Do my sparkplugs need replacing?

**rustyrobot** · 7th October 2010, 11:35

I have probably had my bike for about 3000kms now. I have no idea when the plugs were last changed but I certainly haven't done it. When I took the plugs out they were covered in quite a lot of wet oil residue. I wiped that off, and this is the way the plugs look underneath. They seem OK to me, but I don't really know. I looked at some websites (like this one) but couldn't really tell whether my plugs were on the fine side of normal or the 'replace' side.

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**Jonno.** · 7th October 2010, 11:43

How old's the bike?

The most important question is how much is a new set? Change them if you can afford it and be thankful you don't have a VFR with plugs that cost $40 each

**rustyrobot** · 7th October 2010, 11:46

Bike is 22 years old. Plugs cost about $20 each, so thankfully cheaper than yours. Guess I'll just get a new set then.

**SMOKEU** · 7th October 2010, 12:06

Originally Posted by rustyrobot

Bike is 22 years old. Plugs cost about $20 each, so thankfully cheaper than yours. Guess I'll just get a new set then.

Are those CR8/CR9 plugs?

**rustyrobot** · 7th October 2010, 12:09

Yep, CR9. Going by price on Trademe.

**cbfb** · 7th October 2010, 12:10

They don't look all that bad, bit of carbon fouling round the outsides. Mine are worse but then I've spent enough on the overhaul already so they can wait.

Give them a clean with brake cleaner and a bit of a scrub with a wire brush, blow out any crud with compressed air, check the gap then chuck them back in.

You can sandblast them too apparently but not recommending it coz I've never done it personally.

Also if they are carbon fouling changing to a hotter plug might help.

Now the oil is a bit of a concern, might want to get that checked out. Mine is doing it on one cylinder but not figured out why yet.

**rustyrobot** · 7th October 2010, 12:12

Don't have any brake cleaner but got a can of degreaser. Will that be an ok substitute?

**cbfb** · 7th October 2010, 12:15

Dunno to be honest, I've always used brake cleaner. Doubt it would do any harm so long as you dry it off after, but don't think it would do much to the carbon fouling like the brake cleaner does. The zuki shop manual for my Bandit says to use a pointed tool to carefully scrape the crap off.

**SMOKEU** · 7th October 2010, 12:35

Originally Posted by rustyrobot

Yep, CR9. Going by price on Trademe.

I've got the same ones on my CBR. Try Super Cheap Colombo St, they're often a bit cheaper than the rest.

**rustyrobot** · 7th October 2010, 12:42

Originally Posted by SMOKEU

I've got the same ones on my CBR. Try Super Cheap Colombo St, they're often a bit cheaper than the rest.

Cool, will check out Super Cheap, but I'm not riding down to Christchurch to do it, I'll just try the one round the corner.

**SMOKEU** · 7th October 2010, 13:19

Originally Posted by rustyrobot

Cool, will check out Super Cheap, but I'm not riding down to Christchurch to do it, I'll just try the one round the corner.

Sorry, my bad. I thought you were in Christchurch.

**porky** · 7th October 2010, 14:00

Not even run in.

Plugs will tell you what was happening prior to shutting the motor down. Looks like a bit of tootling around.
a couple of questions. The oil was around the electrode? or on the thread. Was it oil? Oil in the pot would have it running like a two stroke (blue exhaust smoke) unless its only a small amount and synthetic.
As said clean them, warm bike up, take it for a good ride, dont tootle, kill the bike, pull the plugs

**rustyrobot** · 7th October 2010, 21:06

Originally Posted by porky

Not even run in.

Plugs will tell you what was happening prior to shutting the motor down. Looks like a bit of tootling around.
a couple of questions. The oil was around the electrode? or on the thread. Was it oil? Oil in the pot would have it running like a two stroke (blue exhaust smoke) unless its only a small amount and synthetic.
As said clean them, warm bike up, take it for a good ride, dont tootle, kill the bike, pull the plugs

It was oil on the thread, and when I say oil, I mean a black oil-like substance. Not a huge amount, but was still unexpected.

**porky** · 7th October 2010, 22:54

Originally Posted by rustyrobot

It was oil on the thread, and when I say oil, I mean a black oil-like substance. Not a huge amount, but was still unexpected.

My take on the situation for what its worth. Oil on the threads was put there, black around electrode is standard carbon deposits, plugs arnt wet so sparks good. Clean plugs , take her for a blast, kill the beast and pull the plugs. (dont let it idle to much before shutting it down) Get ya magic chart out and compare. Should be a nice clean burn.