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Post by lcstevie on Sept 1, 2022 18:19:02 GMT 1
Hi All, Anyone got any ideas. I have just got out on the bike for the first time since buying it as it needed to be registered for UK. It is a 350LC4Lo which has been fully rebuilt. I have seen pictures of the stripdown so am sure the work has been done. New pistons, Rings, Bearings, Cables, electrics etc. The carbs have been ultasonically cleaned and rebiult. It starts fine and sounds sweet on tick over and revving but it runs like shite whilst riding it i.e under load. Feels like is running on choke all the time. The engine is spluttering after about 2000 revs through all the gears. Cant get more than 40mph as it splutters so bad.
Also it has Motul Transoil 10w-30 mineral in it. The manual says it should use 10W-40. I know its a temperature rating figure but was wondering if this was being used whilst the bike is being run in.
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Post by geoffb on Sept 1, 2022 18:38:31 GMT 1
Sounds carburettor related to me.
There’s lots of advice on here regarding proper set up and jetting if you search the forum.
Good luck
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Post by dusty350 on Sept 1, 2022 19:26:33 GMT 1
Did you ride it before you bought it ? Has it started playing up since ? Basically, do you know it ran without issues when you bought it ? And what is the spec ie, pipes, airbox/filters etc, and has it been jetted depending on the spec ? Dusty ![:)](//storage.proboards.com/forum/images/smiley/smiley.png)
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Post by abar121 on Sept 1, 2022 19:30:25 GMT 1
As Dusty says, more info needed.
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Post by arrow on Sept 1, 2022 19:33:54 GMT 1
Don't have any concerns about the trans oil. Lots of people are using what's in yours. For your info. the factory recommended oil is 10w/30 anyway.
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Post by shaunthe2nd on Sept 1, 2022 19:44:25 GMT 1
Did the previous owner do the balls out clean of the air circuit on the carbs? Lots of info on here, but as said above could be lots of things.
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Post by keith101 on Sept 2, 2022 23:16:49 GMT 1
Check the usual, timing and jetting, are slides opening together and synchronised, slow running jets and also air adjustment screws, check they are both set as per manual and also the the needles.
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Post by lcstevie on Sept 3, 2022 14:09:57 GMT 1
Hi guys I have swapped the carb with a mate of mine (LCLea). What a good guy, and with his carbs it runs great. His jet sizes are main 220 + pilot 22.5. The bike has Allspeed pipes and a standard air box. The carbs have been ultrasonically cleaned. Needles are set in the middle
My poor carbs have main 240 + pilot 22.5. Didnt think that such a little difference on the main jet could cause such a difference. What do you reckon.
Pulling my hair out now.
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Post by abar121 on Sept 3, 2022 16:29:46 GMT 1
It's more than just the main jet.
Get your carbs cleaned properly and check that they are genuine jets. Check float levels, air screw, balance etc too.
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Post by midlifecrisisrd on Sept 3, 2022 16:34:09 GMT 1
Wouldn't think 2 up on the main would make it so bad. I'd expect it to not rev out
I'd suspect the air correction circuit behind the brass ball
If blocked it makes it mega rich
Steve
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Post by elsiefan on Sept 3, 2022 18:42:02 GMT 1
Try your carbs with the 220 mains in and see if that makes any difference. I also have a std engine, airbox and allspeeds running 220s, if it does then you know what to buy to fix it, if it doesn't then it could well be the air corrector circuit on your carbs.
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Post by muttsnuts on Sept 3, 2022 18:58:43 GMT 1
which model of carb is fitted ? - long before looking at the jetting, need to know which carbs are fitted
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Post by 4l04ever on Sept 3, 2022 19:24:34 GMT 1
Carbs may have been serviced using substandard parts...i.e. Yambits or keyster/shyster.
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Post by elsiefan on Sept 3, 2022 19:56:08 GMT 1
Carbs may have been serviced using substandard parts...i.e. Yambits or keyster/shyster. Having just replaced some of the 'pattern' parts in my carbs with the genuine article, I can confirm the difference this can make in the way the bike runs.
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Post by lcstevie on Sept 4, 2022 0:31:58 GMT 1
Carbs may have been serviced using substandard parts...i.e. Yambits or keyster/shyster. The carbs are 4L0-01. The brass balls look a lot shinier than the others so I think the air correction circuit may have been done but I can’t be sure so I think I’ll have to try and do it to make sure. Rather than putting the brass ball back in can the hole just be filled with aryldite in case the brass ball get demolished on removal.
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Post by 4l04ever on Sept 4, 2022 10:51:43 GMT 1
The brass balls can be changed for brass grub screws so they are easier to service in the future.
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Post by keith101 on Sept 4, 2022 19:20:14 GMT 1
Hi, we all do the same, get our engines rebuilt, rebore,new pistons, bearings, seals rebuilt cranks etc but we put the same old worn out carbs on, yes we change jets but slides, carb bodies, passages ways, needles all wear, if you can afford it buy new carbs it's one of the best things you can do on an engine and then at least your not chasing your brass balls.....
