Project Can 'O Worms

[Motorious]

Well, a couple weeks ago an ad on craigslist motorcycle section caught my eye: a Yamaha Tri-Moto 175, runs, needs carb adjustment, $150. So I check it out: tires are decent and hold air, plastics are faded and a little scratched, but are otherwise ok, seatcover is shredded and faded, but foam is still usable, missing parts of the fender/seat latch, oil tank/pump cable missing, oil hoses blocked off, oil pump cover had a corner of it broken off, carburetor mostly all there, air box off, but is there, missing exhaust endpiece. Frame and forks seemed straight, and best of all, it ran, although quite badly. Offered the seller $100, he sells it to me for $125. I give him a $100 bill and a $25 check.

I transport it home, take the carb apart and clean it thoroughly, get it running, but have a hard time tuning it to run right. doesn't want to idle very low, and tends to bog and die at mid-high RPM's. Little to no smoke coming out exhaust (uh-oh, not good). So after about ten minutes I shut her down.

It sits for about a week or so. Weather turns cold again. I decide to drain the old gas and fill it with fresh 40-1 fuel mix. Thing will not start for nothing. Odd, it had previously started real easy, sometimes needed a little priming of fuel through the carb, but would always fire right up. This time nothing, except the occasional pop. Great spark (even changed plugs at one point), compression seemed decent (enough to blow my finger off the hole), and was definitely getting fuel. I even tried removing the carb and spraying fuel directly into the reeds. Nada. So know I'm getting worried. I pull the exhaust, have a look at the piston. Crap.:( Significant scoring on the rings and piston. So I figure that running it lean musta effed it up. Start pricing piston kits on ebay.


So I have this pretty cool old nitro RC heli that I traded (along with a Traxxas Stampede monster truck) for an old '84 Yamaha VMax snowmobile with a busted track that I needed to get rid of. I decide to trade a guy the heli for a Tri-Moto 175 parts trike with a good motor but a bent frame. What the hell, I figured I'd have a hard time getting $200 for the 'copter (I decided I'd rather sell it than crash it), and that I'd likely spend well over $200 for a top end rebuild.

Right before I leave to go check the parts trike out, just for crap and giggles I decide to try starting the original motor one more time. With the carb off I shoot a little mix into the reed cage and give 'er a pull. Whadda you know, the damn thing starts right up:rolleyes: But based on what I saw when I looked at the rings and piston thru the exhaust port, I decided to check out the parts trike anyway.

Pulling the motors turned out to be more time consuming than I thought, and I discovered the donor motor had a pretty good oil leak. The shifter shaft seal was really loose, and I hoped that was the culprit. So I ordered the part, replaced the seal, cleaned the motor and the trike up as best I could (amazing how rock hard the dirt on the frame becomes after years of use and never being properly cleaned).
I got her back together and used the parts bike plastics, fender mount, seat (homemade recover job, kinda amateurish, but still better than the original seat by far), and exhaust. I also decided to use the oil injection system that came with the donor bike and drained the old oil from the tank and mounted it to it's new frame. Before starting the motor for the first time in it's new home, I decided to change the transmission oil. I was pretty bummed when a large amount of gray, watery oil came gushing out. :eek: Apparently, a lot of water got in the tranny. I thought I'd been careful not to spray any water down the carb and exhaust port when I washed it. IDK...maybe it was already there before I washed it. Only thing I could do was to try to get all of the water out, so I replaced the drain bolt, added about 2/3 of a quart, and pulled the starter cord a few times. Then I drained the fluid until clean oil came out, replaced with clean 30 weight motor oil.

Time to fire her up. To my pleasant surprise, it started the very first pull and ran pretty good.
Took her for the maiden run, and that's when the trouble began. First, it tended to die when I shifted into gear while stationary. I tried lowering the idle, but still no dice. Hopefully, just needs a clutch adjustment. But I was able to keep it running in gear if I gave it a little throttle and allowed it to move while shifting into 1st. I quickly realized something was seriously screwed up when I had to lean hard to the left to go straight, and that it was seriously hard to make a left turn on it. That's when I realized I probably had a bent frame.:cry:

There's more to this saga, but I gotta quit writing and go to bed right now. Probably lost most of ya anyway with this long post, but if you're still interested, Ill try to add more to it (pics included) tomorrow. I'll end this tonight by saying there's more problems with this 'ol beater than a bent frame and maladjusted clutch. But I'm determined to fix this 'ol relic just the same.

