spark plug caps thunderace.

to v or not to v · World Chat Champion Joined: 24 Nov 2020 Karma :

bikes running very rough since changing the plugs. think it might need new plug caps?
where do people buy them from? i had a look on ebay and they were over £60 each. it seems a bit excessive.

to v or not to v · World Chat Champion Joined: 24 Nov 2020 Karma :

have taken out the innards and 3 of the four brass screw in bits that the plug end slots into are badly corroded. the springs in them that grip the spark plug have disappeared.
are these bits the same in other caps? could i buy some cheap caps and swap them out?

Fizzer Thou · World Chat Champion Joined: 06 Aug 2011 Karma :

I had a problem the other year with my Exup-R when the engine would cut on to three cylinders,even though I had serviced the bike thoroughly over the Winter during heavy snow.I managed to get home on three and a half cylinders and set about checking everything and found that the internal resistors in the OEM plug caps had slightly corroded and one in particular was worse.Instead of sourcing expensive OEM plug caps I only replaced the resistors with a similar length of brazing rod and rebuilt them.Sorted.

The engine ran okay until I started to have an erratic situation once it got really hot.It transpired that two OEM caps were expanding and the coil voltage was escaping to the cylinder head,visible in the dark.I replaced all four plug caps with NGK straight caps with the resistors replaced as before as I did not want to have a similar fault while miles from home.
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to v or not to v · World Chat Champion Joined: 24 Nov 2020 Karma :

ive ordered 4 ngk plug caps for a yzf750. £18 as opposed to £250 for the ace's ones!

SW Motech Shop UK · Scooby Slapper Joined: 22 Nov 2004 Karma :

I would imagine the NGK ones will be universal based on length. The probably don't have the waterproof caps of the OEM ones. I used NGK on my old Bandit and every time it rained i got a misfire. I modified the old covers to fit on top of the NGK ones and it was fine. I don't know how exposed to rain your plugs are. Might be OK.
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to v or not to v · World Chat Champion Joined: 24 Nov 2020 Karma :

unfortunately the NGK caps are about 10mm shorter, makes trying to fit them even more fun Sad

Fizzer Thou · World Chat Champion Joined: 06 Aug 2011 Karma :

to v or not to v · World Chat Champion Joined: 24 Nov 2020 Karma :