Bought a kit from Racers Warehouse. It included The Red Line 20W50 for the engine The transmission lube with shockproof for the trany and Red Line primary fluid for the primary. Ran it most of last year and the bike ran great shifted good and the clutch feel was better taking off with a full load of vacation gear and the wife on back. Now I had Fuel Moto add cams lifters and head pipe. Gained 30 hp or so and now the clutch slips under hard acceleration in fifth gear. Jamie suggested to switch back to regular 20W50 and try that as the synthetic just may be to slick. Only have a 100 easy miles but today it slipped aging when I romped on it on the highway. He said I might have to go to a stiffer clutch spring or that the synthetic may have slicked up the clutch for good. Might have to replace the plates. On the stock dyno run there was not a problem but after the cams and the increased power this showed up. Anyone else have a problem with the Red Line primary fluid? Per Jamie's suggestion I will drain the trany a time or two first and replace with regular 20W50 first to see if that helps. Just looking to see if anyone else ever run into this.

 

Assuming that the plates are slipping and it's not the fluid, then I would suggest that you install a completely new clutch kit designed for heavier peak torque. You have to remove the primary anyway, even if you just want to install a new spring. So if it was me, with your bike, I would replace the whole clutch assembly while in there. Then you know it's fixed. You certainly don't want to just replace the spring and find that it did not fix the problem, then have to take the primary off once again to replace the plates.

Or quit getting on the throttle so hard. Your choice.

 

It's not the oil.....you pushed the limit of the DESIGN and now you are in the vicious circle of beefing up from one weak link to the next and the next etc. All a person needs to do is get rid of the pollution garbage, let it breath a LITTLE and richen up the AFR. I've done the HP/TRQ game before and almost did it again, but am trying to stay with an almost stock (balanced) design. Good Luck in your decisions.

 

There have been probably a dozen posts on this very subject the past couple of months. Listed below are the springs that Harley has to offer. They run around $30 a piece. Most guys have had luck just replacing the clutch spring with the 37871-98A. You DO have to pull the OUTER primary cover to install the spring. It's no big deal, just a little time consuming (maybe an hour or so) and I just reused the same gasket and had no leaks afterwards. There's a noticeable increase in lever pull but you quickly become accustomed to it. Also, while you have the outer primary cover off you have the opportunity to clean out the primary lube that gets in all the little nooks and crannies and you get a more thorough "flush".

37882-06 blue dot (117 KgF/258 lbs/ft) 2006-88", 2007 thru 2010-96"
37871-04 yellow dot (135 KgF/ 298 lbs/ft) 2004-05 88" and 2010 Limited
37871-98A (145 KgF/ 320 lbs/ft) 1998-2003 Most recommended on forum for touring
37807-03 pink dot (165 KgF/ 364 lbs/ft) 2007 thru 2010-103 "Police"
37951-98 (175 KgF/ 386 lbs/ft) Current SE

 

when I beefed up my engine I was also getting clutch slipage. I did not want the stiffer spring as the clutch lever would be harder to pull. I went with the AIM variable pressure clutch and it solved all problems and had an easier clutch lever pull than stock. Easy install. Good luck.
http://www.aim-tamachi.com/home.php?cat=3

 

Yes I had problems using the Redline in my Primary as well. Thought I would try it and after about a month my 5th gear started slipping. I'm getting ready to install cams as well so I said hell with it and ordered the SE compensator, SE heavy spring and a Barnett extra disk Kevlar clutch pack. Installed it all today in about three hours after looking through all the threads. Took it for about 100 miles this afternoon and it hooks up great and theres not much more clutch handle squeeze. Reused the same primary gasket and no leaks so far that I can see. Bike on has 23K miles and a stage 1 so I thought it was a little soon for the stock clutch to be going out. The only thing that I had changed from when it was working great was the Redline in the primary. Before that I just used the Harley syn3. Who know if it was the Redline or my throttle that made the 5th start slipping but I had been wondering the same about the Redline. Using the Harley syn3 again so we'll see how long this cluch pack last. Looking at ordering the AIM variable pressure clutch to add on as well. Should be enough to handle the Woods TW-555 and the future FM 107 that getting installed after Christmas.

 

IMHO, "It's not the oil.....you pushed the limit of the DESIGN and now you are in the vicious circle of beefing up from one weak link to the next and the next etc" this is the most interesting comment I have read on any forum in a long time. I have nothing but good wishes to anyone who adds to their performance machine. And I guess this is a common pitfall for any of us who add on and having to keep making changes to correct the "next weak link". Maybe a warning label of "Caution, making any performance changes to your motorcycle may be hazardous to your wallet!" should be added to the top of each bike's gas tank when sold from the dealership.

Personally, this is a good reason to have a stable of bikes. One that goes fast, one for touring, one to play with, one to have fun with, one to just have because it's cool and one to ...... well you get the picture, to many needs, not enough money, time, space, etc.....

 

I guess anything is possible, but I doubt that the Redline by itself is the cause of the problem. Its more likely to me any combination of , wear, adjustment, additional power, initial assembly. Redline oil products are used in all kinds of bikes from street to race and overall they are very successful.

Ive used Redline in all 3 of my HDs for more than 6 years and over 100,000 miles. My 04 RK was a 88ci Stage 1, my 05 Fatbiy a 95ci Stage 2 and my current 11 RGC 103 stage 1. We also use Redline products in our MX bikes , Quad and my cars, never seen a problem.

I ride my bikes hard , run them up to redline and hard up shifts and down shifts frequently still stock clutches and no problems for me.

 

Don't use 20-50 motor oil in primary or tranny, not heavy enough for compensator or gears. Use H-D primary+.

 

Running the apropriate Redline product in all 3 holes. The only differences I have found is an easier time finding Neutral and a quieter 5th gear.