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PW50 K&N Air Filter

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Hello, anybody know which K&N filter will fit on a pw50. I am assuming it would be a universal but not sure which one. I am also considering getting the PHCB (? something like that) carb I hear a lot about so I am wondering if the filter only fits that carb or stock or both????

Also was looking at a Uni but prefer something I can clean when the time comes.

By the way I am taking off the box completely, he does not ride hard enough to worry about water and such. My goal is to try to muster a little more bottom end out of the bike so he is not pinning it to get her moving. Also thinking about the boyseen reeds and FMF system later. Any experience would be great so I am not learning the expensive way:worthy:

Oh, going for bottom end because I don't have a nice flat area, it is filled with nasty ruts and ledges so I am hoping by improving the bottom end he will not need to go so fast to get going from a stop. Well that is my theory anyway. Thanks for your time guys:thumbsup:

Oh, 3 and half, 81 pw50 stock (having some problems with her so I am just replacing the top end crank and clutch (check my other forum on cheep pw parts) and wieghs about 35lbs.

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Another question/idea, has anybody tired reroute the filter and carb to the front of the engine for a semi forced induction theory (low speeds = turbo lag:lol:)? Use a conical air filter facing forward and maybe a reverse direction cone to force air in. My only concern would be jetting... the extra air pressure at speed may need an entirely different jet set up then at idle. I am thinking of using a radiator fan as a "electronic induction motor:cool:" controlled by engine speed. The hard part is weather the electrical system could handle it.

Just looking at it, I don't think it would be to difficult the worst being the intake manifold starts circular but enters the engine as a square. Probably best to cut it off just above the flange so as not to obstruct reeds. Just TIG her back 180 degrees and grind it to clean it up... probably make it easier to bore out the manifold too.

While sitting here with nothing else to do (sorry guys:moon:) I want to bring up a few other thoughts.

First, cutting or modifying the frame where it holds the triple clamp to hold a better fork system like the ktm 50 minis. Know you have more then double your suspension travel, good suspension, handle bar options, and hydraulic front disc brakes.:banana:

next, the rear, I would remove the entire shaft system for a legit swing arm and mono shock. Looking at the schematic it seems like it would be simple to form/construct a cover where the transmission shaft exits through a hole and seal with a machined end to fit a chain gear on it. The only problem I foresee is, if the chain would line up with our retrofitted/replacement wheel and swing arm. Looking to a brand like ktm you again get a hydraulic disc brake several inches more of travel and in theory a much better shock then the dual springs in the rear if the shock has the necessary clearances to weld up support for it. I think you would actually shave some wieght in the rear.

Why do all this? well I would counter with the desire to give my son a better performing bike that is still small enough for a 3/4 year old but not over powering. The bike (again, completely hypothetical) being an 81 is not worth much, there are many advantages that the softer hitting pw50 would give like confidence and these engines are quite respectable with porting, reeds, carb, etc. It would trail better and last longer then the full bore racing machines yet behave similarly and you can mod up or down depending on the child behind the bars. I have always thought that it is better to have a machine under powered and over controlled then the other way around. These I feel are valid points but the fact is still looming, can I make it work:busted:

Well if you actually read this stupid post (I owe you an apology first) and give you the floor, what do you guys think, not should I but could I. Well any of us for that matter pull this off with limited resources, equipment, and money:ride:

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when i was in my teens and early twenties i raced motocross and desert my mom rarely came to my races she said she couldnt take it, it used to bum me out... flash forward 15 years... my boy started riding when he was 2 and just now is starting to get brave hes three now... and you know i called my mom and told her now i understand why you didnt like coming to the races... my boy rides a 05 jr 50 and i dont even have the throttle open 1/2 and hes nuts he wants to jump he wants to do what he sees the other kids doing it is nerve racking as hell... i was like you i wanna do this and do that but they dont need it all he wants is more gas ... heres my .02 get the bike running bone stock buy him all his gear get him 5 gallons of gas and go have fun he doent need adjustable preload and carbon fiber reeds he needs seat time, and when hes ready for more suspension sell tha p dub for probably more than you bought it for and buy a ktm :banana: Brad

