justyr
Thrash Merchant
Posts: 331
|
Post by justyr on Mar 28, 2012 22:13:47 GMT 1
Hi all - some of your expertise required here.
I have rescued & rebuilt a basketcase LC350 and am now running it in. At 4krpm (just at my rev limit for now) it starts to gurgle/4-stroke so I assume too rich as I go on to the needle. If I drop the needle a notch the issue goes away but the plug just ain't a nice coffee colour, more like a grey. Also in this setup I don't see a nice heat transition on the outer plug electrode, it's just a uniform hue.
With standard carb settings the plugs look perfect, it just doesn't run smoothly.
I'm wondering if there's something else I'm missing, maybe like a worn slide - could this cause this kind of problem, or what do you reckon? (the slides do show signs of wear on lower edges)
Advice welcome!
Justy
|
|
justyr
Thrash Merchant
Posts: 331
|
Post by justyr on Mar 28, 2012 22:14:54 GMT 1
PS - standard pipes and filter.
|
|
|
|
Post by bare on Mar 29, 2012 3:28:14 GMT 1
standard/oem jettings are designed as rich. Best review your carb rebuilds.. using oem parts :_)
|
|
|
|
Post by midlifecrisisrd on Mar 29, 2012 9:16:13 GMT 1
Standard bike should be good on standard settings.
Have you stripped and cleaned the carbs including the emulsion tubes.
Steve
|
|
justyr
Thrash Merchant
Posts: 331
|
Post by justyr on Mar 29, 2012 10:07:47 GMT 1
Good point Steve - I omitted to clean the emulsion tubes when I was in there. Just ignorance at the time. Looks like a carbs off job again. Just to check - the emulsion tubes are a mild force fit, so are driven out, yes? Best method for doing that?
Thanks,
J
|
|
|
|
Post by 47x on Mar 29, 2012 11:42:34 GMT 1
take out main jet,remove the washer,put back main jet and tap it lightly and the tube will fall out of the carb body. hth.richy
|
|
|
|
Post by arrow on Mar 29, 2012 13:23:27 GMT 1
The emulsion tubes can wear a bit around the top (fuel metering area), this will also cause the problem you have.
|
|
|
|
Post by Tone on Mar 29, 2012 17:22:37 GMT 1
What year is it ? If it is an early one without the engine stabiliser bars and with the carbs Id marked as 4L0 00 this was a well known problem.
|
|
btlc
Weekend rider
Posts: 74
|
Post by btlc on Mar 29, 2012 19:35:44 GMT 1
You could try a set of boyesen reeds, i think they could cure this problem.
|
|
justyr
Thrash Merchant
Posts: 331
|
Post by justyr on Apr 9, 2012 13:11:04 GMT 1
Update - just as Steve suggested, it appears that the problem is emulsion tube related. I 'popped' them out (much easier fitting the new ones) and lo/L0 one of them has bad deterioration of the brass around the needle entry hole. It'l like the metal has simply been eaten away by corrosion, time and/or petrol/chemicals. Now in the process of rebuild and will report back shortly how it now runs.
Carbs are stamped as later units and reeds are very good condition standard metal ones. New emulsion tubes sourced from Mr. Yamaha were about £30/pair btw.
Thanks for all the replies folks!
JR
|
|
justyr
Thrash Merchant
Posts: 331
|
Post by justyr on Apr 16, 2012 12:53:24 GMT 1
Confirmed btw - my running problem @ ~4k was indeed due to worn/corroded emulsion tube/s.
Thanks arrow/midlifecrisis for the tips, very helpful.
Justyr
|
|
