75 Mint 400 Carb Question

[KJDonovan]

I am getting ready to start working on a 75 Mint 400 and have a carb question I am hoping someone can answer.  In looking at the parts manual for this bike, it calls out a 38 MM Bing as the stock carb, the book does not tell me if it should be a 54 or and 84.  This particular bike presently has a 36MM type 54 (#1/36/103).  Problem is this carb is so tall, about 6-1/8" from top to bottom, that in order to level it out there is a dent in the pipe so the so the top of the carb will clear it.  So my question is, was this dent by design, I am guessing not.  Also if anyone else has a 74 or 75 Mint 400, is the carb a type 54 or 84 and about how tall is it from top to bottom.




Thanks,

Kevin

[454MRW]

The bigger carbs, (bigger than 32mm) are type 54, and at least all of the MC5 pipes have a dent for carb clearance, and I would assume the same would go for a Mint 400 as well. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1980 KTM 175-400'S
1975 Can Am 175 TNT & 77 250 Black Widow
1979 Husqvarna OR390
1976-78 RM & 77-79 PE Suzuki's
1974 CR250M 07 CR125R 79 CR250R

[Daniel P. McEntee]

I will concur what Mike Winter said, it's common to see at least the seam flange on the pipe bent over, or a nice flat spot hammered at the carb location. If the carb you have fits, I'm going to guess that it is indeed a 38MM and maybe you just measured wrong? I would have to wonder if a 400 would run well at all with a 36mm Bing?
   Good luck and have fun,
    Dan McEntee

[Daniel P. McEntee]

What is the story on the bike?  I just notice in the picture what looks like maker paint and a hole for a head/cylinder seal like was required for ISDT qualifiers.
   Type at you later,
   Dan McEntee

[brian kirby]

The 400 came with a 38mm Bing 54 but many had 36mm put on them to try to smooth them out. The 36mm Bing 54 is physically the same size as the 38, only the venturi size is different. The numbers he gave, 1/36/103, identify it as a 36mm.

Brian

[KJDonovan]

Guys,

Thank you for the information.  The carb is definitely a 36, based on the neck numbers.  The carb fits, I was just thrown off by the dent; it looks like it was done during assembly with a ball peen hammer and not by design, and so I wanted to check before I rework the pipe.  I don't want to remove something that should be there.  Dan, the bike was an ISDT bike.  

Thanks,

Kevin


Kevin J. Donovan
Foster, Rhode Island
72 Jack Piner (My Ride)
72 Six Day (Wifes Ride)
71 Suzuki TS125
72 Montesa Cota 123

[firstturn]

Kevin,
  We discussed this back 10years ago on this site.  When the 400 came out the ones we had came with a 38mm Bing.  Since we used our bikes for hareScrambles and MX we switched to a 36mm Bing to make it more manageable.  Some people tell me that used a 38 and loved it...I guess those people were better riders than we were?

Ron Carbaugh

[tomale]

Unless your using the bike in places were you will be holding the throttle wide open a lot, it will give you no advantage at all to run a 38 mm carb, In fact the 36 will give you a better throttle response. This bike has a powerband like a 125 on steroids.  Putting a 38 on there only  makes it more like that.  Keep the 36.

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

[KJDonovan]

Ron / Thom,

Thank you for the advice on the 36 over the 38.  When I start digging deeper into this bike, I will be looking for one.  It seems the long term residents (mice or chipmunks) of the airbox were using the carb as a porta potty and the bottom part of the bell and area below the slide are rotted away.  I guess the good news is the angle on the bottom of the slide kept everything out of the intake.

Thanks,

Kevin


Kevin J. Donovan
Foster, Rhode Island
72 Jack Piner (My Ride)
72 Six Day (Wifes Ride)
71 Suzuki TS125
72 Montesa Cota 123

[firstturn]

Kevin I may have a NOS body.  If you are interested I can check and see what I have?  

firstturn at hotmail.com

Ron Carbaugh

[KJDonovan]

Ron,

Please take a look and let me know if you have one.  The one I have is spent.

Thanks,

Kevin

Kevin J. Donovan
Foster, Rhode Island
72 Jack Piner (My Ride)
72 Six Day (Wifes Ride)
71 Suzuki TS125
72 Montesa Cota 123

[firstturn]

Kevin,
   I had bought a box of NOS Bing parts sometime back and I looked at the box and all I had left was 24/27/28/32/38. but no 36mm bodies?  I will check around and see if any of them got out of place.  At this point I am saying I am out of 36mm.

Ron Carbaugh

[tlanders]

Gee, I put a 38mm Mikuni on mine and then bored it out to 40mm. It had a 38mm Bing, but the Bings don't seem to last a whole season without having to buy another slide. The Bings breathe better than the Mikunis so that is why I made it bigger.

[KJDonovan]

Found a carb.  The owner of the bike stopped by last night with a pristine 38MM Bing he had tucked away so looks like I will be good to go.

Thanks,

Kevin

Kevin J. Donovan
Foster, Rhode Island
72 Jack Piner (My Ride)
72 Six Day (Wifes Ride)
71 Suzuki TS125
72 Montesa Cota 123