Author Topic: Velocipod install (Read 9527 times)

eurban · « **on:** April 08, 2010, 04:08:46 PM »

Well after getting the itch to start tinkering again on my 78 750 K project, I decided to attempt an improved pod filter setup for the bike. Aesthetics are an important part of my project and to my sensibilities the stock air box just didn't work with the leaned down look of the bike. I had been running a set of K&N oval pods which functioned adequately but I figured I might be able to reduce some of the Pod negatives (over the stock air box) including increased turbulence in the incoming air and performance fluctuations due to crosswinds. I also hoped to reduce any differences between the air charge for the inner and outer carburetors.

Trolling Ebay, I found a seller who was selling a filter setup for the pre 77 750 carbs that combined a set of Delrin velocity stack / adapters with a pair of K&N dual flange filters. I contacted him about producing a set of stack / adapters to fit the 77/78 PD series carbs (larger intake flange) and designed to work with a larger dual flange K&N filter (RU-2922 which is a set of 2 Dual filters for around $60) and with measurements that I provided, he CNCd a set for me.

I installed the adapters and filters today and they went on just about perfectly. I did have to chamfer the lip of the adapter so that it would ride over the ridge on the carb flange but once past the ridge it locks into place solidly since there is a groove machined into it for ridge. The filters have just enough room between the frame rails and the adapter to fit in easily and there is no interference with the cable pull choke on the PDs which is a problem with the typical pod install. I haven't had the opportunity to test ride as the weather turned sour but I will do so and report back. I also expect to be spending some time with carburetor tuning as the carbs may have some different requirements with the new filter setup (things weren't 100% sorted with the K&N ovals either)

Here's a cut away drawing of the adapter

Here's the set of stack / adapters and views of the the initial mock up on a spare set of carbs followed by the install on the bike. Note that in the mock up shots the stacks are only part of the way on the carb flanges.

mlinder · « **Reply #1 on:** April 08, 2010, 04:14:43 PM »

Nice!

I own the term velocipod though!

Looks really great, I like it, and has to be better than regular pods.

mystic_1 · « **Reply #2 on:** April 08, 2010, 04:58:20 PM »

Well done! I like what you did with the airbox hanger too

mystic_1

mlinder · « **Reply #3 on:** April 08, 2010, 04:58:48 PM »

awmahgawd, I can't believe I'm the only person who's commented on this awesome thing.

/edit: oh, there's someone...

Retro Rocket · « **Reply #4 on:** April 08, 2010, 05:03:13 PM »

Interesting, i wonder if it would be possible to mount the top half of the air box just to keep the induction howl down, i don't think it would restrict airflow and would reduce the effect of side wind..

Mick

gtyler5 · « **Reply #5 on:** April 08, 2010, 05:24:06 PM »

that looks smooth. what are the adapters made of? could he make some carb to engine boots too?

CBJoe · « **Reply #6 on:** April 08, 2010, 05:59:22 PM »

Quote from: gtyler5 on April 08, 2010, 05:24:06 PM

that looks smooth. what are the adapters made of? could he make some carb to engine boots too?

Made of Delrin

http://en.wikipedia.org/wiki/Polyoxymethylene_plastic

Very slick.... I'm curious to hear how it runs compared to the Individual pods.

Cheers, Joe

nokrome · « **Reply #7 on:** April 08, 2010, 06:02:40 PM »

wow, very nice original, practical idea
so when do you go into production

i just bought a set of k&n filters for my project, they look cool but i think your set up looks better
i will be very interested in the ride report

mystic_1 · « **Reply #8 on:** April 09, 2010, 08:39:40 AM »

Quote from: mlinder on April 08, 2010, 04:58:48 PM

awmahgawd, I can't believe I'm the only person who's commented on this awesome thing.

/edit: oh, there's someone...

Hurray! I'm someone

mystic_1

eurban · « **Reply #9 on:** April 09, 2010, 08:56:58 AM »

The design idea really belongs to Juan (wompy5000 on Ebay) who a offers a similar setup for the earlier carbs. His blogspot is http://jpriderdesigns.blogspot.com He was excellent to work with and turned the parts around quickly.
I can't see using the same CNC techniques for shaping rubber for intakes but I don't really know the limits. Delrin probably wouldn't be suited to mounting the carbs to the engine either. I will give Juan the link to this thread so perhaps he can weigh in on whats possible.
One thought I had was to continue the stack farther into the airbox (like Mlinder had in his velocipod drawing) and have the stacks internal expansion more gradual. This would likely mean that the filters would have to mount the stacks first and then the assembly be pushed onto the carb flanges. This would make install and removal a bit more challenging but might gain more of the benefits of velocity stacks.
Overall, dyno testing would probably be required to quantify any gains from this setup (or variations) over standard pods and would be particularly difficult if the carb tuning needs to be changed for each setup. Going on theory alone I am hopeful that I will notice some improvements and I should have some time over the weekend to give a butt dyno / ride report.
To be continued . . . . .

mlinder · « **Reply #10 on:** April 09, 2010, 09:06:41 AM »

wompy5000 · « **Reply #11 on:** April 09, 2010, 01:33:51 PM »

Just joined your forum. Very cool tech stuff going on here. I'm glad you like the vel. stacks!!! I've been running mine since september with no issues on my '79 KZ650 soon to be 700cc with some Keihin 32cvk carbs mixing the nectar. Any ?'s just shoot, but don't hijack the thread like I just did. PEACE!!

steamnjn23 · « **Reply #12 on:** April 09, 2010, 02:56:34 PM »

wow! now that looks slick!

dusterdude · « **Reply #13 on:** April 09, 2010, 04:47:37 PM »

very nice

Retro Rocket · « **Reply #14 on:** April 09, 2010, 04:53:10 PM »

Quote from: wompy5000 on April 09, 2010, 01:33:51 PM

Just joined your forum. Very cool tech stuff going on here. I'm glad you like the vel. stacks!!! I've been running mine since september with no issues on my '79 KZ650 soon to be 700cc with some Keihin 32cvk carbs mixing the nectar. Any ?'s just shoot, but don't hijack the thread like I just did. PEACE!!

