Exhaust Mod Causing Problem ?? - Stromtrooper Forum : Suzuki V-Strom Motorcycle Forums
DL650 and DL650A - 2004 to 2011 DL650 from 2004-2006 (K4-K6) and DL650 or DL650A from 2007-2011 (K7-L1)

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post #1 of 16 Old 01-22-2019, 07:39 PM Thread Starter
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Exhaust Mod Causing Problem ??

1st - I well know some on this forum get upset & noisy at the idea of modifying a bike. Please keep your flaming to yourself. I went into this deliberately after careful consideration.

That said - I wanted a more positive sound from the exhaust of my '05 Wee and 1) can't afford an aftermarket muffler, and no assurance it'd sound the way I want, anyway, and 2) read about this on this forum and decided to try it - I took a long piece of rebar and ground a sharp taper onto an end, then inserted it into exhaust till it hit bottom. Carefully hit it with a heavy hammer and punched 3 equidistant holes in there.

It sounds a bit strange, compared to, say, a Harley exhaust, but much nicer than stock - to my ears. It's kind of a flat growl that's fairly quiet at low to moderate throttle and has a hard, flat rasp that I've grown to enjoy at high power settings. Can't hear it at all on the highway. Best of both worlds. :-)

I rode it like that for several months and enjoyed it. Later on, quite a few miles later on, I started getting a hesitation when cracking the throttle. When leaving a light, hit the gas and it'll go kinda....GAAAaaawwwhhOOOMM....if it doesn't die completely. Power is erratic and it hesitates before accelerating at any speed. Seems to be slowly getting worse and it's a pain to ride now. Quite a bit of reading on forums leads me to believe my TPS is bad, but bike only has ~<35,000 miles on it, so seems a bit early for that.

Putting it into dealer mode shows a readout of -C00 - dash in the middle at idle. It's very hard to start when cold - takes ½ dozen tries, but starts quickly and easily after that - it's 40º here now and warming to operating temp isn't practical - but the - dash shifts to upper position on C00 at about 2200 rpm when showing 1 bar on temp gauge. Idle is a bit lumpy at 1300 rpm. I did try adjusting idle speed with screw on the left side and it does make a difference, but doesn't cure the problem.

More reading and it may be possible for the change in exhaust back pressure could be affecting it. Before spending the money on a new TPS, I'd like to ask here if you-all think that may be a possibility ?? Plugging the punch-outs in exhaust and restoring it to stock will be easy with a 1" engine freeze plug.....but I hate to give up the nifty sound - it's just right. Whaddaya think ?? Again - please, no flaming on mod-ing the bike.
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post #2 of 16 Old 01-23-2019, 12:50 AM
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Your hole punch mod isn’t the issue, mileage doesn’t mean squat for a TPS to go bad, you also need to do a fuel pump flow test as well.
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post #3 of 16 Old 01-23-2019, 04:18 AM
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If it ran well for any reasonable length of time after the hole punching, then that's not the problem. It wouldn't evolve into a problem. The holes haven't changed.
PS: I have made six significant mods to my 1000's engine alone.
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post #4 of 16 Old 01-23-2019, 04:58 AM
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Humor me: With the engine at 1300 rpm you say the engine is "lumpy". At that point, partially close off the exhaust with your hand and a shop towel and see if the engine smooths out, and maybe revs quicker. Quick, simple, and wont cost you a cent. After that, youre into Engine Mechanical( compression or leakdown testing, valve clearance), Engine Ignition, Fuel system testing. Not real hard or expensive, but you dont know what you dont know, and you can't know until you check. And it's possible to have more than one problem at the same time.
Over the 'net no forum can tell you exactly what your issue is, but I can tell you how to eliminate possible causes.
I'd rather diagnose an issue than replace parts or perform procedures that wont help you.
The TPS setting you described in no way tests the TPS other than it's idle setting. Not cheap, but I test them with a labscope looking for dropouts in a waveform. You CAN test the TPS if you use a DC voltmeter, one lead at the sensor wire at the engine control unit TPS terminal still plugged in(backprobing), the other lead grounded with key on. SLOWLY roll on the throttle and check for a smooth rise in TPS sensor voltage.
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post #5 of 16 Old 01-23-2019, 11:12 AM
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You are not the first to poke holes with a pointy bit of rebar.
i did that to my R65LS BMW. Made a great change to a throaty vicious snarling demon that would set off car alarms, just like a piped Ducati.
But I never experienced a loss of power or change in performance.
My project Wee has the outlet stub snipped off and perhaps the can has been vented so it doesn't sound stock anymore.
Haven't had it on the road yet so I can't vouch for the operation.
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post #6 of 16 Old 01-23-2019, 03:49 PM
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Quote:
Originally Posted by BigLar75 View Post

