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My '79 XS11F Saga - Please Help.
My ’79 XS11F Saga
Well…where to start. I wish I’d been documenting every move along the way, but I’m pretty sure I can recall all that’s been done and gone on since my “Saga” began. I really hope someone can help me figure out what’s going on. I ride year around and unfortunately had to miss the 2nd Annual Bob Jones Memorial Ride. I’m going nuts!!! Luckily my brother is letting me ride his bike for a benefit this weekend. So, thank you taking the time to read this.
First of all, let me give you some history on what’s been done to the bike. The carbs have been completely torn down, cleaned and rebuilt by a mechanic (on labor trade). See parts list & changes below. Also, refer to article (below) “Motorcycle Carburetor Jetting Recommendations” by Denny Zander. I referred to this article when deciding which jetting changes to make since I have the exact same bike & configuration as Mr. Zander other than exhaust type. Unfortunately, I apparently have another issue. The bike loses power on the highway when traveling at 75mph (5,000 RPMs) for a few minutes. I can usually downshift and start back again, but it has died and did not want to restart once. I originally thought it was a fuel starvation issue since the plugs were showing a lean condition and my new pipes were turning. I began by partially covering the holes in the air box with duct tape and opening up the Pilot screws. I then tried raising the Slide needles, but it became too rich on the low to mid range. So, I moved them back and drilled the Slides with the #39 drill bit. The interesting thing is that it did not do it one day when I took it out for a long ride to Lawrence after drilling the Slides, but it acted up on the way back to KC. BTW, I have tried popping the gas cap while it was bogging out to verify that it was not a venting issue. Recently, I’ve had the bike on a Dyno and verified there’s a severe issue at 5,000 rpms where it becomes very rich. I’m really hoping that they’re wrong and it’s not something to do with my pipes since I do not have the pipes that came with the bike. I wish I had $4-500+ dollars for a shop to diagnose the problem. I’m wondering if I’m having some sort of ignition breakdown. The shop with the Dyno has repaired my air box rather than duct tape it up before they ran the second set of “pulls”. So, needless to say the bike is really rich now and I haven’t had it out since it died on the way home. I did turn the Pilot jets in about ¾ turn, but the throttle isn’t near as crisp as it has been. It was sputtering a bit, but I probably didn’t let it warm up fully nor did I have time to ride it. I’m not sure where to go from here. Thoughts anyone?
Also, let me say again that I do ride year around and I have a full setup of Gerbing’s heated gear for those cold winter nights. Is there a possibility that I’ve damaged my electrical system in some way from the large amount of current draw? I do have a new Yuasa AGM battery, but I actually managed to zap it late one night. Just wanting to ‘cover all the bases’ so to speak. Thanks again for any feedback or suggestions. I’m NOT a mechanic, but I sure have gotten good at getting my carbs in an out. Thanks again and I apologize this is so long.
Marker
“I don’t want no pickle. Just want to ride my motorsickle.” Arlo Guthrie
MAC 4-1 header (Probably not as good as Jardine, but it sure did bolt on like a dream. )
K&N air filter in box (now intact)
New Yamaha Needles, Seats & Floats (Glad I got them at cost. Ouch!)
Increased 3 main jet sizes to 145
Increased 1 Pilot jet size to 45
Raised the slide needles, but it ran too rich at low to mid range so I lowered them back when I drilled the Slides. (At the time I still thought it was a starvation issue.)
Drilled Slides with Dyno jet kit #39 drill bit. (I was informed that the late Mr. Jones used this drill bit when modifying the Dyno kit #4101 for 80-83 XS-XJ.)
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Motorcycle Carburetor Jetting Recommendations.
Copied from the xs11 list @ www.xs11.com This should give you an idea of which way to go in regard to different Intake Exhaust configurations.
Note:
This document is based on Mikuni Carburetors. But the theory follows through on all carburetors. Be aware that Mikuni Main jets increment in steps of 2.5, Hitachi Main jets increment in steps of 2.0. Hitachi Main jets (screw in style [Yamaha XJ's] are available in sizes from 110-134 in increments of 2.0. All this means that if you find you need to go up 4 steps on the main jets according to this chart (2.5x4) the step up would be 10.0. For Hitachi mains the step up would be 5 jet sizes (2.0x5) since following this chart for Hitachi mains would put you at 8.0 which is very close to 7.5 which would be 3 steps according to this chart.
