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MarkT Exhaust
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Author Topic: Gas mileage drop with new glasspacks  (Read 1437 times)
Davemn
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Posts: 830

Minnetrista, Minnesota


« on: October 10, 2019, 01:09:22 PM »

I changed my glasspacks going to a more restricted flow.......from straight through to a baffle pack. My mileage went from approximately 34 down to 28. I have never touched the carbs. I’m guessing the new baffle packs are less restrictive than the stock Honda mufflers but that’s just a guess based on visual observation.
Any thoughts?
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sandy
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Posts: 5388


Mesa, AZ.


« Reply #1 on: October 10, 2019, 01:32:00 PM »

Your new baffles are MORE restrictive, not less. My guess would be the pilot screws are too far out. Turn them all back in lightly and open them 2 turns and run another tankful or two.
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Davemn
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Posts: 830

Minnetrista, Minnesota


« Reply #2 on: October 10, 2019, 03:01:48 PM »

Where exactly are the pilot screws?
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Ramie
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Posts: 1318


2001 I/S St. Michael MN


« Reply #3 on: October 10, 2019, 05:41:54 PM »

It's the D screw right under the intake.  It can be a pain to get to and you need something like this from Amazon
https://www.amazon.com/Motion-Pro-Replacement-D-Shaped-08-0242/dp/B00VKNOEW6/ref=sr_1_1?keywords=d+socket&qid=1570758565&sr=8-1

Or one from Redeye

https://redeye.ecrater.com/p/20824302/hella-stubby-pilot-screw-tool-on

I inadvertently ordered two from redeye so I have an extra one, it's yours if you want it.  Just PM me and we could meet up somewhere, I'll check back here tomorrow after work.  Were both on the same side of the city, I'm just a little farther north.

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“I am not a courageous person by nature. I have simply discovered that, at certain key moments in this life, you must find courage in yourself, in order to move forward and live. It is like a muscle and it must be exercised, first a little, and then more and more.  A deep breath and a leap.”
Davemn
Member
*****
Posts: 830

Minnetrista, Minnesota


« Reply #4 on: October 10, 2019, 06:11:20 PM »

It's the D screw right under the intake.  It can be a pain to get to and you need something like this from Amazon
https://www.amazon.com/Motion-Pro-Replacement-D-Shaped-08-0242/dp/B00VKNOEW6/ref=sr_1_1?keywords=d+socket&qid=1570758565&sr=8-1

Or one from Redeye

https://redeye.ecrater.com/p/20824302/hella-stubby-pilot-screw-tool-on

I inadvertently ordered two from redeye so I have an extra one, it's yours if you want it.  Just PM me and we could meet up somewhere, I'll check back here tomorrow after work.  Were both on the same side of the city, I'm just a little farther north.



Ah St Michael.....real nice up there. For $10 I will just get one. Can I do this without taking the tank off?
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Ramie
Member
*****
Posts: 1318


2001 I/S St. Michael MN


« Reply #5 on: October 10, 2019, 06:22:27 PM »

It's the D screw right under the intake.  It can be a pain to get to and you need something like this from Amazon
https://www.amazon.com/Motion-Pro-Replacement-D-Shaped-08-0242/dp/B00VKNOEW6/ref=sr_1_1?keywords=d+socket&qid=1570758565&sr=8-1

Or one from Redeye

https://redeye.ecrater.com/p/20824302/hella-stubby-pilot-screw-tool-on

I inadvertently ordered two from redeye so I have an extra one, it's yours if you want it.  Just PM me and we could meet up somewhere, I'll check back here tomorrow after work.  Were both on the same side of the city, I'm just a little farther north.



Ah St Michael.....real nice up there. For $10 I will just get one. Can I do this without taking the tank off?

No problem, taking the tank off wouldn't help.  If you look up under the carb at the throat that connects to the intake tube you'll see it.  You won't see the D screw you'll see the casting around it.  (You can see it with a small inspection mirror)  They say you can also use the casing of a 22 shell and just flattened on one side so you have a D shape.
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“I am not a courageous person by nature. I have simply discovered that, at certain key moments in this life, you must find courage in yourself, in order to move forward and live. It is like a muscle and it must be exercised, first a little, and then more and more.  A deep breath and a leap.”
sandy
Member
*****
Posts: 5388


Mesa, AZ.


« Reply #6 on: October 10, 2019, 07:02:48 PM »

Another from Amazon;

https://www.amazon.com/dp/B003CMWC4U/ref=dp_cerb_1
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Davemn
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Posts: 830

Minnetrista, Minnesota


« Reply #7 on: October 11, 2019, 05:50:02 AM »

Those screws look hard to get to. Do I need to remove the intake runners to get to?
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Ricky-D
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Posts: 5031


South Carolina midlands


« Reply #8 on: October 11, 2019, 06:02:10 AM »

The thinking that giving those screws a turn or two will have an affect upon your mileage (28mpg to 34mpg) is folly.

