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Workshop => Carburetor, Intake, and Exhaust => Topic started by: fast350r on August 12, 2015, 10:28:12 AM

Title: 431 puma jetting
Post by: fast350r on August 12, 2015, 10:28:12 AM

Im getting ready to fire up my new puma, and need baseline jetting advise?

431 puma, 110 race gas, mid to top end porting by Matt Shearer
4mm hotrod crank, welded and balanced ,yz490 rod
gigot lock up , billet basket, driveline clutch
back cut tranny, cryo treated, billet 2nd and 3rd
cr500 v-force 3
LED Puma in-frame
2001 cr250 ign
41.5 bored pwk
LED intake

Temp here is around 105 right now
elevation is 1100ft

Title: 431 puma jetting
Post by: JesseA420 on August 12, 2015, 11:10:43 AM

i would ask shearer since he built it.

Title: 431 puma jetting
Post by: fast350r on August 12, 2015, 12:43:48 PM

he was steering me towards buying a mikuni or a lectron, he said he doesn't run a keihin unless he runs a pump.

Title: 431 puma jetting
Post by: jadleybray on August 12, 2015, 01:42:43 PM

Are you running a pump then?

Title: 431 puma jetting
Post by: Skeans1 on August 12, 2015, 02:03:28 PM

I'd take Matt's advice and go with what the motor has been set up for, did you ask Matt about running that pipe with the porting you have?

Title: 431 puma jetting
Post by: fast350r on August 12, 2015, 04:04:44 PM

Yeah pipe will be fine with the porting, and no i prefer not to run a pump i dont think i need it for a dune set up


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Title: 431 puma jetting
Post by: Pumashine on August 12, 2015, 04:11:14 PM

It seems we were running a 180-182 main jet for the dunes. Proly Want to to start with a 190-192 to be safe

Title: 431 puma jetting
Post by: fast350r on August 12, 2015, 05:35:47 PM

Yeah puma Il break her in with a 190m , and then move down to 185 or 182 and see what happens Thanks

Title: 431 puma jetting
Post by: havinnoj on August 12, 2015, 08:22:33 PM

Quote from: Pumashine;57064

It seems we were running a 180-182 main jet for the dunes. Proly Want to to start with a 190-192 to be safe

Just food for thought since I learned this only last year.. Keihin makes a 190 and a 195.  So if you need a 192, it will 100% be aftermarket. I prefer genuine Keihin but can't say I've found anything detrimental with aftermarket jet manufacturers.

Title: 431 puma jetting
Post by: Pumashine on August 12, 2015, 11:51:05 PM

Quote from: havinnoj;57068

Just food for thought since I learned this only last year.. Keihin makes a 190 and a 195.  So if you need a 192, it will 100% be aftermarket. I prefer genuine Keihin but can't say I've found anything detrimental with aftermarket jet manufacturers.

Yeah, I forgot that they only go up  in increments of 5 after 190 and up. The theory going at that point little increments don't have enough change in fuel supply.

Title: 431 puma jetting
Post by: Pumashine on August 13, 2015, 02:39:34 PM

Quote from: fast350r;57065

Yeah puma Il break her in with a 190m , and then move down to 185 or 182 and see what happens Thanks

I just pulled the main jet where we were running the dune puma ... its a 185. I switched to smart carb after that.