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Old 05-13-2010, 09:26 AM   #76
XRider
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I knew a #20 pilot shouldn't have been too lean. To seal the intake adapter (spigot) to the carb body I use red locktite.
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Old 05-13-2010, 07:45 PM   #77
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Still has a poor idle - dang!

The idle is still crummy (lean) even after my JB weld fix. I put the 25 pilot in before I found the vacuum leak and left it in there.

I can finally lean it out with the idle mixture screw if I turn it in - but I can also turn it out until it almost falls out and doesn't make much difference. I can also turn the idle speed knob until it almost falls out but it still idles at about 1900 ~ 2000rpm when it's warmed up. (Yes - the throttle is completely closed.)

Here's my theory: It must be the slide wear. The larger 25 pilot jet is feeding enough fuel along with the air around with the worn slide as it rattles back and forth too far at idle - and this is keeping my idle high.

I guess I shouldn't have bought a used carb off from a Harley. I can just imagine now how long it must have banged the slide back and forth with its "potato, potato" engine rhythm. Maybe I should just bite the bullet and get a new carb. I wonder if I can get the intake adapter off now that I JB welded it on...
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Old 05-14-2010, 04:18 AM   #78
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Slide ware seems unlikely, it rides in a pair of grooves on each side of the carb and would have to be very worn to let a significant amount of air pass. It does sound like you're leaking air somewhere though. Normaly if you can turn the fuel screw out more than 3 turns with no effect it means the pilot jet is too small but there's just no way a #25 is too small. If the slide is closed and the engine rpm is racing then you've got a moster air leak somewhere and it shouldn't be too hard to find. Check the vacuum port on the head. Some times the little hose barb is just plugged with a little rubber cap that can crack with age. Check the intake boot were it mates to the head. Make sure there aren't any nipples on the carb that don't have a hose or a cap on them. Although I'd bet $5 it's the vacuum port on the head, I'd check it first.

You can also get a re-build kit for your carb from Sudco:
KHS-001 order No. 002-985
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Old 05-15-2010, 05:21 AM   #79
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May I aslkconfirm a thing?

All I'm after is easyier starting after a lie-down, which happens far too often. There is enough power for me in the UK.

From what I've read, an Edlebrook would be the way to go?
(Bike starts easy when upright, I know the drill! Just after looping at Weston, took me 10 exhausting minutes.)
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Old 05-15-2010, 05:48 AM   #80
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Quote:
Originally Posted by Mudwiz
May I aslkconfirm a thing?

All I'm after is easyier starting after a lie-down, which happens far too often. There is enough power for me in the UK.

From what I've read, an Edlebrook would be the way to go?
(Bike starts easy when upright, I know the drill! Just after looping at Weston, took me 10 exhausting minutes.)
Before splashing the cash try a few techniques. I hated mine stalling on steep climbs as there was no way the PIG would start.
After a simple lie down. The race technique I had read about. Fully open the throttle bring the engine just over TDC and kick. Nine times out of 10 it will start.
If it did not I turned off the fuel, pulled in the decomp, kicked it through a few times, then tried to start it no throttle. If it started great if not I would fully open the throttle again and kick. Yes

One of the above works.
Turning off the fuel is a big help as long as you remember to turn it back on once it is going.

I also went for the Edelbrock second hand from the states but when it arrived it was a mikuni
Too much hassle to return it so I jetted and fitted the mikuni and absolutely love it.
Once I had tweaked the float height (something I should have done more with on the standard carb) it is easy to start 95% of the time. If not I use the techniques above.
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Old 05-15-2010, 11:59 AM   #81
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The Edelbrock is resistant to flooding but I just can't bring myself to recomend it. It falls short in so many other areas.
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Old 05-16-2010, 06:40 PM   #82
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Must still have a vacuum leak...

Quote:
Originally Posted by XRider
Slide ware seems unlikely, it rides in a pair of grooves on each side of the carb and would have to be very worn to let a significant amount of air pass. It does sound like you're leaking air somewhere though. Normaly if you can turn the fuel screw out more than 3 turns with no effect it means the pilot jet is too small but there's just no way a #25 is too small. If the slide is closed and the engine rpm is racing then you've got a moster air leak somewhere and it shouldn't be too hard to find. Check the vacuum port on the head. Some times the little hose barb is just plugged with a little rubber cap that can crack with age. Check the intake boot were it mates to the head. Make sure there aren't any nipples on the carb that don't have a hose or a cap on them. Although I'd bet $5 it's the vacuum port on the head, I'd check it first.

You can also get a re-build kit for your carb from Sudco:
KHS-001 order No. 002-985
Thanks XRider. Yes, I must still have a vacuum leak somewhere. Thanks for the part number. Already have a kit in there. My bike is a 2000 and the only port I see on the head has a bolt in it (its right next to the intake boot). I'm not sure if it came that way but the bolt is tight. I sprayed it at idle and no change. I can't perceive any change now when I spray the carb/intake area now that I JB Welded the adapter on.

I have a new rubber cap on the vacuum port on the carb. The hoses are on both bowl vents (shouldn't affect the idle anyway unless they were kinked or plugged).

Has to be something with the carb or intake boot itself because it idles perfect with the stock carb. Didn't touch anything else.

