Hello, I have a question if I may?
Thinking it's time to source appropriate air filters for the Suzuki GT200 build. I have in mind the foam style, or maybe the K&N gauze type...but finding them in 34mm neck size is tricky tbh. Some do look like they're really poor quality, even the K&Ns look similarly poor....and the prices aren't cheap either
Seen these RamAir foam filters....anyone had direct working experience of these, of similar? I'm open to suggestions, but cannot use the stock intake system so pods is it.
(https://i.imgur.com/lbnJN4C.jpg)
Thank you.
Over the years I've found if using the stock intake is an option it's often the best one. Far less headache tuning and such. Especially on a bike that didn't see huge sales numbers.
I can only talk about my experience with an RZ350 I owned with pods.... they ruined that bike. jetting was a nightmare and anything but wide open high revs experienced issues with them. The intake drone was awful as well. The happiest I ever was with any two-stroke is with stock intake system. I had an RD400 with a 2-1 on it... when I took that out (intake drone killing me) the bike smoothed out, bottom end returned... the bike was just better all round.
With my recent 1976 Rd400 project I wanted nothing but stock intake and exhaust. Those engineers knew what they were doing. Now... if I was racing on a track and the bike was always going to be revving to the moon... Id consider pods or 2-1.. but for a street bike... no thanks.
run the ram airs, all foam, no problem to tune if you are patient.
my rz had 5" long all foam unis and was an absolute dream to ride, but was also tuned as such with pwk flatslides. actually, pretty much all my 2-strokes run them except the r5 (yboot) and the t-500 (stock as the day it was built).
you will see benefit adding at least a 1" smooth runner, even at an angle, ahead fo the carb belmouth. I've had good luck on other projects fitting a short open velocity stack and an all foam uni filter at the end of it.
I had the k&n folded types with the metal backs.... any truth in the metal backs causing pulse timing issues in the intake track and messing up carburation?
YES. I actually did my final paper on that in college. ;)
reversion is a biach
Quote from: m in sc on May 22, 2020, 12:10:21 PM
YES. I actually did my final paper on that in college. ;)
That's awesome!
he he wow... ok then! Maybe one day I will give the ones the OP shows a try.... just for my curiosity.
just use the longest all foam ones you can. :twocents:
How much room do you have between bellmouths and your oil tank holder, Colin? I'm wondering if a Y-boot would fit in there.
I measured my Y-boot ('85 US-spec RZ350 carbs) just now:43mm bellmouths, 98mm center-to-center, 152mm length.
Quote from: 85RZwade on May 23, 2020, 10:30:00 AM
I measured my Y-boot ('85 US-spec RZ350 carbs) just now:43mm bellmouths, 98mm center-to-center, 152mm length.
I'll have to offer them up and measure precisely, think I roughed it a 80mm filter...but dimensions will be critical. Thank you.
Thank you gents, for you input and advice.
I'll explore trumpets and foam socks, but defo going foam/oil rather than gauze with caps.
Cheers
PS Got some lectrickery going on yesterday on the Suzonda
(https://i.imgur.com/eB4F8pZ.jpg)
Check out uni.com for filter dimensions.
With that said be careful of the end caps. I found filters to fit my RD350 which I thought would be good (in their snowmobile line) but they had plastic ends. Thought I would take a chance and buy some, but off eBay, and they were very old and had metal end caps. Unsure of the difference between metal or plastic ends, but I'm going to run them and see how it runs I guess. The first all foams I bought were too long and Mark bought them.
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...
Quote from: motodreams on May 25, 2020, 10:03:32 AM
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 :)
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?
Maybe K&N has something
https://www.knfilters.com/rd-5010-special-order-dual-flng-oval-univ-fltr (https://www.knfilters.com/rd-5010-special-order-dual-flng-oval-univ-fltr)
Quote from: 85RZwade on May 25, 2020, 01:49:45 PM
Maybe K&N has something
https://www.knfilters.com/rd-5010-special-order-dual-flng-oval-univ-fltr (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.
Quote from: Dvsrd on May 25, 2020, 01:24:51 PM
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 :)
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!
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. :)
Quote from: Dvsrd on May 26, 2020, 06:11:26 AM
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.
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:
(https://i.postimg.cc/qqsbhJGz/tightsqueeze1.jpg) (https://postimages.org/)
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...
(https://i.imgur.com/lbnJN4C.jpg)
I'm not anticipating any space issues....he said!!
K&N filters typically incorporate a velocity stack inside the filter.
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
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.
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. :twocents:
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? :)
Quote from: motodreams on May 25, 2020, 10:03:32 AM
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...
Thank you. I'm having to order some small O rings on the throttle stop thingy....the supplier carries all types of jets etc, so thought to order a few to play with.....what increments would make sense?
Or, should I bite the bullet and order a Sigma jetting kit from the US?
Stock jet sizing:
Main - 82.5
Pilot - 20
Needle position - 4
I think raising or lowering the needle alters fuel intake, along with a rise in jet size would also enrichen the fuel....does this compensate for the pod filter? Plug colour will be the test...or a blown engine!! Haha.
Stripped the carbs and found the mains are 87.5,so does that mean they've been upgraded by 5.0?
In which case that might balance the pod filter with a richer position on the needle too, perhaps?
New to carb jetting etc. Any help appreciated.
One size prob wont do it, usually 3 or 4 will get close on a piston port. (assuming it sized in 2.5 incrememnts) few more sizes for the chambers. you're just going to have to test. this si from experiences with a GT250 and rd chambers. so, similar.
Quote from: m in sc on May 29, 2020, 06:07:49 PM
One size prob wont do it, usually 3 or 4 will get close on a piston port. (assuming it sized in 2.5 incrememnts) few more sizes for the chambers. you're just going to have to test. this si from experiences with a GT250 and rd chambers. so, similar.
Ah, Ok thanx...never jetted up before so interested to hear your advice. Looks like I can get varying sizes, so a selection might work when it comes to it?
you'll probably need to rejet for the foam.