After market plugs - top and bottom - for Rockster

[whaycoc]

This is probably old stuff but I want to confirm the correct after market plugs for my Rockster. Getting ready for the 12k service and since I have been off the forum awhile I was wondering if the information I have is still good. The following is the info i have for the top and bottom plugs - still OK?

Top plugs: NGK Iridium-BKR7EIX - Park number 2667

Bottom plugs: NGK Iridium-DCPR8EIX - Park number 6546

Alternative bottom plug (one range hotter then OEM)

NGK Iridium-DCPR7EIX - Part number 6046

These plugs are available from:

http://www.sparkplugs.com/default.asp

The rear drive oil and tranny oil is specified to be 75-90 Hypoid gear oil. I have some notes in my file that some are recommending 75-140 in the tranny. Any comments on this?

Is the use of the K&N air filter in place of the OEM air filter still considered to be a good improvement?

Appreciate your patience with these old questions.

[jm1515]

Bill ... those are the correct NGK numbers. I put them in 2yrs ago and ~18k miles later they look great. Clean & gap at every service. I went w/ the hotter secondary plug...
You can special order them at AdvanceAuto and they'll have them for you in about a day.

I use Mobil1 75w/140 in the tranny and the 75w/90 in the FD. I think the wider viscosity range in the tranny helps smooth out shifting.

No comment on the K&Ns....

[whaycoc]

Thanks JM for the reply and confirmation - I just wanted to be sure things had not changed since I last received that info.

[DSKYZD]

I'm looking at the same service on my bike. The Hypoid oil included in the kit from SierraBMW here:

http://www.sierrabmw.bigstep.com/item.j ... ID=1118363

is 75W140. I can only assume that is for the tranny and final drive. But since 1 quart = 946.35295cc there isn't really even enough to put 1000cc in the transmission. Color me confused.


DSKYZD

[whaycoc]

DSKYZD,

Looking at the Rockster service book I found the following:

Transmission holds/requires .85 qts (.80 l)

Final drive (rear end) holds/requires .26 qts (.25 l)

This is indeed slightly more then one quart - maybe Sierra figures you really don't need two quarts as there would probably be some residual oil left in the tranny and rear end after draining. I really don't know. I will buy two quarts of Hypoid gear oil (probably Mobil 1)

As far as the viscosity is concerned the book calls for SAE 90 (75-90) but a guy who knows a lot about service (Deans BMW) recommends 75-90 in the rear drive and 75-140 in the tranny. Many seem to follow this suggestion. I will as I have talked with a number of mechanics and they seem to agree. Thus, I will buy one quart of each viscosity described above.

The sierra service kit you reference must be for the dual plug models as they only send two plugs and they are not the correct ones for the Rockster!