[jb2wheels]

I feel your frustration. That's how it goes with 25 year old project toys sometimes. I was really bummed when I got my $75 ATC 200s apart only to figure out the frame was too far gone to use.

On the plus side, it's a great feeling when you finish one and it looks and runs great! YOu'll get ther eand see what I mean.

[4cylinders]

hey, before you check your frame, check the rear tires and hubs.

[HONDA_ATC_FREAK]

definetly check the hubs they might be stripped I had the same problem on my 200es it won't turn worth a crap because the axle is just spinning in the hubs.

[daniel_250r]

i feel your pain but those tri motos are garbage along with the klt get a honda atc and dont look back just my 2 cent

[factoryX]

whoa there johnny them fighting words.

[Motorious]

Yeah, unfortunately, it's definitely a bent frame. The splines are good, and when I took a good look at the front end, it became obvious that the steering tube had somehow gotten twisted to the right. It's weird because there is no obvious damage anywhere on the bike, and the forks are straight as an arrow.

So I remove the headlight, handlebars, gas tank cover, gas tank, forks, and see if there's anything I can do to straighten the frame. What a huge PITA! This is a short, stout, little frame, made even tougher to bend by the thick bracing and gussets tying the top and bottom tubes to the steering tube. Truthfully, the only way to properly straighten this frame is to strip everything off it and take it to a body shop that has the right tools to do the job. But since it ain't very cost effective and I'm way too poor to afford that option, I break out my sledge hammer, blow torch, 6' long iron pipe cheater bar, and various other primitive tools in my arsenal and get busy trying to straighten the steering tube. So I spend several hours heating and beating the snot out of the frame, and even though it seems like a next to impossible task, I manage to straighten it out a bit. I hope it's enough to make it rideable again, but I don't want to beat on it anymore, starting to damage it a bit too much from so many blows.

So I put it back together, and proceed to attempt to adjust the clutch. Can't find any specific instructions on how to do this, and I have yet to procure a manual, but I find some posts on how to adjust the automatic clutch on similar trikes (ATC 200, DX 225, etc.), and decide to give it a shot. It's pretty simple: you remove an access cover on the right side of the engine case, loosen a locknut, and turn a big slotted bolt counter clockwise with a large screwdriver until you feel some resistance, turn the bolt clockwise about 1/8-1/4 turn, then re-tighten the locknut while holding the bolt from turning with the screwdriver.

This being accomplished, I decide to test it out by sitting the trike on a milk crate, thus raising the rear wheels off the ground. Fire up the motor, warm 'er up, shift 'er into gear. It is hard to get into gear, and the clutch doesn't seem to be fully engaging. However, when I shift up to the higher gears and the wheels increase their speed, I notice a nasty wobble to the rear axle, enough to shake the hell out of the trike and send it tumbling off the crate if I hadn't been holding it. Crap. What now?:wondering

A close look at the axle reveals the problem: sloppy bearings. A huge amount of play in the axle bearings. Fortunately, the bearings in the parts trike seem good, so I simply replace the original axle with the parts trike axle. Pretty easy job, just time consuming.

Ok. Time to try adjusting the clutch, and maybe, finally, take 'er for another test drive. With a bit of trial and error, I get the clutch adjusted properly, yet not without some more grief: I break part of the shifter linkage by trying shift to neutral with the clutch maladjusted and too stiff. Fortunately, I'm able to scavenge the same part off the parts trike and keep working.

Start 'er up on the milk crate again and put 'er in gear. The new axle from the parts trike spins nice and straight, and wobble free, however the right wheel may be a little bent because it spins a little elliptically. Damn. Oh well, it's still a hell of a lot better than it was, and I decide it'll be good enough to try riding.

Moment of truth: I do a few laps around the neighborhood. The motor runs awesome, and has a surprising amount of power for it's size. I can see why so many people dig on these little 2 strokers, they're natural wheelie machines. Small, light and punchy, when you hit the powerband it's hard to keep the front end down.

It still pulls to the right a bit, but at least it's rideable, and I'm sure it'll handle a lot better in the dirt. Still, it's a damn shame the frame is bent and I couldn't quite straighten it.

