1995 Vulcan 1500 only runs to 30mph...
 

...

Rebuild and synch the carbs.

Edit (now that I'm on a computer instead of a phone):
I went through this with my wife's ZZR that had been sitting for a long time. We chased our tail on it forever, but the ultimate fix was getting the bike into the hands of someone who was a LOT better at carbs than I am. I'm not certain if he did a full rebuild or what because he didn't speak English and my Japanese is pretty limited, but after I got it back from him it ran absolutely AMAZING.

If he got the bike for free, it's definitely worth the price of a good carb guy taking care of that for him. He invests a little bit of money and has a great-running bike. Win-win.

My ZX-11 would go through this every year at the start of the new season.
Sea Foam and miles.
After about 200 miles it cleared up.

Reminds me that I have to clean those carbs up.....

Reminds me of a time in the 80's when I was visiting a mechanic friend of mine who worked at a Yamaha dealer. A kid brings in an RD350 and says it won't go over 30mph. Greg lifts the seat and sees a beach towel folded neatly on top of the intake snorkel.

When I see something like this, I check the ignition first. You can fiddle with the carbs until the world ends, but if the ignition ain't working right, it won't run right. Spark to both plugs and check the timing. Then I check the fuel petcock, related hoses including the vacuum and fuel line, change the filter, and check the choke.

As for the carbs, the engine runs on the idle jets until about 30mph, then the needles lift out of the main jets. If the piston/needles are stuck in their bore, the bike will only run on idle jets. And I believe that they are very lean on the big Vulcan. You can run an ocean of Sea Foam through the carbs and it won't clean the pistons or bores. The tops of the carbs have to come off to clean them.

On my 79 Suzuki, the piston needles are connected directly to the throttle cable. They never stick. I think all carbs after 79 used Constant-Velocity (CV) carbs. The piston/needles rise by the vacuum of the engine, and the piston and bore has to be squeaky clean for them to operate correctly.

Clean the carbs.

And yes 2 months is enough time to turn gas to shi. Also, did it run once 2 months ago for 2 minutes, again for 2 minutes 2 months before that, and so on, until that gas is a year old.

That was my issue when trying out my friend's gs750 bobber. Id never ridden a bike with the old style carbs and with four of em to pull that throttle was HEAVY :lol: