jontow Posted September 27, 2013 Author Report Share Posted September 27, 2013 (edited) Quick update before I head to bed: it looks like jets can still be had for this carb in the states, but you have to mess with part numbers a little bit. xxx-14342-xx-00 is the rough template. The reason I have a #48 pilot at least is because thats the only part listed in the USA for a "38V" (which mine is technically not). 38V-14342-24-00: #48 pilot. For instance, a 14342-19-00 is a #38 pilot.. and it looks like you can get it in the states if you order it for a different model, say, 43F-14342-19-00: http://www.partzilla...4342-19-00.html On partzilla, it even lists it as valid for the TY350. Will write up more as I figure it out. With that in mind: does anyone have the *actual spec sheet* for a 1984 canadian TY250 mono that lists jet sizes as installed? The manual I have is for a TY350, and I wouldn't doubt that its slightly different, being a bigger motor. Edited September 27, 2013 by jontow Quote Link to comment Share on other sites More sharing options...
guy53 Posted September 27, 2013 Report Share Posted September 27, 2013 I just sent you a pm Guy Quote Link to comment Share on other sites More sharing options...
jontow Posted September 27, 2013 Author Report Share Posted September 27, 2013 (edited) Well, per some advice retrieved (and translated poorly from french) from guy53's sources, I popped open the crank case drain (didn't even realize this bike had one!) and drained quite a lot of nasty old fuel out, reinstalled my busted up silencer, then cleaned the plug and the bike fired right up. It ran for a good 15mins before I shut it off (yes, *I manually shut it off!*). Waited ~15mins and then fired it up again, got another 5-10mins out of it before it quit in the side yard, flooded. Pulled the plug and have a fairly dry but very soot covered plug. Wife and kids went off adventuring somewhere, so I'm thinking about trying a much smaller pilot jet that I happen to have around (from my TW200). It's a #40 Teikei jet. ... I've also got a #120 main jet that should fit as well, from the same TW200 Teikei carb. I'm wondering if thats *too lean*. I know the french bikes got a ~#112-116 from the factory, but (?) I guess I don't (yet?) spend too much time from 1/2 open to WOT, but I really don't want to buy a new piston yet, so I'm on the fence about that one. Edited September 27, 2013 by jontow Quote Link to comment Share on other sites More sharing options...
jontow Posted September 27, 2013 Author Report Share Posted September 27, 2013 On a whim, I pulled both jets and swapped the TW 40/120 in, and fired it up.. pulls like a freight train now. I'm gonna let it cool a bit and pull the plug to see how it looks. Might be getting closer though. Quote Link to comment Share on other sites More sharing options...
jontow Posted September 28, 2013 Author Report Share Posted September 28, 2013 (edited) Had a few moments today, and tonight, and wrote up some bits that may help someone (work in progress): http://old2strokes.c...aha-ty250-mono/ http://old2strokes.com/yamaha-ty250-mono/84-tuning-notes.php Edited October 9, 2013 by jontow Quote Link to comment Share on other sites More sharing options...
jontow Posted October 9, 2013 Author Report Share Posted October 9, 2013 I haven't updated this thread in a while, since my progress is very much day-by-day tweaking and tuning and trying small variations of similar things. Figured I'd update the thread, though: At this point, I have a bike that runs most of the time, but is extremely hard to start, especially when warm. I'm running a #40 pilot and #120 main, needle in 3rd (center) position. I've tried BP6EV, B7ES, and B8ES plugs gapped from 0.030" to 0.018", and quite a few settings of the air and idle screws. With current jetting, when the bike runs, it runs VERY well for 30-40mins, which has allowed me quite a lot of good practice time out back. However, due to the hard starting issue, I have an inhumanely strong right leg, and have lost a few US pounds pushing the bike around and kicking it until I'm drenched in sweat. After 30-40mins of runtime (varies slightly with temperature, and how the bike is ridden), the bike heats up to the point of pinging (I believe thats the noise I hear), and I have to shut it off and let it cool. When this happens, I can pull the plug, and its dry fouled every time, which contributes to the hard starting issue. The bike ACTS like its running lean, but is dry fouling the plug. I'm running the same QuickSilver 2T oil at 58:1 with 91 octane non-ethanol gas. I'm almost out of this can of gas, so on the next mix, I'm tempted to try bumping my ratio up into the 60s:1. Does this seem legitimate? I'm not sure what safe ratios are for this engine with this oil. I can't find anyone anywhere that has a bike that acts lean and gets hot enough to ping on 91 octane and is actually dry fouling plugs. Revving the engine doesn't seem to clean it up or stop the pinging. My CDI is currently on an extended wiring whip and in a bag on the front of the forks, as I was troubleshooting whether or not heat had a factor in my weak/inconsistent spark issues. It seems like maybe the spark is still a little weak, but again, once the bike is running, its a monster, and certainly not lame as a sheep, as the 350 has been noted to be. I've also never rode another trials bike: maybe this one is, and I just don't know any better. Seems pretty darn ok, to me, though. Good hard hit, great throttle response, plenty of extra power, nice amount of torque down low. I do dislike the iron-man stiff clutch, though ... Pretty good amount of update for one night, and kinda sums up where I'm at. I'm thinking from here, I should go to a #42 pilot, and 65:1 premix. I don't feel like I'm getting into main jet territory much. My riding is all at/slightly above idle with a few good hits before a climb. Any thoughts, suggestions, contradictions, or otherwise? Quote Link to comment Share on other sites More sharing options...
