Topic: Anti-Pod mod?

[orkid1989]

ill check it out and see. good luck

[orkid1989]

found a picture of what you were talking about for the CR carbs

from the pitcure it looks like their is no type of filtration at all for the pilot circuit.

also found some for the RS carbs

their is no hole or groove on these for the pilots but they do appear to bell out a little to fill in the extra space but that could also mostly just be added thickness for the area where the clamp goes. any opinions on what i should do? keep the cut to fit aspect or add the groove and not be cut to fit?

[Retro Rocket]

http://www.ebay.com/itm/Mikuni-RS-50mm-Velocity-Stacks-Intake-Racing-Set-4-/170646869864?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item27bb589768

I don't think there is much to worry about at the carb end, i may buy these and send them to you {if you are going to make some} and when finished, you could send them to me with your newly made stacks..?   

[orkid1989]

http://www.ebay.com/itm/Mikuni-RS-50mm-Velocity-Stacks-Intake-Racing-Set-4-/170646869864?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item27bb589768

I don't think there is much to worry about at the carb end, i may buy these and send them to you {if you are going to make some} and when finished, you could send them to me with your newly made stacks..?   

Thanks for the offer but you don't have to do that. I am going to make a couple of disks that should simulate the spacing and size of the carbs.

[Retro Rocket]

http://www.ebay.com/itm/Mikuni-RS-50mm-Velocity-Stacks-Intake-Racing-Set-4-/170646869864?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item27bb589768

I don't think there is much to worry about at the carb end, i may buy these and send them to you {if you are going to make some} and when finished, you could send them to me with your newly made stacks..?   

Thanks for the offer but you don't have to do that. I am going to make a couple of disks that should simulate the spacing and size of the carbs.

Thats ok, i'm all about doing things right, maybe one of our American members has a set of stacks that you could borrow, just to have a detailed look at..?

[orkid1989]

http://www.ebay.com/itm/Mikuni-RS-50mm-Velocity-Stacks-Intake-Racing-Set-4-/170646869864?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item27bb589768

I don't think there is much to worry about at the carb end, i may buy these and send them to you {if you are going to make some} and when finished, you could send them to me with your newly made stacks..?   

Thanks for the offer but you don't have to do that. I am going to make a couple of disks that should simulate the spacing and size of the carbs.

Thats ok, i'm all about doing things right, maybe one of our American members has a set of stacks that you could borrow, just to have a detailed look at..?

That would be awesome. I don't think their is anyone is near me though.

[bwaller]

I'm not sure you want to use those as any kind of pattern. I bought a set for my Mic smoothbores early on for the same reason you're thinking and they couldn't be more cheaply made.  Maybe junk is a better word! The transition carb/stack is the stuff of amateurs in my case.

[Retro Rocket]

I'm not sure you want to use those as any kind of pattern. I bought a set for my Mic smoothbores early on for the same reason you're thinking and they couldn't be more cheaply made.  Maybe junk is a better word! The transition carb/stack is the stuff of amateurs in my case.

Gday Brent, Orkid just wants to look at where the stack meets the carb opening, a Mikuni stack {made by Mikuni} would be great just as a point of reference....

[bwaller]

Hey RR. It was that very transition point (carb/stack) I was most disappointed with. These are also labelled as Mikuni, available from Sudco. I quess you have to start somewhere, and that part of the stack can be improved in the final design. I had some made of Delrin and the inside surface through the throat is smooth as silk. Or, as smooth as the older Mics can allow. 

[orkid1989]

So did you make ones that just went straight back or do they have a groove?

[bwaller]

What I know about this science is dismall and maybe should have kept my beak shut on your topic. I didn't follow the leaders with the whole race engine induction thing. I wanted to use a filter and ended up with dual socks over stacks. There is 40mm space between bellmouth & filter end.

I originally bought these Mikuni stacks and that is why I spoke up when I read you were thinking about them for a pattern.

