Traded my '14 Street Bob in for a '12 Road Glide Custom. Same 103.

I always used Mobil 1 Synth 20w 50 in the motor and the primary, with BelRay 75/140 in the trans. I had some clutch slippage but nothing majorly out of line.

I've been reading that the clutch doesn't really even need a synthetic, that HD Syn3 is more than adequate and will probably completely eliminate the slipping.

Anyone else notice slight slipping when using synthetic in the primary? And if you switched to a blend and it went away?

I still plan on using the Mobil 1 synth for the motor and the BelRay for the trans.

 

I use Shell Rotella syn in my primary & engine with no problems

 

There are so many options available to us there is no simple answer. I've never used any synth in my primary, just good ole H-D primary oil - which has been fine for donkey's years!

 

For me, any oil that is going to lubricate my clutch is going to be JASO MA/MA2 certified. JASO is strict, its focus is MOTORCYCLE clutch performance, and if an oil can't meet JASO, I won't use it.

Having said that, give Mobile1 Racing 4T (10w40 or 15w50) a try in your primary.

PS> Recently had a Japanese bike with terrible clutch slippage...oil was 10w40 as recommended, but it was not JASO...changed out to Racing 4T and it only slipped at high RPM..ran the bike ~50 miles, changed oil again...no more clutch slippage at any RPM...100% of the oil never drains out...when switching oils, it takes at least 2 changes to get near 100% of the oil being the new oil.

 

I would just used the SYN3 in the primary - should never be a problem.

 

The jaso ma/ma2 rating is what to look for.With the higher torque motors you will have problems with any oil that has friction modifiers in it.Been using mobile 1 4t racing 10-40 for many years in my primaries on several different bikes and have never had a clutch slip.

 

The JASO rating MA/MA2 is a motor oil only rating for wet clutch performance.

If you purchase a primary/wet clutch specific product, it will not have this rating

on the label, it just says its for a wet clutch/primary application.

Ken

 

I just used HD stuff until I installed a Barnett clutch, Barnett recommended Redline... they must have shares in Redline because HOLY Fork... it’s expensive...

 

Sorry sir, but nope..."It will not have this (JASO) rating" because....It can't meet the standard...not because it's a primary specific product.

Example...Amsoil sells a Primary specific product...and lookee here...it's JASO MA/MA2 rated.

AMSOIL V-Twin Synthetic Primary Fluid
https://www.amsoil.com/lit/databulletins/g3302.pdf

JASO is a friction test concerning motorcycle clutches...doesn't matter if the bike is wet or 3 hole...JASO is JASO...and if your clutch oil isn't JASO...especially in high torque bikes, you don't have the optimal fluid in play...

 

I sit corrected, but I would find it hard to believe a manufacture of "primary/wet clutch specific oil would make/sell a product that would cause clutch issues.

Just my .02 cents

Ken