Frequently Asked Questions

The information was put together just as a general resource on some basic questions. Please do your own due diligence and research accordingly, discuss with your mechanic on what they may prefer and why, it's your bike so ask questions! With the number of models and years of Big Dog's produced and the changes from year-to-year there are many differences. Simply click the below question to expand the detailed information.

S&S Recommends Conventional or Synthetic 20w50 VTWIN motor Oil for use in all their Engines. 

Also, if you want to do some reading - here is a research study available online from AMSOIL very detailed and offers you a little technical information on each 20w50 tested.

A few common customer preferred options for you to consider:

  • Mobil 1 Synthetic VTWIN 20w50
  • AMSOIL MCV Synthetic 20w50
  • Bel-Ray VTWIN Semi-Synthetic 20w50
  • Royal Purple MAX-CYCLE Synthetic VTWIN 20w50 

S&S Recommendations are:


Both motors spark plugs should be gapped between .038- and .042-inch

ENERGY-ONE clutches are in all Big Dog’s original from the manufacture and directly from their website is the below:

“The type of fluids we recommend are any HD petroleum based, non-synthetic, primary oil, as light weight as possible, or even a good petroleum-based motor oil such as 10/40 or 20/50 in weight. You can even use ATF Type F or B&M Trickshift. THE USE OF SYNTHETICS IS NOT RECOMMENDED AS THEY TEND TO CAUSE SLIPPAGE.”

The clutches designed from ENERGY-ONE can be ran dry!  The oil is only in the primary for chain lubrication and that’s why they prefer a light weight non-synthetic!

Common debate on the amount of oil on the 05-11. Considering clutch can be ran dry, 18-20 ounces is plenty and also helps prevent any oil getting back in the starter.

2004 & Early can stick with 32 ounces.

A few common customer preferred options for you to consider:

  • Harley Davidson Primary Oil Non-Synthetic
  • REVTECH Primary Oil Non-Synthetic
  • Bel-Ray Primary Chaincase Lubricant Oil
  • B&M Trickshift
  • ATF Type F 

Only 20 oz in the Baker Transmissions!

Baker made the transmission on these Big Dog’s and they work with Spectro and Redline which are advertised on their website.  I think sticking to either of those two options is the preferred safe bet!

From Baker Website:

“Picking the right transmission fluid ensures the life and durability of your transmission, that’s why BAKER recommends a fully synthetic GL-5 rated gear weight oil of 75W-140. “

10 ounces of oil in each leg with standard 41mm tubes.

  •  30w is recommended for the +10 & +12 Front end on the Choppers, Ridgebacks and K9's.
  • 10w oil is recommended for the +2 Front Ends on the Prostreet Models. Pitbull's, Mastiff,Coyote,Bulldog's, etc.

Not much information on inverted front ends except in the 04 Service Manual for the inverted Front Ends, it states Inverted forks use 350cc in each leg of Bel-Ray HVI 15w Racing Suspension fluid. 

HDM INC does not stock tires, the prices from a lot of online tire shops is less than we would be able to offer them for with shipping. Also, we want to ensure customers get the newest fresh tire and these online store specialize in tire sales so they will have the most recently manufactured tires available.

Check out this link to more information on tires and a few good tire websites to order from. 

HDM does not sell batteries, we would rather make sure customers get the best price and newest inventory available! Amazon also moves a ton of batteries so you should expect to get the freshest battery manufactured possible, which is ideal!

Check out this link for some more information on battery selection for your bike. It also has direct links to buy on Amazon or other online retailers! 

All Big Dog's 1994-11 used DOT 5 Brake Fluid.  DOT 5 is a synthetic brake fluid designed to not damage the paint & it also does not absorb water during water storage.  

NEVER mix DOT 5 with DOT 3 or the newer DOT 5.1 it will gum it and will be incredibly difficult to flush the system. 

DOT 5 only!  That is what is in all our kits, should be a greenish tint to it out of the bottle.  It turns clear fairly quickly after running in the bike.  

Plenty of information online, hopefully this just gives your a general starting point to perform any research you may desire.