Throttle Body Modifications the SCHMIDT314 Way - SV1000 Portal
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post #1 of 61 (permalink) Old 26th October 2013, 01:51 AM Thread Starter
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Throttle Body Modifications the SCHMIDT314 Way

A week or two ago, I pulled out another set of spare 54mm throttle bodies to start modifying for my bike built from all the spares I had laying around.
http://www.sv-portal.com/forums/showthread.php?t=46697
I have made these modifications on several sets of SV1000 throttle bodies in the past, but have also made these types of modifications on other bikes too.

I figured while I was in the process of making these, I would take some pictures and show what can be done to improve flow in a set of stock bore throttle bodies. These modifications can be made on the 52 or the 54mm units and can also benefit bored throttle bodies too.

These modification will increase the total flow area at the main bore section of the throttle body.

The modifications will consist of the following:
  1. Smoothing and blending the inner bore of the casting prior to reaching the throttle plate.
  2. Removal of the STV plates, shafts and stepper motor
  3. Modification of the vacuum port tubes that extend into the flow area of the throttle body.
  4. Cutting and modifying the primary throttle shaft.
  5. Modifying the primary throttle plate to use counter sunk flat head screws and removing excess threads.

Lets start with item #1
I dismantle the throttle bodies completely down to the bare castings. I then hand finish the inner parts of the bore prior to the throttle plates. I don't think there is too much explanation needed here. The question does come up about up about surface finishes and boundary layers to assist in flow. The attached images show that the surfaces are smoothed but not polished.

Item #2
Several people have removed the STV plates, but not too many have fully removed the STV system from the throttle bodies all together. Removal of the plates and shafts both increase the flow are into the throttle body. The four existing holes where the STV shafts used to then need to be plugged. In the past I have used some custom machined Delrin inserts I can press in and then smooth and blend from the inside of the bore. This particular time I used JB Weld to fill the holes and then smoothed them from the inner bore. If the system is completely eliminated, a STV eliminator unit should be purchased to prevent the FI light from coming on. Thanks to D'Ecosse (SVRider name) and RecoilRob, they got the eliminator unit working much better on the SV1000. Previous units like the ones I have currently, would still throw codes now and again. Several of my units are being sent in for modification. Thanks Guys! Please contact D'Ecosse for purchase of an eliminator unit.

-MS
Attached Images
File Type: jpg Before_Cleaned_Smoothed1.jpg (564.9 KB, 271 views)
File Type: jpg Cleaned_Smoothed1.jpg (586.0 KB, 268 views)
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post #2 of 61 (permalink) Old 26th October 2013, 02:06 AM Thread Starter
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Item #3
The vacuum ports have long brass inserts pressed into the bores. To get these out of the flow area they can either be ground smooth or pressed out, cut shorter and re installed. I prefer to take them out and modify them and then press them back onto holes. In theory this could cause some vacuum signal issues. I have never run a set of these throttle bodies on a street bike before, but we will find out soon if they might cause issues to the manifold pressure sensor(s). There are no problems I have observed on a race bike at least.

Item #4
Once the STV shafts have been removed and the vacuum tubes have been removed out of the flow path, the only things taking up flow area is the primary throttle shaft, the throttle plate and the heads and tails of the mounting screws. Significant area is taken up by throttle shaft itself, so lets cut half of it out. One image shows a stock shaft and the other shows the modified shaft. If you want to perform this modification, make sure to cut the section of the shaft out that does not have the threads to hold the plate in. You still need these for sure.
Attached Images
File Type: jpg Stock_Primary_Throttle_Plate.jpg (579.3 KB, 223 views)
File Type: jpg Stock_Shaft.jpg (148.0 KB, 209 views)
File Type: jpg Completed_Shaft.jpg (158.2 KB, 210 views)


