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Old 08-26-2012, 10:24 PM   #2221
Rx4Pain
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Super Sherpa TAT Ride Report

Wanted to let my fellow Super Sherpa owners, that I have started my Western TAT ride report over in the "Ride Reports" section. I have included the link here. I will be doing a day by day format, complete with pics.

http://www.advrider.com/forums/showthread.php?t=820992

Ken
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Old 08-26-2012, 10:49 PM   #2222
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Carb Jetting beyond Dr Jeckle

While preparing for the TAT, I had to look over my friends KLX300 and make sure it was ready for the trip. When I rode the KLX, I was amazed at the throttle response. It uses a constant velocity carb, but it has instant, and I mean instant...throttle rsponse, compared to my Super Sherpa.

His KLX has a couple of "free mods", that include removal of the air box cover and screen and a re-routing of a crankcase vent line. While i realize the KLX enjoy a bit more compression than our Sherpas, is it possible that even after the increased jet sizes most of us employ, that we are still a bit too lean to get "snappy" throttle response? I mean, I cant "snap my throttle open" and get the throttle response/hit that the KLX does...but I sure wish I had it!

I wondered if anyone else thought about this, or has tried a bit richer jetting?

Ken
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Old 08-27-2012, 06:30 AM   #2223
Hawk62cj5
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Not sure if many people have tried +2 jetting , I thought I read somewhere that someone switched out the carb with mixed results .

Oh I didnt see any pics of your loaded setup on the sherpa , could you post some here or on the RR .
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Old 08-27-2012, 08:56 AM   #2224
RayAlazzurra
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Holes?

I wonder about the hole in the vacuum piston. Some jet kits come with instructions to enlarge the hole. Ideally this causes the vacuum piston to respond more quickly when you move the butterfly valve. Enlarge the hole too much and you are left with the problem of a slide valve carb with no accelerator pump. (airflow increases instantly, but fuel flow lags) I'm reluctant to change anything about our Sherpa's jetting--it is stock and I like it.

The main jet size can be determined by full throttle runs with an O2 sensor, or perhaps plug readings if you prefer the shade tree method. Anyway, there are so many variables in carb tuning that I thought I would mention the hole...

Quote:
Originally Posted by Rx4Pain View Post
While preparing for the TAT, I had to look over my friends KLX300 and make sure it was ready for the trip. When I rode the KLX, I was amazed at the throttle response. It uses a constant velocity carb, but it has instant, and I mean instant...throttle rsponse, compared to my Super Sherpa.

His KLX has a couple of "free mods", that include removal of the air box cover and screen and a re-routing of a crankcase vent line. While i realize the KLX enjoy a bit more compression than our Sherpas, is it possible that even after the increased jet sizes most of us employ, that we are still a bit too lean to get "snappy" throttle response? I mean, I cant "snap my throttle open" and get the throttle response/hit that the KLX does...but I sure wish I had it!

I wondered if anyone else thought about this, or has tried a bit richer jetting?

Ken
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Old 08-27-2012, 09:26 PM   #2225
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Setup For The TAT

Well, I went pretty minimalist. I carried 30 oz of fuel in an MSR Bottle mounted where the tool tube used to be, I installed "Kristen's Rack" and had a single neavy nylon/canvas bag that sat on top of the rack. (Contained a sleeping bag, tent, air mattress, first aid kit, and an Ogio Tool Belt that contained 10-12 lbs of tools. Also contained 5 oz of engine oil, 4 oz of 90W oil for the chain, a spare plug, spare oil filter, spare air filter and a spare 21"tube) I carried the roll maps./maps in my backpack, along with 2 liters of water, 12 "lara Bars" toiletries, cell phone and one change of clothes..minus pants.

Here is a pic of the bike with those contents in the bag, the fuel bottle mounted and me with my small backpack.




Pretty light by TAT standards...but most ride reports had people saying..."I wish I would have brought less"....sooooo...

Posted several pics today of the second days ride.
Heres the link. http://advrider.com/forums/showthread.php?t=820992

I also wore all in one chest/shoulder/elbow protecter and knee pads under the riding pants.

Ken

Rx4Pain screwed with this post 08-28-2012 at 10:56 AM
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Old 08-27-2012, 09:28 PM   #2226
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Carb Jetting question

I pulled the seat today, and taped over half of the intake snorkel. Took the bike down the road, and it honestly felt as though the initial "snap" of opening the throttle was stronger/faster to respond. I will be looking into this a bit more. There is no reason that even this CV Carb should have so little "snap". It is fine as is, I just want a bit more initial umphhh when I twist the throttle open.

Ken
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Old 08-28-2012, 06:43 AM   #2227
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Thanks for the shout-out on the rack! I am glad that it worked well for you.
That is a great picture.
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Old 08-28-2012, 10:38 AM   #2228
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Thanks...I am still trying to figure out Photobucket and its options. Seems it diminishes the quality of my pics when I upload them. Sooo, I am trying to play with the upload sizing.

Thanks for taking care of me with the Rack!!

