Spark plug covers for new engines/spark plugs with NGK plugs

The new covers/boots will work with NGK plugs.  Both plug types have the same threaded stud terminal and both plugs are resistor type.  The boots are also resistor type, and the new and old boots have the same resistance.  That being said, it’s unclear to me what Rotax’s stance is regarding going backwards on an engine equipped from the factory with the new style plugs.  The Service Letter states that you are not required to up-fit older engines, but going back to the old plugs on a new engine is not specifically addressed.  I have to believe they would discourage it, but many are doing it.  

I had the old style boots, and last year I lost one to heat damage and upgraded all eight boots to the new style along with new wires.  They are not cheap, but I do believe they are better.  They are silicone so they should hold up to heat longer, plus the 90 degree form factor tucks them in better.  I’m still running the NGK plugs.  

New plug caps will work with NGK's.

Thanks both. I had to ask because someone told me when they went to the new spark plugs (to solve a carb problem it was eventually diagnosed), they had to upgrade to the new caps. So again, barking up the wrong tree.

Hi Roger, I’m doing my annual and I did my compression checks and noticed that my number two cylinder spark plug caps were loose and they don’t really clip on as tight as the rest with the ratcheting sound and force! and they’re easy to pull off in comparison to the other three cylinders, what caps would I use to replace my spark plug caps? , i’m concerned I’m not getting a solid connection at this point  , However, there’s no issues on my Meg checks after start up ,,.? thanks John,

Do not mix different types of plug caps. If you don't have a new engine then they are probably this one.

 Ngk 8425 Vd05Fmh