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Title: Carb jetting Post by: bugnut68 on August 19, 2010, 22:35:37 pm I posted this in my 2017 build thread, but it doesn't seem to be attracting too many onlookers...;D
I'm getting a bit ahead of myself, but I'm curious about carb jetting. I've got a pair of 45 DRLA Dellortos with 38mm venturis. Jets currently in them include 75 idles, 200 main air correctors, 180 mains (I believe) and can't remember the emulsion tubes. Just wondering where I need to go to get into the ball park when I fire this engine for the first time. To reiterate the specs: 2017, 42x37.5mm valves, 8.5:1 compression, 1-5/8" exhaust. Oh yeah, and Engle 125 with 1.25 rockers. Title: Re: Carb jetting Post by: bugnut68 on August 19, 2010, 23:42:13 pm Forgot to mention I'm at about 4,800 feet elevation.
Title: Re: Carb jetting Post by: javabug on August 20, 2010, 03:05:15 am I started this summer working on dialing in my DRLA 48s, and my 48's probably DON'T translate straight across to your 45s. BUT, here's what I learned that might apply to you:
The Dellorto tuning manual is quite useful. The above manual says that 180 airs will work for just about everything. There is also one particular emulsion tube that is the "VW one." I forget what number it is but you probably already have it. Your jets seem on the rich side all around except for the 200 air, but again, my animal is different than yours. For comparison, my jet stack is 65/150/180 with 36mm vents and seems close for what I need. CB has lots of parts, including stuff you would think they don't really have (like 36mm vents for 48s!). Title: Re: Carb jetting Post by: Bruce on August 20, 2010, 06:06:15 am Take the the 75 idle jets and throw them in the garbage. Your engine won't even run with them.
At your elevation, I would start with a 60 idle jet and go down from there. Check your tubes. You need 9164.2 tubes. If you don't have this one, don't bother trying what you have. CB says the 180 air jet always works. I've never seen it not work. Just get them. CB is notorious for supplying super rich jets. With your 45 DRLAs, they installed a 162 main. I think a 150 will be rich, but it's a good starting point. Title: Re: Carb jetting Post by: Cal-Look66 on August 20, 2010, 16:07:25 pm Just bought jets the other day from a supplier in Washington state. On his site he has some information as well as sells jets for all types of applications for all types of carbs. Has original dellorto and weber parts. His site is www.carburetion.com, name of the company is carbs unlimited. Hope this helps.
Brandon |