2 STROKE WORLD .net

The 2-Stroke Garage => Turning Wrenches => Topic started by: Aloha808 on July 09, 2024, 02:17:53 PM

Title: Jetting question
Post by: Aloha808 on July 09, 2024, 02:17:53 PM
Any recommendation on a good starting point for my rd400. I had the top end rebuilt and ported for the street. It has:

-Mikuni VM 28, Dave f mod
-cross over tube
-boyseen reeds
-y boot, k&n filter
-oil injection
-DG chambers

Before it was ported the main was #115 and the pilot was #25.

Thanks

Title: Re: Jetting question
Post by: m in sc on July 09, 2024, 02:42:23 PM
270 main, 30 pilot, 1.5 out on airscrew, needle in middle as start. might wind up around 250-260 main.
Title: Re: Jetting question
Post by: Aloha808 on July 09, 2024, 03:36:06 PM
Thank you very much Mark.

Title: Re: Jetting question
Post by: Aloha808 on November 30, 2024, 08:45:43 PM
Finally had some time to work on the Daytona.

I went with Mark's suggestion.  Thank you.

 Anyway, runs pretty well/smooth up until 3/4 throttle, around 6,ooo to 6,500 rpm and then it will bog.  When I accelerate slowly it has less bog at that level compared to quick acceleration. Hopefully that makes sense.

Not sure, but I am guessing I need to go from the 270 main to a 260???

Any advice would be greatly appreciated.

Thanks,
Russell

Title: Re: Jetting question
Post by: 2steve on December 01, 2024, 10:09:13 AM
I ended up working my way down to 210 mains. FPP pipes, Chuck Q update porting,stock reeds and UNI pods with the stock intake rubber runners.
Main difference is that I am running UFO's in the 2.5 slides, which have a huge effect on reducing the pilot jets.
600 ft above sea level.
Seems like you need to carefully work your way down and might have to work the needle heights at the same time.
Title: Re: Jetting question
Post by: m in sc on December 01, 2024, 10:39:13 AM
yup. i suggested a large main on purpose. try 250, then 230, etc. keep going down in '10' increments till it feel better, then 'up' in 5s until its right.  :toot:  :cheers:
Title: Re: Jetting question
Post by: Aloha808 on December 01, 2024, 01:18:41 PM
Thank you very much gentlemen. 

I will take it down to 250's and see how it runs.