guy53 Posted October 9, 2013 Report Share Posted October 9, 2013 Stiff clutch ? On a TY Mono ?????? Not on my 250 and not on the 350 I had for a little while. I think you need to understand jetting before you continue tweeking , or be more specific on the way you ride. Just '' cracking '' the throttle to hop on a rock or half throttle all the time..... Guy Quote Link to comment Share on other sites More sharing options...
htrdoug Posted October 10, 2013 Report Share Posted October 10, 2013 Good cable,O.E.clutch lever(not shorty),had a extender on my 350,clutch pull was pretty decent.My 350 didn't like to be ridden like a trail bike,If you rode it from section to section,walked the section,then rode it,cruise to the next section and repeat it was happy and ran well.The brief cool down periods kept it from getting to the point of pinging. Next test session try imitating a trials event to see if it runs more consistent. Don't know if the 250's have the same issue. The 350's did have a reputation for pinging. Quote Link to comment Share on other sites More sharing options...
jontow Posted October 10, 2013 Author Report Share Posted October 10, 2013 guy53: Definitely stiff clutch pull. I unhooked the return spring down at the arm to test and it has no effect on the stiffness. I think I'm going to crack open the side case and see what the spring arrangement looks like. Also going to get the cable cleaner/lube after it and see if theres any effect. I do understand jetting on a 4T, but the oil in 2T fuel may be throwing me off, here. I don't necessarily understand the process of elimination as well. Any recommendations on 2T oil to try, and at what ratio? Again: I'm almost out of what I have and therefor will be looking for something different (better). I'm also riding with the throttle just cracked almost all of the time, meaning I should be well within the territory of operating on pilot jet / needle clip position only. htrdoug: Running a long clutch lever (no idea if its OE the bike has been messed with), no extender/torque multiplier gadgetry inline. My TW200's clutch feels like it isn't even there compared to this bike, and my 85 honda XL600R is the same way. I've tried multiple riding patterns, imitating an event a few times. It does work better, in the sense that it won't heat up to the point of pinging as quickly, but being such a bear to start makes it a tiring effort Quote Link to comment Share on other sites More sharing options...
jontow Posted October 10, 2013 Author Report Share Posted October 10, 2013 (edited) Hey, hey.. not the best of news: but I think I found a few things of note, that I need to solve before "tuning". Mechanical problems can't be fixed by tuning, but they can sometimes be masked. After I got home from work, I fancied a go on the bike, and fired it up (first kick, mind you), then let it idle down to an appropriate level, and promptly sprayed down a number of key areas with a magic mix of mild dish soap and water. I found a few small leaks at the rear of the expansion chamber that I suspected were there, and that was about it. So I rode it around, roughly a short jaunt from "section to section", plus a few minutes of figure 8s and such, then brought it back to the garage, put it on the stand and shut it off. As I was standing there smelling the burning soap and looking it over, I noticed some small bubbles forming (which is what I had hoped, that an air leak might appear after warm-up), right at the rubber grommet that the wiring whip passes through headed into the stator ! Now, I am sure to understand, thats not an area that should have any pressure in it.. So I grabbed a screwdriver and loosened one screw, and heard the tune of a slight 'hisssss' and the bubbles stopped. I finished removing the stator cover, and had a few drips of fuel mix in the bottom, confirmed by smell. Here's the questions, then, which seal is toast for this to be the case, and does it require case-splitting or jug removal to replace? It could certainly be my weird lean behavior, masked by jetting and crappy mix ratio as 'rich' on the plug. Air leaks are death to 2T engines, as I well know from my old Kawasaki enduros. I suppose there's a good chance if this side of the (presumably crank?) seal is dead, the other side could well be too. Bonus pic, hard to see the bubble, but look at the lower right corner of the grommet: Edited October 10, 2013 by jontow Quote Link to comment Share on other sites More sharing options...
guy53 Posted October 10, 2013 Report Share Posted October 10, 2013 Your right on with the low speed jet and the needle. If the crankshaft seal is the problem, if my memory serve me right, you don't have to split the crankcase to change it. Hopefully you put your finger on the problem. Guy Quote Link to comment Share on other sites More sharing options...
jontow Posted October 10, 2013 Author Report Share Posted October 10, 2013 Well, on my old2strokes.com page, I made a table of a number of the oil seals with part #s, example pricing from partzilla, etc. I'll dig up some cash and see if I can find a place to make an order. The biggest problem is, I have a really solid feeling the insides of the head are carboned up fiercely, given what I saw in the exhaust tract. Sourcing a head/cylinder gasket is a bit harder, and I suspect the TY350 gaskets will NOT match up for this. Quote Link to comment Share on other sites More sharing options...
jontow Posted October 10, 2013 Author Report Share Posted October 10, 2013 (edited) Will this flywheel puller work, by the way?: https://www.denniski...2.prd/28282.sku Claims 27mm x 1.0 LH threads. Seems right, but want to verify: I can't find a listing anywhere for threading specs. EDIT: from a bit more digging, it looks like it will, and is ordered, along with some seals. Slow boat from Japan should put it all here around xmas 2014! (or .. a bit nearer to end of the month) Edited October 11, 2013 by jontow Quote Link to comment Share on other sites More sharing options...
guy53 Posted October 11, 2013 Report Share Posted October 11, 2013 Head gasket on my 250 is copper, so no problem reusing it. Guy Quote Link to comment Share on other sites More sharing options...
jse Posted October 13, 2013 Report Share Posted October 13, 2013 Head gasket on my 250 is copper, so no problem reusing it. Guy Head gasket on 350 is also copper. Should be annealed before re-use, heat to cherry red and let cool on it's own. It will then conform to irregularities upon installation. Jon Quote Link to comment Share on other sites More sharing options...
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