spark plug

[jeepnu24me]

i have a 2007 drx50 air cooled and a 2007 drx90 liquid cooled and was wondering what is the best spark plug to run in it the drr website seems to conflict itself also we have had to 50 for a while and it seems to be alot more peppier than the 90 alot more high strung do i have the 90 set up wrong or is there a difference in the liquid and air cooled

[hotquads1]

I believe the difference, you are referring to in the 50 and 90 is the rpm range "power band", the 50 turns the rpm's higher and quicker , the 90 makes more low end torque, therfore can operate in a lower rpm range , so does not scream like the 50cc.
I like the NGK plugs, if your bikes are still "stock" (no changes have been made) , then the stock plug works great "BR8HSA" , you can pay more for Iridium type plugs but it will not run any different . Now with that said , your 90cc w/c should out perform your 50cc by far, so you might need to investigate further to see if you another issue that needs to be addressed.
marc

[bulldogfallon]

On your 90 you will need to know what head you have on your machine.

The std head will work fine with an NGK B8HS and if it is the high compression head you can use a longer plug such as a B8ES, but you would need 3 index washer to provide clearance.

In the HC heads the normal plug would still be in the threaded area of the head.