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Old 11-01-2013, 05:50 PM   #1456
Sparrowhawk
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Quote:
Originally Posted by motolab View Post
So, if you changed a light bulb, and the engine ran poorly afterward, you would change it back?

Regards,

Derek
If you updated some wiring and changed out a working light bulb, and the light shines poorly afterwards, would you change it back?

That said, I agree that a faulty slip on muffler is not likely to have a great effect on idle but run fine otherwise.

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Old 11-01-2013, 06:04 PM   #1457
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Originally Posted by motolab View Post
The installation of a slip-on muffler alone will not make such a drastic change at idle that a mixture screw adjustment can't fix it. If it won't, it's a foregone conclusion that something else is wrong.

Regards,

Derek
I don't entertain your level of confidence.
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Old 11-01-2013, 07:32 PM   #1458
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Originally Posted by Boon Booni View Post
I don't entertain your level of confidence.
Test the continuity of the light bulb, run some water thru the pipe. First tighten the carb.

Pull the rag out of the air intake, ya I'm an idiot, yes I did that, ran a little, then quit.


b
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Old 11-01-2013, 07:38 PM   #1459
motolab
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Originally Posted by Boon Booni View Post
I don't entertain your level of confidence.
That means you need to gain some additional experience.

Regards,

Derek
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Old 11-01-2013, 10:07 PM   #1460
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Originally Posted by meat popsicle View Post
But now onto my issue: what makes bikes not want to stay running when cold, even with the enrichner?
tight valves can cause this
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Old 11-01-2013, 10:12 PM   #1461
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Originally Posted by 2 SPOT View Post
tight valves can cause this
This would be more pronounced when the engine is hot.

Regards,

Derek
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Old 11-01-2013, 10:19 PM   #1462
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not always.
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Old 11-01-2013, 10:25 PM   #1463
motolab
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not always.
Name such an instance and the reason for it.

Regards,

Derek
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Old 11-01-2013, 11:21 PM   #1464
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i cant, i pulled that suggestion right out of my ass with absolutely no background or experience to come up with it,,,,,

so sorry, wont happen again.
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Old 11-02-2013, 07:21 AM   #1465
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Question Lc4 bst 40

I posted this on the incredibly good LC4 thread, but maybe this one is more appropiate. Please excuse me for the copy&paste. Pictures here :
http://www.advrider.com/forums/showt...86958&page=312

I found some time to pull the carb after the bike completely stopped and refused to start again when at single track steepy sections. As usual, it run fine on road but not so fine offroad, continously stalling.
The carb was full of gas, flooded. Apart from the weird colour of the needle all the rest looked fine. The needle was in the 4th slot from the top ... before I lost its circlip.
A few of you suggested it could be running lean and causing overheating, but taking a look inside the carb it doesn't seem to be the case.
I was hoping to take a look at the jets but haven't yet succeeded in unbolting those butter screws at the bottom of the carb.
This carb is a second hand one with only 12k kms, plus another 5k I've done, since the older one needed a new slide&guide, membrane and needle at 50k kms.
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Old 11-02-2013, 07:30 AM   #1466
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Its real easy to misconstrue a person's tone or intent in forum posts. Thanks to all for throwing their ideas on the table.

2 SPOT: Valves were adjusted by Scuderia West less than a thousand miles ago (I didn't have time to do it myself, but they are a good shop). If they've slipped this quickly I'd be real pissed.

bill, I'm guess if the new exhaust can was a dud it would effect how it runs when hot too. I'm going to chase down these other possibilities first (air leaks, old jets, fine tuning). Although I would just pull the exhaust can and test cold start before running water through it.

Now I did have a paper towel blocking the engine-side carb boot; I'm pretty sure I pulled it before shoving the carb back on... but wouldn't a blockage enrich the air-fuel mixture like a true choke and interfere with warm running?
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Old 11-02-2013, 08:47 AM   #1467
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we'll assume the valves are in spec, next i go to a low float height.

my suggestions are based on the bike running fine before you didnt really do anything but a mild carb rebuild including moving the float height, you didnt say how the float height was set but i am thinking you found it high and lowered it?
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Old 11-02-2013, 10:45 AM   #1468
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Originally Posted by 2 SPOT View Post
we'll assume the valves are in spec, next i go to a low float height.
Low float height equals high fuel level.
Quote:
my suggestions are based on the bike running fine before you didnt really do anything but a mild carb rebuild including moving the float height, you didnt say how the float height was set but i am thinking you found it high and lowered it?
My advice to Meat was and is to set the float height between 14.7 (standard) and 16.7mm. The reason for suggesting more than 14.7mm is because the mixture on BST40-equipped 620-660 LC4s tends to be richer toward the bottom (in terms of rpm), which will be exacerbated by opening the airbox and installing the correct main jet to go with that (not recommended on pre-highflow models unless significant measures have been taken to prevent detonation), as well as by emulsion tube wear (over time). That said, a strange float height adjustment alone will not cause the idle mixture to be so far off that adjusting the fuel screw can't correct it. If anything, a low float height will cause the engine to start more easily from cold.

Regards,

Derek
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Old 11-02-2013, 12:41 PM   #1469
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Originally Posted by Tonicu View Post
I posted this on the incredibly good LC4 thread, but maybe this one is more appropiate.
I think this one is more appropriate.
Quote:
The carb was full of gas, flooded.
Make sure that the float seat is clean, free of debris and undamaged. Replace the float seat o-ring if it is cracked/shrunken/deformed/hardened or otherwise damaged. Replace the float needle if there is a witness line evident under magnification where the tip has been contacting the seat. Replace the float assembly if one or both of the floats are fuel logged (this happens rarely). Using a float height setting tool, set the float height to 14.7-16.7 mm.
Quote:
A few of you suggested it could be running lean and causing overheating, but taking a look inside the carb it doesn't seem to be the case.
Does it run better when the engine is cold, or when it is hot?
Quote:
I was hoping to take a look at the jets but haven't yet succeeded in unbolting those butter screws at the bottom of the carb.
Use a hand impact driver with the appropriately sized JIS bit. Reassemble with socket head cap screws.

Regards,

Derek
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Old 11-02-2013, 12:58 PM   #1470
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Originally Posted by Sparrowhawk View Post
Meat, is it possible that you have some schmutz in your idle jet or circuit causing it to be a little lean and unresponsive to adjustment?
I was thinking the same thing... If it has sat for any length of time perhaps it has ethanol poisoning.
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