I did notice something tonight - the idle mixture screw can move side to side a lot (especially when I have it screwed out 3 1/2 turns). I put some teflon tape carefully around the threads and will see if it makes any difference on the ride to work in the morning.
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Old 05-16-2010, 09:52 PM   #83
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What throttle cables I should use with tm40? I have one from ktm and I'd like to install it to the xr.
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Old 05-16-2010, 10:59 PM   #84
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Quote:
Originally Posted by V-rider
Thanks XRider. Yes, I must still have a vacuum leak somewhere. Thanks for the part number. Already have a kit in there. My bike is a 2000 and the only port I see on the head has a bolt in it (its right next to the intake boot). I'm not sure if it came that way but the bolt is tight. I sprayed it at idle and no change. I can't perceive any change now when I spray the carb/intake area now that I JB Welded the adapter on.

I have a new rubber cap on the vacuum port on the carb. The hoses are on both bowl vents (shouldn't affect the idle anyway unless they were kinked or plugged).

Has to be something with the carb or intake boot itself because it idles perfect with the stock carb. Didn't touch anything else.

I did notice something tonight - the idle mixture screw can move side to side a lot (especially when I have it screwed out 3 1/2 turns). I put some teflon tape carefully around the threads and will see if it makes any difference on the ride to work in the morning.
Don't use teflon tape on your mixture screw or you'll be cleaning little bits of tape out of your jets forever more. On the fuel screw make sure the o-ring is on top with the little washer under it then the spring. Also, check to see if there is an old o-ring from the needle stuck inside the body

Lex
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Old 05-17-2010, 06:23 AM   #85
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I heard that Sudco has the cables.

Quote:
Originally Posted by Tctic
What throttle cables I should use with tm40? I have one from ktm and I'd like to install it to the xr.
I am waiting for a reply from Sudco and then I will let you know the part number, etc. I have looked thru their catalog but haven't found them listed individually. I do know that they sell them with their XR650R TM40 carb kit.

I modified an old set of cables to work on my carb. First I cut the carb side cable ends off to length. Then I cut the ends off two small clevis pins that were the exact same diameter as the old cable ends. I drilled and tapped the clevis pin ends for set screws. I soldered the ends of the cables so they wouldn't fray and so that the set screws had something more to dig into. I put the cable ends into the clevis pin holes and tightened the set screws. I used loctite on the set screws just in case. I pulled on the cables pretty hard to test them and they didn't budge.

I know it seems like a lot of work and buying the cables would be easier - but they are the dumb things I do when I can't wait to go for a ride.
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Old 05-17-2010, 06:37 AM   #86
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Yeah, I know that teflon tape is usually a bad idea.

Quote:
Originally Posted by XRider
Don't use teflon tape on your mixture screw or you'll be cleaning little bits of tape out of your jets forever more. On the fuel screw make sure the o-ring is on top with the little washer under it then the spring. Also, check to see if there is an old o-ring from the needle stuck inside the body

Lex
I just put a little strand near the bottom of the threads as to keep it out of the jet circuit. Didn't make any difference anyway so I took it back off this morning.

Yes, I have checked the o-ring numerous times. Made sure the order was right, no old o-ring pieces left up in there, etc.

Like I mentioned before, the kit I got from Sudco was missing the two smallest o-rings - one of them being the idle screw o-ring. I could have tried to use the old original o-ring, but I lost it when I was cleaning the carb.

I tried an o-ring out of my generic o-ring kit but it was too fat. I ended up just using the o-ring out of my parts Keihin carb for now and it seems to fit fine.
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Old 05-17-2010, 08:24 PM   #87
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Since we're talking carbs and vacuum leaks a cool way to search for leaks that doesn't make so much of a mess is with a propane torch. Turn it all the way up but don't light it. Use the tip of the torch to probe around for vac leaks. The gas from the torch is easily drawn in and the engine speed will go up. Of course you have to use this method outside.
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Old 05-18-2010, 03:59 AM   #88
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Fuel consumption

So does a pumper make much difference in fuel consumption? Fuel range is very important for me.
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Old 05-18-2010, 06:48 PM   #89
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Thanks for the reminder.

Quote:
Originally Posted by XRider
Since we're talking carbs and vacuum leaks a cool way to search for leaks that doesn't make so much of a mess is with a propane torch. Turn it all the way up but don't light it. Use the tip of the torch to probe around for vac leaks. The gas from the torch is easily drawn in and the engine speed will go up. Of course you have to use this method outside.
I remember hearing about the propane method before. I have never had the opportunity to try it - until now.

But I took the carb back off yesterday because I was tired of the high idle. After I got it off I happened to notice that the throttle stop screw on the top was still holding the slide open a little even though I had the idle speed screw on the side backed all the way off. I backed that top screw out until it didn't touch anymore. I am going to go thru the carb again and make sure all the passages are clean before I put it back on.

For the meantime, I put the stock carb back on so I can ride the bike. Perfectly smooth idle. Must be something with that TM40...

Also, I will post my mileage after I get the TM40 working. Right now with the re-jetted stock carb I am getting 43mpg around town.
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Old 05-25-2010, 01:16 AM   #90
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Will the ktm lc4 throttle cables fit to xrr? They'll fit to tm40 but are they long enough?
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