Jetting Recommendations
by Denny Zander
Here is a simple set of jetting guidelines that have worked for me. For those considering jet changes, this might help select a starting point.
1 jet size for custom 4 into 2 exhaust
2 jet sizes for 4 into 1 exhaust
1 jet size for K&N filter (single inside airbox)
1 jet size for drilling out the bottom of the airbox
2 jet sizes for both single K&N and drilled airbox
2 jet sizes for individual filters
2 jet sizes for no muffler (open header)
1 pilot jet size for every 3 main jet size increase
Add up all the jet size increases and subtract one. (Remember they go in steps of 2.5 for each jet size)
Under a mismatch condition, like individual filters and stock exhaust or 4 into 1 header with stock filter and air box, subtract an additional 1 jet size.
Check plug color often, sync carbs after each jet change, make sure the floats are set correctly, and seriously consider purchasing a Colour Tune. (See "Colortuning Carburetors" in the Maintenance Section).
Make sure your carbs are in perfect working order before making jet changes.
Example from my '79 XS1100 F:
Stock main jets: 137.5
Stock pilot jets: 42.5
2 sizes for 4:1 exhaust (Jardine)
1 size for single K&N
1 size for drilled air box
4 (main sizes) - 1 = 3 or 137.5 + (2.5 * 3) = 145.0
1 (pilot jet size) or 42.5 + (2.5 * 1) = 45.0
With this jet configuration I get 32-38 mpg on the open road, Smooth idle, very strong exceleration from off idle to 80+ mph, and steady pull past 120 mph. My "F" has 65K mile on it, of which I have put 33K with this jet configuration.
I have applied this to the '78-'79 carb set with great success. These guidelines should work for the '80-'81 carbs also. The only part I have not tested is pilot jet changing on the second generation carbs.
Happy Jetting
Additional info: decrease main jet size one step per 2000' above sea level.
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Well…where to start. I wish I’d been documenting every move along the way, but I’m pretty sure I can recall all that’s been done and gone on since my “Saga” began. I really hope someone can help me figure out what’s going on. I ride year around and unfortunately had to miss the 2nd Annual Bob Jones Memorial Ride. I’m going nuts!!! Luckily my brother is letting me ride his bike for a benefit this weekend. So, thank you taking the time to read this.
First of all, let me give you some history on what’s been done to the bike. The carbs have been completely torn down, cleaned and rebuilt by a mechanic (on labor trade). See parts list & changes below. Also, refer to article (below) “Motorcycle Carburetor Jetting Recommendations” by Denny Zander. I referred to this article when deciding which jetting changes to make since I have the exact same bike & configuration as Mr. Zander other than exhaust type. Unfortunately, I apparently have another issue. The bike loses power on the highway when traveling at 75mph (5,000 RPMs) for a few minutes. I can usually downshift and start back again, but it has died and did not want to restart once. I originally thought it was a fuel starvation issue since the plugs were showing a lean condition and my new pipes were turning. I began by partially covering the holes in the air box with duct tape and opening up the Pilot screws. I then tried raising the Slide needles, but it became too rich on the low to mid range. So, I moved them back and drilled the Slides with the #39 drill bit. The interesting thing is that it did not do it one day when I took it out for a long ride to Lawrence after drilling the Slides, but it acted up on the way back to KC. BTW, I have tried popping the gas cap while it was bogging out to verify that it was not a venting issue. Recently, I’ve had the bike on a Dyno and verified there’s a severe issue at 5,000 rpms where it becomes very rich. I’m really hoping that they’re wrong and it’s not something to do with my pipes since I do not have the pipes that came with the bike. I wish I had $4-500+ dollars for a shop to diagnose the problem. I’m wondering if I’m having some sort of ignition breakdown. The shop with the Dyno has repaired my air box rather than duct tape it up before they ran the second set of “pulls”. So, needless to say the bike is really rich now and I haven’t had it out since it died on the way home. I did turn the Pilot jets in about ¾ turn, but the throttle isn’t near as crisp as it has been. It was sputtering a bit, but I probably didn’t let it warm up fully nor did I have time to ride it. I’m not sure where to go from here. Thoughts anyone?
