Quite the engineer that machine had..
Top pic: some goof drilled holes, then for some reason added that "T" affair for the vent (I'm guessing). I'd take that stuff off and run that clear line from the carb vent (front port) to up under the hood like Suzuki had it. I'd also duct tape the holes over.
2nd pic: oil injection block off plate. Def run pre-mix.

 

Yes...that's an injector block-off plate...

 

Any thoughts on why it's running the way it is? It appears to be getting too much air, or not enough fuel. How do you know if reeds are bad? I spoke with the previous owner, and he said that is what it was doing to him before he parked it. Would only run high speed, no idle. He wasn't sure about if it would stay running with the choke pulled out. And do you mean to tape up all the holes , or just the one with the T?

 

I see where the carb came dis-assembled. You cleaned it all up including removing the jets and making sure all the holes are open?
You must remove the reed block to check the reeds.
I didn't see where you did a compression test. I'd do that!
I'd tape all those holes up. The stock airbox works well.

 

Yes, i pulled it apart and cleaned. It was a mess. perhaps something still in it. I had the reeds out. They looked ok, moved freely . What would bad reeds look like? Or would it be obvious? I did not do a compression test. I will try to do it this weekend. What is good compression? Thank you for your help thus far.

 

The reeds will be bad if you see any crack in them (where they bend)...


Good compression is north of 120psi, but It'll run north of 90psi


If you have a gravity fed petcock and premix the only line going into the carb should be for fuel...all other should be blocked off (I know I owe a pic...just keep forgetting)

 

I tested the compression. Only 70-75. I pulled the top end apart. cylinder is worn some, has a ridge. Do you know the end gap for the rings? And how about the stock specs? The last owner says he was told it was bored. I don't see any markings on the piston other than an arrow, which was pointing towards the rear.

 

Well that explains that.
Sounds like stock bore. Now you get to bore it .05 over.

 

Have to replace the piston also, or just use oversize rings? Do you know the specs off hand?

 

New piston, new rings, new piston pin, new pin bearing, new cir-clips. I use Suzuki parts.
Then you take the cylinder to shop that bores cylinders and have them fit the new piston to the cylinder. They should measure the cylinder first to make sure of the current bore size before parts are ordered. I get $135 plus shipping.
Or you can get a cheapo kit off of ebay for 50 bucks.