Carb needed for Mint 400

[Tim Brown]

Wanted: BING,ready to bolt on,jetted for the Next C/C in SC. I have ridden Ahrma SE C/C events off and on for years. I won several on a 74 Penton 250 until motor issues that I just didn't take time to fix. I got on a Yamaha that was sitting in the shop. I see that the next C/C is Penton sponsored so I feel obligated to ride a Penton for that event. I have just acquired a 400 with a flat side carb that needs to be replaced. Please help, the race is in two weeks and I really don't want to ride a Yamaha over there.
Thanks,
Tim Brown
706-347-0316 cell

[Big Mac]

I put a 36mm Bing from a 250 on my Mint 400 because I couldn't find a decent 38, works great, runs like a spotted ape. I figure I'm very rarely going to pull the slide to the top anyway, and 36s are easy to find. Stock jetting per the manual with needle in mid slot seems to carburete just fine bottom to top.

[Tim Brown]

I put the best 36mm on it I had, slide is tight. Bought $200 of new parts from Bing,#1 slide, #1 needle (middle position), 185 main, 285 needle jet, 35 pilot 1 1/4 out, 93 pump gas. Plug looks good, but it is fat in the middle. The only other needle jet I have is a 280. Runs better in the middle, plug slightly lean, but still a little fat. Bad thing is, it runs good with the new Keihin that was on it when I got it but not Vintage legal. What about a different slide? Any suggestions?
Thanks,
Tim

[john durrill]

Tim.
 This may help some.







Someone may have to measure the slide cutaway they have that is working for them and then you could modify yours.

John D.

[Lew Mayer]

John, I think you missed one page and printed another twice.
Sorry I missed seeing you in Gainesville.

Lew Mayer

[john durrill]

Thanks Lew,
 Thats the second time transferring the address from Flickr has done that.
I doubled the page at first , then went back and deleted the double , I thought , but the double stayed on POG.
it should be right now ( i hope ) []
John D.

[Big Mac]

The 36mm on my '75 400 has a #1 slide, 195 main, 40 pilot, 285 NJ, worn #1 needle, clip in middle slot, running 50/50 premium and LL100 octane, BUT has a GEM reed valve...which I believe generally runs a fatter main to be right. 195 just happened to be what I had on hand, but seems to run right in cold-clear winter racing at close to sea level. Might be too rich in summer or at a bit of elevation.

I'd try a bigger pilot, maybe even a 45. On the 400, 35 pilot makes mine hard to start. My 2cent.

[Tim Brown]

Thanks to everyone for the input. Vintage riders, especially Penton riders, are a great bunch of folks. I think I have it jetted close enough to race. We'll find out in South Carolina this weekend.
Tim