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he has all the gear except for a neck brace, but again this is just hypothetical. Wife is doing homework for school (mid terms) so I have the kids and when they are actually doing their own thing this is what I think about. Hell at this point I just want it to run (waiting on parts now actually) It has been pulled apart since early Jan cause I just did not have spare cash. So I would not do anyting now, I just want him on it agian instead of pushing the casis up hills and riding it down... the back wheel is not on, it is currently a trike, 10" in front and 2 6" traing wheels in the middle. It is cute to see him that desperate but he needs his bike back. Anyway just so mental moddifying I like to do when bored, since the PW is top priority it is what I mess with in my head. But I hear you, he jumps on and want to pin it and we are not exactly on smooth flat ground, that is how boys tend to learn, pain I mean expeirence.

Edited by entrpner71
asdfh

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if you want something for low end, try the QT50 gear. or step up to a 60cc cyl and piston.

otherwise you're going to throw a lot of money in to minimal gains.

also check the compression, it may be time for new rings and piston. i just rebuilt the top end for the race this weekend, and my boy was able to pull up on the bars a little and get the Pdub to wheelie. he is about 60 lbs.

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Save your money and buy a PW80. For what you're going to pay for a K&N and a fancy carb, you can get yourself a whole PW80 project bike. By project, the two $300 ones I bought needed foot pegs, throttle cable, two kill switches and a carb cleaning, between the both of them.

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he is a little small for an 80, he won't be 4 until july. The filter is a must, his is dirty and it is nice to to be able to clean them. Reeds too, for $20, why not? The carb won't come for some time if ever, they are only $90 new and take the tiny 12mm up to a more respectable 19mm but I would do this and mild professional porting so it would be expensive and take the bike beyond its purpose. Since I have 2 jugs I may do it just to see how it reacts but I would rather get him a mx bike if he needs it (wants to race) if I had a few hundred dollars to throw around. I think that bike would still be friendly but fun with the throttle restriction. AGAIN NOT DOING IT, he is far from needing a fast high performance bike.

Again, the suspension, intake, etc is purely just a thought, I just want the bike to run now. I had nothing to do this weekend since my wife had mid terms to study for. I like to play with these kinds of things in my head that is all. So please no more buy this bike responses, will place an order for filter and reeds today and about the only equipment I have is a dremel. I am just having some fun with mod ideas. Thanks for your suggestions though they are appreciated.

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19mm? Serious? Good luck with that. Sounds do able but a jetting night mare on such a small bore low RPM bike. Now if it was turning 20,000 RPM that would be different.

I'll rephrase, buy a PW80 project, by the time he's big enough for it, you'll have it fixed up like new.

From what I've read the QT swap is the most bang for the buck mod for the PW50. Forced induction, or I should say "ram air" doesn't do so hot on carburetted machines. I had one that the carb would freeze in high humidity because of the air flow cooling the venturi at such a rapid rate, then the condensation would form which would then freeze around the orifices starving it of fuel. I don't think that would happen to a PW50, there isn't enough volume or enough air speed to do it. But I highly doubt you'd get anything measurable, let alone noticeable for your efforts.

None the less, I salute your desire to tweak your bikes and you've got some pretty good ideas otherwise. I'd simply wait for a better application.

I have one suggestion, no matter what you do, involve your kid to some extent. He's only four, but he's plenty old enough to hand you screw drivers and wrenches. At the very least, it'll help him with his number recognition when he heads off to kindergarten next year.

Last weekend, my 14 year old and I replaced the top end on a 300ex. He had done the majority of disassembly with his 10 year old cousin. Given adequate supervision, I think he could have reassembled it too.

It ran, so rewarding.