***
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2000_Valkyrie_Interstate
sandy
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*****
Posts: 5388


Mesa, AZ.


« Reply #9 on: October 11, 2019, 06:47:28 AM »

The thinking that giving those screws a turn or two will have an affect upon your mileage (28mpg to 34mpg) is folly.

***

I have a friend who was getting 25-28 MPG. He had just bought his Valk and asked me for help. I checked his needles (stock), and reset all his pilot screws. They were set from 3 to 4 1/2 turns out. Resetting them to 2 turns brought his mileage up to 33-34 depending on speed.
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Ramie
Member
*****
Posts: 1318


2001 I/S St. Michael MN


« Reply #10 on: October 11, 2019, 06:10:34 PM »

Those screws look hard to get to. Do I need to remove the intake runners to get to?

No need to remove the intakes but it is tight, that's why I suggested a mirror to first check which way to insert the tool.  The red eye tool is just the correct length to fit and still give you something to grab with your fingers so you can turn it.
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“I am not a courageous person by nature. I have simply discovered that, at certain key moments in this life, you must find courage in yourself, in order to move forward and live. It is like a muscle and it must be exercised, first a little, and then more and more.  A deep breath and a leap.”
Bret SD
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Posts: 4306


***

San Diego, Ca.


« Reply #11 on: October 12, 2019, 01:31:58 PM »

The thinking that giving those screws a turn or two will have an affect upon your mileage (28mpg to 34mpg) is folly.

***

I have a friend who was getting 25-28 MPG. He had just bought his Valk and asked me for help. I checked his needles (stock), and reset all his pilot screws. They were set from 3 to 4 1/2 turns out. Resetting them to 2 turns brought his mileage up to 33-34 depending on speed.
Hello,
I have an 02 standard  (since Jan or so) and have some crap mileage (26 mpg) after a carb rebuild using #38 slow jets, how do I check the needles, are there markings on the OEM ones? Also the PO drilled out the exhaust and had double washers on the needles.. still my mpg was better then.

With the clogged jets (#35s) and down tube vac leaks I found during the rebuild I got 36 mpg going 2 up riding at around 3000 rpm. I have the pilots turned out 1-3/4 turns and have re-tightened all clamps etc. I've also synced the carbs and the bike runs great, doesn't miss a beat..

Also the idle wanders a bit, this am I rode about 10 miles at 4200 rpm on the freeway, the idle had been wandering but seems to have steadied the last 2 weeks, that is until this morning when it wandered up to 11-1200 rpm after the higher rpm session. Does this point to a vacuum leak?

I also installed a pingel valve and as i said earlier it's running great other than the mpg problem.

Sorry, don't want to hijack the thread and can post my own if needed.

Thanks much
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Bret

02 Standard -- Blue & White
82 Aspencade -- Red
“No man has the right to be an amateur in the matter of physical training. It is a shame for a man to grow old without seeing the beauty and strength of which his body is capable.” Socrates
98valk
Member
*****
Posts: 13487


South Jersey


« Reply #12 on: October 12, 2019, 05:44:35 PM »

The thinking that giving those screws a turn or two will have an affect upon your mileage (28mpg to 34mpg) is folly.

***

I have a friend who was getting 25-28 MPG. He had just bought his Valk and asked me for help. I checked his needles (stock), and reset all his pilot screws. They were set from 3 to 4 1/2 turns out. Resetting them to 2 turns brought his mileage up to 33-34 depending on speed.
Hello,
I have an 02 standard  (since Jan or so) and have some crap mileage (26 mpg) after a carb rebuild using #38 slow jets, how do I check the needles, are there markings on the OEM ones? Also the PO drilled out the exhaust and had double washers on the needles.. still my mpg was better then.

With the clogged jets (#35s) and down tube vac leaks I found during the rebuild I got 36 mpg going 2 up riding at around 3000 rpm. I have the pilots turned out 1-3/4 turns and have re-tightened all clamps etc. I've also synced the carbs and the bike runs great, doesn't miss a beat..

Also the idle wanders a bit, this am I rode about 10 miles at 4200 rpm on the freeway, the idle had been wandering but seems to have steadied the last 2 weeks, that is until this morning when it wandered up to 11-1200 rpm after the higher rpm session. Does this point to a vacuum leak?

I also installed a pingel valve and as i said earlier it's running great other than the mpg problem.

Sorry, don't want to hijack the thread and can post my own if needed.

Thanks much

38 pilot jets are too rich for a non-modified engine.  oem needles are non adjustable. Stock all needles have one factory washer.  It will run better if only the front two carbs have two washers others as from factory one washer.
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1998 Std/Tourer, 2007 DR200SE, 1981 CB900C  10speed
1973 Duster 340 4-speed rare A/C, 2001 F250 4x4 7.3L, 6sp

"Our Constitution was made only for a Moral and Religious people. It is wholly inadequate to the goverment of any other."
John Adams 10/11/1798
Bret SD
Member
*****
Posts: 4306


***

San Diego, Ca.


