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Old 07-04-2013, 09:21 AM   #9016
alonzo
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Quote:
Originally Posted by jspringator View Post
What is your altitude? I'm at 800 feet and I use the bike mainly for beach vacations. I'm wondering how your mods would work at 1,000 feet and below.

I just removed my snorkle last week and will try drilling my muffler today.
I'm at about 1400'.

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Old 07-04-2013, 10:21 AM   #9017
alonzo
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Quote:
Originally Posted by ER70S-2 View Post
I think that gasoline will eat your credit cards. Just like my ex-wife.
Maybe. I threw one in some gasoline for a few hours with no obvious deterioration but that doesn't mean that they will hold for the long term.

Fuel proof - maybe. Ex-wife proof - unfortunately not.

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Old 07-04-2013, 10:40 AM   #9018
Tom S
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Quote:
Originally Posted by alonzo View Post
... no obvious deterioration but that doesn't mean that they will hold for the long term.
1/8” pop rivet washers are 0.0575”, (1.4605 mm), thick.
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Old 07-04-2013, 10:54 AM   #9019
ER70S-2
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Quote:
Originally Posted by uniberp View Post
"Shimming the needle works for many carbed bikes."

I suspect that means uses more gas, richer?
A 20% drop in XT gas mileage is still good mileage. More heat too.
More power less life, broke stuff aside.
Yep, that would be more gas, richer. But not necessarily less life, too lean can mean running too hot.

Quote:
Originally Posted by alonzo View Post
Maybe. I threw one in some gasoline for a few hours with no obvious deterioration but that doesn't mean that they will hold for the long term.

Fuel proof - maybe. Ex-wife proof - unfortunately not.

-- alonzo


Quote:
Originally Posted by Tom S View Post
1/8” pop rivet washers are 0.0575”, (1.4605 mm), thick.
Kewl
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Originally Posted by Threewheelbonnie View Post
"BTW, I don't do style. It's a dirt bike, not some girlie dress-up thing." -
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Old 07-04-2013, 11:03 AM   #9020
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From a while back....
Quote:
Originally Posted by kingbee View Post
On Mikuni carbs with adjustable needles, the slots are 1mm apart. When I set up the carb on my (wife's) XT, I made a shim from a nylon R/C aircraft control horn. It is 1.5 mm thick, of the equivalent of a slot and a half if these bikes had adjustable needles which they don't.

You can probably find suitable small washers at a hardware store- take a micrometer or caliper with you to check thickness. Or you could order them here: http://www.motorcyclecarbs.com/Jet_N...12__P10478.cfm

Cheers,
Dave
Quote from above link....
"12 pack of jet needle shims. Fits all Keihin, and Mikuni CV (Vacuum Slide)Carbs. Shims are .5mm thick and 2 of them stacked together equal approxamately one needle clip position. Use these for richening up your midrange to compensate for air filter, and exhaust modifications that promote more air flow. "

Shipping to me would have been $9.50 Pass!
Another guy also suggested that "one thin electrical washer" would be the same thickness as the jet needle shims, .5mm.
Never looked for any electrical washers & not really sure what they are.
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Old 07-04-2013, 05:59 PM   #9021
J5k
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There's a lot of talk about shimming the needle. Does anyone know a) how this is done and b) what is shimming the needle doing? I've bumped up a few jet sizes and before installing the fmf, the bike ran damn near perfectly. Since the fmf install it seems to be running hotter/leaner but with noticably more punch down low. I liked how I didn't have to worry about heat once re-jetting. I'm going to go up one or two more sizes on the jets and see what the effects are but like I said, am very interesting in the reasoning behind the needle shims, and of course, how it's done. It's been about a year since I opened my carb so any pointers in doing the shim would be awesome.
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Old 07-04-2013, 06:42 PM   #9022
ER70S-2
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Shimmed needle (not an XT), the washer between the c-clip and plastic washer has been added. This raises the needle, making the mixture richer throughout the midrange.

Photo thanks to Jessepitt:
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Quote:
Originally Posted by Threewheelbonnie View Post
"BTW, I don't do style. It's a dirt bike, not some girlie dress-up thing." -
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Old 07-04-2013, 09:06 PM   #9023
alonzo
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Quote:
Originally Posted by J5k View Post
There's a lot of talk about shimming the needle. Does anyone know a) how this is done and b) what is shimming the needle doing? I've bumped up a few jet sizes and before installing the fmf, the bike ran damn near perfectly. Since the fmf install it seems to be running hotter/leaner but with noticably more punch down low. I liked how I didn't have to worry about heat once re-jetting. I'm going to go up one or two more sizes on the jets and see what the effects are but like I said, am very interesting in the reasoning behind the needle shims, and of course, how it's done. It's been about a year since I opened my carb so any pointers in doing the shim would be awesome.
B. Shimming the needle raises it slightly in the slide. This alters the way that the needle interferes with the main jet. Raising (by shimming) the needle allows more fuel to flow through the jet. Many of us that have made jet changes and open up the air/exhaust flow have experienced lean running at higher rpms. Shimming is a way to richen up the mid to upper range. Many carbs have notches in the top of the needle and an E-clip that allows easy adjustment. My XT carb does not.

