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Post by loudy on Mar 5, 2020 14:26:02 GMT 1
I've recently acquired a 31k LC2. It was restored about 6 years ago. The chap never managed to start the bike after a full recondition of the engine Inc crank rebuild and rebores etc. It then stood until I bought it.
I have now got it running after some help from here with regard to CDI/flywheel/stator combinations.
It does run roughly, so I decided to clean the carbs. They're filthy! ( Should of done it before attempting to start it)
For some reason the carbs have been fitted with 260 mains, so I'll change them back to 240's (they are 31k0 carbs). The rest of the bike appears to be standard.
My question is about the brass balls?
Where are they? Should I drill them? Why should I drill them? Do I replace them once I've drilled them ? Why are they there??
Can someone explain please!!!?
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Post by loudy on Mar 6, 2020 7:33:17 GMT 1
Are they the two balls that blank two of the three holes in the inlet of the venturi ?
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Post by midlifecrisisrd on Mar 6, 2020 10:04:09 GMT 1
It's the bigger of the 2 at the inlet
Steve
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Post by midlifecrisisrd on Mar 6, 2020 10:12:22 GMT 1
They are there to blank off the drilling point as they can't drill round corners so drill from 2 directions and meet in the middle then blank off the entry point at the carb mouth so the air correction circuit is fed with air from the outside rather than at the inlet
The air passage goes from behind the emulsion tube, into the area behind the ball then over to the air passage that runs from the vent pipe on the side of the carb down to the float bowl
If you strip the carb bare then put your thumb and fore finger over the top and bottom of the emulsion tube section of the carb then a finger on the other hand over the hole into the float bowl area and blow in the vent tube and remove a finger from the emulsion tube passage you should be able to blow air freely through
Doesn't tell you if partially blocked but you get the idea
Steve
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Post by loudy on Mar 6, 2020 11:00:35 GMT 1
Thank you very much, very helpful.
I've just ultrasonically cleaned them both so why spoil the ship for hap'neth of tar and all that piffle.....
Cheers..
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Post by Gunny on Mar 6, 2020 19:20:07 GMT 1
They are there to blank off the drilling point as they can't drill round corners so drill from 2 directions and meet in the middle then blank off the entry point at the carb mouth so the air correction circuit is fed with air from the outside rather than at the inlet The air passage goes from behind the emulsion tube, into the area behind the ball then over to the air passage that runs from the vent pipe on the side of the carb down to the float bowl If you strip the carb bare then put your thumb and fore finger over the top and bottom of the emulsion tube section of the carb then a finger on the other hand over the hole into the float bowl area and blow in the vent tube and remove a finger from the emulsion tube passage you should be able to blow air freely through Doesn't tell you if partially blocked but you get the idea Steve This needs a drawing as to the loaction of fingers, or a nice picture with arrows on |
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Post by loudy on Mar 7, 2020 10:56:19 GMT 1
They are there to blank off the drilling point as they can't drill round corners so drill from 2 directions and meet in the middle then blank off the entry point at the carb mouth so the air correction circuit is fed with air from the outside rather than at the inlet The air passage goes from behind the emulsion tube, into the area behind the ball then over to the air passage that runs from the vent pipe on the side of the carb down to the float bowl If you strip the carb bare then put your thumb and fore finger over the top and bottom of the emulsion tube section of the carb then a finger on the other hand over the hole into the float bowl area and blow in the vent tube and remove a finger from the emulsion tube passage you should be able to blow air freely through Doesn't tell you if partially blocked but you get the idea Steve This needs a drawing as to the loaction of fingers, or a nice picture with arrows on If nothing else, by utilising steady mouth pressure, careful use of the choke nob and alternating the finger/thumb combinations as described, I've blown a great rendition of 'greensleeves'! |
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Post by loudy on Mar 7, 2020 16:54:10 GMT 1
Top advice!
Just drilled the left carbs ball out.. completely blocked...took half hour of faffing with bits of wire and cotton buds to shift the crap...
I'll check the right hand too, although I can blow through it....I get a G sharp from the right but a flat D from the left now. If I could contort my fingers enough, I can learn Stairway to Heaven by playing both at once!
Great forum.
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Post by beardy on Mar 7, 2020 17:09:20 GMT 1
Pipe that man on board
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Post by Gitram on Mar 13, 2020 19:29:04 GMT 1
that's one way to "tune" a motor...
marti
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Post by roger on Apr 6, 2020 8:14:18 GMT 1
They are there to blank off the drilling point as they can't drill round corners so drill from 2 directions and meet in the middle then blank off the entry point at the carb mouth so the air correction circuit is fed with air from the outside rather than at the inlet The air passage goes from behind the emulsion tube, into the area behind the ball then over to the air passage that runs from the vent pipe on the side of the carb down to the float bowl If you strip the carb bare then put your thumb and fore finger over the top and bottom of the emulsion tube section of the carb then a finger on the other hand over the hole into the float bowl area and blow in the vent tube and remove a finger from the emulsion tube passage you should be able to blow air freely through Doesn't tell you if partially blocked but you get the idea Steve |
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Post by roger on Apr 6, 2020 8:27:49 GMT 1
Hi Steve and Loudy
I removed these balls and replaced them with what I thought were 5mm items. The RH one is fine but the LH ball went in a little too far in and it could be pressed in with just light finger pressure. I thought I should try and get it out to put a proper fitting one in. First school-boy error.
