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Enduro Intake/Carburetion - 2 stroke Jetting, Reeds, Air Filters, etc.


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  #1  
Old 02-25-2007, 11:40 PM
mattmax mattmax is offline
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Default LTR needle wear

I just went to raise the clip on my needle from the LTR kit in my 05 MC250 and noticed wear that I've never seen before on a needle, even an old one. On two of the tapers, the first being the straight section at top, and then the second one down from that. It looks almost like scuffing and has a rough looking finish. It has very little time on it.

I raised the clip, and power was definitely increased, but it stuck the needle lower in the bore, so this concerns me. Is the LTR needle made out of softer metal than a Keihin?

Also, unless I'm mistaken, my kit came with a 48 pilot, and I think stock was a 40 or 42. The air screw tunes in just fine, so I know the 48 is working, but I think it's only because the needle is very snug at the top. I know you can go with a bigger pilot if you run a fatter needle because fuel leaks past the needle even when the slide is closed. I'm afraid my needle is too fat and causing wear.

Anybody's kit come with a 48 and anyone see wear?


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05 GG MC250- street titled
95 Honda CR500- ported with bigger carb
81 Yam XS650- restored from rusted yard ornament
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"Old" bikes>
06 KTM 300XCW- returned-dealer scam- 1st owner seized & returned prior to sale to me as "new"
87 Yam YZ490
81 Yam IT250
84 Honda v45 Magna
74 Suzuki TS400
76 CZ motocross 250-bought new in 81-should have kept
74 Kawasaki G5100
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  #2  
Old 02-26-2007, 07:51 AM
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GMP GMP is offline
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Matt,

What you describe is a classic case of dirt being caught between the needle and the needle jet, causing scratches and wear. Sometimes it can cause the needle to jam and then you go for a real thrill ride. The dirt makes its way in through the vent hoses and settles in the float bowl. Split them and run the little filters. I've also had the stock GG throttle cable let water in that collected in the top of the slide. If for some reason the needle cannot "float" in the slide there will be a side load on the needle jet and cause wear, it must float. The LTR needles are made exactly like a standard Keihin needle.
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Old 02-26-2007, 07:04 PM
Eric K Eric K is offline
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I have had the LTR needle wear slightly and the nozzle jet (where the needle goes in) wear as well on my '01 XC300. I expect it was the result of a lot of use.

As GMP said, the LTR needle is just like Keihin.

If the nozzle jet is worn, you need a new carb or someone to replace the nozzle jet (good luck). A short term, marginally effective solution is to experiment with different needles to compensate for wear.
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Old 02-27-2007, 03:21 AM
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iancp5 iancp5 is offline
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Pretty sure the LTR is just a needle and shouldn't wear any different.
Yes LTR ship big pilots - I couldn't get them to work but many can. I run a 35 in my 300!
Vagaries of environment, production tolerances, pipe & fuel??

Quote:
Originally Posted by mattmax View Post
I just went to raise the clip on my needle from the LTR kit in my 05 MC250 and noticed wear that I've never seen before on a needle, even an old one. On two of the tapers, the first being the straight section at top, and then the second one down from that. It looks almost like scuffing and has a rough looking finish. It has very little time on it.

I raised the clip, and power was definitely increased, but it stuck the needle lower in the bore, so this concerns me. Is the LTR needle made out of softer metal than a Keihin?

Also, unless I'm mistaken, my kit came with a 48 pilot, and I think stock was a 40 or 42. The air screw tunes in just fine, so I know the 48 is working, but I think it's only because the needle is very snug at the top. I know you can go with a bigger pilot if you run a fatter needle because fuel leaks past the needle even when the slide is closed. I'm afraid my needle is too fat and causing wear.

Anybody's kit come with a 48 and anyone see wear?
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  #5  
Old 02-28-2007, 12:46 AM
mattmax mattmax is offline
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Default needle wear

I inspected the needle closely and found the place it is really worn is were it is inside the slide and goes up to the clip and never touches the bore.

It has circular rings grooved into the needle and it's has no more than 3 hours on it, and no more than 8 hours on the bike.

The taper is not really worn, just the shininess worn off it. I've never seen a needle do this.
__________________
05 GG MC250- street titled
95 Honda CR500- ported with bigger carb
81 Yam XS650- restored from rusted yard ornament
- - - - - - - - - -
"Old" bikes>
06 KTM 300XCW- returned-dealer scam- 1st owner seized & returned prior to sale to me as "new"
87 Yam YZ490
81 Yam IT250
84 Honda v45 Magna
74 Suzuki TS400
76 CZ motocross 250-bought new in 81-should have kept
74 Kawasaki G5100
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  #6  
Old 02-28-2007, 07:07 AM
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Post a photo. Does it fit/float in the slide normally?
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  #7  
Old 02-28-2007, 12:05 PM
jeffd jeffd is offline
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Hey Matt,
The LTR needles are made by keihin for the keihin pwk carb that you have in your bike. The part number is machined off to protect it from being copied; This accounts for the wear marks you see near the grooves for the clip. By the way, JD jetting machines the numbers off all their needles as well...

So, to answer your original question, no the LTR needle isn't softer than a keihin needle; It is a keihin needle!

The keihin pwk carb doesn't have a replaceable nozzle jet (where the needle fits into the carb body) - this is machined into the body of the carb. It could be this was a little rough causing some initial break-in wear on both the carb body and the needle; Or as Glenn said, you had some ingestion of dirt which caused some wear.


jeff
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  #8  
Old 03-01-2007, 07:46 AM
Eric K Eric K is offline
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Measure the straight diameter of the needle and check with LTR on what the straight diameter of your needle should be. That way you can determine how much the needle is actually worn.

As a note, my needle wore about 0.0005" over about 5 years.
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  #9  
Old 03-01-2007, 02:35 PM
RBD RBD is offline
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Quote:
JD jetting machines the numbers off all their needles as well...
JD makes his own needles....

Ron
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  #10  
Old 03-01-2007, 03:26 PM
jeffd jeffd is offline
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My bad - I assumed he did. I stand corrected. Thanks Ron.


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