Edit: I just wanted to say that I checked the plug and it looks pretty perfect to me! At first but it may actually be a little lean? I’m really not sure. I will upload a picture later tonight!

But if you need a new float for your Mikuni 248A2 carburettor I recommend one made for a 1972 - 1977 Suzuki GT550 or the GT300 I think it’s the same float. 

Hello everyone, I have a 1971 AT1-C I recently replaced the original float (because it had holes I couldn’t fix) with an identical float from a 1972-1977 Suzuki GT550 I set the float height to 25mm and the bike runs great I can ride 50mph all day long, but when cold starting the bike smokes a lot and doesn’t want to idle, I have to ride it for about 2 minutes around my neighbourhood and then the smoking all of a sudden stops the running condition fixes it self and it can idle on its own.

I had the height at 27mm when I bought the float and the bike didn’t have this issue. the float valve is also not stuck on the float it moves freely.

 I was thinking about setting it to this again, it ran a little lean but I didn’t have the correct sized o-ring on the jet settler.

I also Fouled a spark plug but I’m not sure if it couldn’t be because I had another carburettor on and before with my original float my height may have gotten really low (and it did because fuel got inside and the bike burned a lot of fuel but still ran well).

I still need to check the plug if it’s oily or not because I can’t tell if it’s rich or not, I think it sounds good.I rode 19 miles yesterday and didn’t have any problems. when I fouled the plug the first time I also rode 19 miles and then it fouled.  

but that smoking thing really confuses me, that’s my question for today, the rest is just for some context, is my float height too low? I know the specification is 25.75mm with a tolerance of 2.5mm. Now it’s on 25mm or maybe 24.9mm 

 

A fouling plug tells me it’s oil. So are you using the injection system? Perhaps just enuff oil seeping past the pump and accumulating in the crank case, and that’s what’s causing it to smoke?
Just a thought..

Float arms parallel to gasket surface. 

I think Sneezles nailed it on the smoking...  likely pump check valve isn't sealing and lets oil seep into crankcase when parked.

I've not read the complete story so maybe I shouldn't comment except to say if the plug looks good & the bike is running faultless then the exhaust is soaked inside & will continue to smoke for a long time unless you give it a burn out or go for a 50 mile ride at speed--revs.

Yes the oil pump is what I’m using. I checked the plug and it’s not oily at all. And when I ride the bike it doesn’t smoke at all, or should I say not much at all. It’s very little. But I just want to say that the bike is running perfect now apart from when cold starting. I installed the baffle properly and it has a nice sound and it helped it correct it’s running condition because it wasn’t installed properly before so I think it was drawing air in causing it to lean out a little more.

That’s true. I need to burn out all the oil in the exhaust actually, I had the bike for two years now and I rode it over 500 miles now, maybe that will help it out. 

You know what. That sounds like a good idea actually, when I finish my last exam I’m going to go out for a ride like that. Or at least try. I already have a great route in mind. Speeds of 50mph and more (maybe) will be done.