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Old 12-18-2012, 09:18 PM   #1
Umarth OP
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Question Couple of LC4 questions

Got a few questions on the LC4 that I'm hoping some kind souls on here will be able to clarify for me.

1. Replacing the cam bearings, I inspected the cam shaft and noticed this:

That pin seems pretty rought arround the edges and I'm wondering if this is normal wear? Heavy wear? About done?

2. Taking off the radiators, I noticed that the two lower "tabs" that bolt the radiator to the frame have snapped off at the weld. Since this part of the frame holds oil I'm wondering if there are any special conciderations to weld them back on?

3. Is this normal and expected amount of gunk on a cylinder? If not, what would it be symptomatic of?


4. The spark plug's color, is it what it should be?


thanks guies...
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Old 12-18-2012, 10:08 PM   #2
gunnerbuck
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The plug looks like the proper light brown color...

The carbon deposit on the piston top looks pretty light to me though a bit tarry ... How do the deposits look in the valve passageways? Do the valves still sit above the seats or are they more flush with the surface {a bit recessed}?


The leading edge of your decomp pin does look pretty worn... I compared it to one I have sitting here that was so worn that it no longer engaged the cam: Yours looks like it is about 25% better than my completely shot unit... Was it still working? Did it make the klick to set itself when you rolled the engine over? If you plan to do a long trip with the bike then it would be worthwhile to replace the whole cam/decomp unit...
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Old 12-19-2012, 03:08 AM   #3
Tseta
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Urmath, are you by chance running Holan crash bars on your LC4? This is related to the radiator mounting tabs...

Cheers,

Tseta
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Old 12-19-2012, 09:10 AM   #4
Umarth OP
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Quote:
Originally Posted by Tseta View Post
Urmath, are you by chance running Holan crash bars on your LC4? This is related to the radiator mounting tabs...

Cheers,

Tseta
At the moment, nop; dont have any crash protection on the bike.
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Old 12-19-2012, 01:34 PM   #5
bisbonian
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Even if the pin wears completely out, you can still use the decompression lever on the bars, right?
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Old 12-19-2012, 04:42 PM   #6
gunnerbuck
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Quote:
Originally Posted by bisbonian View Post
Even if the pin wears completely out, you can still use the decompression lever on the bars, right?
Yes you can... I believe the original LC 4 engine did not have an autodecomp at all and were kickstart only... When the E-start was added so was the auto decomp so both would work in harmony to keep the start procedure simple for the operator {just push the button}...
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Old 12-19-2012, 09:09 AM   #7
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ah crap!

Quote:
Originally Posted by gunnerbuck View Post
The plug looks like the proper light brown color...

The carbon deposit on the piston top looks pretty light to me though a bit tarry ... How do the deposits look in the valve passageways? Do the valves still sit above the seats or are they more flush with the surface {a bit recessed}?


The leading edge of your decomp pin does look pretty worn... I compared it to one I have sitting here that was so worn that it no longer engaged the cam: Yours looks like it is about 25% better than my completely shot unit... Was it still working? Did it make the klick to set itself when you rolled the engine over? If you plan to do a long trip with the bike then it would be worthwhile to replace the whole cam/decomp unit...
Here's a pic of the head before getting it cleaned:


As for the pin, yup it was still doing it's job. But I'm leaving on very long trip in spring (100k+) so if it shows sign of needing to be replaced then I'll replace it. I only asked the question in the event that the pins always look that way and dont deteriorate past that point: no sense in replace parts just for the fun of it. I wonder if I could spin the pin arround? I could then carry it as a spare. Maybe...
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Old 02-10-2013, 11:09 AM   #8
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Tuning the carb & Fuel air ratio sensor

Came upon an interesting product today: a wide band Air/Fuel digital gauge plus sensor and controler for 200$.

I'm wondering if this would be a good thing to add to the lc4 for my coming trip.
Since the bike will be going to lots at varing altitudes (front coastals to higher regions of patagonia) and me not being use to tunning carbs. Would having a display telling me just how lean/rich the mixture is help in keeping the carb properly setup?

And if so, would the 14.7 to 1 (i think) be where I would want to keep it at all times or would I rather err on the the rich side a bit?
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Old 02-10-2013, 11:46 AM   #9
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Quote:
Originally Posted by Umarth View Post
Came upon an interesting product today: a wide band Air/Fuel digital gauge plus sensor and controler for 200$.

I'm wondering if this would be a good thing to add to the lc4 for my coming trip.
Since the bike will be going to lots at varing altitudes (front coastals to higher regions of patagonia) and me not being use to tunning carbs. Would having a display telling me just how lean/rich the mixture is help in keeping the carb properly setup?

And if so, would the 14.7 to 1 (i think) be where I would want to keep it at all times or would I rather err on the the rich side a bit?
The short answer is no.

Regards,

Derek
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Old 02-10-2013, 11:22 PM   #10
bmwktmbill
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UM,
The BST40 is designed to self compensate for altitude changes, the KTM factory is 60 miles from the Alps where they test their motorcycles like the Adventure series.

You can play with this map to see the relationship between the factory at Mattigofen and the Alps.

http://www.maplandia.com/austria/obe...n/mattighofen/

bill
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