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Old 07-09-2012, 07:41 AM   #15
caryder OP
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Joined: Nov 2007
Location: Phoenix
Oddometer: 217
Based on what I'm reading into it

Based on what I'm reading, and what I know about the jets, the 5DP7 needle is very lean compared to the stock needle. When first reading up on the latest jetting techniques I purchased the 5DP7 needles but I didn't buy the needle jets. With 35 pilots and the 5DP7 by itself the motor won't run off idle. It just stalls the bike. Comparing the needles side by side I could see the 5DP7 is very fat around the mid section and doesn't taper narrow until much lower down toward the main jet. So I became very skeptical about what I had read. The 169-P0 or P2 needle jets must flow a lot more fuel.

I expect to lower the main jet down from 290 to around 250 which is where is seems most people have landed with similar mods. I wish I had known all of this in 1980 when I was racing my RD350.

With respect to timing, I wasn't sure if everyone responding realized that the 1.8mm BTDC is the recommended setting for RD350's running pump gas. An equivalent measure for the RD400 is 2.0mm. Stock timing on the 400 is 2.3mm. Stock on the 350 is 2.0 (if I recall).

On a degree conversion chart:
(Stock timing) 2.0mm on a RD350 = 19.92 degrees
1.8mm on a RD350 = 18.88 degrees

(Stock timing) 2.3mm on a RD400 = 19.74 degrees
2.1mm on a RD400 = 18.85 degrees

When I had the right cylinder accidentally set to 3mm (due to a stripped screw) that was equal to 22.60 degrees BTDC which lead to a melted piston crown similar to pre-ignition. The right cylinder seized because the piston melt flowed forward out the exhaust port and wrapped around the front of the piston and collapsed the top ring grove.
2012 Honda NC700X
2006 Gas Gas 300 Pro
2003 Kawasaki KDX220R
1976 Yamaha RD400C
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