hi everybody! got a Yamaha yt125

[ironslavery]

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Just dropping in a line and sying hi to everyone. My brother got ahold of a Yamaha YT125 for me which I believe is a 1985. It is in need of a rebuild and missing parts so I will be on here seeking as much help as needed. I found a condensed sevice manual and a wiring diagram so far. So far I need a breather box assembly all the way down to the carb (any aftermarket solutions?), Front fender, head light and all the mounting stuff including the plastic, bearings for the front steering, and a cap for the oil tank... I might just premix though. It does not run so I need to see if I can get it to start with some cleaning. the wiring needs to be troubleshot as there are loose wires all over. I also found a clear tube just hanging out by the Carburator and I have no clue what It's for yet. I got it lastnight and had to go to work. Does this thing use a battery? pics soon.

I think I will bring my carburator to work and clean it tonight. I am hoping to atleast get it running without having to open up the engine. Anyone got an E-owners manual for this thing?

[ironslavery]

Bad luck so far. Took the reed valve assy out and itt was full of dirt and grass. Hope it was from sitting. But I looked at the piston from the hole and low and behold... The piston has several scrates and they look pretty bad. The carburetor was already cleaned once and they did a poor job. Several ports were gunked up. All the hard work was done though. Looks like it has been sitting for a while be because the inside was rusting. There is still oil in the crank case and I am trying to figure out what all the hoses are on the bike. I found 4 loose hoses so far and I know one of them should probably go to that tank in the back left but I don't know what it is for? Is it a reserve tank? Really wish I had an owners manual. There is a large clear hose running from the back right wheel area to the gas tank area on the left side... Not hooked up. I also found a short hose under the carb when I took it off. No clue what all needs to hook up so I will just premix my gas and see what I need to do to try to get this thing running.

[nyshawn]

hey i got the same trike as you and i had to rebuild the the topend it cost me $60 for the 2nd over size pistion wristpin rings and the 2 snap rings and $20 for all the topend gaksets including the muffler gasket ebay is the bestplace to get parts i think i called all the yamaha dealerships and they wonted double the cost to what i found on ebay and all the parts i bought were genuin yamaha, i got a really good deal for the pistion set iv seen them go upto $180 but you just gotta keep looking. and the as for the tube you were talking about what side was it on? there are 2 breathers that have black vent things on them and the one that goes out the bottom of the carb is the over flow and the one on the opposite side of the fuel intake closest to the engine is where the oil is pumped into the carb if your going to pre mix you need to plug that hole i just took the odl oil line cut it melted the end and squished it so no air or water could get in, and if you dont want to cut the oil pump out i just put premix in the oil pump intake line and looped the oil injection line into the intake one so it just pushes oil back threw the pump i dont want to ruin the pump because if i sell it i want it to be as original as it can be. as for the air box i found that it doesnt realy run good without it on i couldnt even get mine started. i hope you get your tri moto running they're a ton of fun and pretty fast, iv taken mine threw a pond and floated it haha but if your going in deep water make sure you have all your vents vented up to the gas tank. oh last thing dont spend more than $75 on getting your cylinder bored out i only spent $65 and picked it up same day but some motor cycle shops wanted $100+ and they wouldnt have it done for 5 days and i had some machine shops as cheap as $40 a cyclinder but i told them my bore was 50mm(might have been 56) and they said they couldnt bore out that small. good luck bro building your trike, its only half the fun of owning one!

[ironslavery]

thanks for the reply. My brother knows someone who can bore out the block for about 60$. Ive started looking around for some pistons but so far all iv'e gotten is confused. Anyone know how big I can bore this out without being dangerous? I was hoping to get to 66mm. Anyone got a good 175 top end with the piston and rings in good shape?

[ironslavery]

looking at the condensed service manual I can see one of the mystery tubes I am talking about pg 373 figure yt-1 the very back has a fat clear tube. It runs across the frame to the other side of the engine and goes up to the gas tank but dosent connect to anything. I assume the smaller one in front of it goes to the carburator.

[thestud25]

Welcome to the addiction. Pics are crucial in identifying a problem. Otherwise, we are all just guessing from your description.

[ironslavery]

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here is the photo from the manual. the large one in the back is the one I am curious about. It runs to the otherside of the trike and is long enough to reach the gas tank but isnt plugged into anything... I did not notice the small one before I saw this photo so I need to look at it when I get home. I havent had much time to play with this thing yet so I might just figure it out on my own. I am waiting for my taxes to buy parts so in the mean time I am cleaning it and making a parts list.

[ironslavery]

got to play with this thing for a while. Fuel tank was clogged so I cleaned it out and cleaned the petcock. I put the top end back on and put the carb on. still lost on the hoses except the oil feed line to the carb from the oil pump. anyway, I tried to start it and it was a no go. The spark is a nice blue but it takes a good hard pull for it to be bright. the exhaust pushes out a nice pump of air with the pipe off. Fuel is getting into the chamber, got spark, but no boom. how far is the slide supposed to go into the carb? my throttle has no play and the slide sits about 1/4 of an inch above the bottom of the chamber. I notice there are notches so the slide could go all they way down. I covered the carb with a loose bag and it sucked it in but didn't blow it back out so the reed valves seem to work. I am thinking coil or CDI. Ether and new plug first though.

Anyone know if I could use a coil off of another device like a mower or a different ATV?

is it possible to volt/amp out the coil with a multimeter or is ohms the only test?

Edit: metered coil at 415 ohms. Manual sez 300. Bad enough to fail?

Got fuel, air, compression, and spark... Why no workie?

[TeamGreenOmaha1]

James call me about the cdi we can get one from nebraska cycle. Call me for the numbr forthe big bore. Max piston size will most likely be. 080 over . And safe is just a word. Its all aboit the rider!