RN9YC

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Supercat

Supercat

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Hey there,

I've been checking out spark plug threads here but I haven't been able to find a clear answer to the following question:

Are Champion RN9YC plugs safe to use in a 1972 750 Commando?

Thanks!
 
The Champion heat range that Norton recommends for the 72 is a N7YC
Its all in the shop manual.
Cheers,
Thomas
 
Thanks Thomas. Yes, I've got the service and owners manuals, but I've been having a bit more trouble than expected finding the correct plugs. The nearest supplier of Norton parts doesn't sell plugs, and the nearest Napa doesn't have the Champion or NGK plugs suitable for Commandos either. I'm sure I can track some down, and in the meantime I've got these RN9YC plugs that the PO had in the bike. I'm wondering if I can use them while I wait for others to come in, or if I'm risking engine damage. Thanks again,

J
 
Thanks Brooking 850. So I'm thinking I'm probably ok for short rides around town while I find proper plugs eh.
 
Try walridge motors or British cycle supply here in Canada. They both carry N7YC plugs. I buy 10 at a time. Change out once a year. Mailed to you via Canada Post.
Cheers,
Thomas
 
Thanks Thomas, that is excellent info :). British Cycle is where I've been getting most of my parts since I discovered them a few months ago. But they were temporarily out of the recommended plugs when I was recently trying to order some. I haven't tried Walridge yet though, but I will now.
 
From the cold, remote climate you live in, I would say the the N9YC would not be a problem in your bike in a pinch.
(R is the resistor type designation and may apply depending on your ignition set-up)

What sort of fuel octane rating do you run in the 750?
What is the highest posted speed limit up there?
I suspect you would not run flat out on the main jet for long periods!
 
I'm not sure where Supercat lives but here in Ontario most of my igloo has melted so back to a tent for the summer:D
Typical summer temps are roughly 25-30C and I've always used N7Y or BP7ES. Perhaps the N9 was used to compensate for carb problems?
 
Supercat said:
:). British Cycle is where I've been getting most of my parts since I discovered them a few months ago. But they were temporarily out of the recommended plugs when I was recently trying to order some.
Click to expand...
Its probably because I took what they had in stock which was 8 units back in May. I Beat you to it.:rolleyes:

Cheers,
Thomas
 
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Nain and it's the furthest north permanent community in Newfoundland and Labrador (eastern Canada).
triumph2 said:
I'm not sure where Supercat lives but here in Ontario most of my igloo has melted so back to a tent for the summer:D
Typical summer temps are roughly 25-30C and I've always used N7Y or BP7ES. Perhaps the N9 was used to compensate for carb problems?
Click to expand...
Its remote!
T
 
n7y , bp7es bp7ey are whats listed. the r in the plug you mentioned, is for resistor and should not effect the result.

I ran n9y [ BP6ey, BP6es equivalent] in my 750 for years without problems. If you ride your bike normally, then n9y is ok. If you thrash the shit out of it like the teenagers did when they were new, then stick to n7y or equivalent.
I have been using n7c when going to rallies on my 850, but they tend to foul up after cruising for 3000 odd miles. [ I dont thrash either of my bikes ]

Where I live, the temp rarely gets to 29 degrees C in the summer and in winter rarely below 8 degrees C. I also live in a country area, so when I ride, it is mostly at 60 mph and hardly ever having to stop for intersections.

If you live in a super hot desert area, then probably the n7y is what you ought to stick to.

Safe riding.

Dereck
 
Thanks Triumph2: It is possible that they were being used to compensate for carb issues. The carb was definitely a mess when I first got the bike. It wasn't easy getting her to run for the first time last year, and it was still running a bit rich after tearing the carb down and going through it repeatedly. I've done a little more tinkering with it and have cleaned the plugs thoroughly, so I'm hoping she runs good when the last of the parts arrive.
 
Thanks Bob z., Thomas, and Dereck.

Not sure what the fuel octane rating is - there is only one choice here, so I try not to think about it :). I'm guessing it's probably whatever the worst possible rating is, lol.

The highest posted speed limit here is... cough... 25 km/hr... cough.. yeah, stop laughing now please ;). There are roads and trails that extend a ways outside of town, but you can rest assured that I will not be running flat out on the main jet for any length of time :).

And that is helpful and comforting Dereck. Where I live is the opposite of a super hot desert area. The ocean is still frozen solid, and we're supposed to get snow tomorrow :). And I'll be driving tamely - I try to be gentle to any machine I'm running.
 
To be fair, I should point out that you can obviously go faster than 25 km/hr outside of town. There are just no posted speed limits out there.
 
What ignition does it have? If electronic ignition some require resistance in either the plug itself or the plug caps or the plug leads. Maybe the PO used a resistor plug on purpose. If there is no resistance the sharper spark pulses can radiate or be conducted back into the ignition box and upset the poor thing.
 
It's got a Boyer ignition. Is it best to use a resistor plug with this type of electronic ignition?
 
Supercat,
If you are running the analogue Boyer MkIII or MkIV these do not require resistor plugs. Some digital EI's need to use resistor type plugs and wires to operate.
Cheers,
Thomas
 
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