Eagler's Nest

Engines => 2 Cylinder => 1/2 vw => Topic started by: Bob Wood on June 01, 2018, 08:29:06 AM

Title: Mikuni Bleed vs Primary system
Post by: Bob Wood on June 01, 2018, 08:29:06 AM

When looking through the Mikuni tuning manual......  It says the Bleed system is for 2 or 4 strokes  and the Primary is for 2 strokes. (Page 3)

The VM 28 carbs we run come with the Primary system.  Had anybody replaced it with the bleed system? 

Which is best for our use?

Bob

Title: Re: Mikuni Bleed vs Primary system
Post by: Dan_ on June 04, 2018, 03:19:02 PM

Bob,
Here are a couple of links...

http://xs650temp.proboards.com/thread/7499/vm-needle-jet-theory (http://xs650temp.proboards.com/thread/7499/vm-needle-jet-theory)

http://www.dotheton.com/forum/index.php?topic=39693 (http://www.dotheton.com/forum/index.php?topic=39693.0)


I read one of your earlier posts, and you said you tried a 130 main jet and got 1060 rpm and EGT 1050-1100.



I would keep going down on the main jet until it will take WOT and the plugs look right.  Then and only then start changing the needle parameters.  Work your way down in 1/4 throttle positions to the idle circuit. 


It should go to full WOT smoothly from any throttle position...

Here are the numbers from GPAS...

 Minimum oil temperature 160°F
 
 Maximum oil temperature 230°F
 
 Cruise oil temperature 200°F
 
 Minimum oil pressure at cruise 23 PSI
 
 Maximum oil pressure at cruise 70 PSI
 
 Maximum oil pressure - cold 100 PSI
 
 Cylinder head temperature at cruise 350°-375°F
 
 Cylinder head temperature during climb 420°F (5 min)
 
 Do not exceed cylinder head temperature 450°F
 
 Exhaust gas temperature at cruise 1150°F
 
 Do not exceed exhaust gas temperature 1500°F
 
 
 Great Plains Aircraft Supply Co., Inc.
 info@greatplainsas.com (info@greatplainsas.com)

BTW,  I dint read anything about those motorcycles having carb heat.

(https://media.giphy.com/media/DLKQ0AJOIpfZ6/giphy.gif)