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post #3 of 61 (permalink) Old 26th October 2013, 02:11 AM Thread Starter
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Now onto item #5
Now that the shaft has been modified, you don't want screw heads or thread poking their heads out int the flow area. To gain even more flow area the throttle plates are counter sunk to accept some tapered seat flat head screws. The screw used are lathed down slightly to be completely flush with the surface of the plate. The screws are also then shortened to make sure no threads are sticking out the back side of the shaft. The plate and screws are now low profile and take up significantly less area than when in the stock form. When the screws are installed I use LocTite and them center punch the back of the screw right were the thread of the screw meets the threads of the shaft to pin into place.
Attached Images
File Type: jpg Unmodified_Throttle_Plate1.jpg (579.4 KB, 162 views)
File Type: jpg Modified_Throttle_Plate1.jpg (574.4 KB, 169 views)
File Type: jpg Modified_Shaft_Plate_Screws1.jpg (514.4 KB, 192 views)
File Type: jpg Modified_Shaft_Plate_Screws2.jpg (513.7 KB, 189 views)
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post #4 of 61 (permalink) Old 26th October 2013, 02:12 AM Thread Starter
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Now we can assemble all the modified pieces. You can now really see the significant difference from a set of stock throttle bodies. I sure hope these will work on a street bike. As a component I have not run back to back with just changing the throttle bodies on a dyno. I have only run these on built engines along with heavy head and cam work with a bunch of compression.

To be honest I am not sure in the reality of riding a street bike around if you would notice a seat of the pants gain or not, but I am going to try for the first time on a street bike quickly!

Cheers
-MS
Attached Images
File Type: jpg Stock_Throttle_Body_ThroughView2.jpg (488.0 KB, 194 views)
File Type: jpg Stock_Throttle_Body_ThroughView3.jpg (523.1 KB, 192 views)
File Type: jpg Finished_Plate_Closed2.JPG (968.6 KB, 189 views)
File Type: jpg FlushScrews.jpg (75.3 KB, 185 views)
File Type: jpg Modified_Through_View3.JPG (814.2 KB, 201 views)
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post #5 of 61 (permalink) Old 26th October 2013, 07:54 AM
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Great write up and pics. A1. Keep us posted on street impressions
Please mister admin could you find your way to put this mod in the stickies. It's ever so good.

Mr Schmidt, he makes exceedingly good moods.


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post #6 of 61 (permalink) Old 26th October 2013, 08:32 AM Thread Starter
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Quote:
Originally Posted by stephv View Post
Mr Schmidt, he makes exceedingly good moods.
I am glad to know that you are now in a good mood and that I create feelings in others that they themselves don't understand. Time for a Guinness!

On a serious note, thanks for the compliments.

Cheers
-MS


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post #7 of 61 (permalink) Old 27th October 2013, 08:12 PM
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Absolutely excellent write up.

As of this season, I'm running a 1000S K3 as Track bike. It has only 15K Km. on it, and is completely stock.
Due to strict noise regulations, I need to be running stock exhausts as well, until my friend welds up a 2in1 and I find a suitable older Gixx1000 exhaust that should do the noisetrick together with weight reduction.

Would a tune up of air intake (racefilter, airbox lid, TB etc ) make any sense, as the "rear end" of the system is still (partially) clogged ????

BR from Denmark
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post #8 of 61 (permalink) Old 28th October 2013, 04:57 PM Thread Starter
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Quote:
Originally Posted by SFJ View Post
Absolutely excellent write up.

As of this season, I'm running a 1000S K3 as Track bike. It has only 15K Km. on it, and is completely stock.
Due to strict noise regulations, I need to be running stock exhausts as well, until my friend welds up a 2in1 and I find a suitable older Gixx1000 exhaust that should do the noisetrick together with weight reduction.

Would a tune up of air intake (racefilter, airbox lid, TB etc ) make any sense, as the "rear end" of the system is still (partially) clogged ????

BR from Denmark
I would be concerned over going to a 2-1 system with a single OEM can performance wise due to a loss in volume. If you are going to drop total exhaust volume and use a relatively restrictive can, this can be a bad combo in many situations. Some of the OEM cans are pretty good though so it might be interesting to try. I think if the motor is relatively stock a good flowing airfilter and leave the air box lid on, it would still run great. Some of the other stuff might be expensive and time consuming and benefit power output marginally if you are stuck with an OEM can.

-MS


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post #9 of 61 (permalink) Old 28th October 2013, 05:18 PM
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Very nice work MS
I've done similar to my Triumph TB's which have (had!) a significant step right below the main throttle plates.
It's too bad there is no ready source for Velocity Stacks for the 1000 - that would complete the picture I think.
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post #10 of 61 (permalink) Old 28th October 2013, 06:49 PM Thread Starter
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Very nice work MS
I've done similar to my Triumph TB's which have (had!) a significant step right below the main throttle plates.
It's too bad there is no ready source for Velocity Stacks for the 1000 - that would complete the picture I think.
Thank you. A couple of folks on here have fabricated some stacks. The bodies are relatively long so I would assume it would not need a huge stack. I had a set from a 748 Ducati I scooped up because it looked like they might fit but never got around to trying. Maybe I should find them and try

-ms


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post #11 of 61 (permalink) Old 28th October 2013, 10:06 PM
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Over the winter, I had everything apart and carefully measured the intake tracts...and according to the calculators I found online the intake is tuned for about 9000 rpm's. This is about right for the cams and redline in my mind so altering the stack length would only move the torque peak downward...which isn't really needed, is it?