I don't know why you hate on these trikes so much daniel_250r, these are great little machines. I've owned a couple of ATC
200's, and although they're also a blast to ride, I've gotta say this Tri-Moto 175 would be a funner ride if the frame wasn't bent. It just feels a bit lighter and more powerful. Now it ain't no 250R or Tri-Z 250, if I had the money, those would be the trikes for me (hell, if money were no object I'd LOVE to buy me a Tiger 500), but as I wrote before, I'm a pretty dirt poor boy, and that's why I look for cheap projects like these because it's all I can afford. A running trike is better than no trike at all.

I'm just glad it's rideable now. I'm going to try it in the dirt first and then decide whether to attempt to straighten the frame again, or look for a donor frame (a helluva lot of work) :rolleyes:. We'll see.

Thanks for all the comments.

The Can 'O Worms lives. Pictures, as promised:http://i737.photobucket.com/albums/xx11/Cychotic/Tri-Moto3.jpg
http://i737.photobucket.com/albums/xx11/Cychotic/Tri-Moto2.jpg
http://i737.photobucket.com/albums/xx11/Cychotic/Tri-Moto1.jpg

[Motorious]

The frame is still too bent. It's rideable, but pulls pretty hard to the right. Go faster than third gear and the front end lifts up so much you can't steer straight, and left turns are extremely difficult to accomplish. Handling is just really f'ed up. It's a damn shame 'cause otherwise it's a great trike, and runs awesome. Anybody got any ideas on how to straighten the frame? Are there any shops that might be able to do this for a reasonable fee? I'd hate to have to replace the frame, especially after all the work I've already put into it, and the frames I've seen on ebay aren't cheap ($150 + shipping), and there's no guarantee that they're straight either.:wondering

[old-yellow]

Its not that hard to switch the frame.

[Motorious]

This is true, it's just a time consuming hassle I'd rather not deal with, particularly after all the work I've already done to it (i.e. swapping the motor, axle, pulling the fork, plastics, and gas tank and banging the sh$# out of the frame trying to straighten it, cleaning the carb, cleaning 27 years of caked-on dirt off it, fixing wonky wiring, adjusting the clutch, etc.) Would be a heckuva lot easier if I could just straighten the frame, especially without having to take it all apart again.:rolleyes:

Plus, I'm not inclined to buy an ebay frame, the few I've seen are expensive, and I don't wanna buy any frame I can't inspect in person beforehand (not like I'm gonna be able to return it if it turns out to be crap with a $50 shipping fee). Other option is to try and find another parts bike locally, but like I've already wrote, I'm not too enthused about the idea of having to swap everything over again (not to mention buying a second parts bike).

This thing is really living up to it's name.Dammit :D

[cox]

i feel your pain but those tri motos are garbage along with the klt get a honda atc and dont look back just my 2 cent
you make me giggle..... Funny how i have had more problems with my ATC's then my YT's. My ATC's hide in shame everytime i ride by them on the YT's.:lol::lol:

[Motorious]

Well, persistence does pay off. After considerable effort, I was able to straighten the frame enough to make the trike handle MUCH better. Decided to take the front end and gas tank off again and heated up the metal with a blow torch (in an attempt to soften the material), and beat the snot out of it again. This time I studied the frame much more carefully and discovered it had a lot more subtle bends than I had previously thought. Initially, I had thought that only the steering tube was bent, that somehow it had gotten twisted in such a way that the top and bottom of the tube was no longer level, which tilted the end of the forks to the left causing the wheel to sit cockeyed on the ground, which of course pulled the trike to the right when in motion. I soon realized that the frame tubes were also out of whack, and were slightly bent way down towards the middle of the trike where the top and bottom tubes were tied into the rest of the frame under the seat. Really hard to see the bend. Took a chance and hammered away again, this time further down the frame where I noticed the top and bottom tubes were slightly bent. Results not pretty, put some dents in the top and bottom tubes (fortunately the plastics hide the ugly pretty well), but the front wheel rides almost perfectly horizontal with the ground now (still just slightly cockeyed), and she rides so much better. Not perfect, but I'm happy: it went well all things considered. Trying to straighten a bent trike frame with the most primitive of tools is nerve racking, and could have resulted in completely ruining the frame.

Took it for a spin around the neighborhood, the thing flat out flew, and steered fairly straight with perhaps a slight pull to the right. Punchy, peaky little 2-stroke powerband.

Then I took it for a ride up to the Hunter Lake area, a very challenging OHV area, extremely steep, with very technical, loose, rocky, and uneven surfaces. Not the best place to ride, but it's close by. It handled well and felt stable at slow speeds (area is too rough to go fast), and got me safely up some steep, hairy, rocky, off-camber inclines. It felt a little squirrelly at higher speeds, though, and the front end has a tendency to rise unexpectedly when you goose the throttle, but overall a very fun machine.