A. All this assuming a fairly late model XT - mine's an `06.
Remove side panels and cowling under front of tank. Remove seat then tank. Now, on the left side of the bike: With pliers, pinch the clamp ears on the breather hose clamp where it connects to the valve cover and pull the hose off of the valve cover. Slip off (at the carb) the vent tube that runs from just over the fuel inlet on the carb to the inside of the top tube of the frame. With a 10mm open-end wrench loosen and remove the nut at the bottom of the rear most throttle cable at the carb (nut will stay on cable) and slip cable out (not totally necessary but it makes it easier to tilt the carb.) Then loosen the front most throttle cable (from the top -- the nut is captured below the fork on the carb bracket) and turn until nut is about 1/4" - 3/8" below the fork on the bracket then slip the adjuster out of the fork.
Loosen the two clamp screws on the rubber boots in front of and behind the carb (carb to engine boot and carb to airbox boot (you'll need a 3mm allen wrench for the front clamp and a phillips (or JIS) screwdriver for the rear one.))

Now tilt the top of the carb to the left exposing the 4 screws that hold the top cap of the carb on. Remove the screws while putting a little pressure on the cap (there's a spring under there.) At this point it would be a good idea to have a pan (or something) under the bike to catch anything that might get away from you such as the spring, the small O-ring that's under the cap where the tab on the right front of the cap is and the nylon washer that's under the spring (and on top of the needle inside the slide.

Carefully loosen the edge of the slide diaphragm and lift out the slide. Turn it upside down and the needle should fall out (Watch that nylon washer!)

Now you can shim the needle as shown in the photo in ER70S-2's post. http://www.advrider.com/forums/showp...postcount=9025

Re-assemble in reverse order. Before putting the slide back into the carb, drop the nylon washer in on top of the needle - it usually just falls into place. Then put slide into carb (Watch the little tab on the edge of the diaphragm -- it only goes one way.) Then put one end of the spring onto the peg on the inside of the cap, then guide the other end of the spring into the slide and seat the cap in place.

N.B., the two screws at the front of the cap (the ones securing the throttle cable bracket) are very slightly longer than the two at the rear of the cap. You do not need to remove the choke cable from the carb but you do need to be mindful of it. Also, the float bowl overflow tube that exits the carb just under the fuel inlet should be treated carefully (or removed.) Don't re-install the side panels or the cowling until after you've ride-tested the bike and are happy with how it runs. And,,, each time you go through this it gets easier!

Aarg! Does any of that make sense? I flunked tech writing 101!

-- alonzo
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Old 07-05-2013, 06:03 AM   #9024
J5k
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Awesome!! Thanks Alonzo for the detailed write-up, and ER70S-2 for the photo. I'm going to bump my jet sizes a bit hopefully this weekend. I realize now, why I've never run into the need to shim.... I hardly ever get into high rpms! My xt sees mostly dirt and slow, technical trails.
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Old 07-05-2013, 08:42 AM   #9025
alonzo
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Quote:
Originally Posted by J5k View Post
...
I realize now, why I've never run into the need to shim.... I hardly ever get into high rpms! My xt sees mostly dirt and slow, technical trails.
But, even there the improvement in mid-range power could be very useful.

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Old 07-05-2013, 09:18 AM   #9026
rhollamby
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Tire pressure

Hey guys, heading out to run about 1,000 miles through Colorado and Moab. Have a T63 on the front and rear wheel. What air pressure would you run on the pavement, with high heat of 100 degrees?

Off road all set, but not sure with ~800 miles of pavement at high heat. 20lbs?

Thanks
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Old 07-05-2013, 04:48 PM   #9027
woofer2609
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Quote:
Originally Posted by rhollamby View Post
Hey guys, heading out to run about 1,000 miles through Colorado and Moab. Have a T63 on the front and rear wheel. What air pressure would you run on the pavement, with high heat of 100 degrees?

Off road all set, but not sure with ~800 miles of pavement at high heat. 20lbs?

Thanks
I am unfamiliar with the T63, but PERSONALLY I would run near 26 psi minimum (dependent on load being carried) for longer runs at high speed over blacktop. The lower the pressure, the more friction between the molecules and the more heat that is generated leading to wear and possible blowout (probably unlikely below 15psi). Look on the sidewall for a max pressure. I believe that the xt itself recommends 26psi for the stock tires, what ever they were.
Just my opinion, FWIW
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Old 07-05-2013, 05:00 PM   #9028
Tom S
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Quote:
Originally Posted by rhollamby View Post
What air pressure ...
XT225 manual

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Old 07-05-2013, 06:17 PM   #9029
Dirt2Street
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Chain Tightening.

Alright guys, I can't find it anywhere. (I really should invest in a manual)
How much chain slack is there supposed to be in our chains with stock gearing.? And where do you measure it?
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Old 07-05-2013, 06:58 PM   #9030
Tom S
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Quote:
Originally Posted by Dirt2Street View Post
Alright guys, I can't find it anywhere. (I really should invest in a manual)
How much chain slack is there supposed to be in our chains with stock any
gearing.? And where do you measure it?
See posts 2075 thru 2079.
http://www.advrider.com/forums/showt...78968&page=139
Get pdf owners manual here, bottom of page. Free.
http://www.yamahamotorsports.com/spo...starthere.aspx
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