As I tried to drill a hole in the 'recessed' ball it went further and further in. As I tried, more and more desperately to recover the ball (think Rowan Atkinson Mr Bean Film when he wiped the priceless oil painting clean...) it went on in until it was probably 10-15mm in. To make it really bad, I then tried larger drill bits to try and break up the ball to get the pieces out and just ended up with a mass of brass - and - ally shavings eveyrwhere - including the float bowl!!! Aaarrghhhh!!!!
In the end, I sensed I should stop.
I can't start the machine at present (it's in winter storage) I was just prepping it for summer use (I'm in a real icy country) - so I can't test it. Do you think I've ****ed the whole carb? I can't find anywhere online that even touches on maintenance of this part of the carb and anyway I haven't got the workshop to even attempt any further recovery.
PS Did anyone produce a drawing or pic with arrows to illustrate your post on blowing through emulsion tubes etc?
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Post by midlifecrisisrd on Apr 6, 2020 8:46:00 GMT 1
If you have knocked it that far in you are blocking it
Even if loose you would have been better putting some epoxy or even thread lock on it to stop it moving
As long as you can seal the case back up and leave the passage clear you should still be ok but you need to get that ball out somehow
Steve
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Post by loudy on Apr 6, 2020 15:23:54 GMT 1
Oh dear.!
Have you managed to remove the remainder of the ball?
If not, I'd try to blow it out with compressed air if it's fairly loose.
I think others will agree, try to seal the hole with a small grub screw with a little loctite once you've removed any swarf etc. Especially if the hole has oversized slightly.
Simon.
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Post by roger on Apr 7, 2020 16:52:26 GMT 1
I fear I've gone an' ****ed it. There's no way I can get the remains of the ball out - it's not loose or crumbly, just nicely moulded in with the ally... I'll put another ball in generously coated in epoxy and we'll see what happens when I get it outside to try and start it. Thanks all.
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Post by loudy on Apr 7, 2020 21:55:31 GMT 1
The remains of the ball have to be removed if they've been pushed down the hole, otherwise the tiny jet behind will be blocked by its presence.
Can you make a bush/drill guide with a 2.5mm hole through the centre and an outside diameter of 4.5mm? Pop this in the hole and gently drill the remainder of the ball until you break through it, being very careful not to touch the jet behind..
You can then try using an easy out to remove the remaining debris or try gluing the shank of the 2.5mm drill into the ball to give you something to pull it with?
Even screwing an M3 taper tap into the 2.5mm hole will give you something to pull it with..
Good luck!!!!
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Post by shaunthe2nd on Apr 8, 2020 9:35:45 GMT 1
You need to remove it otherwise the bike won't rev. If you can't remove it just buy another carb body and transfer your internals across.
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Post by muttsnuts on Apr 8, 2020 9:45:40 GMT 1
I fear I've gone an' ****ed it. There's no way I can get the remains of the ball out - it's not loose or crumbly, just nicely moulded in with the ally... I'll put another ball in generously coated in epoxy and we'll see what happens when I get it outside to try and start it. Thanks all.
if you send it to me I'll see if I can machine it out for you, but no promises as I've no idea how bad the situation is, but given I've serviced over 300 pairs of carbs over the years, if I can't get it out, then I suspect nobody can, I am assuming you used brass balls and not ball bearings, if its ball bearings then I can't remove them as they need a special drill which are very expensive and they don't do one long enough in the size I need |
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Post by dougw on Mar 12, 2021 12:26:48 GMT 1
They are there to blank off the drilling point as they can't drill round corners so drill from 2 directions and meet in the middle then blank off the entry point at the carb mouth so the air correction circuit is fed with air from the outside rather than at the inlet The air passage goes from behind the emulsion tube, into the area behind the ball then over to the air passage that runs from the vent pipe on the side of the carb down to the float bowl If you strip the carb bare then put your thumb and fore finger over the top and bottom of the emulsion tube section of the carb then a finger on the other hand over the hole into the float bowl area and blow in the vent tube and remove a finger from the emulsion tube passage you should be able to blow air freely through Doesn't tell you if partially blocked but you get the idea Steve Great info on this site, thanks all. My emulsion tubes where both totally blocked and caked in crap, cleaning them made little or no difference to to the 4 to 6k flat spot. My carbs are original 4L00 ones modified with aluminium blanking plugs where the brass ball are on other models. Grub screws arrived today, not taken out the aluminium blanks fitted in my carbs where the brass balls would be yet , but blocking off the emulsion tube and carb inner vent and blowing through a pipe attached to the outer vent I could get a little amount of flow when blowing hard. (free innuendo there) Attaching the same tube to a 210 main jet and blowing I get a lot more flow , so if the inner drilling is 0.5 mm I guess the drillings are pretty blocked. |
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