« Reply #13 on: October 12, 2019, 06:37:56 PM »

Thanks for the reply and info, I'll try 2 washers on the front carb needles, as far as the 38s go my mileage will suck until I can get to putting 35s in it? I'd like to do it with the carbs still on the bike, they should unscrew fairly easily after only being in for a few months.

Damn, wish I would have known about the crap mileage with 38s. I did alot of reading here on the rebuild but didn't pick up the mileage being affected.

One other thing, when I pull the vacuum caps off the down tubes for carb sync I see and smell liquid fuel in the caps, is this just dribbling from the 'too big' slow jets or is something else? The motor runs slightly rich but not too bad, I understand from reading here that too rich is fairly common with these machines and is preferable to running a too lean mixture. Is the dribbling gas just being blown out the exhaust and wasted, thereby giving poor fuel mpg?

Sorry for all the questions but I'm a relative noob here with some mechanic background.
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Bret

02 Standard -- Blue & White
82 Aspencade -- Red
“No man has the right to be an amateur in the matter of physical training. It is a shame for a man to grow old without seeing the beauty and strength of which his body is capable.” Socrates
98valk
Member
*****
Posts: 13487


South Jersey


« Reply #14 on: October 12, 2019, 06:47:35 PM »

Thanks for the reply and info, I'll try 2 washers on the front carb needles, as far as the 38s go my mileage will suck until I can get to putting 35s in it? I'd like to do it with the carbs still on the bike, they should unscrew fairly easily after only being in for a few months.

Damn, wish I would have known about the crap mileage with 38s. I did alot of reading here on the rebuild but didn't pick up the mileage being affected.

One other thing, when I pull the vacuum caps off the down tubes for carb sync I see and smell liquid fuel in the caps, is this just dribbling from the 'too big' slow jets or is something else? The motor runs slightly rich but not too bad, I understand from reading here that too rich is fairly common with these machines and is preferable to running a too lean mixture. Is the dribbling gas just being blown out the exhaust and wasted, thereby giving poor fuel mpg?

Sorry for all the questions but I'm a relative noob here with some mechanic background.


with the 38s the idle mixture screws need to be 1 1/2 turns open from very lightly seated.  35s would be about 3 open.
first try same one washer all carbs, test ride 100s of miles.
the gas dribble is common, nothing to worry about, can be worst when running rich.

this will help to understand carb tuning.  http://www.factorypro.com/tech/tech_tuning_procedures/tuning_carbtune,CV,lower_rpm_engines.html
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1998 Std/Tourer, 2007 DR200SE, 1981 CB900C  10speed
1973 Duster 340 4-speed rare A/C, 2001 F250 4x4 7.3L, 6sp

"Our Constitution was made only for a Moral and Religious people. It is wholly inadequate to the goverment of any other."
John Adams 10/11/1798
Bret SD
Member
*****
Posts: 4306


***

San Diego, Ca.


« Reply #15 on: October 12, 2019, 07:38:58 PM »

Thank you for the link, over the next months I'll play with it, right now is hectic unfortunately.

It's running so good now I hate to touch it while busy and distracted, and have an unnecessary problem, I've learned that after 60 yrs haha! Riding is great stress relief and I don't want to muck it up.

Turning the mixture screws in 1/4 turn is doable and I have the tool from the Redeye kit, from there another carb sync is in order no?

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Bret

02 Standard -- Blue & White
82 Aspencade -- Red
“No man has the right to be an amateur in the matter of physical training. It is a shame for a man to grow old without seeing the beauty and strength of which his body is capable.” Socrates
sandy
Member
*****
Posts: 5388


Mesa, AZ.


« Reply #16 on: October 12, 2019, 09:41:41 PM »

A most trusted and well known mechanic on this site, gave me some info in Taos. With an exhaust gas analyzer, he said 38s were showing too rich when the pilot screws were only opened 1/8th of a turn. Hondas info says 2 turns out with 35 idle jets. Not 3 turns. If you smell fuel or start your Valk without any fuel enrichment, it's too rich. I get 34-38 MPGs around town. Sometimes 39-40+ on the highway.

'97 tourer
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Bret SD
Member
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Posts: 4306


***

San Diego, Ca.


« Reply #17 on: October 13, 2019, 08:44:54 AM »

Thanks for the info, I'll be changing back to 35s when I can, damn frustrating.. my choke just kills the motor if it's running and doesn't work for starting the bike AFAIK. Though I don't need the choke most of the time in San Diego.
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Bret

02 Standard -- Blue & White
82 Aspencade -- Red
“No man has the right to be an amateur in the matter of physical training. It is a shame for a man to grow old without seeing the beauty and strength of which his body is capable.” Socrates
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