We fixed that Sumbitch! - Stromtrooper Forum : Suzuki V-Strom Motorcycle Forums
DL1000 from 2002-2012 DL1000 from 2002-2012 (K2-L2)

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post #1 of 13 Old 07-20-2019, 08:05 PM Thread Starter
Join Date: Feb 2016
Location: Spearfish, SD, USA
Posts: 97
We fixed that Sumbitch!

On our recent trip to Prudhoe Bay, my friend Brian's (Festar) ManStrom {02 DL1000} got atrocious fuel mileage 30-33mpg was the best he saw. The bike was obviously running rich and would emit some brown smoke from the tailpipes when under WOT conditions.

We knew that one of the previous owners had screwed with the ECU using a "Yosh Box".

The Yosh Box is a scarce item made by Yoshimura in the early days of motorcycle EFI to enable their Pipe selling dealers to make tuning adjustments to early EFI bikes to solve lean issues after pipe installation. Much research and searching on both this Forums and ADVrider, as well as some emails to knowledgable inmates, led us to believe that we needed to "Un-Yosh" the ECU and get back to ground zero on the EFI tuning as well as establish a baseline of engine setup.

In our diagnostic checks, we discovered that the rear cylinder exhaust temp was running hundreds of degrees cooler than the front and as we got home to Spearfish from Alaska the bike had begun to miss, especially at low speeds and a idle.

We replaced the sparkplugs and cleaned the air filter, performed a leak down check on the engine and discovered that the rear cylinder was leaking past the intake valves, Hmmmm.

We pulled all the plastic and went to work to check the valves. Both sets of intake valves were tight and the rear cylinder Intake valves had no to negative clearance. Exhausts were all marginally in spec.

A friend had a brand new shim kit at his house which he was kind enough to let us use.

We reshimmed the valves so all were at the loose end of the spec.

As we reassembled the rear cylinder Camshaft assy something didn't look right. The compression release was on the intake side as the head was disassembled. Upon further investigation, the Cams have Cast INT and EXH right in them and the Cam Gears are labeled E and I, the last person to assemble the head (previous owner we surmise) had put the cams in the wrong side of the rear cylinder head. It is a wonder the bike even ran!

We put it together correctly, verified our valve clearances and after a few more adjustments, reassembled and fired it up.

The bike ran much better, a quick Throttle Body balance and she was quite smooth. Brian did a little Spearfish Canyon test run and was much happier with the smoothness but was still depressed about the crappy Fuel mileage.

However, "Help was on the way," On Sunday I noticed in a VStrom for sale ad that a guy in Iowa had an elusive "Yosh Box" to go with his bike. I reached out to him and promised my first and second grandchild if he would loan it, rent it, sell it to us. Just like the typical Forumite, he said, of course, you can use it, please cover my postage costs. He put it in the mail and it arrived on Thursday at noon.

We immediately hooked up the box and performed the simple 10-minute procedure to return the VStrom ECU back to stock. A quick Idle adjustment later and we each went for a test ride. Both of us thought the bike ran much smoother and noticed no flat spots or lean surge.

Yesterday evening we made a 160-mile loop through the Black Hills, Spearfish Canyon, Highway 85 South to Newcastle, over to Upton, then Sundance and back to Spearfish on I-90. Speed from mid 50's to '80s.

When we fueled after the run Brian got 39.25 MPG! By George, I think we've got it!

P.S. Today another 150-mile run and the bike ran great, very smooth, no surging or flat spots and 40 mpg.
notacop, Spec, Hard miles and 7 others like this.

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post #2 of 13 Old 07-20-2019, 08:19 PM
PerazziMx14's Avatar
Join Date: Aug 2016
Posts: 1,672
A testament to how un-fragile ICE motor truly are. To think people are worried about a grade of oil the is 5W different than the manufacturers call for thinking it'll do irreparable harm. Heck you buddies bike ran with cams in the wrong spot and fuel washing down the cylinder walls for miles and miles.

Glad you got it fingered out!
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post #3 of 13 Old 07-20-2019, 09:37 PM
Join Date: Feb 2017
Location: Vancouver Island-Canada
Posts: 477
Hey, great story and fantastic outcome! Good on ya for figuring it out and sharing the story here!
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post #4 of 13 Old 07-21-2019, 02:36 AM
Join Date: Jan 2012
Location: Bremerton, Washington
Posts: 1,428
Big John, get your friend a 4 degree ignition advancer for his Vee from a Power Commander dealer. I get 45-50 mpg on a much-modified Vee.
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post #5 of 13 Old 07-21-2019, 03:16 AM
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Join Date: May 2019
Location: Lacey, WA
Posts: 131
That's an awesome story. Thanks for sharing.


1. 2004 DL1000
2. Next bike
3. Next bike
4. Next bike
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post #6 of 13 Old 07-30-2019, 12:33 AM Thread Starter
Join Date: Feb 2016
Location: Spearfish, SD, USA
Posts: 97
The Saga continues:

2,000 miles later, multiple day rides and a 1,000 mile run over to the Beartooth, Chief Joseph, Ten Sleep, etc and the FestarStrom began to idle poorly, pretty soon it wouldn't start again!

No Codes, Quick spark plug check, good spark and - they looked good.

Compression check revealed only 60# in each cylinder, performed another leak down test which revealed intakes leaking again, WTF?

Checked the valves - Intakes tight again all 4 valves had no to marginal (.051mm on two) clearance.
No change on exhaust Valves from the previous adjustment.

Reshimmed Intakes and checked clearances at .2mm after complete.

Bike once again runs great.

I'm thinking the intakes were/are carboned up and as the carbon wears/burns off the valve clearance is decreasing as the valves come back to the seats.

We put a can of Seafoam in the tank and we'll run it a while and watch, recheck valves in another 2,000 miles.

More later........
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post #7 of 13 Old 07-30-2019, 12:54 AM
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Join Date: Apr 2008
Location: north east, Buffalo NY area
Posts: 2,604
Well you guys are having experiences that nobody else probably had. What a story!
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Blau1 2004 DL650-sold
Blau2 2014 DL1000A
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post #8 of 13 Old 07-30-2019, 03:00 AM
Join Date: Sep 2017
Location: Perth, Western Australia
Posts: 59
You must be getting real good at stripping the bike to change shims by now!
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post #9 of 13 Old 07-30-2019, 06:24 PM Thread Starter
Join Date: Feb 2016
Location: Spearfish, SD, USA
Posts: 97
Originally Posted by Chipwidget View Post
You must be getting real good at stripping the bike to change shims by now!
Wearing out the Fasteners and Plastic Rivets! LOL

"The only dumb question is the unasked question" - Anonymous
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post #10 of 13 Old 07-30-2019, 06:34 PM
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Join Date: Nov 2016
Location: Kentucky
Posts: 3,690
Not to sound negative here, having carbon build up like that would be unusual. I am trying to come up with another way this could be happening short of the valve seats are going south.
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"If its not broke yet, it can still be fixed"

Last edited by STCorndog; 07-30-2019 at 06:38 PM.
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