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he is a little small for an 80, he won't be 4 until july. The filter is a must, his is dirty and it is nice to to be able to clean them. Reeds too, for $20, why not? The carb won't come for some time if ever, they are only $90 new and take the tiny 12mm up to a more respectable 19mm but I would do this and mild professional porting so it would be expensive and take the bike beyond its purpose. Since I have 2 jugs I may do it just to see how it reacts but I would rather get him a mx bike if he needs it (wants to race) if I had a few hundred dollars to throw around. I think that bike would still be friendly but fun with the throttle restriction. AGAIN NOT DOING IT, he is far from needing a fast high performance bike.

Again, the suspension, intake, etc is purely just a thought, I just want the bike to run now. I had nothing to do this weekend since my wife had mid terms to study for. I like to play with these kinds of things in my head that is all. So please no more buy this bike responses, will place an order for filter and reeds today and about the only equipment I have is a dremel. I am just having some fun with mod ideas. Thanks for your suggestions though they are appreciated.

if he is only 4 and wants to race, you should let him race the PW. they are great starter bikes into racing. also they are bullet proof. change the air filter after every race and you are golden. it will kick over everytime.

just becaureful, because if he races, they will probably be a stock class and if modified, will be DQed if not all stock.

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It may be 17mm, not 100% Yes either way it is big! But that is where you get the extra HP

Not 4 until July 7

His position on racing? I don't honestly know, he is 3 and a half and has very little seat time. Tomorrow that should change now that mid terms are over and my wife can watch the kids till I am finished. However I will keep all stock parts in light of your point (Thanks for the heads up, would suck to buy performace to only spend more for stock components he already had)

Good point, and I do, he has already had his hand in many misplaced tools, more then his grandpa and it is hard to beat my dad!:banana: He is actually smart enough (before he was 3 he could, once threaded, use the ratchet and socket to drive or remove bolts... once "broke" of course) but he can't sit still for more then 3 seconds to complete the task at hand or to learn a new one. Really frustrating actually:banghead:

As for the my redneck turbo charging of his 50, I think with a conical funnel (widest diameter set forward) with a conical filter (widest diameter/hole facing rear) would boost pressure noticeably in comparison to the stock restricted filter. Your mention of the carb is a problem though however I think the aftermarket carb could take the extra demand in volume/speed with it's reduced bottleneck. I will say I live just north of San Diego and at sea level with the extra air density may give me a slight advantage versus the situation you described. Again not doing it, just something to talk about.

I was also thinking why not use the oil pump access to power a impeller to liquid cool his bike... this was a big problem for him in the summer (just turned 3) at such a low speed, again dangerous terrain, his bike I think was getting hot just a idol for such long periods of time. Thoughts?

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take him out to the races and let him interact with the other kids out there. if he likes it, then he can give it a shot, he may like racing or not. all kids are different.

one thing of caution about open filters, you cant ride in the wet. anytime its muddy or wet out they will saturate. this is a even bigger issue because these bikes sit so low to the ground.

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If it's getting really hot, you might want to confirm your jetting is correct. At or near sea level, many factory bikes will run lean. Lean is hot, hot as we know is bad.

Liquid cooling is a nice thought, but is going to take a lot more work than converting the oil pump drive to pump liquid as you'd need some way to transfer the heat from the cylinder to the liquid.

Nice thought though. I've spent much time staring at the PW80 cylinder wondering nearly the same thing, except I was planning to use a second stator to drive a water pump. I think the 50 could use a similar set up IF you figure out how to get the heat to the coolant.

The cheap solution would be wrapping the cylinder with copper tubing - 3/8" or so. The ideal solution would be to create cooling channels with a mill and plug the external holes. OR remove the sleeve, create channels and re-insert the sleeve. The cylinders are quite thick.

You'd also need to do something similar with the head.

An alternative if you had a foundry at your disposal would be to make your own molds.

Lots and lots of work no matter how you look at it.

Cool idea though.

Yes, my kid has helped me misplace many tools too, I guess even his mechanical ability education is expensive.

