Don't be fooled by your spark plugs.....

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J-Revo

J-Revo

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Hamar, Norway
My new engine died today and didn't want to start up again.
As i always have done I pull the plug and check for sparks, and there was sparks. Put the plug back in, it fired right up but with a bad shake and died again.
Thought I had flooded the engine trying to get it started. Pulled the plug again, tipped the engine over gave it a few pulls on the starter, before I put the plug back in I tested it one more time. This time with the plug slightly wet of fuel there was no spark. Gave it a hard blow of air and the plug had spark again.
Put it back in, fired right up this time also, but had a bad shake.

My thought is that there is enough left in the plug to make a spark when it's bone dry, but with just a little fuel added, it won't spark.

I was aware that this would happen, as I did run it with extra oil and very rich for the break in.
 
Ive never bothered checking the spark against the head. If it don't run right or has difficulty starting I just bang a new plug in & test it with that. If it doesn't work with the new plug something is fooked :w00t:
 
Yes, but buying a plug at my local dealer was a NO GO! 26USD/16GBP, that ain't happening! Found a lot on ebay for 3.48USD a piece. Ordered 10 so I have some spares ;)
 
J-Revo said:
Yes, but buying a plug at my local dealer was a NO GO! 26USD/16GBP, that ain't happening! Found a lot on ebay for 3.48USD a piece. Ordered 10 so I have some spares ;)
Click to expand...

Thats what I did mate! They are £5 from the model shop but called into a place near Stoke & got them for £2ish each so bought 10 myself :D
 
What spark plug are you using. I honestly have had the same spark plugs in all my rigs for years. I run at 25:1. If you ever tear a spark plug apart there really is no way it can fail unless the electrode cracks inside or it carbon fouls on the outside. If you flood it, it will not spark enough to start even if its new. Once these little 2 strokes flood the fuel stands in the bottom end in with the crank. Thats the reason we tip them upside down, so that the fuel runs back past the ports and to the top end where it can get out and not build up fuel gas again.

Take that back I broke one on a top landing on the baja.:o:

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What is the bad shake all about?
 
I ordered the same spark plug as it came with, CMR7H.
I also have never changed a spark plug on my earlier setup, as the FG beetle many yers ago or my no sold HPI Baja. But then again non of them were new engines. The reason of this spark plug failing, I write of to the break in and carb tune proceedure. It also said so in the manual, to keep a spare plug ready as it most likely would foul.
 
I'm not recommending this but I have been known to put the air compressor int he plug hole when pulling over to "speed" the dry time. A bit dangerous if your head is dirty but I get a bit impatient sometimes. :o
 
cmr7h is this the only plug to run, what about a 6 or a 5 will a richer mixter on the high speed needle fix the plug difference.
 
Ive changed plugs twice - 1st time the Champion plug it came with was badly fouled & 2nd time had a bad off & it refused to start again but under normal conditions they do last for ever.
 
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