Throttle Body Overbore Teaser

[CandyRedRC46]

I just received a spare set of throttle bodies in the mail today. I am going to send them to maxbore.com Monday to be overbored, have the throttle shafts thinned and then filled with larger butterflies. I will be then port matching the boots to the throttle bodies and intake ports on the heads to the boots. Here's what we are starting with, I'll post up the new dimensions in a week or two when I get them back. I'm hopping for at least 42mm (as the entrances are already 40mm) but really anything over 36mm will be an improvement. (As the exits are only 32mm x 35mm)

[Dutchy]

WOW!!!

Major flashback, seeing those graphs....

Fingers crossed it brings what you expect from it!!

[CandyRedRC46]

I can't see the picture. Maybe its just my phone.

[Mohawk]

No pic, just a reference to tetris

[The Phantom]

Just a typical Dutch dyno graph... you can even see flying elephants if you look at it long enough.

[CandyRedRC46]

Oh lol.

[Rush2112]

How's the overbore TB and RB Race working out? Any time to get it on a dyno and see how much juice is squeezed out on the top end?

[Switchblade]

I think he has finals at school .

[Rush2112]

I think he has finals at school .

Finals should be over by now... figured an update may be available. I'm Living vicariously... I've been traveling for work heavily the past couple of months and my Race unit is still sitting on my desk. Plus CRRC has year round riding weather...

[CandyRedRC46]

Okay guys the overbore throttle bodies have been on for a while and I have ironed out all the kinks. It was running perfect with the installation of the Rapid Bike Racing module and the factory lightly ported throttle bodies, but after installing the overbore throttle bodies it seemed to be pretty rough. So, then I synchronized the overbore throttle bodies and it seemed to help some what, but the 0-4% throttle was really rough. Checking my Rapid bike racing wide band o2 sensor readings showed that cylinder 3 was very very lean (over 16:1) and cylinder 4 was very very rich (less than 11:1), in the low throttle opening range (less than 5%). I tried to manually iron this out by adding and subtracting fuel in the 0% throttle column range, but this resulted in additions of 20% more fuel and still didn't seem to be in the ideal range. Also while riding in first gear, light throttle range and high rpms resulted in a lot of lean surging and popping when maintaining over 6000 rpms. Again I tried to iron this out by manually punching in more fuel in the 0% throttle range in that area but it did not help. (as a side note, you really do not want to make fueling corrections at idle, especially as a band-aid for another unknown issue)

Well curiosity got the best of me and I started switching the fuel injectors around to make sure that I did't have a bad injector. This resulted in no changes in o2 sensor readings, so I knew the injectors were fine. Then just for shits and giggles I switched cylinders 3 and 4's injector connections, and for some reason or another the fueling became perfect in the 0-4% throttle range (with all cylinders right around 13:1). The only logical explanation that I can come up for this is that there is some difference in the throttle body harness that came with my 2009 throttle bodies and my factory 2007 throttle bodies. Maybe the newer harness was mislabeled or something, I really am not sure, but for some reason or another the low throttle fueling was shit with cylinder 3 plugged into cylinder 3 and became perfect when 3 and 4 were switched, so I stuck with that and then switched the o2 sensors accordingly so that the Rapid Bike Racing module would again read the correct cylinders.

As far as the rough running at high rpms and low throttle positions in 1st and 2nd gear, this turnded out to actually be in the 5% throttle column and not the 0% column. Now the Rapid bike will self tune 5% throttle and up, but I think between the weird 3/4 cylinder mix up and me making a plus 20 fuel map (very bad idea) the fueling was just to far away from the ideal range for the rapid bike to correct and just resulted in over corrections. So after switching the fuel injector connections of cylinders 3 and 4 zero'ing out the 5% column in the fuel maps, everything sorted out and the bike was now running great everywhere!

