jontow

Well, slightly new turn of events tonight: my known dodgy exhaust decided to share a look at its dirty underwear when I was kicking it over after making more carb adjustments. Good bit of backfire and *poof* the seam split. Damage done, I decided to see if I could pull it apart the rest of the way and clean it out, not being sure if I'd be able to reassemble or not. It's mostly an unwelded pinch seam around the outside edge, with just a few welds, so I cut them and found a lot of pieces rattling, some oil/mud plugged packing, and a lot of carbon. Not sure if I have the cash on hand to get new packing on the way, but it looks like I will at least have a good shot at reassembly. There's been a lot of dirty oil dripping out of a leak in the bottom of it since I got it, and it's been running rich when it's been running at all, so I'm not surprised it finally lit up a bit.

Thanks for the pictures and info, folks! Extremely helpful. jse: is that a piece of radiator or fuel filler neck hose used as a spacer/intake tube for the carb? Here's another one, trying to identify what's original vs. what isn't on this bike: I have what is obviously a 44H frame and engine bottom end, but it looks like the cylinder/top end/much of the ignition/electronics are from a 38V, and the carb is cast-labelled as a 44J. Do the stamps I'm finding mean what I believe, or did they make a habit of using whatever model code parts they had / could get? Also, for what it's worth, it looks like I have (much of ) the 82nd 1984 TY250 from Canada, per the serial number and identification info I can find: neat, or at least I think so.

Oh, another note, because my exhaust has seen better days. I've noticed a few TY250/350 pictures around with an aftermarket silencer of some sort, just a small round polished aluminum/stainless can type. Does anyone have any info on this, or shall I just measure and start digging? Since it seems to be a separate expansion chamber / silencer, the silencer shouldn't have a great effect on how well the engine runs, correct? Mostly just an effect on the noise output.

Well, call me concerned, but is there any way I can convince you to take a (good?) picture of the fit of the carb, with the frame notch shown? Thank you: great info, and I can see I'm not the only one interested.

I, too, am interested in this info: is it a VM28-418 by chance? is the choke lever on the wrong side as it appears? Did you have to do anything regarding the rubber boots, or is it a direct fit?

Thanks everyone, this is a great start. Glad to hear the TY350 is similar, gives me another search term to work with No old yamaha shops nearby, just a honda dealer that I may talk to. He's done a lot of work on random machines over the years, and as you say, who knows. The carb seems to be in good shape, and I'm familiar with working on TK carbs (aforementioned yamaha TW200 uses them); as long as nothing mechanical goes wrong, they seem to work well enough. I think if I can correct the o-ring fuel leak, and get the exhaust sorted, the bike will run more consistently.

I recently acquired (and tonight, got running!) an 84 TY250 mono from Canada, but I'm in the states. It was brought over for use at someone's camp, and has clearly seen better days. But: it seems to have good compression, is mechanically in decent shape, and looks like crap. I've got some exhaust leaks to sort out, and it seems the muffler is full of muddy old oil. Is there a way to clean it out? Take it off, flush with gas and let air dry for a few days maybe? I'm not sure, and not willing to try that yet. I didn't see any convenient cleanout plates. Maybe an aftermarket replacement for the whole assembly? Mine's dented, and brazed, and epoxied, and in generally quite bad shape. The ignition coil (and spare I got with it) both seem toasted: secondary winding reads open on both, but a spare off an early 90s TW200 got it going for testing purposes at least. The resistance readings are pretty close to the TY manual I found online. The odd thing, it was flooding like crazy when I first got it running, and with a little help, we narrowed it down to the rubber o-ring in the main jet holder leaking. With the fuel cock on, the bike would bog and barely stay running, but if you let the bowl fill, then shut the gas off, within a few seconds the bike ran great. The leaky o-ring was letting fuel come up through and get sucked raw into the intake tract. I've got a (smaller) o-ring in it now that helps, but isn't big enough to fully seal. Which leads me to a real point.. Is there a good parts source for this bike within the USA? Or, optionally, for carb parts, is there another US-distributed bike that used the same TK carb? I understand many parts are available on ebay, but I'm not having much luck with rubber bits in the carb that have taken abuse over the years.