I didn't use them but read until I was blue in the face on the topic and decided to make some with a six degree flair over the 30mm working length of the stack. 30mm seemed to be a good length for my application. I wanted the stack to fit on the carb so the transition was perfectly smooth, the alloy stacks certainly don't. Hopefully it's obvious in the pictures.

In the pics it is also obvious my guy became creative and didn't hold to the planned six degree flair front to back.  Ultimately I ran out of dyno time and haven't a clue whether the stacks work for or against me. There are no flat spots in power delivery, but the dyno graph does show a strange line where the power flattens out. Turboguzzi thinks it could be stacks and may well be. I plan to re-visit the dyno in the spring to try to find out.





The back side of the bellmouth inlet is flat in case I ever get an airbox made.





Alloy stack, the picture makes the fit look better than it is.





These carbs are older tech stuff but class rules don't allow modern. This fit is tight & seamless.

[orkid1989]

What I know about this science is dismall and maybe should have kept my beak shut on your topic. I didn't follow the leaders with the whole race engine induction thing. I wanted to use a filter and ended up with dual socks over stacks. There is 40mm space between bellmouth & filter end.

I originally bought these Mikuni stacks and that is why I spoke up when I read you were thinking about them for a pattern.

I didn't use them but read until I was blue in the face on the topic and decided to make some with a six degree flair over the 30mm working length of the stack. 30mm seemed to be a good length for my application. I wanted the stack to fit on the carb so the transition was perfectly smooth, the alloy stacks certainly don't. Hopefully it's obvious in the pictures.

In the pics it is also obvious my guy became creative and didn't hold to the planned six degree flair front to back.  Ultimately I ran out of dyno time and haven't a clue whether the stacks work for or against me. There are no flat spots in power delivery, but the dyno graph does show a strange line where the power flattens out. Turboguzzi thinks it could be stacks and may well be. I plan to re-visit the dyno in the spring to try to find out.





The back side of the bellmouth inlet is flat in case I ever get an airbox made.





Alloy stack, the picture makes the fit look better than it is.





These carbs are older tech stuff but class rules don't allow modern. This fit is tight & seamless.

thanks for the pictures but what carbs are those on? they look completely different from the previous pictures of the RS34 carbs?

[bwaller]

No these are old school Mikuni VM29.

[orkid1989]

No these are old school Mikuni VM29.

o ok well they look great. cant really tell you if they work or not. the ones that i am making are quite a bit different though also the carbs are different aswell.

[bwaller]

Yea well that's part of my point. The only way to know for sure if they actually work as intended is on a dyno. Even then it would be necessary to have options to compare. For one, no stack at all.

In both our cases we want to run a stack & filter. Ultimately it's safe to say the filter may cost a little power, but you sure don't want to create a problem designing a stack that doesn't work well. It may be a lot of trial & error.

Good luck, I'll be following along.

[orkid1989]

the only thing i can think of is compare the stacks with filter to the individual pod filters. but also the problem is switching from pod filters to these stacks with tintop's filter would be the change in a/f ratio. not sure how much the change will be seeing as i don't know the difference in flow between the pod filters and tintop's filter but i would guess that tintop's would flow much better causing it to be just a slight bit leaner. and as far as them working they are very similar to tintop's stacks that he has made and those work very well from what i have heard. if i get a set of RS34's ill run some dyno's with it and see if their is a difference but that wont be till the beginning of next year at the soonest

[Tintop]

Finally back on line.

One thing to remember with stacks is that the length effects different parts of the power band.  Generally the longer the stack the lower in the power band they take effect.  This produces more torque, but at the expense of top end power.  In bwaller's case (race engine) your looking for top end, with a relatively narrow power band.  So a short stack is best.  Currently he's using 30mm, but 15mm may be even better.  The dyno will answer that.  For the street, torque is king so the opposite is required.  Also the longer stack improves initial air flow, which gives better idle, and part throttle response.  Not a necessity for racing.