Also, let me say again that I do ride year around and I have a full setup of Gerbing’s heated gear for those cold winter nights. Is there a possibility that I’ve damaged my electrical system in some way from the large amount of current draw? I do have a new Yuasa AGM battery, but I actually managed to zap it late one night. Just wanting to ‘cover all the bases’ so to speak. Thanks again for any feedback or suggestions. I’m NOT a mechanic, but I sure have gotten good at getting my carbs in an out. Thanks again and I apologize this is so long.
Marker
“I don’t want no pickle. Just want to ride my motorsickle.” Arlo Guthrie
MAC 4-1 header (Probably not as good as Jardine, but it sure did bolt on like a dream. )
K&N air filter in box (now intact)
New Yamaha Needles, Seats & Floats (Glad I got them at cost. Ouch!)
Increased 3 main jet sizes to 145
Increased 1 Pilot jet size to 45
Raised the slide needles, but it ran too rich at low to mid range so I lowered them back when I drilled the Slides. (At the time I still thought it was a starvation issue.)
Drilled Slides with Dyno jet kit #39 drill bit. (I was informed that the late Mr. Jones used this drill bit when modifying the Dyno kit #4101 for 80-83 XS-XJ.)
------------------------------------------------------------------------------------------------------------------------------------------
Motorcycle Carburetor Jetting Recommendations.
Copied from the xs11 list @ www.xs11.com This should give you an idea of which way to go in regard to different Intake Exhaust configurations.
Note:
This document is based on Mikuni Carburetors. But the theory follows through on all carburetors. Be aware that Mikuni Main jets increment in steps of 2.5, Hitachi Main jets increment in steps of 2.0. Hitachi Main jets (screw in style [Yamaha XJ's] are available in sizes from 110-134 in increments of 2.0. All this means that if you find you need to go up 4 steps on the main jets according to this chart (2.5x4) the step up would be 10.0. For Hitachi mains the step up would be 5 jet sizes (2.0x5) since following this chart for Hitachi mains would put you at 8.0 which is very close to 7.5 which would be 3 steps according to this chart.
Jetting Recommendations
by Denny Zander
Here is a simple set of jetting guidelines that have worked for me. For those considering jet changes, this might help select a starting point.
1 jet size for custom 4 into 2 exhaust
2 jet sizes for 4 into 1 exhaust
1 jet size for K&N filter (single inside airbox)
1 jet size for drilling out the bottom of the airbox
2 jet sizes for both single K&N and drilled airbox
2 jet sizes for individual filters
2 jet sizes for no muffler (open header)
1 pilot jet size for every 3 main jet size increase
Add up all the jet size increases and subtract one. (Remember they go in steps of 2.5 for each jet size)
Under a mismatch condition, like individual filters and stock exhaust or 4 into 1 header with stock filter and air box, subtract an additional 1 jet size.
Check plug color often, sync carbs after each jet change, make sure the floats are set correctly, and seriously consider purchasing a Colour Tune. (See "Colortuning Carburetors" in the Maintenance Section).
Make sure your carbs are in perfect working order before making jet changes.
Example from my '79 XS1100 F:
Stock main jets: 137.5
Stock pilot jets: 42.5
2 sizes for 4:1 exhaust (Jardine)
1 size for single K&N
1 size for drilled air box
4 (main sizes) - 1 = 3 or 137.5 + (2.5 * 3) = 145.0
1 (pilot jet size) or 42.5 + (2.5 * 1) = 45.0
With this jet configuration I get 32-38 mpg on the open road, Smooth idle, very strong exceleration from off idle to 80+ mph, and steady pull past 120 mph. My "F" has 65K mile on it, of which I have put 33K with this jet configuration.
I have applied this to the '78-'79 carb set with great success. These guidelines should work for the '80-'81 carbs also. The only part I have not tested is pilot jet changing on the second generation carbs.
Happy Jetting
Additional info: decrease main jet size one step per 2000' above sea level.
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