It worked very well, in fact, if you read the ride reports I am doing, you will see how sturdy the rack/Sherpa is compared to my friends. We found out the hard way! I have since had the rack over to "Line-X" where a bedliner coating was applied and I finished it all off with black allen bolts. I will post up a pic here so you can see it,





Ken

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Old 08-28-2012, 02:12 PM   #2229
RayAlazzurra
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Ooops--no drills

Hi Ken:

Please disregard my earlier advice to drill the slide lift hole. Do not drill. I did not realize that you were the guy in the middle of the big trip and this is not a mod that is easily undone.

Here's a safer shade tree trick that perhaps you already know. Set idle speed to spec and open the throttle in neutral so that the engine is spinning 3000 rpm or so. Suddenly let go of it so that the throttle snaps shut. If the rpm hangs a bit high momentarily before settling back to idle speed it is lean. If the engine bogs below idle speed and comes up it is rich. If it settles perfectly back to idle you are in the ballpark. Obviously this is a pilot jet tuning trick--not main jet.

I am confused as to your symptoms. Even with the stock jetting the bike should be a wee bet rich at 8000 feet, and you have richer jetting plus you have restricted the airflow...

Are you a vintage bike guy by any chance? Imo nothing beats a well tuned manual slide carb for responsiveness. CV carbs have the vacuum piston lag as mentioned earlier, and many efi systems have a secondary computer controlled butterfly. I think the 97 GSXR actually used vacuum pistons in the throttle bodies combined with efi in order to keep velocity high. The manual slide valve is a direct connection between your right hand and airflow.

The more I think about it the more I like the slide lift hole theory of enhanced responsiveness, but I would not do it mid trip.

Our 2009 Sherpa seems to carburate perfectly except when cold, but I have not tried it at altitude yet.



Quote:
Originally Posted by Rx4Pain View Post
I pulled the seat today, and taped over half of the intake snorkel. Took the bike down the road, and it honestly felt as though the initial "snap" of opening the throttle was stronger/faster to respond. I will be looking into this a bit more. There is no reason that even this CV Carb should have so little "snap". It is fine as is, I just want a bit more initial umphhh when I twist the throttle open.

Ken
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Old 08-28-2012, 03:02 PM   #2230
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When I had the Sherpa in Colorado, it ran like a champ after rejetting. Even before, it ran well except when cold. Didn't notice any lag, and I owned a CBR simultaneously to compare with. I brought the Sherpa back to Hawaii, and it runs great here too.
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Old 08-28-2012, 05:52 PM   #2231
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I am since home and messing with the jetting. (at sea level) I am posting the ride report in a "day by day" format so it reads easier/makes sense.(Didnt take a computer with) My Sherpa runs fine...it simply isnt as "snappy" off idle as I would like. So I threw the question out to see if there was anyone else that has considered this/improved it. I think one of my issues, is that I tend to like a lower idle speed...and if I were to raise the idle speed up to the 1300 or so it should be at (instead of the 800-900 its likely at) the bike will respond better as well. The 4 strokes with CV carbs just arent as "fantastic" as I would like, but the Sherpa runs nicely...just prefers a "roll on" vs a "quick snap" of the throttle down low. But, so do most 4 strokes.

I would add that the Sherpa ran fine even at 12,000 feet...it just lacked power...like any other bike. Never fouled a plug etc. and went up every hill I asked it to...no complaints...I am happy with how well the little bike did. But that was just a lack of power based on a lack of oxygen, not really a tuning issue. It simply didnt start with much power to begin with...poor little Sherpa!!

Ken
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Old 08-28-2012, 07:08 PM   #2232
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I also have one of your racks. It has worked great. Survived 3 trips to North Ga w/ a bunch of stuff strapped on it. Made a mounting plate so I could fit a 1 gal Rotopac fuel can on it. No squeeks,rattles,bends and great product. Thanks
Quote:
Originally Posted by Kristen View Post
Thanks for the shout-out on the rack! I am glad that it worked well for you.
That is a great picture.
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Old 08-29-2012, 08:43 AM   #2233
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Quote:
Originally Posted by flyinfuzz View Post
I also have one of your racks. It has worked great. Survived 3 trips to North Ga w/ a bunch of stuff strapped on it. Made a mounting plate so I could fit a 1 gal Rotopac fuel can on it. No squeeks,rattles,bends and great product. Thanks
Thanks! We have another rack almost ready to go if anyone is interested.

Ken- I like the way the bedliner finish looks on your rack. Neat idea.
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Old 08-30-2012, 10:50 PM   #2234
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Disabling the parking feature ??

Has anyone or does anyone know how to disable the parking feature on the sherpa ???

Needless to say, I accidently went past "lock" to PARK & the taillight was on for 9 hours draining my battery !!!

It jumped right off with a small jump starter security had, & I got home fine, but I don't want this happening again !!!!
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Old 09-01-2012, 07:01 PM   #2235
Rx4Pain
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Day 2, 3 and 4 posted

My Westerns TAT Ride Report continues...I have Day 1, 2, 3, and 4 posted. (Out of 10 days)

http://www.advrider.com/forums/showthread.php?t=820992

Ken
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