Some new and better pictures:
http://i737.photobucket.com/albums/xx11/Cychotic/Tri-Moto175004.jpg
http://i737.photobucket.com/albums/xx11/Cychotic/Tri-Moto175001.jpg
http://i737.photobucket.com/albums/xx11/Cychotic/Tri-Moto175006.jpg
http://i737.photobucket.com/albums/xx11/Cychotic/Tri-Moto175002.jpg
http://i737.photobucket.com/albums/xx11/Cychotic/Tri-Moto175003.jpg

[200XMichigan]

you make me giggle..... Funny how i have had more problems with my ATC's then my YT's. My ATC's hide in shame everytime i ride by them on the YT's.:lol::lol:

My 200X blew the engine out of spite the day after I brought home my super clean YT175. Not that I am saying any one is better than the other. I like them all.

Nice YT too. Glad all the work paid off. They are a lot of fun.

[the great gazoo]

One heck of a story, & a pretty nice YT too. Is that a PK Racing pipe I spy? I ask because I've got one on my YT & it looks(from what I can see) like mine from the rear shot.

[Vealmonkey]

Almost looks like a bassanit from the way you have to mount it and cut the rear fenders.

[the great gazoo]

Oh right, like the 125's rear were cut for the Bassani, oh yeah. The PK points down. in fact so far down when we were mounting it up, I thought it wasn't going to fit, remember, Pat?

[Vealmonkey]

I remember. It seems pretty strange, but it fits and it works and it hasn't melted anything.

[Motorious]

Thanks for the kind words fellas. Was a real PITA, but it turned out ok in the end.


Is that a PK Racing pipe I spy? I ask because I've got one on my YT & it looks(from what I can see) like mine from the rear shot.


Almost looks like a bassanit from the way you have to mount it and cut the rear fenders.

I wish it were a PK or Bassani, but I'm afraid it's neither one. I don't know what it is actually, it's some mystery pipe that came with the donor motor off the parts trike. It's better than the first pipe I had on the original motor which looked like the head pipe off a DT 175. That thing was LOUD! Maybe I'll take another picture of it today with the fenders off so you all can have a better look at it. Perhaps someone out there can identify it.


It seems pretty strange, but it fits and it works and it hasn't melted anything

It fits quite nicely (as you can see the clamp around the end of the can secures it perfectly into that mysterious mounting hole in the grab bar), but I actually didn't cut the fender.:naughty:

The original fender that came with the parts trike had a pretty big crescent cut out of it to clear the pipe, too big in fact, and I didn't like the looks of it. The fenders that came with the first trike were a bit nicer (better color and thicker, higher quality plastic), but they were uncut because of the different pipe. I contemplated cutting it, but since the fenders just barely rested upon the pipe, I thought I'd just ride it and let the pipe melt the necessary clearance into the fenders. Sounds lazy of me, but it actually turned out well, and melted the perfect shape and amount of clearance into the fender without discoloring the plastic, getting goo on the pipe, or even giving off a noxious smell. It left a hard little ridge of melted plastic around the perimeter of the crescent, which I trimmed off (after that picture was taken BTW, if you look closely you can still see the little lip of melted plastic) with a sharp knife. Looks better than if I had cut it.

Gazoo and Vealmonkey: your Pro-Tech YT's are freakin' awesome, and I thoroughly enjoyed reading that thread on how you modded your trikes. I bet the rear suspension alone makes a huge improvement in the performance. Wish I could do that to mine, but right now I don't have the means to do any mods like that. Still, even bone stock, these under-appreciated 'ol trikes have a lot of kick to 'em!

One more thing: there are a couple of hose nipples on the right rear side of the transmission case. Are these just air vents? Or do they connect to the motor somehow? For the life of me I can't tell where they'd go so currently I just have a couple of hoses on them that I route out the rear of the trike (they're the red hoses hanging out the rear in the picture).

[the great gazoo]

I think the hose nipples are part of the oil injection system, I've got nothing attached to mine, & if your oil tank has been eliminated I wouldn't worry about it.
If you're seriously interested in a Pro Tec rear for your YT, keep scanning EvilBay & CL, one will turn up.

[Motorious]

Well maybe I should worry, because I do have my oil injection hooked up.:wondering

[Vealmonkey]

We can't tell without pics. Get busy with that camera! LOL

[Motorious]

Whoops! Got busy with some ebay bidding today and almost forgot.

