So I just purchased a boat with a 2008 2 stroke 150 vmax. Owners manual indicates for spark plugs I need a ngk BR7HS-10. I noticed the outboard had just the BR7HS plugs in them which have a smaller gap than required.
Im experiencing an issue with the engine surging at higher rpm’s, sometimes losing rpm’s and speed. Would the spark with too small of a gap cause this issue? Other than that the engine runs great at idling, low rpm and accelerating.
Is it the 150 HPDI or carbed 150? I would first verify you have the correct plugs, then gap them to spec. Plugs can definitely affect performance. I had some carbon buildup on just one of my plugs and it would surge on top end. Cleaned it up and ran great afterwards.
2008 Ranger 178VX
150 Yamaha V-max
GO Fins!!!
The BR7HS-10 and BR7HS are same plug, but the "10" has no resistor. Either way, you definitely have to gap your plugs to the correct spec.
2002 Skeeter ZX200
2018 200SHO
It is just the carbed version not the hpdi. And if you noticed in the specs between those two plugs the BR7HS-10 is pre gapped a bit bigger than the normal BR7HS plugs. I did swap them out and measure the gap on the plugs that were previously in there. Gapping was way too short on all 6 plugs plus they were all sooted up black pretty good. Changed a couple filters, and replaced the fuel pumps, just waiting for a chance to get it out for a spin in the next couple days to see if it improves.
I will say I did notice a little piece of inner plastic hosing inside the one of the fuel pumps I replaced, that may have been causing an issue.
According to NGK, the difference between the two plugs is the gap. As they come from the factory. No mention of taking a BR7HS and merely opening up the gap so that it becomes the equivalent of a BR7HS-10. Which I suspect to be the situation.
https://www.ngk.com/ngk-spark-plug-numbering-systems
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