YT175 frankinstien, idling problems

[bobotech]

Where should I start to look for idling problems in gear? I have a 85 YT175 (was a 125 but cobbled together with other parts from YT175 and even some 175 dirtbike piston). Also has some unknown (bassini?) aftermarket pipe.

The carb is some 32mm or so that is quite a bit larger than the one that was on my 125 engine. I rebuilt it and it seems to be clean.

I can start the engine and it will idle but as soon as I put it in gear, it wants to die. if I gently tweak the throttle, i can keep it running. It is running really rich right now, the needle is at the bottom slot, I know I need to move it up. Is using an infrared thermometer to keep an eye on engine temps a good idea when leaning it out?

[RubberSalt]

This is almost always 1 of 2 issues, this case sounds extremely rich or extremely lean. Or in this case, possibly extremely dirty clutches.

If you cant get out of an idle, you to make 2 adjustments. Change the needle position to the middle. The bottom slot on the needle pulls the needle up, making it run richer in the mid range. After you change that, you may need to tweak your pilot jetting. Turning it out makes it leaner.

Idle to 1/4 throttle is your air screw.
1/4-3/4 is your needle
3/4-WOT is your main.

If you bog, you have to much gas, if it hesitates, your lean. <-- not always true.

You can also tweak the clutches on that bike, that way it engages later, like having a stall.

[bobotech]

Hmm, dirty clutches, I haven't changed the oil yet, I need to do that in the case. Good point there. I shall then see how it reacts. Then I will alter the needle position and check again.

How do I adjust the clutches?

[RubberSalt]

On the right side, there's a cover held on with 6 bolts. Same cover is where you fill with oil. Pull that off, you'll need 2 14mm wrenches and a flat head screw driver. Loosen the 2 jam nuts and turn the screw until it drags just the slightest amount. Then tighten the 2 nuts, don't let it turn the screw when you tighten them!

The needle is honestly my best guess in this situation.

[bobotech]

Well I adjusted the needle and put it in the center slot and it does seem to be a little better. I'm going to try another slightly smaller carb and see if that helps. I jsut wonder if I have too much carb on there.

[RubberSalt]

32mm should work, I've ran a 34 no problem.

You may probably just need a richer jet. Changing the needle helps=more gas. But it's not enough gas still, you need a bigger main jet. Is it a mikuni or keihin carb?

If you want, i could trade the stock carb for the 32. I have all the stock parts+jets and what not. I'm using a 28mm blaster carb, but a 32 would be best for me. Custom pipe+portwork+big reeds+other junk.

[bobotech]

Oh neato, so you have a factory YT175 carb that you would be willing to trade for? I would like to get one, just because I"m not the most knowledgeable about these things. I will take a couple pictures of the carb so you can see what it is. Not sure on the make yet.

[RubberSalt]

Ok, yup carb is complete factory. If we do trade, it would probably be best to include the throttle cables. The factory 1 for the carb is a little different than most.

Get pictures of the carb, throttle and cable. Want to make sure it will fit your set up.

[bobotech]

It is a Mikuni. Its pouring out so I haven't gotten pictures yet.

[Nevkilahonda3]

I had the same problem with my 125 tri moto I cleaned everything in the carb and still died when I put in gear unless I gave it the right amount of gas. Later I found out their was dirt and crap in the reed valve holding it open an 1/8 inch cleaned it out and it ran perfect.

[bobotech]

Ok, yup carb is complete factory. If we do trade, it would probably be best to include the throttle cables. The factory 1 for the carb is a little different than most.

Get pictures of the carb, throttle and cable. Want to make sure it will fit your set up.Here are pictures:

http://i904.photobucket.com/albums/ac245/bobo_snyder/yt175%20carb/IMG_5601.jpg

http://i904.photobucket.com/albums/ac245/bobo_snyder/yt175%20carb/IMG_5600.jpg

http://i904.photobucket.com/albums/ac245/bobo_snyder/yt175%20carb/IMG_5599.jpg

http://i904.photobucket.com/albums/ac245/bobo_snyder/yt175%20carb/IMG_5598.jpg

http://i904.photobucket.com/albums/ac245/bobo_snyder/yt175%20carb/IMG_5597.jpg

http://i904.photobucket.com/albums/ac245/bobo_snyder/yt175%20carb/IMG_5596.jpg

[RubberSalt]

I thought so, they have different throttle cables. I've still got the original throttle cable also if your willing to trade.

[bobotech]

Odd thing is that is the factory throttle cable for the 85 YT125 that was on the trike originally. Are the 175 and 125 cables different? And do you have pictures of the factory carb and throttle cables? Remember, the throttle cable also has the oil injection pump cable attached to it as well. And the oil injection unit on my trike does function.

[RubberSalt]

Yup, The 175 carb has an angled end that swivels. It lets you face it to the front of the bike. It does have the oil injection setup still. I put the set up on my 125, cable, and carb. Oil injection works fine on it, but that carb is to much for the stock 125, I'm putting the 125 back to stock lol. I'll include the choke cable/plunger thing to, because it's a pain in the butt to find the exact 1 for that carb.

Everything of mine is at my moms, I'll get pictures later today for you. But here is what they look like. http://cgi.ebay.com/ebaymotors/Yamaha-1982-YT175-NOS-Carburetor-J-M-_W0QQcmdZViewItemQQhashZitem25589f1332QQitemZ16040 0610098QQptZMotorsQ5fATVQ5fPartsQ5fAccessories

[bobotech]

I have a stock 125 carb as well, the one that came with the trike when I first got it, would you rather have that one or the one that is currently attached to my 175 engine in the pictures?