I rode it like that for several months and enjoyed it. Later on, quite a few miles later on, I started getting a hesitation when cracking the throttle. When leaving a light, hit the gas and it'll go kinda....GAAAaaawwwhhOOOMM....if it doesn't die completely. Power is erratic and it hesitates before accelerating at any speed. Seems to be slowly getting worse and it's a pain to ride now.
On the simple / free things to test list:
Open the gas cap - test for hesitation
Check out your air filter and air box
If your bike has a charcoal filter - disconnect and test
Using a turkey baster and tube grab some fuel from the lowest point in the tank and check for water
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post #7 of 16 Old 01-24-2019, 06:48 PM Thread Starter
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Originally Posted by MAZ4ME View Post
Humor me: With the engine at 1300 rpm you say the engine is "lumpy". At that point, partially close off the exhaust with your hand and a shop towel and see if the engine smooths out, and maybe revs quicker. Quick, simple, and wont cost you a cent. After that, youre into Engine Mechanical( compression or leakdown testing, valve clearance), Engine Ignition, Fuel system testing. Not real hard or expensive, but you dont know what you dont know, and you can't know until you check. And it's possible to have more than one problem at the same time.
Over the 'net no forum can tell you exactly what your issue is, but I can tell you how to eliminate possible causes.
I'd rather diagnose an issue than replace parts or perform procedures that wont help you.
The TPS setting you described in no way tests the TPS other than it's idle setting. Not cheap, but I test them with a labscope looking for dropouts in a waveform. You CAN test the TPS if you use a DC voltmeter, one lead at the sensor wire at the engine control unit TPS terminal still plugged in(backprobing), the other lead grounded with key on. SLOWLY roll on the throttle and check for a smooth rise in TPS sensor voltage.
Thanks for the reply. I agree - I'd rather diagnose it on the spot than replace parts.

I tried the "cover the exhaust" idea and it seems to smooth the idle a bit. With it uncovered and 1 bar showing on temp, the idle sounds sorta like, "mmmmpppmmmppmmmmmppp, but idle speed stays steady at 1300. With exhaust partly covered it seems a bit smoother and steady at 1300. Either way, when I rev it, it hesitates and pops a bit, just for a fraction of a second, then roars.

I'd appreciate it if you could hand-hold me thru the voltmeter test. I have a good quality digital multimeter and am very familiar with its' operation. I'm also very good with pre-electronic engines, but still feeling my way with modern stuff.

Which wires where, specifically ?? You're talking to a real dumbo on this stuff. Thanks.
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post #8 of 16 Old 01-24-2019, 06:52 PM Thread Starter
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Quote:
Originally Posted by NVDucati View Post
On the simple / free things to test list:
Open the gas cap - test for hesitation
Check out your air filter and air box
If your bike has a charcoal filter - disconnect and test
Using a turkey baster and tube grab some fuel from the lowest point in the tank and check for water
Thanks. Air filter is recently cleaned and no charcoal filter. For flow test, I did the in-pump/in-tank filter by-pass/external fuel filter just a few 100 miles ago and pressure/flow was excellent. (mercy, I had gas everywhere :-) No water in gas. Good thoughts.
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post #9 of 16 Old 01-24-2019, 07:00 PM Thread Starter
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Originally Posted by notacop View Post
You are not the first to poke holes with a pointy bit of rebar.
i did that to my R65LS BMW. Made a great change to a throaty vicious snarling demon that would set off car alarms, just like a piped Ducati.
But I never experienced a loss of power or change in performance.
My project Wee has the outlet stub snipped off and perhaps the can has been vented so it doesn't sound stock anymore.
Haven't had it on the road yet so I can't vouch for the operation.
I did the hole punching carefully and in stages. Much easier to punch deeper than to undo a punch. I went a bit at a time in a triangular pattern till it sounded "pretty good," then rode it, then punched deeper, then tried it, etc. I like it now. :-) Holes are about ~½" and flat on the outside circumference. Mine isn't a loud or harsh sound at all. Like I said, kind of a flat growl at moderate settings that sounds like a much smaller bike. At high throttle settings, it roars pretty good, still with a kind of flat sound. I like it, but was unsure at 1st - took a bit of getting used to. It's a very different sound than anything I've heard before. Didn't notice any change in power.
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post #10 of 16 Old 01-25-2019, 06:54 AM
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You said it's "very hard to start when cold" which typically means a lean condition, often worse when the ambient temps get lower. With the old carbed bikes it was usually an air intake leak. An easy check would be to spray some carb cleaner around the intake with the bike running, if idle changes there's a leak.
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Last edited by om28; 01-25-2019 at 11:54 AM.
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