Exhaust Cam Mod For Low End Torque? - Stromtrooper Forum : Suzuki V-Strom Motorcycle Forums
DL1000 from 2002-2012 DL1000 from 2002-2012 (K2-L2)

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post #1 of 4 Old 05-07-2019, 10:04 PM Thread Starter
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Exhaust Cam Mod For Low End Torque?

Coming from the KLR world, there is a well known "Mc Mod" that has been talk about ad nauseam. It is advancing the exhaust valve 1 tooth increasing torque down low at the cost of HP up high. The thought was that the torque gain is in a much more usable range while the HP loss is so high up on the rev range that you would not miss it.

Now, one would argue that no way would any such simple hack work, i can tell you it did for me on both KLR's. And being that they are now varying (VVT) cams for power and fuel efficiency, it seems it would be a same idea, just static.

I wanted proof on my last KLR so i ran the mod, undid it, then redid it testing. It absolutely made a difference with no other changes. So I wonder if this would work with a more complex bike as the DL is...
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post #2 of 4 Old 05-07-2019, 11:44 PM
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Originally Posted by Kaine Beedenbender View Post
Coming from the KLR world, there is a well known "Mc Mod" that has been talk about ad nauseam. It is advancing the exhaust valve 1 tooth increasing torque down low at the cost of HP up high. The thought was that the torque gain is in a much more usable range while the HP loss is so high up on the rev range that you would not miss it.

Now, one would argue that no way would any such simple hack work, i can tell you it did for me on both KLR's. And being that they are now varying (VVT) cams for power and fuel efficiency, it seems it would be a same idea, just static.

I wanted proof on my last KLR so i ran the mod, undid it, then redid it testing. It absolutely made a difference with no other changes. So I wonder if this would work with a more complex bike as the DL is...
This was the difference in the top ends between YZ and WR426 motors back in the day from factory retard the WR cam and it's a YZ with a heavy flywheel.

The only part that is in reality more complex is the second cylinder, if anything with the cam drive layout it would be a simpler job to perform on the DL in comparison to the KLR just do the same thing twice .
One gear tooth might be too much of a jump, that's a suck it and see situation, like what you did with the Kawasaki.
So with any possible timing and piston to valve clearance issues aside I can't see a reason why it couldn't be done.
Whether or not you get any noticeable gain from doing this depends on how well Suzuki's engineers set the thing up to start with, could be great, might not be...
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post #3 of 4 Old 05-08-2019, 06:40 AM
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intriguing idea

So you are talking about advancing the exhaust cam one tooth?

Presumably this has the same effect as decreasing the lobe separation angle:

COMP CamsŪ - Sorry...

Note that one of the effects is to increase the effective compression, making the engine even more octane-sensitive, most significant in the lower rev range, where you are talking about operating. Probably want to check the valve-piston clearance as well.

Very possibly it would just 'upset' the engine. Most modern engines have all the systems (intake, exhaust, timing, cams) coordinated to work together. Changing one thing, without changing others, ends up degrading the tuning. Might kill top-end power without gaining much torque down low.

If you wanted tuning similar to the Honda 700 series, with low redline and high torque, probably need to replace both cams, the intake system (smaller runners, longer if possible) and perhaps change the ignition timing curve. With a vastly oversquare engine (bore much greater than stroke, 98 x 66) might be tough to get the cylinder pressure you need at low revs without being very octane sensitive. Would likely need an ECU with a 'manifold pressure' sensor input to vary ignition timing according to load.

So please experiment, and let us know how it turns out. Dyno charts would be much appreciated.

FWIW, gearing changes are much easier, and yield similar results, if you want more torque at lower vehicle speeds.

I get the impression that the KLR has a very 'soft' state of tune, so plenty of leeway for 'sharpening' it without running into problems. Perhaps the same is not true for the DL.

Last edited by Jimding; 05-08-2019 at 06:43 AM.
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post #4 of 4 Old 05-09-2019, 09:06 PM
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I'd sooner swap cams with a SV1K/TLS/TLR, before I monkeyed with the timing

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