the N2. As they're not as widespread as the NGK, there's little chance on falling for counterfeits as well.

Could be the guide, could be the rings... your guess is as good as mine, Rob. Easy enough to swap out the valve stem seal next time you have the cams out to adjust clearances.

piet
 
motoddrob said:
Hi Hocksey
Mains 122 iirc
Pilot 117.5.
Raised the needle 1 notch when carbs first installed. Has been running like that for 15 years.
I had the carbs off last week to clean the pilots refitted and balanced.
Got them pretty damn close with the carbi tune. Pretty sure it's a fine tune with the air/fuel.
1/2 turn you say. Have set at 1 turn.
Red said 3/4 to 1.
I haven't touched these carbs in years.
Always ran good.
Remind me out to enrich?
Click to expand...
Yep ya on the money Rob out to enrich.
Run mine halfa turn out, starts on the button and idles from cold, certainly diff state of tune to your Motodd. (Mines 981 A11’s - 17.5 pilot/127.5main y4 emulsion tube 👍 Fact 3 into 1 zorst.)
As Piet mentioned idle circuit not in play if ya at the track!
Pretty sure 4 notches on them needles try clip on bottom notch 👍
 
Hi Dave, now thinking of going larger mains looking at your main size.
Motodd 1145, axtel cams, Red's hc Ross Pistons, toddy 3/1
No more track days till Sept, need to sort it before then.
Maybe use B9es as Piet suggests.
Oil on #3 is a worry, most probably the guide. 2nd hand 81 head and valves. Hand lapped the valves and fitted and don't know it's history.
Piet, what's the secret to replace the guide seals with head in place?
I'm going to play with the pilots tomorrow and order larger mains.
Thanks for your input
 
motoddrob said:
Hi Dave, now thinking of going larger mains looking at your main size.
Motodd 1145, axtel cams, Red's hc Ross Pistons, toddy 3/1
No more track days till Sept, need to sort it before then.
Maybe use B9es as Piet suggests.
Oil on #3 is a worry, most probably the guide. 2nd hand 81 head and valves. Hand lapped the valves and fitted and don't know it's history.
Piet, what's the secret to replace the guide seals with head in place?
I'm going to play with the pilots tomorrow and order larger mains.
Thanks for your input
Click to expand...
Cams out, feed a thin rope into the offending cylinder and turn it towards TDC, the coiled rope prevents the valve from dropping into the cellar... Remove spring and seal, replace seal and spring and throw the caboodle back together, after pulling out the rope, of which you surely did fasten the outer end so it wouldn't drop inside. ;)

It's fiddly, but far quicker and loads cheaper than removing the lump and lifting the head.

piet
 
Wot fuel, we have summer and winter "blends" in Australia. Top plug is running rich at lower rpm, middle plug the ash colour is sort of new age, no additives in the fuel tank Rob? Lower is a cross polination of the other two.

Agree with Piet, flat out track the 8's are running too hot, 9's perhaps... if me the carbs as presented are not working in unison ( ignition notwithstanding also ), some work to do....notwithstanding could be a best setup for usual law abiding road rides. Then am off the pace these days with assessing older motors on modern fuel soups.... j.
 
I have alot to learn regarding carbs.
No fuel additives, using BP Ultimate 98.
So I've decided to order 127.5 and 130 mains. Also change the 17.5 pilots to 120 and put the needle back to middle and go from there.
Also for track use use B9s.
Piet has thrown a spanner in the works with his comment of pulling oil in #3, so will replace the guide seals. Next time the cams are out.
Great tip Piet re: rope.
Your right Jon about the carbs being not in sync. Ignition should be ok but I'll recheck anyway.
I had the carbs off last week as it wouldn't run off choke after sitting for 3-4 months. I drained the tank and carbs to store it before heading off to Thailand for 2 months.
I sprayed carb cleaner through all the nooks and crannies as well as air, set the mixture screw to 1 turn [probably too much as Hooksie sez 1/2 turn and Red 3/4-1 turn]refitted and balanced with Carbitune gauges.
was running sweet in the shed after that. Didn't take it for a proper test ride apart from around the block in lower gears. It has been pissing down raining!!!!.
Next track day is Sept so have some time to play
 
In all honesty Rob, it seems to be very little oil... probably not worth the trouble.

Keep an eye on consumption and quiz your fellow trackday riders if your bike smokes a lot on the overrun, a good indicator on how bad it might actually be.

My 3C consistently throws out a pretty plume on overrun, but overall consumption is still less than 0.25l/1000km, so it's going to have to wait. Because it emits a fair bit of clatter from the cam box, new seals are not going to suffice... :rolleyes:

piet
 
Rob,

Only way to take any doubt away and be able to sleep the night before your next track day floggin….. is to plonk it on a Dyno 👌🏼
Takes the guess wrk out of it. That’s why I fattened up my emulsion tube, because it was reading a little lean on the needle. No great concern on the hwy but throw in the odd track day and could get ugly. Rather be runnin rich on the hwy 👍
 
Thanks to Hooksie, Piet and Tom's input I'm now thinking the mains are too lean for trackdays so have just ordered 127.5 as a start. Also have ordered 20 pilots up from 17.5.
I have recently started noticing a little smoke from the exhaust when I run it stationary. I also had to add about 250ml of oil after Saturdays run so maybe Piet is on the money and the #3 guide is pulling oil.
Will also run B9s on track.
A dyno run would be great but logistics are difficult living where I do.
My main concern now is the oil. Maybe a head job is on the cards.
 
motoddrob said:
Thanks to Hooksie, Piet and Tom's input I'm now thinking the mains are too lean for trackdays so have just ordered 127.5 as a start. Also have ordered 20 pilots up from 17.5.
I have recently started noticing a little smoke from the exhaust when I run it stationary. I also had to add about 250ml of oil after Saturdays run so maybe Piet is on the money and the #3 guide is pulling oil.
Will also run B9s on track.
A dyno run would be great but logistics are difficult living where I do.
My main concern now is the oil. Maybe a head job is on the cards.
Click to expand...
You may need 8's to warm the engine and then switch to 9s or 10s.
Paul
 
A Redaxed triple with Ross hi comp slugs and Mikunis will not need 8s for track work, starting or otherwise. I'd be running 9s in it on the road as well - and I'd be very surprised if it fouled one.

Also agree with Hooksey - if you really want to sus out your carburation, Rob, a quick run on the dyno to check AF ratio is highly recommended, even if it's just to set the main jet (which is where the majority of risk lies on the track).
 
Other than not being a 1200, my 3c has a very similar engine configuration, and nobody has ever suggested I run 9s. Is this common on Redax motors?
 
Last edited:
You must log in or register to reply here.
Back
Top