As a side note, setting the fueling to plus 20% everywhere after the over bore throttle bodies were installed and letting the rapid bike sort it out was a bad idea. The Overbore throttle bodies did not require that much extra fuel, and the fueling was now way off; probably too far off and out of the range for the rapid bike to sort out on its own. This seemed to have caused other weird tuning issues such as over compensations. I should have just stayed with the map that was already made for my pre overbore throttle bodies set up and let the rapid bike make the necessary adjustments for the larger throttle bodies.

After sorting out all these issues (that are totally the result of my abnormal modifications, dumb plus 20% fuel map and not the rapid bike itself) I can now say the bike is running like a dream again, just as it was when I initially installed the rapid bike with the factory throttle bodies, except now, the bike has a little more mid and top end pull to it.

Factory throttle bodies with light porting

Throttle bodies removed

2mm overbore throttle bodies. From the original 40mm at entry, 36mm at butterfly, 35mmx32mm at exit; now 40mm at entrance and 38mm the butterfly and exit.

Throttle body boots were bore from factory 35mm x 32mm to over bore 38mm

Lightly ported entrances versus overbored

Lightly port matched heads to over bored throttle body boots

Factory heads with the over bored throttle body boots.

Take note of the extra intake port material that needed to be removed to make everything flush.

After installation of the bigger throttle bodies, the vacuum was WAY OFF. After synchronizing the starter valves, it was brought to perfect.

[Rush2112]

Wow... that is a strange one. Are the color coded wires on 2009 injector connectors the same color scheme as the '07? I've got a set of '09 throttle bodies I plan on installing on my 5th gen track bike engine so any input or clarification is appreciated. Thanks...

[CandyRedRC46]

I didn't notice any color labeling, but they were labeled 1 2 3 and 4. Honestly, if I didn't have the 4 wide band o2 sensor set up, I would have been totally up S#$% creek. The Rapid Bike really saved me there. I just finished editing my post, read through it again if you didn't already. I tried to label what pictures I took as best as I could.

[Switchblade]

So you removed the material or is this pre-removal ?

[CandyRedRC46]

That picture is pre-material removal. It shows the 38mm boots on top of the 32x35mm intake ports. The now exposed metal needed to be removed and smoothed down:

On 12/23/2014 at 2:07 PM, Switchblade said:

So you removed the material or is this pre-removal ?

This is after port matching.

[rangemaster]

Nice work. Where did you get your Kowa Seiki vacuum guage?

[Switchblade]

Got it thanks .

[CandyRedRC46]

Nice work. Where did you get your Kowa Seiki vacuum guage?

I sync'd the throttle bodies at Cycle Pro in Orlando. You'll have to ask the shop owner, "Yaman".

[Switchblade]

Can't wait for some dyno numbers . Would be a great Christmas present . Hint Hint .

[CandyRedRC46]

Lol okay I'm gonna work on it. See if Yaman can hook it up. I need some one with a stockish VFR800 to dyno with me for a baseline or else there is no point ...

[Switchblade]

Your a good man ...

And thanks .

[Mohawk]

Hey, you got the stock figures from the Dimsport dyno runs for the Rapid Bike, so grack on with yours :) Plus there are a million dyno runs on the web, that show 5th Gen average 95hp & 6th gen average about 98hp bone stock ! Come on get on with it people are waiting & you are one of the few in a place where its warm & salt free to allow you to keep riding.

[Switchblade]

I appreciate you trying to do it. I know you work and go to school .

[CasualSwede]

Lol okay I'm gonna work on it. See if Yaman can hook it up. I need some one with a stockish VFR800 to dyno with me for a baseline or else there is no point ...

Same dyno, same conditions, I agree, no point in shortcuts now...

[CandyRedRC46]

Yup. So who is stepping up to the plate and meeting me in Orlando for a dyno date? :)

[Switchblade]

They scattered like roaches when the lights are turned on.

[Rush2112]

According to the member map there are at least 5 members in the Orlando area...

funny thing is CRRC, you don't show up on the map