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Spark Plugs


davet
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i bought a txt 280 03 model 4 months ago, really pleased with bike,but in the short time ive had bike it has gone through 3 spark plugs. is this normal ? or could there be a fault ? im using npk bpr5es plugs.

hopefully its normal nothing to worry about ,could anyone of you out there be the sender of good news

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Hi

NGK plugs are great plugs heat range 5 or 6 or 7 is about right for a trials bike. Check in your manual or on the NGK web site. I have ftted an Iridum NGK plug and have been really impressed with the huge spark form it - they are expensive.

Normally plugs will run for ages (even years) if the mixture is right. So try these....

Is your air filter clean and properly oiled?

Are the cab mounts and read block snug?

Check that the correct jets are fitted to the bike. Remove them and check. BLOW all the carb passages clean.

Check the idle mixture screw is set correctly. Set a fast idle and turn the screw in and out slowly to get the fastest idle (normally 1.5-2 turns out).

If the bike is running rich the plug will be black and sooty and blub along rather than a clean pop.

For the idle running rich a good sign is that the choke is only needed for a few seconds rather than 30ish seconds. If this is the case try fitting a smaller pilot jet.

Normally the needle clip should be in the middle or one notch up from middle.

Beyond this there is SOOOOOOOOO much more to getting jetting right. Try Googling the subject.

Ralphy

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Hi Dave,

What do you mean by "gone through 3 spark plugs" Can you explain a bit further. Have they oiled up and stopped working. Have they just stopped sparking and are not oiled up? Is the motor burning gearbox oil, is there lots of blue smoke from the exhaust?

Usually, as Ralph said, plugs last for years unless something is amiss with the motor/carb.

NGKBPR5ES is correct for your bike. Is there a good connection between the plug cap and HT lead. Is the voltage regulator mounted tightly onto the underneath of the headstock.

Bye, PeterB.

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thanks all of you for your replys. the spark plugs were slightly oiled not cracked or damaged in any way,just seem to have stopped sparking. the first one stopped working after laying the bike down after a fall, the second one stopped just a few minutes after heading out to practice only 400yrds. third one must have stopped sparking after doing a section because would not start, changed plug and was and still is o k fingers crossed.....

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thanks all of you for your replys. the spark plugs were slightly oiled not cracked or damaged in any way,just seem to have stopped sparking. the first one stopped working after laying the bike down after a fall, the second one stopped just a few minutes after heading out to practice only 400yrds. third one must have stopped sparking after doing a section because would not start, changed plug and was and still is o k fingers crossed.....

May seem like a silly question, but I have experienced this my self... Is the choke fully off??

The choke lever on my old TXT 270 had the habit of getting stuck half way down.

By the way. Do You have a TXT Pro or a TXT "Edition"? Not that it matters..

-Jan

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May seem like a silly question, but I have experienced this my self... Is the choke fully off??

The choke lever on my old TXT 270 had the habit of getting stuck half way down.

By the way. Do You have a TXT Pro or a TXT "Edition"? Not that it matters..

-Jan

Jan has a good point. Sometimes fine grit will prevent the brass plunger from fully seating (and shutting off fuel flow to the "choke" circuit) and the engine will run slightly rich. The best plug I've found for the GasGas is an NGK BPR5EIX set at .024" (.6mm), but it sounds like the problem is not with your plug.

Is your bike a TXT or Pro and what jetting are you running? That may be the problem, and if not, it will help narrow down the possible causes.

Jon

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  • 2 weeks later...
 
Say, what plug do you think is best for an '06 280 TxT Pro?

Thanks!

Same plug: NGK BPR5EIX at .024". I've had one in my 02' 280 Pro for over a year. Resists fouling (never in the last year, so far) and shows very little wear, I checked mine a couple of months ago and it was still where I had set it. It cost a little more but has proved to be a bargain in the long run.

Jon

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Jon, I would be interisted to see if the Gasser will support the even wider gap of .027-.028 with whatever ignition you are running.

I have run this with the VX plugs for the last three years at that gap, which really does seem to help a bit on starting and low end power!

Obviously the resistor plug offers some disadvantage in itself. Not quite sure where the limits are, but the optimum limits are not written!

The question about the IEX plug, does the resistor offset the low resistance of the electrode?

These limits of reliability will only be found at the upper limits of high density air, as you well know.

Thoughts?

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