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Re:changed needle clip from 4th to 3rd
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TOPIC: Re:changed needle clip from 4th to 3rd
#494304
TheSheepdog (User)
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changed needle clip from 4th to 3rd 1 Year ago  
So I'm now washer, clip, spacer, washer 3rd from blunt end.

How much difference could I actually see MPG wise?

Had to adjust the PMS to clean up a slight stumble when opening the throttle and she seems to pull much stronger

Was at 36-38 on the roundtrip to Austin. But that was very loaded down and with a 21" shield.

SD
 
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Re:changed needle clip from 4th to 3rd 1 Year ago  
Speed has always had the biggest effect on my mileage. 70+ and it starts to go in the toilet.
 
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Re:changed needle clip from 4th to 3rd 1 Year ago  
According to the tuning manual for a 42HSR carb, they say that clip placement has no effect to mpg at speeds below approx 70mph. Has more to do with acceleration. Granted, this info is for the 42, but I see no reason why it would not be the same for the CV carb.

I even tested that on my 42. was absolutely accurate. Mikuni uses 65mph as a cruise speed and to check mpg at. Lowering the needle allows for that part of the needle to stay in the cruise portion to a higher rate of speed. I gained 5mpg at 80mph, but my 65mph mileage was not affected. Before the clip change would get 50mpg at 65mph, 40mpg at 80mph. after 50mpg at 65mph, 45mpg at 80mph. However, performance did suffer.
 
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Re:changed needle clip from 4th to 3rd 1 Year ago  
So should I be looking at dropping from a 170 to a 167.5 main?

SD
 
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Re:changed needle clip from 4th to 3rd 1 Year ago  
Sheepdog wrote:
So should I be looking at dropping from a 170 to a 167.5 main?

SD


I'm using the 167.5 right now, and the clip is in the fourth. I'm thinking about going back to the 170 in the future, and moving the clip to the 3rd, with an extra washer under the plastic spacer for the mid point between the 3rd and 4th grooves.
Erbman has posted before, that if you stay out of the throttle, the larger mains aren't that much of a problem, but if you want the performance it'll be there. I can't tell if there is really a difference performance wise between the 170, and the 167.5. It may be slightly less impressive with the 167.5.

You might try adjusting the accelerator pump per this article.

http://roadstarclinic.com/content/view/63/96/

This made a huge difference for me. The blue(duration) screw in the diagram, on my bike is 1 1/2 turns off of the locknut now, with the nut on top of the stop. I tried the nut under, and the screw on the stop, but it was sluggish. Its pretty decent right now. A good compromise. It also helped with the torque snap in first gear. Its alot smoother. Everytime the throttle is twitched, the pump spits fuel, and alot of it, at the factory setting.


As has been said, 70mph is the cutoff for economy. Above that, and the fuel is flowing.
 
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