Here are da pics:

http://i737.photobucket.com/albums/xx11/Cychotic/YT1.jpg

This one shows the hose connections that I'm not sure where they connect to:

http://i737.photobucket.com/albums/xx11/Cychotic/YT2.jpg

http://i737.photobucket.com/albums/xx11/Cychotic/YT3.jpg

http://i737.photobucket.com/albums/xx11/Cychotic/YT4.jpg

[Vealmonkey]

I think that may be an old DG pipe, but not 100% certain on that. Doesn't look like a bassani or PK though. What about the carb pics? Or the pics of the 2 barbs in question. And I think your rear pipe mount is meant to be attached at one of your grab bar bolts.

[squirrel1182]

i feel your pain but those tri motos are garbage along with the klt get a honda atc and dont look back just my 2 cent

Klt's aren't garbage Ive had a lot less problems with mine other than my screw ups than my buddies 200s. and mine looks like it should be a parts bike. If i wasn't such a cheap ass it would run right. (not trying to bash at you just saying there not junk) (all trikes are good!)

[Motorious]

I think that may be an old DG pipe, but not 100% certain on that. Doesn't look like a bassani or PK though. What about the carb pics? Or the pics of the 2 barbs in question. And I think your rear pipe mount is meant to be attached at one of your grab bar bolts.

Carb Pics? Should I have posted carb pics? :confused:I'm pretty sure I've got the oil injection hoses hooked up correctly, it's just those hose barbs off the rear right side of the transmission case (visible in pic #2 from the top, where the red hoses are connected to) that's got me wondering. I could be wrong, but to me they look like they've got nothing to do with the oil injection system, and they just look too big in diameter to support any hoses that might attach to the carb. There are a couple of tiny black plastic hose barbs on opposite sides of the carb that have nothing attached to them (and I've been unsuccessful so far in my attempts at studying the parts fiche to see what they're for), but I'm guessing that they're also air vents (reminds me of the Mikuni carbs that were on an '83 Yamaha Vmax 540 snowmobile I once owned; it had a similar set of barbs that connected to one another via 2 separate hoses that joined in the middle with a dual-pronged barb between them-essentially dual air vents with a single intake).

I'm gonna have another look-see at the parts fiche and see if I've got the oil injection hooked up correctly, and what, if anything, hooks into the mystery hose barbs on the carb and the tranny case.

I'll look into the pipe clamp, but IIRC it didn't want to fit into either of the grab bar rear mounting
holes.

Do you still want me to post carb pics?

Thanks for the suggestions.

[swifty]

ive had over 20 of these things over thr years id say every one had the same old needs the carb cleaned or adjusted story, that is alonge with a new piston rings and bore, the real problem ive found with these is the crank case seals leak and make it impossible to get it running rite and causes the bog syndrome sometimes, the wont start, idels high or low becouse it sucks air threw the seal and makes vacume leak, just a real pain in the ass and most time burns up the piston while people are trying to tune or ride um after they spend a hour and fianaly get it to start with eather or drag it behind a truck to start it then keep the rpms high to keep it running ... thats my 2 cents hope it helps ive been there way too many times on a tri moto

[Motorious]

ive had over 20 of these things over thr years id say every one had the same old needs the carb cleaned or adjusted story, that is alonge with a new piston rings and bore, the real problem ive found with these is the crank case seals leak and make it impossible to get it running rite and causes the bog syndrome sometimes, the wont start, idels high or low becouse it sucks air threw the seal and makes vacume leak, just a real pain in the ass and most time burns up the piston while people are trying to tune or ride um after they spend a hour and fianaly get it to start with eather or drag it behind a truck to start it then keep the rpms high to keep it running ... thats my 2 cents hope it helps ive been there way too many times on a tri moto

Um, nope, sorry swifty...it doesn't help. Quite honestly, your ungrammatical, barely readable post doesn't add anything useful to the conversation. All 2 strokes are prone to bad crank seals, especially if they've been abused and neglected (the rubber tends to dry out and crack when a motor sits dormant for a long period of time). As far as I know, the YT 175 motor (which is essentially the same motor that's found in the venerable DT 175 enduro) is not more prone to crankcase seal failure than any other. Ya gotta remember these are old machines, and most of them have not been treated very kindly during their lifetimes, and often time have sat dormant for many years before being sold. It's fairly easy to recognize the symptoms of a bad crankcase seal once you know what to look for, and very often is an easy thing to fix (hopefully before you fry the piston)- especially if you've got a motor that doesn't require the cases to be split in order to replace the seal.

