RE: Fuel Economy / Consumption

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RE: Fuel Economy / Consumption

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RE: Fuel Economy / Consumption - 5/6/2008 6:28:52 PM

ken12

Posts: 55
Joined: 3/28/2007
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im gettin around 48-52 mpg

(in reply to dalex)

Post #: 16

RE: Fuel Economy / Consumption - 5/7/2008 4:56:46 PM

mrfisher

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Joined: 3/4/2008
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I've been getting around 28-30 mpg on my bike since I bought it last year. I recently pulled the carbs off to clean and check them over. Nothing was dirty or out of spec, but when I put it back together, I noticed that the little brass tubes near the air intakes on my carbs were all uncovered. I remembered reading this thread and realized that I was having a lot of similar problems, i.e. needing to run choke for a long time, sluggish performance, etc. I ended up supergluing some toothpicks into the holes, and WOW! The bike sounds brand new, it's actually holding a steady idle now, and I'm getting near 50 mpg. If it's warm outside, I don't even need to use the choke to start it up now! It's easily been the most significant improvement to the bike I've made. I'm surprised that these tubes and their effect aren't mentioned in either the Honda manual or the Haynes manual I have, since it seems like they're pretty important.

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Post #: 17

RE: Fuel Economy / Consumption - 5/7/2008 9:38:53 PM

rrasco

Posts: 4875
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From: San Antonio, TX
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/\/\ You have a pic of those tubes? Something I want to look into.

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Post #: 18

RE: Fuel Economy / Consumption - 5/8/2008 6:41:35 AM

dalex

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Joined: 1/27/2008
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I did the same as mrfisher and saw a noticeable improvement but it also coincided with many other things I did at the same time. Therefore, I cannot say that blocking those holes was the single factor that made my bike run so much better. However, it seems that doing so has yielded amazing results for all those who have done it so far.

< Message edited by dalex -- 5/8/2008 6:49:14 AM >

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Post #: 19

RE: Fuel Economy / Consumption - 5/8/2008 7:30:14 AM

dalex

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quote:

ORIGINAL: rrasco

/\/\ You have a pic of those tubes? Something I want to look into.

rrasco, pics are attached in the mentioned thread. Click here

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Post #: 20

RE: Fuel Economy / Consumption - 5/8/2008 8:44:20 AM

rrasco

Posts: 4875
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From: San Antonio, TX
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haha, go figure I was the last to comment how I needed to look into it. ah, me so forgetful. thanks for the link dalex, I am going to look at my spare carbs when I go home now.

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Post #: 21

RE: Fuel Economy / Consumption - 5/8/2008 8:49:51 AM

mrfisher

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After I reassembled the bike and started it up again, the bike immediately revved up to about a 6-7K rpm idle. I turned the idle screw way out until it was back to 1500 rpm. I'm wondering if this had something to do with the terrible fuel mileage, the fact that it was basically at 1/8 throttle all the time before. Incidentally, since turning the idle screw back out, the throttle no longer has any free play. Is this good? I'm used to having about 15 degrees of turn in the throttle before the engine starts to respond, but maybe that wasn't normal. I guess it feels kind of unsafe to have the engine respond with the slightest bit of twist, like i'm not going to be able to close the throttle all the way for some reason.

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Post #: 22

RE: Fuel Economy / Consumption - 5/8/2008 9:22:26 AM

rrasco

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From: San Antonio, TX
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the idle screw should not have affected how much play you have, this is adjusted by the throttle cables. and yes, you should have a little bit of play before the bike responds.

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Post #: 23

RE: Fuel Economy / Consumption - 5/8/2008 9:22:41 AM

dalex

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You can adjust the throttle cable at the carbs to give yourself back the 'slack' you previously had. When you put it back together, you just tightened it more than it was when you took it apart.

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Post #: 24

RE: Fuel Economy / Consumption - 5/13/2008 9:09:07 AM

rrasco

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From: San Antonio, TX
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So, did anyone figure out what those tubes were for? I am thinking maybe they are used to synchronize the carbs, the vacuum nipples. Can anyone correct me if I am wrong? I need to sync my carbs anyhow and need to know where to hook up the vacuum tubes.

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Post #: 25

RE: Fuel Economy / Consumption - 5/13/2008 9:28:15 AM

dalex

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The vacuum tubes hook up on the cylinder head itself (not on the carbs), right past the intake boots, positioned at a 45degree angle towards the outside. It take a phillips head screwdriver to remove the plugs.

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Post #: 26

RE: Fuel Economy / Consumption - 5/13/2008 9:41:11 AM

rrasco

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From: San Antonio, TX
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Can you show me where on one of these pics?

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Post #: 27

RE: Fuel Economy / Consumption - 5/13/2008 9:58:59 AM

dalex

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Not easily visible on these pictures but if you look where the arrows point, you can't miss them. They're right under the black rubber boots, actually on the valve head intakes (not cylinder head like indicated in my previous post)

Thumbnail Image

Thumbnail Image

Attachment (3)

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Post #: 28

RE: Fuel Economy / Consumption - 5/13/2008 10:29:34 AM

Gogar

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It looks like a plain-ol' phillips head screw; you take it out, and then you need to screw in the brass fittings that (hopefully) come with your carb-sync kit. Just like dalex said, right on the engine side of the rubber manifolds. The 1-2 face left, the 3-4 face right.

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Post #: 29

RE: Fuel Economy / Consumption - 5/13/2008 11:14:23 AM

rrasco

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From: San Antonio, TX
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Thanks, thats what I wanted to know. That's enough for me to go look at my spare engine so I know for sure.

Anyone have a good tool thats less expensive than the Morgan Carbtune? I'll probably end up getting that one unless I can find a cheaper efficient one. I read an article or two on making one, but they didnt have pictures so it was hard to follow.

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Post #: 30