Mikuni carb and getting bike to run.

[Hasteranger]

175 tri moto with mikuni carb.
I cleaned the carb when I got it and it would run for a few seconds then shut off. We had to pour gas in the spark plug to get it to start at first.
Then I got it running and rode it for a few mins.
It started right up later that day and with the choke manually pulled, it started back up the next day and rode fine.

Fuel lines were rotted so I changed all them and had to carb off as I installed a new choke cable. Now the bike sputters and dies after pull stating. It randomly ran and revved for a minute then died then wouldn't start again. I tried putting some gas in the cyl and that didn't help. The mikuni has a single adjustment valve under where the fuel line comes in. It's easier to pull start with it turned a few turns out but other than that it doesn't seem to make a difference where it is. Just getting frustrated and got a blister trying to pull start it today.

[YTZ drew]

Have you checked to make sure the new choke cable is adjusted properly so that it closes fully when released? Also, there should be 2 adjustment screws, one that lines directly up with the throttle slide that's used to control idle speed, and one closer to the connection to the air filter that's used to control idle mixture. If those don't have any effect, it sounds like there's dirt in the carb. Take it apart, remove all the jets, blow them out and all the passages too, and reassemble. Turn that mixture screw in until it very lightly seats, then back it out 1 to 1.5 turns. While the carb is out, take the plug out too and pull it over a few times to clear any fuel in case it got flooded. Make sure the intake boot to the engine seals well against the carb and is not cracked, 2-strokes don't like air leaks. Let us know how you make out!

[Hasteranger]

There are no air leaks on the boot and I did not see a second adjustment screw when I had the carb out. I blew out all the jets and they were clean when I reinstalled the carb. It's a pain to pull the carb so I'm hoping I don't have to pull it again after I just put everything back. It looks like the vent that goes from crankcase to right under the carb was left off because I broke the barb where the hose goes up from the right side of the crank case. I need to super glue that on or something. The part is obsolete so I'll have to work with what I have. I could plug it but I'm not sure what the purpose of that vent is.

[Hasteranger]

Also I have no idea how to properly adjust the choke, as once you screw it in you can't see if it's engaging or not. I did unscrew it but it didn't seem to make any difference.

[YTZ drew]

To adjust the choke, there should be a locknut and an adjuster just like on the throttle, turn the adjuster in until the cable begins to have some slack to it (you will be able to wiggle it inward and outward a little bit at the carb end). The free play ensures that the choke stays shut when its not needed. If you don't want to pull the carb, at least try clearing out the engine with the plug removed, I had a 200 Blaster engine with a stuck float load up really bad on me once, would NOT start until I pulled the plug out and kicked it over about a hundred times.

[Hasteranger]

Ok I will adjust the choke till it's loose and try clearing it out without the plug in. Didn't have any time to mess with it today despite the beautiful 70 degree weather. I'm sure I'll have time Wednesday when we have a foot of snow in the forecast. Lol

[Hasteranger]

So I walked out just now, it's 40 degrees, flipped the choke and pulled the starter and it came to life on the second pull idled and died. Third pull it started again and I gave it some revs. Revved a little bit and then died then would not start again regardless of choke on or off. Did see some arcing coming from a connector by the bars but it appears to be the headlight circuit. I unplugged them and plugged them back in and it looks like it was just a bullet connector that wasn't in tight. Anyway I dunno why it would start when it's stone cold like that and not at least try to idle after it ran for a few seconds. I didn't have time to do anything to it since my last post. I was out to let the dogs out and figured I'd see if it would run since I was out there.

[YTZ drew]

Intermittant problems like that are more likely electrical than fuel related. Coils, cdi's, and stators sometimes fail when warm, and I've seen bad spark plugs and caps do some infuriating things. I'd try a new plug and plug cap and go from there.

[Hasteranger]

Well it was drawing fuel through the original rubber fuel line before when I rode it but that fuel line had a pin hole and was leaking. It was stretched tight to bypass the oem mikuni fuel pulse pump. Like I said, it ran fine on a few occasions over several days. New fuel line and I initially bypassed the fuel pump as I wanted to duplicate the earlier results before hooking it back up and making sure it still ran. So today I noticed the fuel line was not being filled with fuel for some reason so I did plumb the pulse pump back in. It still wasn't getting fuel but when I turned the petcock to reserve the lines filled with fuel between the tank and pump and between the pump and carb.
I poured a little gas in the cyl and it started up and ran until the fuel line went dry. I don't know why it would have done this. There isn't a ton of gas in the tank as I'm almost out but even on reserve it should be enough to let it idle.
I'm starting to get frustrated as hell. This is a very simple pieces of equipment and it's kicking my ass.

[Hasteranger]

Ok I appreciate the help so far. So I poured gas in it some yesterday and couldn't get it to run very long. Just a few seconds. I was concerned the new choke cable wasn't adjusted or working right so I disconnected it.

Went out today and added a half gallon of gas, plugged the vacuum port that was unplugged and poured gas in it and it ran for like 10-20 seconds then died.Did it again and it ran and I revved it some. Ran 10 seconds then died.
Did it again and said screw it. Let it idle.It just ran and ran and ran for a minute so I tried giving it revs. It revved. I messed with the air adjustment screw and it moved the idle up and down and made the revs hang.Adjusted it like they said online but it wants to idle high or it bogs when you Rev it.
Kicked it in gear and it bogged hard. Stalled out when I gave it gas.Restarted it. Did the same thing. Revs free in neutral but bogs when you give it gas in gear.
Did that a few times then it died and wouldn't restart on ten pulls. Pulled spark plug and gave it a touch of gas. Fired back up and stayed running. Put it in gear and it would move if you blipped the throttle but would die if you eased into it.

Took it down the street and back and as long as you blip into it, it's good. I tore ass through the development. Front tire went completely flat so it may need some liquid tube, it has some dry cracks. Not worried about that part.

My friend said he wonders if it has the right jetting in it even though it appears to be all stock except the uni filter I put in.But if you ease into it it dies down low. Blip it past the low and it goes fine.
What do you guys think? I really need some assistance from people with more experience that me.

The good news is it runs pretty much the same as it did without the fuel pump hooked up, so I'd say we can rule out the fuel pump as a problem. I'm considering ordering a manual choke lever so I won't have to worry about adjusting the cable. I'd rather have to pull the seat every time and have it start than pull it till my arm hurts and have to pull the plastic to add gas to the spark plug to get it to start anyway.

Thank you very much.

[YTZ drew]

You are welcome! In reference to your friend questioning the jetting, your description of the throttle response makes it sound like its running lean. With the uni-filter you may need to go one size bigger on the pilot jet. I think your carb has a push-in style jet, which may be tricky to find oversize. The dealer will be your best bet there. I have drilled jets in the past, but only when I knew for sure that it was what the engine needed, or I had a spare jet to experiment with. Its really hard to drill them smaller after you go too big...