Hello,

I have a hard time buying the correct plug for my bike. It is supposed to use a BR9ES which has threads that are about 1" long. In my town I found a similar plug but the threads are only about 1/2" long. The store owner told me that since it is shorter it won't get as fouled up as my other one. And so far my bike has been running better. But am I hurting it?

Thanks

Hello,

I have a hard time buying the correct plug for my bike. It is supposed to use a BR9ES which has threads that are about 1" long. In my town I found a similar plug but the threads are only about 1/2" long. The store owner told me that since it is shorter it won't get as fouled up as my other one. And so far my bike has been running better. But am I hurting it?

Thanks

shouldn't think so, reduce compression if anything

I really cannot recommend it, one if it is the wrong heat range it could melt, 2 the threads that are left exposed by the short plug will coke up and make it very very difficult to put the corrrectone back in, possibly stripping threads and needing a thread restoration/new head, can you not order the correct plugs from an internet supplier

Merv

...the threads that are left exposed by the short plug will coke up and make it very very difficult to put the corrrect one back in...

Agreed.

To answer the original query, yes change your plug to the correct one . An alternative to the BR9ES is the BR8ES , if you are fouling plugs because of slow running you could try an Iridium plug , they resist fouling so I am told by trials riders, I run an NGK BR8EIX as I ride tight trails with very little full revs and have no problem with plug fouling .

Ok I found a Champion N9YC which is the same as NGK BP6ES. It looks a lot like the BR9ES. I was told it is usually used in generators. Is there really much difference in spark plugs?

NGK technical link

what alll the letters and numbers mean

Be careful as i remember the N9y has a longer reach electrode, so put the plug in and turn over carefully in case it contacts

as it is the wrong heat range it may foul or melt though

merv

well I put it in and it ran great, so far

DO NOT use the N9YC as you WILL end up burning a hole in the top of your piston. On NGK plugs the lower the number in the code means that the plug runs hotter. Look in your manual if it says a BR9ES then find someone who has one . Tony

DO NOT use the N9YC as you WILL end up burning a hole in the top of your piston. On NGK plugs the lower the number in the code means that the plug runs hotter. Look in your manual if it says a BR9ES then find someone who has one . Tony

OK good to know. I usually only ride about 5kms at a time so it is probably wise to find the right plug.

I melted an incorrect Bosch plug in my FS1E in under 5 km,s

mind you it was guess work as i was desperate and the storeman at work did not have a cross reference chart at the time

I looked all over my town again and all I can find that is close to my plug is a BP6ES. It looks the same but I am concerned about that heat rating of 6 instead of 9. If I melt my piston head, is that easy to fix?

If it calls for a 9 and you're doing a lot of short trips, then you can go to an 8 safe enough. I would resist the temptation to use the 6 you found. That's 3 heat ranges HOTTER. If you melt the piston it's a very large repair. Are you changing the plug as maintenance or are you trying to cure a running problem? I.E., where's the plug you are replacing?

If it calls for a 9 and you're doing a lot of short trips, then you can go to an 8 safe enough. I would resist the temptation to use the 6 you found. That's 3 heat ranges HOTTER. If you melt the piston it's a very large repair. Are you changing the plug as maintenance or are you trying to cure a running problem? I.E., where's the plug you are replacing?

My plugs are fouling up too quickly.

Where is a good place online to buy plugs from?