I wondered why my bike was running like sh*t...

[Dom_]

https://img143.imageshack.us/img143/9016/sparkplug6ht.jpg

What zee hell has caused that, they were changed fairly recently.

[shammon]

Thats Gubbed! I can only think it was the wrong plug for it to get a pounding like that.
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YAMAHA YZF 1000cc THUNDERACE- 'ƃuıןןǝds ʇnoqɐ ʇıɥs ɐ ǝʌıƃ ʇuop ı

[fazed]

What do the other's look like ? have you got a race can, different air filter etc?
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gixxer thou K6 , Cbr400 gullarm x 2 , cb400 superhack.

[Dom_]

Not taken the others out yet, i've been asleep all day.

Got a K and N, full stainless system.

[stinkwheel]

Either the piston has hit that plug, or the pot it came from is running lean as hell.

If it is the latter, you are not far away from a holing a piston. Get it sorted quick.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Dom_]

Erm,,,,f*ck!

I've got some spare time saturday morning, i'll get the rest of them out and see what they look like.

It did only start running like crap after i'd got back from birmingham, most of the motorway was taken at fairly high revs (13-14k.)

The reason i took the plug out was because it spat out, so somehow had vibrated loose, then was spat out under compression as it was only the last couple of threads holding it in.

Am i looking at 2 different problems here do you think?

[sickpup]

If the plug was loose the cylinder would run lean.

[Dom_]

I was thinking exactly that sickpup. Still i'll have a look at the other plugs and see how they are.

[ancientd]

I would do a compression test on the bike, there is another option to explain the damage, and that is that a valve has broken up and the bits took out the plug before it went through the rest of the engine
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I ride 3 bikes, a Thundercat, an FZRexup 1000 Streetfighter and a Jawa 350 Combo, something for all seasons.

[Kickstart]

Hi

I take it that the outer electrode has broken off? Looks like it has been running hideously lean. Not sure if would land up that dry and burnt just from leaking around the plug. Serious heat from running lean might well cause the electrode to come off (and it might well have done some damage).

Be interesting to see the state of the other plugs. Also take the carbs off (probably will have to when taking the plugs out), and check the condition of the carb rubbers. Check the mount for that cylinder to check the carb was seated properly. Also worth checking the carb diaphragm (perforrated the slide won't lift so it will run lean).

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Kickstart]

Hi

To go with the compression test, good luck finding an adaptor that will fit.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[sickpup]

[bish777]

[Bezzer]

Did you have it checked - dyno'd/jetted when you fitted the new exhaust and filter?, might have coped with one but both would have probably leaned it right out, the high speed/revs run wouldn't have helped.
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I used to be indecisive but now I'm not quite so sure.

[Dom_]

It had the K and N on before i bought it, i fitted the downpipes.

It's made a fair few motorway journeys since then though, and i do tend to be at high revs a lot of the time.

[Kickstart]

[sickpup]