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Mikuni HSR 42 problem

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Old Jun 10, 2010 | 03:05 AM
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Default Mikuni HSR 42 problem

Hi,
I'm from Poland. I gotta Electra Glide 2003 Standart with HSR 42 carb and Bassani true dual mufflers.
All jets were standart 160 main, 25 pilot (now 20), 97 jet needle (in the midle now second from the top). The problem is poor fuel economy (30 mpg) and black plugs in city riding (in highway now is OK when I changed jet needle position and float level from 16mm to 20mm). I still have a problem with idle mixture (I can screw out pilot air screw and engine still running good). I'm going to change jet needle to 98, pilot jet to 17,5 and main jet 157,5. What do You think about my idea?
Best regards
Martin
 

Last edited by Kret; Jun 10, 2010 at 03:43 AM.
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Old Jun 10, 2010 | 10:16 AM
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I would change the pilot jet first for the mixture screw adjustment.

then try the needle jet change to the middle clip on the #98.

leave the main jet alone until you see what the needle change dose, unless the plugs are dark brown or black right now.
 
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Old Jun 11, 2010 | 05:43 AM
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Thanks. I will have parts on Monday so I'll do it.
Yestarday I changed jet needle clip position on first from the top.
Now max speed is circa 105-108 mph (earlier over 110) and fuel economy 33 mpg (65-70 mph) I think still too rich and still without idle mixture regulation...Hmm...To Monday
 
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Old Jun 11, 2010 | 05:48 AM
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leave main jet, correct needle to '98' middle clip, and change pilot(slow) jet to '20'

Originally Posted by mentor70
I would change the pilot jet first for the mixture screw adjustment.

then try the needle jet change to the middle clip on the #98.

leave the main jet alone until you see what the needle change dose, unless the plugs are dark brown or black right now.
 
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Old Jun 11, 2010 | 05:57 AM
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Now I have 20 pilot jet and I'm still without idle mixture regulation. Yeah, I think that
I should change jet needle to 98, so I'll do it but I'm going to change pilot jet to 17,5 too.
 
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Old Jun 13, 2010 | 11:41 AM
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sums it up..
http://www.americanrider.com/output.cfm?id=1581175
 
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Old Jun 14, 2010 | 11:49 PM
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So, now I have 98 jet needle on middle clip position, 17,5 pilot jet and 160 main. Idle mixture still doesn't work correctly and fuel economy is...28 mpg (65-70 mph)...Is it joke or something!? Hmm...I have V8 not V2 engine maybe...
I don't know what is with my "very special" Mikuni HSR 42 carburetor...
 
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Old Jun 15, 2010 | 12:24 AM
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how dose the bike run. any saggs or boggs in the lower rpm range?

what do the plugs look like?

Head-quarters used to have a Mikuni tuning kit, I tried to get a link but i didnt see it on their site.

Their tuning aide is a smaller emulsion tube that helps tune the mid range. you might try and call them and see if they can get it still.

I would consider
taking the main jet down another size and see if that dose anything.

I think im at 157.5, and 160 is a little too fat for my setup.
 
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Old Jun 15, 2010 | 02:42 AM
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The bike runs good. The engine idling smoothly - 1000 RPM, acceleration is OK, no black smoke from the mufflers. The plugs look like from the shop after highway riding but after city riding they are sooty black (dry but black), so I think the fuel mixture is to rich... I can still screw out the pilot air screw from carburetor and engine runs without any problems...The 17,5 pilot jet is the least size in European aftermarket catalogs. Hmm...Now I haven't any ideas how to fix it.
In that weekend I had 20 pilot, and 97 jet needle in first clip from the top. Economy fuel was 30 mpg (65-70 mph) and 38 mpg (60 mph) with passenger.
Today I'm going to change 98 jet needle clip position to first from the top. Fuel economy maybe will be better but what will be with the idle mixture I don't know...
 

Last edited by Kret; Jun 15, 2010 at 06:33 AM.
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Old Jun 15, 2010 | 11:27 AM
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Originally Posted by Kret
The bike runs good. The engine idling smoothly - 1000 RPM, acceleration is OK, no black smoke from the mufflers. The plugs look like from the shop after highway riding but after city riding they are sooty black (dry but black), so I think the fuel mixture is to rich... I can still screw out the pilot air screw from carburetor and engine runs without any problems...The 17,5 pilot jet is the least size in European aftermarket catalogs. Hmm...Now I haven't any ideas how to fix it.
In that weekend I had 20 pilot, and 97 jet needle in first clip from the top. Economy fuel was 30 mpg (65-70 mph) and 38 mpg (60 mph) with passenger.
Today I'm going to change 98 jet needle clip position to first from the top. Fuel economy maybe will be better but what will be with the idle mixture I don't know...
yes that move should help a bit. the plugs should be a light brown.

on the idle setting, which enricher cable are you using? I had to put the original HD back on mine and had to change some parts with it.

on my tuning, i had a difficult time in the beginning with the mixture screw. Now i just make sure that the motor starts to stall when i turn the screw "in" if i go all the way in, and it stays running i know for sure im way off. I dont much care what it dose past 2-2.5 turns
 
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