Sebastian's Bike Restore

[Sebastian_99]

Sounds like a plan!

[3Phase]

XS11.com Forums | Idle Talk Forum | Links | Colored Wiring Diagrams


I have another one for my '79 Special that I'm working on to draw up another color schematic.

I have to check the wiring harness and make sure the manual and the harness match up before I get carried away.

[Bonz]

Many Gracias!

[3Phase]

Many Gracias!

Nay dada.

[skids]

Cool, let's plan on Friday. If I'm at your place at 3 PM will that work?

Skids, want to join in?

I will be there. 3pm

[Bonz]

See U then!

[Sebastian_99]

Finally had a spare moment to take the bike out for another test ride after Skids and I worked on a few things. Bike still seems sluggish, though not as much as before (did a bit of fuel line rerouting to eliminate slight kinks). I'm wondering what everyone's experience is with altitude changes and carb jetting. When I was riding really consistently I was at about 6k feet. I've since then moved and am living/riding at 9k feet. Would the altitude difference affect performance that much? I mean, the bike is running alright but just doesn't seem to have the get up and go it used to have.

[TopCatGr58]

I found this formula on a Hayabusa sport bike site, not sure where it came from, but here it is.

HP Loss = (elevation in feet x 0.03 x horsepower @ sea level)/1000

Plugged in 9000 into it,Used 95HP for start, ended up with ~25Hp loss!? Seems like alot, but the air is quite a bit thinner up there, less O2 to burn with the fuel!

Found the same type of formula on the Nissan 350Z site, but it used only 1 Hp, and the result was a percentage of loss. You then multiply that percentage by the stock 95 HP and it gives you the same result as the first formula. IT said a ~27% loss which equals a ~25Hp loss!

T.C.

[Sebastian_99]

I found this formula on a Hayabusa sport bike site, not sure where it came from, but here it is.

HP Loss = (elevation in feet x 0.03 x horsepower @ sea level)/1000

Plugged in 9000 into it,Used 95HP for start, ended up with ~25Hp loss!? Seems like alot, but the air is quite a bit thinner up there, less O2 to burn with the fuel!

Found the same type of formula on the Nissan 350Z site, but it used only 1 Hp, and the result was a percentage of loss. You then multiply that percentage by the stock 95 HP and it gives you the same result as the first formula. IT said a ~27% loss which equals a ~25Hp loss!

T.C.

Well that certainly explains a lot! I had a suspicion that it was elevation related. I imagine a good way to test this is ride down to lower elevation and test it.

[motoman]

Finally had a spare moment to take the bike out for another test ride after Skids and I worked on a few things. Bike still seems sluggish, though not as much as before (did a bit of fuel line rerouting to eliminate slight kinks). I'm wondering what everyone's experience is with altitude changes and carb jetting. When I was riding really consistently I was at about 6k feet. I've since then moved and am living/riding at 9k feet. Would the altitude difference affect performance that much? I mean, the bike is running alright but just doesn't seem to have the get up and go it used to have.

Just to advise, there is a 3% loss of horsepower for every 1000ft. of elevation. So, in your bikes case, the jump from 6k feet to 9k ft.elev. resulted in an additional 9% loss of horsepower. You also have less total vacuum draw. At that 9k elev. the total vacuum draw is gonna be in the neighborhood of 17in. of vacuum draw total. Being the carbs are vacuum slide operated, they tend to compensate for altitude increases. I suspect at this point, the idle mixtures AND the sync have not been done correctly. The lean-drop method IS the correct way of setting idle mixtures. If the idle mixtures are done CORRECTLY, then the carb sync will come out done correctly. Idle mixture settings not done correctly WILL affect carb-sync.....even though carb-sync may show even across all four carbs. No guessing here....just a fact!. Second issue can cause bike to be somewhat of a 'slouch' also. That be float levels. All eight floats HAVE to be identically set and perfectly match each other. If that were to need corrected, then idle mixtures and sync HAVE to be re-done...period. Would like to know what you find that is, or has been done incorrectly. Bottom line, if stock jetting still, jetting associated with pilot jets or main jets is NOT the issue. Just know this since I've run my Venturer from when purchased new, everthing from sea-level to well over 12k.....always and still stock jetting.

[Sebastian_99]

Just to advise, there is a 3% loss of horsepower for every 1000ft. of elevation. So, in your bikes case, the jump from 6k feet to 9k ft.elev. resulted in an additional 9% loss of horsepower. You also have less total vacuum draw. At that 9k elev. the total vacuum draw is gonna be in the neighborhood of 17in. of vacuum draw total. Being the carbs are vacuum slide operated, they tend to compensate for altitude increases. I suspect at this point, the idle mixtures AND the sync have not been done correctly. The lean-drop method IS the correct way of setting idle mixtures. If the idle mixtures are done CORRECTLY, then the carb sync will come out done correctly. Idle mixture settings not done correctly WILL affect carb-sync.....even though carb-sync may show even across all four carbs. No guessing here....just a fact!. Second issue can cause bike to be somewhat of a 'slouch' also. That be float levels. All eight floats HAVE to be identically set and perfectly match each other. If that were to need corrected, then idle mixtures and sync HAVE to be re-done...period. Would like to know what you find that is, or has been done incorrectly. Bottom line, if stock jetting still, jetting associated with pilot jets or main jets is NOT the issue. Just know this since I've run my Venturer from when purchased new, everthing from sea-level to well over 12k.....always and still stock jetting.

Bonz was the guy who helped me out with the carb sync. I imagine he did it correctly, this type of stuff is out of my league knowledge-wise. I'll wait till he gets back from his trip and see what he has to say about the way we synced the carbs.

[motoman]

Bonz was the guy who helped me out with the carb sync. I imagine he did it correctly, this type of stuff is out of my league knowledge-wise. I'll wait till he gets back from his trip and see what he has to say about the way we synced the carbs.

Well, from your input, I'm sure the bike would do just fine either way. If interested, I'll have my Mogan Carb Tune with us in the car. If it were to work out, we could pull the seat and flip the tank around backwords, hook back up the fuel lines and just check things associated with the mixture settings and re-sync. Would just hope the fuel lines, if you cris-crossed them to tank are long enough to re-attach them to tank.....JAT to maybe consider. Also, Bonz has a real shorty screw-driver to reach in there if needed without removing tank/seat.

[Sebastian_99]

Well, from your input, I'm sure the bike would do just fine either way. If interested, I'll have my Mogan Carb Tune with us in the car. If it were to work out, we could pull the seat and flip the tank around backwords, hook back up the fuel lines and just check things associated with the mixture settings and re-sync. Would just hope the fuel lines, if you cris-crossed them to tank are long enough to re-attach them to tank.....JAT to maybe consider. Also, Bonz has a real shorty screw-driver to reach in there if needed without removing tank/seat.

Let's play it by ear. I'll see how it rides out to Kremmling. If its behaving any better or worse we can take a look. Appreciate all the help!

[motoman]

Let's play it by ear. I'll see how it rides out to Kremmling. If its behaving any better or worse we can take a look. Appreciate all the help!

Most welcome! I would suggest run a few ounces of Sea-Foam with that first initial fill-up before heading out to Kremmling and again with fuel fill-up on the way there. That trip up to Kremmling will give you a chance to feel any difference, if there is any.

[Sebastian_99]

Most welcome! I would suggest run a few ounces of Sea-Foam with that first initial fill-up before heading out to Kremmling and again with fuel fill-up on the way there. That trip up to Kremmling will give you a chance to feel any difference, if there is any.

I have a can already set aside!