More Mint 400 questions

[dirtymartini]

After sitting for so many years I got the bike fired up but the carburetion (38mm bing)is not good.I know I haven't ridden it in 35 years, I heard my brother got it running briefly in the mid 90's
 I can get a full rebuild kit from Bing for $106. Do I have any other options? Can a Mikuni be fitted?

Also the fork stanchions are slightly bent, should I try and get them straightened or are new ones available?

[tomale]

I have had good success cleaning up Bing carbs. The biggest problem with them is they wear fairly fast. Once a year  the needle jet and jet needle should be replaced.  The slides wear as well.  They get a smiley face on the intake side and if it is too worn, the bike will tend to load up, or not meter well.  Having a rebuild kit is a good place to start.  Make sure you flush out everything.  There are two areas of interest, the pilot circuit and the air circuit.  Both of these have small holes that run through the carb and can get plugged up with varnish.  Use a good carb cleaner.  More than likely, the jets just need cleaning and the replacing of all the gaskets should get you rolling again.  Putting a mikuni on the bike is tricky but do able. I did that to my 76' 250 and it works great.  

I have never had a set of tubes straightened  but I know of a few that have and it works well.  Maybe someone here knows a good place to have that done. Maybe you can find a set of good used tubes.  That would be cheaper than buying a new set.  It will shock you to know how expensive they  are! And they tend to be not nearly as good as the originals.

Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)
74' 1/2 440 maico
70' 400 maico (project)
72' cr125 Husky (project)
93' RMx 250 suzuki
Honda TL 125
2004 Suzuki DL1000

[dirtymartini]

Thanks for the reply Thom. I  soaked the carb well in carb cleaner, I am thinking the float is a big part of the problem. I also noticed the float needle is spring loaded and according to manual I have it should not be depressed when the carb is inverted while checking float height. Mine is definitely being depressed. Maybe the float is too heavy from many years of soaking up gas while it sat?

I would rather keep it original. I am going to try the full rebuild kit from http://www.bingcarburetor.com/

The other I will have to replace are the petcocks, I tried cleaning them but don't think they are flowing enough fuel...they also allow a little fuel through when closed.

The brief time it ran I was able to ride it in the yard in first and second gears...I forgot how much power the old girl has!

[Daniel P. McEntee]

Nice looking bike! In all of the photos that I have looked at over the past several years of various Pentons, you don't see many complete "white bikes" like this one. It's kind of growing on me. Can I say it's "rare?" You see some GS models with orage tanks, and even some MC models like my '77 that have the orange tanks. I'm working on a '75 400 now that I have a large Hi-Point aluminum tank for, but I also have a spare watermelon tank that I think I'll paint up to match the air box and switch off now and then. Got a ways to go yet, but this is a photo I'll have to save for reference later.
  Type at you later,
   Dan McEntee

[Richard]

Don't worry about the float needle spring depressing when turning the carburetor upside down, that's normal. What the manual is trying to show is you should adjust the float tang so that the float is parallel to the lower carb to float bowl mating surface when the float needle spring is extended.

[tomale]

You maybe on to something with the petcocks . The 400's use alot of fuel. If you replace them, make sure the inside diameter is as big as the stock one, if not bigger. Not all after market peacocks are created equal.

Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)
74' 1/2 440 maico
70' 400 maico (project)
72' cr125 Husky (project)
93' RMx 250 suzuki
Honda TL 125
2004 Suzuki DL1000

[chicagojerry]

jerry birky at penton racing products does a great job of straightening fork tubes...    chi jer

[dirtymartini]

Thanks ChicagoJerry, I'll check that out. I'm also watching e-bay and others to see if I can find a better set. Is there any way to identify whether the forks are Ceriani or Marzocchi? I can't find any markings....

[Richard]

Marzocchi

[dirtymartini]

Thanks Richard, I thought they were Marzocchi but wasn't sure.  I received my new petcocks and installed them...It ought to be getting enough fuel now! Just waiting for my bing parts then hopefully a little test ride.

[dirtymartini]

Got my petcocks installed and today  UPS brought my Bing parts. I fired her up and got to do a couple of laps in the yard...first true ride on this bike since 1978!
  A couple more minor tweaks and I'll be ready for a longer ride...