To pod or not to pod? Suzuki GT200 carbs

[NoRiders]

Metal likely worse for reasons mentioned above!

RZ responds very well to filters as Mark said! 

I would expect a slight increase in performance and gas consumption along with a lot of jetting work to get it right using pods!  Personally I use stock airbox unless I don't have one or trying to squeeze out a bit more power.  Pods look better and perform better plus are usually a lot cheaper than finding a stock airbox.  There must be an application out there that may be non-motorcycle you will have to source as I've seen pods on all sorts of motors...

Well, I don't have and cannot use a stock airbox as that space is taken up by the oil tank...so some form of standalone filter/intake system has to be the way to go.

After advice and feedback on here I'm leaning towards a trumpet and foam sock....but finding a trumpet for the 34mm carb mouth is tricky. I've seen an inlet adapter in rubber that I can reverse, so the rubber clamps to the carb mouth and the flange would provide a bolt on trumpet, maybe off a car Weber/Dellorto carb if the dimensions work out...then find a foam sock to slide over it.
I do expect some tinkering with the carbs with the new intake method....that remains to be seen. I'm not too far from an initial fire up I think.

Thanks to all who have taken the time to share your wisdom :)

[Dvsrd]

Machining a velocity stack from alloy tubing or POM is pretty straightforward, either a straight or tapered one. A nice, rolled radius at the filter end is slightly more tricky, but definitely doable. A CNC lathe or an external radius tool post (ball turning fixture) is handy for that.
So the carb OD at the filter side is 34 mm?

[85RZwade]

Maybe K&N has something

https://www.knfilters.com/rd-5010-special-order-dual-flng-oval-univ-fltr

[Dvsrd]

Maybe K&N has something

https://www.knfilters.com/rd-5010-special-order-dual-flng-oval-univ-fltr

Many K&N filters have a built in radius, so all that is needed is a straight or slightly tapered (up to 5-6 degrees) runner/tube. Although the radius is mostly smaller than a proper velocity stack/ air horn.
I guess the issue with the pressure wave reflection from the back of the filter is reduced when using a velocity stack between carb and filter. After all, a large K&N works fine together with the RD Y-boot.

[NoRiders]

Machining a velocity stack from alloy tubing or POM is pretty straightforward, either a straight or tapered one. A nice, rolled radius at the filter end is slightly more tricky, but definitely doable. A CNC lathe or an external radius tool post (ball turning fixture) is handy for that.
So the carb OD at the filter side is 34 mm?

Sadly, I don't have access to such equipment, so an off the shelf option is my only...option. The carb inlet is 34mm o/d which appears to be much too small for the common velocity/trumpet offering out there. (the only one I've found on ebay will take 6 weeks to deliver from China)

I've seen a rubber inlet manifold with 34mm round Jubilee style clamp and flange fitting at the other end, reversing this could provide a fitting point for a flanged trumpet......but getting the dimension across the mounting hole centres is tricky as most sell the trumpet for a particular model and don't bother offering dimensions. Also, some turned alloy trumpets are hideously expensive.

I'm seriously considering just buying the RamAir 34mm foam filter...rather than spending so much time sourcing a suitable trumpet/sock set up that'll fit.

I've yet to contact RamAir.

Thanks to all posting with suggestion and advice, cheers :)

[Dvsrd]

These K&N filters: https://www.knfilters.com/ru-0155-universal-clamp-on-air-filter
and a couple of pieces of 38 mm OD tubing could be a workable solution. Stainless hydraulic tubing comes in 38 mm OD and several wall thicknesses, from 2.0 to at least 3.0 mm. But that normally would require turning down to reduce weught.
1 1/2" exhaust tubing can be used as well, with the carb end crimped and slotted. I have had decent luck crimping tubing in hydraulic hose presses,  and muffler shops may also have suitable equipment for this.

Good luck!

[NoRiders]

OK, so a quick update on teh pod or not to pod issue.

I've spoken to RamAir, very helpful....they do the foam socks, the double socks are nice at £30 + del, but they don't offer trumpets.

Eurocarb offer trumpets for Dellorto carbs at £20 each + del that I could modify to fit (elongate the mounting holes).

The intake adapter I'd have to order off ebay, delivery mid June to Early August!! At a cost of £12.

Total cost for this solution = £ 82 + delivery

Or, order 34mm clamp on RamAir foam filter pods for £38 the pair...simple and will do the job.

Total cost = £38

The approx £50 saving would buy me a 130/70x17 flat tracker tyre and as I've hammered my budget lately, this could be my preferred option.

If I find the performance could be improved I'll make that decision at the time, bearing in mind all the advice on here of course.

