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Pseudo-slipper clutch

Old 07-26-2011, 03:29 PM
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Pseudo-slipper clutch

I have been pondering the idea of a slipper clutch or some form of engine braking reduction on the VTR for some time now. While I have finally stumbled across a slipper clutch for the VTR (made by TSS, but ridiculously expensive), the introduction of air bleed anti-compression braking systems on snowmobile four-strokes engines in the recent past has left me thinking those fateful words "hey, I can do that". Well, it seems I was not alone with that thought and one of the fine chaps on the vtr1000.org site did more than think about it, he went out and fashioned just such a system using a couple of vacuum relief valves (www.vtr1000.org • View topic - inTech vacuum control system?)

So, after looking long and hard, I finally found (what I deem to be) a suitable valve:
Saab Manual Boost Controller - Smart Performance

I just ordured one up (less the elbow on the far left side) adn will be hooking it up to both cylinders via a T and the necessary hoses. Based on Benny's results in the UK, I am confident it can work, and quite well at that.

This will likely wait until winter but it should be fun to experiment.

cheers
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Old 07-26-2011, 03:53 PM
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So what this is (if I am understanding it right) is a way to let air into the engine when the vacuum gets too high?

Kinda neat, though at the speeds I ride, totally superfluous

edit: and couldn't you control this just as well by not totally slamming the throttle shut in the corner?
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Old 07-26-2011, 04:04 PM
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It is more of a matter of preventing rear wheel lock-ups in the case of a muffed up downshift or something of the like..... The valve is adjustable so you can set it to get the amount of intervention you want.... It's also a case of wanting to try something new and different.....
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Old 07-26-2011, 10:46 PM
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Well I have been thinking on this one a bit and I would say it's usefulness would be determined by how "tunable" it is and also your riding style.

Also this could be of more use on a stage 1 motor, like yours, than a stock motor due to the increased engine braking.

Personally I do like the engine braking and tend to use it to my advantage with my style. So I would want a very small setting but depending on how it "hits" or "engages" or what ever, might cause other problems. What I mean is it could upset the chassis or the rider if you had a good amount of engine braking and then it just kind of went away. So I am interested in hearing your impressions of how it feels when it actuates.

Though others do better with less engine braking more like an I4, which is back to how tunable is this set up?

Also, for a filtered air inlet, I would plumb it to where the PAIR system used to draw air from (the hole in the bottom of the airbox you had to plug when you remover the PAIR valve)


So keep us informed on what you find.
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Old 07-27-2011, 04:32 AM
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this is a neat idea and im interested in seeing if and how itll work for you. i know when i tracked my hawk id have rear wheel lock up lots of time while down gearing hard at high rpms so something like this would have been great.
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Old 07-27-2011, 06:48 PM
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don't you guys want to back it in?
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Old 07-27-2011, 07:12 PM
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I think a placebo-slipper clutch would be a whole lot easier to "build"
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Old 07-27-2011, 08:08 PM
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Number one thing i hate about the VTR is the wheel hope when riding aggressive and downshifting.

I finally fixed mine, by buying a KTM950SM v-twin that i can downshift with high engine RPM and not wheel hope and no slipper.
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Old 07-27-2011, 09:12 PM
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I guess I try not to dump the clutch when going down a gear without reving? I have done down shifts that have required all of the rrrrrr's for the next gear down, shifting in at 9-9500. No wheel hop. You just have to trust the rev limiter, rev above the rpm you are going to need, and just release the clutch. An engine decelerates quicker than it accelerates (via an outside input). I am glad it isnt a bmw shaftie from the 70's.
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Old 07-31-2011, 01:45 PM
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An old racer trick from back in the day before stuff like slipper clutches was to set the idle speed at 3000rpm or more. Kind of weird in the pits but does the trick out on the track. Probably not an option for the street though.
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Old 08-03-2011, 02:55 PM
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anyone have pics of these mounted... I understand the concept but am having trouble picturing it (Im a visual kinda guy)
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Old 10-14-2011, 08:27 PM
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Originally Posted by scottiemann View Post
anyone have pics of these mounted... I understand the concept but am having trouble picturing it (Im a visual kinda guy)
+1


Any update on this mick?

Just got back from a spirited ride today and am tired of the rear chattering around.
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Old 10-14-2011, 08:36 PM
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I have all of the necessary parts (bleeder valve, hose, tees) just haven`t had the time to set it up. Given that the season is winding down here, I likely will do it once the bike is in storage, giving me time to mount it neatly for testing in the spring. One of the chaps on the vtr1000.org site has gone that route (see above link). The key differences in my plan is that he went with two smaller bleeders, one for each cylinder, whereas I will be running both into a single valve, partly for ease of adjustment, partly to ensure bleed synchronization between cylinders. Also, both his bleeders are positioned in the airbox (to draw clean air), whereas I will be fitting a small air filter over the intake end of the valve, allowing me to mount it outside the box (virtually anywhere) for ease of access and adjustment.

Rest assured I will post info and pics once finished.....

Last edited by mikstr; 10-14-2011 at 08:39 PM.
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