You also state that "every one had the same old needs the carb cleaned or adjusted story, that is alonge with a new piston rings and bore". To me that doesn't mean there isn't anything intrinsically wrong with the make or the model, just that you happen to have a rare knack for acquiring really abused trikes.

Anybody with even a little mechanical sense knows that if you have to pull a trike (or a motorcycle) behind a car in order to start it that something is seriously wrong with the machine.


If you've had such terrible experiences with YT's and they all are such crappy machines, why did you own 20 of 'em over the years? What, were they all gifts?

Look, I don't like bustin' anyone's chops, and I don't want to make myself look like a pompous ass, but for some reason (maybe it's the title) this thread has attracted a couple members who are using it as an outlet just to mindlessly bash a particular trike (Tri-Moto's and KLT's to be specific) that-for whatever reason-they happen to hate. It kinda reminds me of those numbskulls who think all Fords suck, and all Chevy's rule, or that all Chevy's suck, and all Fords rule.

Whatever.

I happen to like all trikes, some more than others, but I think that for the most part, all the major 3 wheeler makers have produced decent machines, and in spite of the many obstacles I had in fixing this particular unit, the Tri-Moto 175 is a great little trike and doesn't deserve to be unfairly slammed.

[Vealmonkey]

Okay, the 2 barbs on either side of the carb are air vents. One gets a hose and goes towards bottom or trike. The other gets a hose and it goes up along the backbone of the trike frame. I believe the other 2 barbs you are referring to go to the little black box on the back of the engine. There should be a vent that runs from your casing, then to that box. And I can't remember for sure if the one barb that runs off the carb runs into there or not. There is mention of it in the shop manual if you read enough, but I don't think there's a picture. Also you need to make sure that little black box is cleaned out since all kinds of crap accumulates in there. Oil vapor, dirt, sand, it gets really messy in there. And that is what it is for, but it won't vent right full of gunk. Hopefully that helps.

[Motorious]

Thanks Vealmonkey, that helps A LOT. There is a brief description and a little picture of it in my manual (see section 14, Pic 14.3, and fig. 1.23 below):http://i737.photobucket.com/albums/xx11/Cychotic/OverflowChamber.jpg

Still a little unclear to me (would've been nice if they showed where the other ends of the overflow chamber hoses connect to), but I'm guessing that the smaller diameter hose on the right in pic 14.3 connects to the overflow barb on the bottom of the float bowl, and the function of the overflow chamber is just that, it serves as a catch basin for the excess fuel from the float bowl. Why else would it say: "If gasoline begins to build up in the large tube, remove the three screws and separate the chamber from the engine to drain it"?

It appears that there is a water release valve in the airbox (see fig. 1.23) which I'm guessing does not connect to the overflow chamber in anyway, although for some confusing reason the manual refers to both parts in tandem ("Water release valve/overflow chamber"). If the water release valve connected to the overflow chamber, why doesn't it show a hose coming from it in fig. 1.23? There is no hose present in the parts fiche diagram either. Why would you want water going there anyway?

I'm sure someone will correct me if I'm wrong on this.

[Vealmonkey]

If I remember right, the water release valve is basically a piece of rubber hose that is formed and pinched in such a way to not let water in, but can be "pinched" to let water out. And that mysterious hole on the back of the grab bar is for a visibility flag like people use at the desert.

[Motorious]

Well the parts fiche at Bike Bandit.com shows the valve as consisting of three parts: an oil seal, a plate, and a compression spring (parts # 20, 21, and 22 respectively):
http://i737.photobucket.com/albums/xx11/Cychotic/YA4943_07.gif

Although there is no hose shown attached to the valve, it makes sense that there should be one for as you can see there is a hole in the center of the seal, and that you'd simply push up on the hose to drain the water from the airbox.

Guess these things were designed for some serious mud-bogging, which becomes obvious when you see the commercials for 'em back in the day:http://www.youtube.com/watch?v=7K9zsiJMK68

[Vealmonkey]

I don't know if they were designed for serious mud bogging or not, but yamaha figured people would be going through mud and water and they needed a way to drain the water from the bottom of the airbox. And if you would see what the inside of some peoples' airboxes look like? They will clean their filter, but they won't clean the inside of their airbox. I don't know?