Warmer spark plugs

Hello,

my local dealer sold me NGK CR8-EH9 spark plugs for my 5th Gen, in stead of the normal CR9-EH9. Little did I know then, but after some surfing, I'm already a little wiser. These ones should be a little "warmer" than the original ones. What I don't know, is how much harm they can do.

Not only did I already install them and ridden with them, at the same time I changed the oil and filter (same brand as before) and the radiator coolant (probably hadn't been done since she was manufactured). Since, I've the impression that for the type of weather, she's running 5-10 ° celsius (sorry, don't know what that makes in °F) hotter. And because I've changed the plugs and the coolant at the same time, I don't know what could be the reason.

What say ye ?

 

I'd say pull the easiest spark plug that you can get to and check the color. If it's in the ballpark, I'd be inclined not to worry about the plugs too much, especially if the old ones were towards a dark brown in color. This is about the best internet chart I've ever come across;

Spark Plugs

The only thing I'd add as a preface is that the chart is from 1977, and motors have changed a lot (FI, combustion chambers, and microprocessor control), so it's a bit more difficult to read plugs. They are so much cleaner than they used to be. It's a good indicator of coloring in general, though.

 

V:

1. The easy part first: 5 – 10 ˚C = 9 - 18˚ F.

2. If you just changed the coolant I’d be very suspicious that the system isn’t bled properly and you still have some air in it. No experience personally with 5th gen bikes but I think I’ve read on the forum that they are sensitive to this. The sixth gen manual has a very simple bleeding procedure in it.

3. With due respect to the Uber Guru, I’d be a little nervous about the different heat range spark plug. On the one hand, I doubt that’s causing the engine to run warmer; the heat transferred from the combustion chamber through the plug is not great. It was quite common on older cars and bikes to adjust the range of plug based on the immediate usage; a cooler plug for high speed highway or track day riding, a hotter one for normal street riding. On the other hand; I’ve never heard or seen on this forum of people having issues with the recommended heat range plug. If you spend significant time with the engine at high power, such as high speeds on a highway, you might be adding a bit of heat stress to the cylinder head and valves that they don’t need.

Ride safe, have fun, and good luck

 

FWIW, that's the default title you get when you haven't contributed money lately, and it can't be changed by the member. The title annoys me enough that I'll eventually get off my backside and contribute, which is probably why that title was chosen... :biggrin: Clever, these internet forum people.

 

Actually that's a correct chart for LEADed fuel. The old lead would color the porcelain. That's NOT the way to read plugs with unleaded fuel. The porcelain does not color. Unless you use a gas additive, some will color some don't.

Here's a very good chart and explanation of reading plugs with today's fuels. Plus reading plugs at home is almost useless unless there's a major problem with the cylinder. Yes you can get kind of an idea at best.

Reading Spark Plugs Correctly

Don't let the first line "This is valid for track only (not street driving)" throw you. That's because the only real proper way to read plugs are at a track or the like at WFO then shut down. But it will give you a general idea.

It may be possible the plugs are causing the rise in temp. But your talking 9-19 degrees hotter. That's a lot just for a one step plug change on a stock machine. I might suspect the amount of anti-freeze they used and if they put anything like Water Wetter in also. If you don't need anti-freeze I wouldn't use it then. It will hold the heat more than just water with a rust preventative-water pump lubricant in it. If AF and WW are used together the AF will hold the extra heat that the WW extracts in most cases.

 

HOTTER plugs will not make your engine run hotter.

If you do high speed interstate riding or like to use the upper rpm ranges, you should go back to the standard plugs as hotter plugs don't mix well with high speeds and can cause engine damage in some cases.

 

I agree with Squirrelman. If it's temperature gauge hot that's pretty much all cooling system related.

Spark plug heat range has more to do with a balance between being hot enough to burn the carbon off and not foul plugs vs. being so hot as to create an abnormal type combustion situation, like detonation and pre-ignition. This is something 'old sled' mechanics have a good understanding of. The kind of piston damage caused by too hot a spark plug looks nothing like the kind of damage caused by a cooling system malfunction.

Very likely nothing will happen by running too hot spark plug in your four stroke motorcycle. The same mistake in a high performance two stroke snowmobile is a 'death sentence' for the piston. It's not worth the risk. If it were me, I'd put the correct heat range plugs back in it.

 

Lgn001:

Oops! Sorry, I didn't know. Absolutely no offense was intended.

 

No worries at all, and no offense taken. The first time I saw the title on another member, I wondered about it. Notice that squirrelman is also an Uber Guru.

It does make me laugh, though. It would be worse to be a "Know-it-all Dipshit", which I do qualify for on occasion... :biggrin:

 

Thanks already for the replies. About the coolant : yes, it has antifreeze in it, but I'd like to keep that as I don't intend to flush the cooling system every winter. It could be that there are still some air bubbles left in the system, although I checked the level after a couple of rides, and it was still OK. I'll look up the bleeding procedure.
I haven't ridden all that much since the spark plug change (<1000km), and I don't really use the high RPM's that much. So I guess it will be safe for now, I'll give it a bit more time, and then check the colour as suggested. Meanwhile, I'll query the dealer why he sold me the different plugs in the first place.

 

Probably all he had left on the shelf; it's a crap dealer who doesn't have in stock the right plugs for your bike !!