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shortyr6

I would be surprised if he did not want to race, time will tell I guess but since he was about 18 months on the 250R he would always plead to ride with my friends/family on dirt bikes doing the jumping:banana:s. He always says faster when I ask him (also says Grandpa is to slow:smirk:) and loves to hit the "bumpys" or the jumps I am willing to take him on, he actually always wants to go higher, this is with me pressing him into the gas tank so he can't fly off, it is pretty cool I will have my old man record it and post it.:thumbsup: So racing is coming the problem is money is not so fast to jump in my account. Anybody know a good speech for my parents and grandpa.

Unfortunately our problem down here is dust clouds not mud puddles. But K&N sells a water screen, so when it does rain I can throw that on. But I will buy it now that you mention it (wet season and all). If water is present he will go straight to it, like a fish.:lol:

Smacaroni

Do you know the jet settings for my area? Again sea level, rides between high 50s and mid 80s (hits low 100s a few days out of the summer... july and August mostly) Looking for the best jetting, not so much stock. I am not sure it was over heating but once it stop (rarely died) it refused to start until it sat (cooling IMO) for about 5 minutes. So jetting makes sense. Have no I idea what jet/jets are in it.

I would probably (in theory) weave 1/8 (whatever OD fists best) between the fins and use high temp solder to maximize surface contact and adhesion. Not sure how hot the jug gets but I have seen solder melting point of 650 which should work, it was vibration resistant too. It would be best to round out a "channel in between the fins and that would cut out some of the weight but the thinner she gets the more intense the heat becomes I would think putting the solder at risk. Then cut the fins off grind them level to the pipe heat and tap the tubing flat on the outside a wrap several times with aluminum sheet to protect the soft copper, it wold wrap tighter and be more penetration resistant then a single heavy gauge sheet or welded box.

I think my problem areas would be seperating the head and jug but with independent plumbing to each I think I could solve the gasket problem and lastly how much pressure I would need for good flow through the small diameter tubing and tight bends. Also my gpm and best operating temp. I do agree though an upgraded coil and even magneto to electrically drive everthing would be better... maybe HIDs and EFI:busted: and a electric induction fan for my ram air:p

What do you think... got side tracked today, have to repair the bike tomorrow:rant:

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For a PW50? I can't say.

For us, around 400' above sea level on a PW80, the stock pilot is #17, we went to #30 after doing some mild exhaust work and some moderate intake work.

The stock main is #130 which is too rich stock, however it was just right after the same work mentioned above.

You just have to try new combinations. I recommend reading http://articles.superhunkyforum.com/4/55 for more information on how to jet a bike.

Before you order new jets, be sure to find out what your current jet numbers are.

Ram air electric fan... that's good. I had that discussion with my kid the other day.

Ok, let's see, by golly, I think that braised copper tubing/aluminum sheild could actually work. First, I'd see what for GPM a 12V pump can put out on the PW stator though.

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anybody know the actual universal filter number used for the PW50?

I will have to refer to the manual to see what the stator puts out, I think it would be best to parallel directly off the generator if the amperage produced is high enough. I would have to check with my DMM to get a ruff idea of what is happening. I wonder if I could find a tighter coil pack or stronger magnets to produce some extra V. If the V was not pretty stable I think a regulator would be pretty expensive.

Actually I am almost tempted to see if I could remove the shaft drive to give him a mono shock linkage free swing arm. Although it would probably be much easier to fit the PW engine in a KTM bike and match up the drive and driven gears. I actually don't think it would be to bad to have a machinist modify (might have to build from scratch depending on the distance needed to align both sprockets and its stock length) and machine a hole and cage and or seat for a double lip seal. A stabilizing bearing would probably be a good idea to reduce drag and damage esp if moded.

I still really like the idea of getting independent power source available for things like induction fan/cooling fan pump and EFI potential. I know very little about ignition systems so I would think if you could keep a high V higher A source seperate from controls you could get a better ignition... which of course I would play with to. Anybody have a spare bike:busted:

Edited by entrpner71

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