plug reading help.

getting conflicting ideas about what's going on in this motor.

2 sets of pics, 1st set of pics is br9eix run for about 1.5 hours. 2nd set is br8eg run for 5 minutes just putting around to get some color on it. both are identical jetting, ambient temperature/elevation. on the first set of pics, the float level was bit low. also, timing was more retarded (just 1 degree less advance).


i'm thinking the first plug (which still ran fine) was a bit too cold, and a little rich. i'm assuming the carbon deposits all over is just due to plug too cold. there are no seal leaks.

2nd set of pics still a little rch somewhere, maybe hot enough of a plug now to burn deposits off.

1st plug.







2nd plug

The second set of photos looks like I'd expect if you just poked around for five minutes. Which one of your bikes is it?

Can't tell shit about jetting the way you're doing it anyway. Run WFO for along distance, kill engine and stop with clutch in. Now read the plug.

yes, i'm completely aware of that. it's not a jetting issue i'm trying to figure out. i'm more worried about the carbon deposits - the first plug was run hard - should be no deposits - unless that's what a cold plug will do...

it's a puch 175mx. the jetting is pretty good right now, pulls fine with no stuttering or lean indicators, has as much power as could be expected, and pretty instantaneous.... i guess the question is - even though i was on the pipe 99% of the time on that 1st plug, it didn't clean up. so is this just too cold of a plug doing this, or maybe a combination of too cold of a plug + something else.. it's a non resistor boot, resistor plug, electronic ignition. maybe go non resistor all over to get a little better spark.

2-stroke plugs typically won't burn their carbon deposits off. The NGK 8 heat range should be about right. OK, we all have our gas/oil favorites, but for air-cooled bikes, I had the best results with regular grade gas mixed 32:1 with Golden Spectro. If I was never going to ride hard, an NGK 7 heat range would be ok.

Thats alot of junk built up on the 9 for only 1.5 hours......especially if you were on the pipe alot and you say it wasnt stuttering and seemed to run good.

On that setup, did it four stroke or foul at low RPM or idle ? What kind of fuel are you running. What kind of oil and what ratio ?

Second plug is looking fairly good, but, I woulda guessed you had a hour of run time by its looks.

yeah, i'm not used to seeing plugs with that much stuff on them. it looks way worse in pics than the naked eye.did not foul or 4 stroke at all. idles fine. starts first kick without tickler when hot. needs tickled when cold. runs great at all throttle positions, no bog/stutter anywhere. on the pipe all the time. bike can't get out of it's own way until 6000rpm+.... running 93/112 50/50 ratio. 40:1 amsoil dominator.

i generally jet using the put it in third gear, cruise around, then wack throttle to the throttle position i'm jetting. see if it reacts properly, gets on the pipe right, pulls through transitions properly.. i also extensively check jetting uphill in wrong gear to make sure it pulls hard and doesn't 4 stroke/bog out under load.


i'm thinking b8es might spark better - i think i'm in the right heat range and timing now - the threads/strap are discoloring about right..

I disagree,with a heavy load of modern oil,premium pump gas and correct jetting this is what some old plugs (5K miles or so) from my '84 RZ 350 look like. A healthy spark is required though.

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yeah, but piston port versus reed valve definitely makes a difference on plug life.. either way i don't believe my first plug should look like that.

Are those NGK8 heat range? They look fantastic for 5K miles. However, pre-mix air cooled motors will most likely need to run rich if run hard and that will also create more deposits even with good oil and gas.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
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To the OP, for 1.5 hours, that does look like a terrible amount of carbon deposits. I would try a hotter plug and pull the head and inspect the piston after a hard run. If all is well, then run with the hotter plug. Your diagnosis seems correct.

But of course this advice comes from some random guy on the internet.

Last time I had a plug like that the deposits were molten aluminum from the piston. Sure you're not detonating? Bit lean?

naw, i pullled the head and piston looks fine. the deposits look like carbon, not aluminum

If the jetting is correct and the plug won't clean itself the heat range is off. Or the ignition is weak. Tread lightly here.

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Those look ideal!

would not surprise me - 40 year old electronic ignition... no suitable replacements available - mz-b has one, but it's 10oz. lighter, i need 10oz heavier :)

Have you looked here? http://www.powerdynamo.biz/eng/systems/lists/overview.php

Click on the Union Jack for english.

yes, that's mz-b. a fine ignition, but even less flywheel weight than what is on there now.

have you looked at Ignitech? I've used their stuff on oddball bikes in the past. Just the CDI but that and a good coil will boost output considerably.

i will have to check. this ignition is very strange - it's a bosch, all electronic, but it still has an external condenser... if i could figure out how it worked, it might work. the 'cdi' for it is still available, but it's 40 year old stock...and not too expensive ($90 ish) - it's what i have on there now. i haven't replaced the coil (it's a bosch 2 wire like on many mopeds)...it's available new inexpensively.. i have replaced wire, and plug end, and added an additional ground. i'd like to get flywheel remagnetized - but not sure who does it in usa..