The pursuit for a brown sparkplug
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wrote on 11 Apr 2018, 20:55 last edited by
Alright, trying to set up this Athena kit. Currently running 280 main jet and this is what the sparkplug looks like after ~250km. Looks pretty good huh? Sadly, the bike won´t rev fully, no power beyond 3/4 throttle. Running lumpy, strange. Wouldn´t say bogging but something is certainly not right down there. The question is, should I go down to 270 or up to 290? What´s your opinion? Personally, I´d want to try a smaller since almost everyone with the kit runs 270. However, since I´ve not pushed the bike that much during break-in, and the sparkplug isn´t completely black from a very rich mixture, I´d say I might as well try 290. A safer bet for sure.
And no Calum the pv is not pinned in the closed position
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wrote on 11 Apr 2018, 21:15 last edited by
It's not really appropriate to be judging the fueling on break in, you need to put that engine under load and perform a plug chop to really understand how the fueling is doing.
Once it's bedded in, perform a plug chop and report back what the plug is doing then.
I'd say that plug looks a tad lean to me.
Easiest way to tell is to restrict the air flow into the bike, if it performs better then you know you need to increase the fueling.
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wrote on 12 Apr 2018, 18:00 last edited by
This is mine (no kit though), a bit of deposits from excess oil, but otherwise tan as Hasselhoff!!
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wrote on 12 Apr 2018, 19:37 last edited by
Wow! I'm impressed! I'm now running 290 main jet. Can't feel much difference. My issue is, it does not pull after 3/4 throttle. The revs go up, exhaust getting louder, I brace for the real powerband but then nothing.. Dropping to 3/4 and she goes! But there is definitely power left to scavenge. My next alternative is to try a 270 main jet. And yes I've tried the choke, no results.
Should I really be giving the piston, cylinder full throttle? I'm closing in to 300km.. Shouldn't be an issue right? -
wrote on 13 Apr 2018, 14:30 last edited byThis post is deleted!
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wrote on 1 May 2018, 09:17 last edited by
I've tweaked the oil pump a bit for my Athena, will this dramatically lean the mixture? As I've said, I'm running far bigger jets than anyone I've seen used the big bore kits.
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I've tweaked the oil pump a bit for my Athena, will this dramatically lean the mixture? As I've said, I'm running far bigger jets than anyone I've seen used the big bore kits.
wrote on 1 May 2018, 10:43 last edited by@irongamer727 What is your bike not doing?
I dont get it.
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@irongamer727 What is your bike not doing?
I dont get it.
wrote on 1 May 2018, 10:50 last edited by@darty it's not performing well in the upper revs. The jetting is off, I'm steadily climbing in sizes (now 320) but the plug still looks a bit too lean.
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wrote on 1 May 2018, 10:51 last edited by
And I have a friend running 240 with the kit. We are both running stock Air box and so forth.
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wrote on 1 May 2018, 16:01 last edited by
Are you certain there's no leaks between carburettor and crank case? No head gasket leak, and no leaks in the carburettor itself allowing air in?
I'd say there's definetely a leak somewhere allowing a lot of extra air in. -
Are you certain there's no leaks between carburettor and crank case? No head gasket leak, and no leaks in the carburettor itself allowing air in?
I'd say there's definetely a leak somewhere allowing a lot of extra air in.wrote on 1 May 2018, 16:14 last edited by@glynn123 nope everything is sealing, not leaking etc.
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wrote on 1 May 2018, 17:17 last edited by
You using the stock carb? Pretty sure they use a powerjet which should be the jet you want to be changing.
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You using the stock carb? Pretty sure they use a powerjet which should be the jet you want to be changing.
wrote on 1 May 2018, 17:29 last edited by@calum yep there is a powerjet. I'll give the really big jets a try first. Because again, I've not heard anyone changing anything but the main jet.
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@calum yep there is a powerjet. I'll give the really big jets a try first. Because again, I've not heard anyone changing anything but the main jet.
wrote on 1 May 2018, 17:47 last edited by@irongamer727 So the powerjet kicks in at wide open throttle.
You should be doing a plug chop at WOT.
Therefore, changing the main jet won't affect the colour of the plug during a plug chop.
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wrote on 1 May 2018, 19:02 last edited by
Pretty sure the power jet isn't changeable on these carbs.
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@irongamer727 So the powerjet kicks in at wide open throttle.
You should be doing a plug chop at WOT.
Therefore, changing the main jet won't affect the colour of the plug during a plug chop.
wrote on 1 May 2018, 20:46 last edited by@calum I'm currently going WOT sixth gear and turn ignition off. I can thereby see the plug colour at WOT. And it still looks a tad to white for my taste.
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wrote on 2 May 2018, 11:52 last edited by Darty 5 Feb 2018, 12:55
The Powerjet is a fixed system on the TM28,
I used to run 340 Main, 30 Pilot, only because of extensivly modifing the Airbox volume,
And, it was rubbish mostly.
I had to replace my main body Carburettor gaskets because of symptoms near enough the same as you.
I would recomend throughly checking for Air leaks as this is almost certainly your problem!
Dont just throw fuel at this and hope for results.
Work backwards.
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The Powerjet is a fixed system on the TM28,
I used to run 340 Main, 30 Pilot, only because of extensivly modifing the Airbox volume,
And, it was rubbish mostly.
I had to replace my main body Carburettor gaskets because of symptoms near enough the same as you.
I would recomend throughly checking for Air leaks as this is almost certainly your problem!
Dont just throw fuel at this and hope for results.
Work backwards.
wrote on 2 May 2018, 12:03 last edited by@darty how would you check for Air leaks then?
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wrote on 2 May 2018, 12:08 last edited by
I do have the entire pice where the snorkel existed cut out. So there that as well.
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I do have the entire pice where the snorkel existed cut out. So there that as well.
wrote on 2 May 2018, 12:33 last edited by Darty 5 Feb 2018, 13:34@irongamer727 You donkey,
Why dont you try and restrict Air by patching up a section of the Airbox,
By doing so, i’ll bet a Roast dinner that it sorts out your lean condition.
I’ve played around alot with this, you’ll stuggle to fuel this properly with the TM28