Rekluse EXP 2.0 and overheating

2 replies to this topic
  • cereal killer

Posted August 09, 2012 - 10:22 AM


I'm running the EXP 2.0 in my 2008 YZ450f that I ride and race off-road (enduros and harescrambles). When it's dialed in, it works awesome! There's no doubt that I'm faster and less fatigued when I use it.

However, I think it is causing my bike to run hotter.

I think the problem mostly occurs when I'm on a steep hills with lots of roots and rocks and going a bit slow for full clutch engagement. The rekluse slips the clutch, which I think generates a lot of heat. It's when the clutch is slipping a lot that I have been overheating.

I realize one solution is just to go faster, but that's easier said than done. Another would be to go to lower gearing, but I'm already running a 50-tooth rear sprocket. Also, I don't have the same problem when I run a manual clutch. I think that when I use a manual clutch, it's obvious when I'm going too slow for first gear. When I have to slip the clutch to keep moving, it forces me to either go faster or at least makes me conscious of how much I'm slipping the clutch.

So, I'm looking for suggestions either to help reduce the clutch slippage or to bring down the temperatures (hopefully without spending big bucks).

My ideas so far:
- 51-tooth rear sprocket
- Maybe switch to Engine Ice coolant
- can I get an oil-cooler for this bike?
- should I switch to the "high-engagement" setting on the EXP unit? (I'm using the middle setting right now). Or would this make the problem worse, since the revs would be higher when the EXP engages?

Any input about my ideas or some creative ones of your own would be appreciated!

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  • grayracer513

Posted August 09, 2012 - 11:20 AM


Your clutch may be getting hot, and that may be a concern related to oil temperatures, but it isn't a major contribution to coolant temperature. The only conceivable solid connection between the Rekluse and engine heat is that the Rekluse allows you to go slower more easily that you could have otherwise, and the combination of the reduced air flow over the radiators and the reduced coolant flow at lower RPM's may be sneaking up on you. Hotter oil just doesn't have very many avenues for adding heat to the coolant.

It's probably going to pay more rewards to pursue improving coolant containment and lower coolant temperature directly by the usual approaches; higher cap pressure, Water Wetter, fresh coolant, fans, etc. In an extreme case, you might find it useful to use one of the extreme high temp coolants, like Evans or ZipTy.

  • cereal killer

Posted August 09, 2012 - 01:10 PM


Thanks Grayracer. That makes sense. I assumed that the oil temperature was being transferred to the coolant, but your explanation makes more sense.

The overheating started shortly after I took a spill and I probably wasn't riding at my regular pace afterwards.

Is it safe to just add a higher pressure cap and see if that solves my problem? or is that just going to mask the issue and give me grief later on because the bike is running too hot?

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