The front stack could be a tad longer, but the rear one would foul the air filter with much additional length....so not knowing if longer stacks would actually be beneficial to this motor without lots of work. Especially on Mikes Mad Motor....the stock intake tract is likely a bit too long if anything, at least the way I view it. The TL's had shorter TB's and didn't they have a peakier power delivery? Of course, we all know about their larger intake valves and port volumes, so does the intake length play a major role here?
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post #12 of 61 (permalink) Old 28th October 2013, 10:14 PM
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Quote:
Originally Posted by SFJ View Post
Absolutely excellent write up.

As of this season, I'm running a 1000S K3 as Track bike. It has only 15K Km. on it, and is completely stock.
Due to strict noise regulations, I need to be running stock exhausts as well, until my friend welds up a 2in1 and I find a suitable older Gixx1000 exhaust that should do the noisetrick together with weight reduction.

Would a tune up of air intake (racefilter, airbox lid, TB etc ) make any sense, as the "rear end" of the system is still (partially) clogged ????

BR from Denmark
Just a couple thoughts: If you have to run past a decibel meter, you might consider running the K5+ snorkel as it will direct much of the intake roar (which IS considerable) downward and will likely free up some noise for your exhaust to make. The secret to exhaust noise reduction without excessive restriction is VOLUME. Going to a 2-1 in your situation isn't something I'd consider. Getting a different and better 2-2 would be the way to go if you'd like to mod the exhaust...but keeping twin cans will allow you to be quieter with less restriction than trying to stuff it all down a single poor silencer.

The Yoshimura 3/4 TRS can is pretty quiet (for single can systems) but under throttle it yells pretty loud.

I've done a little experimentation with intake restriction: http://www.svrider.com/forum/showthread.php?t=218561 With severe noise limitations, the stock airbox (w/K&N) isn't much of a handicap. Make sure to lose the STV's!
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post #13 of 61 (permalink) Old 28th October 2013, 11:45 PM
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It's not just about the length, it's also about velocity and the curve of the bell-mouth creates a better turbulent-free transition into the throttle body for better air speed.
If you believe Factory-Pro's data, take a look at what they do for a DL 1000
(strange that they supply for DL, but not for the SV1K for which you might think there would be more demand)
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post #14 of 61 (permalink) Old 29th October 2013, 07:16 AM
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Quote:
Originally Posted by SFJ View Post
Absolutely excellent write up.

As of this season, I'm running a 1000S K3 as Track bike. It has only 15K Km. on it, and is completely stock.
Due to strict noise regulations, I need to be running stock exhausts as well, until my friend welds up a 2in1 and I find a suitable older Gixx1000 exhaust that should do the noisetrick together with weight reduction.

Would a tune up of air intake (racefilter, airbox lid, TB etc ) make any sense, as the "rear end" of the system is still (partially) clogged ????

BR from Denmark
IMHO the biggest advantage of aftermarket exhaust cans is weight reduction, as OEM cans weigh a ton. IIRC two Akrapovič titanium cans with noise baffles weigh less than a single OEM can.

Not sure about US bikes, but EU bikes also have some sort of a catalytic converter inside the cans:

SV_catalyst_small.jpg


So if the limitation is actual noise level, I'd probably go for a set of aftermarket cans (with interchangeable baffles), but wouldn't fiddle with the airbox as that can also add a lot of noise.

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- home made switchable TRE - not sure if it works though
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post #15 of 61 (permalink) Old 29th October 2013, 10:04 AM
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[QUOTE=schmidt314;

To be honest I am not sure in the reality of riding a street bike around if you would notice a seat of the pants gain or not, but I am going to try for the first time on a street bike quickly!

Cheers
-MS[/QUOTE]

Looking forward to hearing about the results

You`ll find it`s a better class of people who own BMW motorcycles
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