Welcome Wompy..

Mick

wsup55 · « **Reply #15 on:** April 09, 2010, 10:08:20 PM »

Watching this for sure.

bucky katt · « **Reply #16 on:** April 09, 2010, 11:17:35 PM »

let us know how they work out. i love the way my bike runs with the airbox but if i could have the look of pods with the rideability and ease of tuning of an airbox i'll be all over that like horse poo in a pasture

bwaller · « **Reply #17 on:** April 10, 2010, 04:43:44 AM »

Good thinking eurban, nice clean installation.

brandEn · « **Reply #18 on:** January 22, 2011, 09:44:07 PM »

eurban just learnt me about these on another forum.... bump for some info and ride report!

KeithB · « **Reply #19 on:** January 23, 2011, 05:05:29 AM »

Nice work! It looks great! Like the term " volocipod"
Some thoughts...
The stock velocity stacks, and stacks in general, are a "tuned" device and are designed with the carb to provide a certain engine performance. Their job is to provide an even air flow to the throat of the carb. They are not there to minimize the effect of side wind. That, and keeping out water, is the job of the air box plenum.
My take on this is if you use velocity stacks then probably the stock ones are best suited to the stock carbs and some kind of filter assembly has to be designed to allow them to fit.
I think someone here(mlinder) put forward a good design idea for that. Don't think it will fit, though...
Having said that, I can't see why this set up won't "work" but is it really any better than just going with single pods?
The only way to test this is to try a stock system, single pod system and the Volocipod system on the same bike, same carb setup.
Some people here have found that the stock intake and air box (with extra intake holes) works the best for a broad range of engine performance for the street. Race bikes are a whole different story.
Just putting some ideas out there

FunJimmy · « **Reply #20 on:** January 23, 2011, 08:22:57 AM »

This looks like a great idea.
I just received a set of Keihin CR26 smoothbores and that have suppled stacks or K&N pods.
If your guy could make a set to work with my CR carbs, that would be cool.

steam-powered man · « **Reply #21 on:** January 23, 2011, 10:50:35 AM »

very nice.

any clearance issue w/the choke assy?

eurban · « **Reply #22 on:** January 23, 2011, 11:29:53 AM »

Back to this site after a long "vacation" working on a different bike. . . .
This airfilter setup offers little more than subtle differences between the 4 pod oval KNs that I used run. Cross wind detrimental effects are definitely reduced as is the intake "suck" noise. Power delivery had always been good once I got the pumper carbs tuned so I can't really be sure if there is much improvement in that area. I didn't make any changes to the carb internal setup as it didn't seem as if it was needed. Probably a testament to the small effects that the change in airfliter style had.

KiethB, reports of cross wind issues are relatively common with the ride reports on podded bikes and I certainly noticed intermittent performance issues with 4 pods when the wind was really blowing. I never noticed any such issues with the stock airbox. Pairing up the cylinders in the dual pod setup and perhaps adding a bit of a "stack" to the end carb inlet has made a noticeable improvement in this area. I could only speculate on the physics behind it but as I said, the real world effect is noticeable. I am pretty confident that with the two pod setup the inner and outer cylinder pairs do see a more similar air stream than with the 4 pod setup. I'm sure stock rubber "stacks" had some real engineering behind them but probably not all that much. No doubt it could be improved upon to flatten out a dip in the power delivery curve but that would take a dyno and likely some carb fiddling with each test. I do think that if I had it to do over I would have the the stack fit inside the filter more deeply making installation a bit more difficult but adding a more significant V stack effect. This should be no issue for the CNC machine.

Steam, there is no clearance issue with the choke mechanism. This is definitely an improvement over the 4 tapered oval pod KNs which would rub the mechanism.

Overall I'm pleased with my experiment. It cost about $150 for setup which isn't too ridiculous and it does seem to be an improvement (although small) over the 4 pod setup I was previously using.

bwaller · « **Reply #23 on:** January 23, 2011, 12:34:34 PM »

Eurban,

I've been trying to reach Wompy to make some stacks for a set of smoothbores, do you have an e-mail?

wompy5000 · « **Reply #24 on:** January 23, 2011, 05:40:40 PM »

Fear not I'm here too, just been busy with some chopper stuff...now for the riders.
I've also been approached by a vintage racer-type with a kz1000 street tracker bumped up to 1075cc. SCREAMIN!!!! He has 29mm smoothbores and wanted velocity stacks deeper into the filter like mlinder drew up. I made a couple of prototypes and we settled on a design which will provide the best airflow, hp, and minimize turbulence.

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Author Topic: Velocipod install (Read 9527 times)