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Interested? Has anyone changed their spark plug yet? I was thinking of getting a NGK 10 Competition plug. I just wondered how hard it is to get to and what has to be taken off to get to it.
The only NGK spark plug type/number that you should be using in your 300 is the same NGK SIMR8A9 as was installed at the factory... using anything else without some controlled testing is potential for trouble IMO. As for the normal operational heat range of the SIMR8A9, I'm sure that Honda engineers got it right for the typical day in & day out street use of the bike. If you were running the bike exclusively on the track, a heat range correction may be in order for optimum performance.

The spark plug replacement interval isn't until 32,000 miles (51,200 km). Inspection of the spark plug is recommended at 16,000 miles (25,600 km), which is at the same service interval as the Valve Clearance Inspection.

As for getting access to the spark plug, you'd need to remove the side cowls, seat, and fuel tank for starters... it's all the same things you'd need to remove in order to do the VCI.
 

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The only NGK spark plug type/number that you should be using in your 300 is the same NGK SIMR8A9 as was installed at the factory... using anything else without some controlled testing is potential for trouble IMO. As for the normal operational heat range of the SIMR8A9, I'm sure that Honda engineers got it right for the typical day in & day out street use of the bike. If you were running the bike exclusively on the track, a heat range correction may be in order for optimum performance.

The spark plug replacement interval isn't until 32,000 miles (51,200 km). Inspection of the spark plug is recommended at 16,000 miles (25,600 km), which is at the same service interval as the Valve Clearance Inspection.

As for getting access to the spark plug, you'd need to remove the side cowls, seat, and fuel tank for starters... it's all the same things you'd need to remove in order to do the VCI.
OH way too much work 1st of all just for that. I was just interested in seeing what it looked like after 2000miles. Then figured once I had it out if there was an upgrade I might as well put one in. But I gotchya. not worth it
 

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I'm bumping up another old thread here....

But is it necessary to remove the fuel tank to remove the spark plug? I was reading the service manual and it says to remove the left middle cowl and disconnect the radiator from the mounting bolt and rubber tabs, and push the radiator to the left. It doesn't even ask to remove any of the radiator hoses.


I already have the cowls off for when I did the oil/filter change and coolant flush...
 
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