As an example.  On my Solo 1/2 Super7 Twin Cam I used both 70 & 90mm stacks.  The 90's were great for parking lot Solo 2, were clean mid range was important.  For Solo 1, on a track, I used 70mm to get slightly better upper mid range & top end power. 

[orkid1989]

Finally back on line.

One thing to remember with stacks is that the length effects different parts of the power band.  Generally the longer the stack the lower in the power band they take effect.  This produces more torque, but at the expense of top end power.  In bwaller's case (race engine) your looking for top end, with a relatively narrow power band.  So a short stack is best.  Currently he's using 30mm, but 15mm may be even better.  The dyno will answer that.  For the street, torque is king so the opposite is required.  Also the longer stack improves initial air flow, which gives better idle, and part throttle response.  Not a necessity for racing.

As an example.  On my Solo 1/2 Super7 Twin Cam I used both 70 & 90mm stacks.  The 90's were great for parking lot Solo 2, were clean mid range was important.  For Solo 1, on a track, I used 70mm to get slightly better upper mid range & top end power.

Exactly. The trick is finding the happy medium. That's also why I am considering making making these cut to fit so they could be modified for best performance

[maduncle]

Bit of a latecomer to the thread (as per usual) but I am planning on putting a set of CR29's on my bike in a couple of months and I like the anti-pod on my stock carbs, so if there is a chance of buying an anti-pod set up for the CR's then please put me down for a set.

And I have noticed that there are quite a few 'antipodeans' (us Aussies) interested in the 'antipods'...

(Don't mind me - I have been reading one too many long threads that start with a discussion on K&N filters over stock ones...)

[Retro Rocket]

Bit of a latecomer to the thread (as per usual) but I am planning on putting a set of CR29's on my bike in a couple of months and I like the anti-pod on my stock carbs, so if there is a chance of buying an anti-pod set up for the CR's then please put me down for a set.

And I have noticed that there are quite a few 'antipodeans' (us Aussies) interested in the 'antipods'...

(Don't mind me - I have been reading one too many long threads that start with a discussion on K&N filters over stock ones...)

Sorry Cliff but if you read the whole thread i think you can work the rest out for yourself, according to them the antipod and anything thats not stock is crap and of no benefit to us at all, that seems to include Terry's oil filters and Pamco pete's ignitions and anything else that they deem not necessary for our bikes.......

[voxonda]

Each his own. I run Tintop Antipod on my racer with FD carb's with choke removed. Runs with the best of them, even with me onboard.

Rob

[Syscrush]

Finally back on line.

One thing to remember with stacks is that the length effects different parts of the power band.  Generally the longer the stack the lower in the power band they take effect.

It's also worth noting that not every stack on a bike has to be the same length.  In principle, you could broaden the torque curve by mixing a pair of shorter stacks with a pair of longer stacks.  In practice, with the way that these stacks mount to the backplate and filter, it wouldn't really work in this application.

[orkid1989]

Finally back on line.

One thing to remember with stacks is that the length effects different parts of the power band.  Generally the longer the stack the lower in the power band they take effect.

It's also worth noting that not every stack on a bike has to be the same length.  In principle, you could broaden the torque curve by mixing a pair of shorter stacks with a pair of longer stacks.  In practice, with the way that these stacks mount to the backplate and filter, it wouldn't really work in this application.

do you mean having 2to different length stacks on the bike? Never heard of that before

[Syscrush]

do you mean having 2to different length stacks on the bike? Never heard of that before

Yes, that's what I mean.  e.g. short stacks on the 2 outboard cylinders, long stacks on the 2 inboard cylinders.

[orkid1989]

do you mean having 2to different length stacks on the bike? Never heard of that before

Yes, that's what I mean.  e.g. short stacks on the 2 outboard cylinders, long stacks on the 2 inboard cylinders.

Wouldn't that make it unbalanced? Also decrease the overall torque and horsepower? Sounds cool in theory though