I have to make this build fit my budget and this is the logical solution at this time. :)

[NoRiders]

These K&N filters: https://www.knfilters.com/ru-0155-universal-clamp-on-air-filter
and a couple of pieces of 38 mm OD tubing could be a workable solution. Stainless hydraulic tubing comes in 38 mm OD and several wall thicknesses, from 2.0 to at least 3.0 mm. But that normally would require turning down to reduce weught.
1 1/2" exhaust tubing can be used as well, with the carb end crimped and slotted. I have had decent luck crimping tubing in hydraulic hose presses,  and muffler shops may also have suitable equipment for this.

Good luck!

Thanx for taking the trouble to post information and links, appreciate it. In the time you posted I'd also posted what I think will be my solution for the time being, given all factors and other financial commitments I still have to make. Not the cheapest, but I hope a workable solution that will see it running....I can then benchmark performance and justify further investment.

[Gil Gallad]

i just used foam filters - off a pit bike apparently - but they work perfectly on the gt350, and being at an angle they fit in all sorts of tight spaces. getting the tacho cable on was a bit fiddly, but i got there in the end. about £15 including the 2 mikalor clips to hold the filters on. i like mikalor better than jubilee, because they are stainless and you can get them in 8mm width, so far narrower than jubilees  8)
cheers, gil.

tight squeeze:

[NoRiders]

Thanx Gil, foam is the way to go, so I'm pleased with my decision to go with a RamAir set up.

Twin single pods incoming...



I'm not anticipating any space issues....he said!!

[thatguy]

K&N filters typically incorporate a velocity stack inside the filter.

[RDFL]

They have a 35 they say will fit 1mm smaller. --  https://www.ebay.com/itm/2FastMoto-Velocity-Stack-Motorcycle-Air-Intake-Filter-Norton-Cafe-Racer-Commando/191715850199?fits=Model%3ARD400%7CMake%3AYamaha&hash=item2ca327b7d7:m:my_Oo8XcT1gFp9kP6MNVzqw

[motodreams]

Check it how it sits with just the filters and go from there.  So much of what is on here is the best theory advice that has little impact in practice in many cases IMO.  the 2% power gain @ WOT or whatever you will see is really only something to talk about with your buddies.   If it sucks then spend the extra money.  Improve the drag on your brake pads by making sure everything is clean (disc) or properly set the cables (drum) and you will offset those losses.

[m in sc]

some ramblings:
in my case on the rz, i ran flat sides and the stock airbox was missing in action. was def better than a 2% increase. 

the beauty of an all foam filter is that it creates a nice still air pocket behind the bellmouth. the longer they are, the more air there is. the downside is it can slow the velocity over the venturi, so jetting is required to  compensate.  the stack will help direct the flow, or int he case of some more modern carbs, the bel-mouth is already long and tapered so a stack isn't needed.

I know chuck did some dyno runs with filters, the curves are great.
physical restrictions especially on specials definitely   require it on some projects. BUT, if you know how to tune it, they work as well as a y boot, and better up top. I did dyno runs very early on the lc hybrid (this was back in 05-06) with smaller pwks on the motor, ran it with a k&n and y boot and large foam unis on the dyno down at james shinaults shop one afternoon. back to back, zero performance difference over all but def pulled better up high a bit. So, that being said, why fuss with a y boot and k&n vs a set of unis when you dont have to?

I have a y boot setup on the r5, but its dead stock. Also starts 1st kick  and is dead reliable . only mod aside from that is a dyna. Running a 17/41 gear set, will still wheelie all day in 1st gear and in second when the pipes are cold. but it also doesn't go over 8k.

on the lc and the lightweight, they both run 34mm carbs, one flatslide, one round-slide, both with big unis pods. again, tuning correctly, they can  pull from idle nicely, no ride-ability problems at all.  You just have to put in the time to tune,t his may require jet tube changes, needles, etc. More air + more fuel always = more hp when done correctly.

But just slamming unis on and going up 5 jet sizes will typically not do much to make them ride any better.



IN regards to piston port motors like your though, they respond very well to pod type filters, they are more forgiving as there isnt a reed slamming shut every cycle. should be good to go with your plan. I ran 2" extensions on the bellmouths on my old S2 with k&n filters ( i know but piston port) and put down 59 RWHP with zero porting, but a programmable curve with 400 carbs. The power curve was about a 45 degree line from 3500-redline. I never would have gotten that with a stock airbox.

But, on a stockish type bike a stock airbox works well (rd400/rz). rd250/350 airboxes are just fucking dismal though, unless it s a dead stocker.   

[NoRiders]

Wow...thank you gents....some good practical suggestions, I feel better for the fact I've not made a grave error.

I understand that there will always be the best, optimised set up and why not suggest that? But, it's also good to hear that there is a work a day solution that will not end in tears...hopefully? :)