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Post by lcstevie on Sept 7, 2022 22:34:44 GMT 1
The brass balls can be changed for brass grub screws so they are easier to service in the future. How many brass balls on each carb should be removed as I have done the large ball but it still runs shite. Was wondering if the small brass ball next to the large one should be removed as well. Any help would be much appreciated as I am pulling my hair out now.
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Post by lcstevie on Sept 7, 2022 22:35:54 GMT 1
The brass balls can be changed for brass grub screws so they are easier to service in the future. How many brass balls on each carb should be removed as I have done the large ball but it still runs shite. Was wondering if the small brass ball next to the large one should be removed as well. Any help would be much appreciated as I am pulling my hair out now.
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Post by lcstevie on Sept 7, 2022 22:41:52 GMT 1
Hi, we all do the same, get our engines rebuilt, rebore,new pistons, bearings, seals rebuilt cranks etc but we put the same old worn out carbs on, yes we change jets but slides, carb bodies, passages ways, needles all wear, if you can afford it buy new carbs it's one of the best things you can do on an engine and then at least your not chasing your brass balls..... Where can I get new 4l0-01 carbs. I looked on the part shop on here but can only find 28mm pre mix ones (no auto lube). If I could get some new ones I will.
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Post by shaunthe2nd on Sept 7, 2022 22:50:59 GMT 1
It's the big brass ball at 6 o'clock on the inlet that is removed to clean the air correction circuit.
You can't buy new 4L0-01 carbs, but you can buy most of the original internals. Were the brass emulsion tubes removed and cleaned when the carbs were done? Some people say they have ultrasonically cleaned the carbs, and simply dump the full carb into an ultrasonic cleaner without stripping out all the brass ware and cleaning all the individual parts as well as the carb bodies.
If you are unsure how to do it and rebuild with genuine parts (some of the copy parts are rubbish) then send them to Muttsnuts for a full service and set up. Money well spent.
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Post by lcstevie on Sept 7, 2022 23:16:53 GMT 1
It's the big brass ball at 6 o'clock on the inlet that is removed to clean the air correction circuit. You can't buy new 4L0-01 carbs, but you can buy most of the original internals. Were the brass emulsion tubes removed and cleaned when the carbs were done? Some people say they have ultrasonically cleaned the carbs, and simply dump the full carb into an ultrasonic cleaner without stripping out all the brass ware and cleaning all the individual parts as well as the carb bodies. If you are unsure how to do it and rebuild with genuine parts (some of the copy parts are rubbish) then send them to Muttsnuts for a full service and set up. Money well spent. removed the big brass ball. There was no blockage. replaced the ball with a grub screw. I have replaced the pilot and main jet. 22.5 and 220. The emultion tubes are not blocked. New mixture screws and springs (1 and a half turns out). I cant understand it. I put my mates carbs on and it ran well. was wondering what else in the carb could need cleaning or what else could be worn. When I put my mates carbs on I used my slide and needle so I know they are okay. This is getting me down
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Post by shaunthe2nd on Sept 7, 2022 23:53:51 GMT 1
It will be something simple, just finding it. It's helpful that it runs well with your mates carbs on, and your needles/slides as that eliminates a lot of things. Some thoughts: -your carbs are definitely 4L0-01 type, not 4L0-00 type? -are float heights set correct (21mm) on both? -needle jet seats correct? -are main jets and pilot jets mikuni make? -are both needle jets fitted? seen them without! -have you balanced the carbs and the pips both show at same time in the sight glass (painting the pips help in misted glass) -correct bowls fitted? LH carb one has the little hole, and check it isn't blocked -are emulsions the correct ones (should be marked 345-P0 from memory) -is choke plunger sealing correctly? (maybe swap that with your mates to eliminate)
Good luck with it, you will sort I'm sure.
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Post by lcstevie on Sept 8, 2022 0:10:33 GMT 1
It will be something simple, just finding it. It's helpful that it runs well with your mates carbs on, and your needles/slides as that eliminates a lot of things. Some thoughts: -your carbs are definitely 4L0-01 type, not 4L0-00 type? -are float heights set correct (21mm) on both? -needle jet seats correct? -are main jets and pilot jets mikuni make? -are both needle jets fitted? seen them without! -have you balanced the carbs and the pips both show at same time in the sight glass (painting the pips help in misted glass) -correct bowls fitted? LH carb one has the little hole, and check it isn't blocked -are emulsions the correct ones (should be marked 345-P0 from memory) -is choke plunger sealing correctly? (maybe swap that with your mates to eliminate) Good luck with it, you will sort I'm sure. The bike starts first kick, idles sweet and revs sweet, problem is under load condition. Answers to your questions -your carbs are definitely 4L0-01 type, not 4L0-00 type?----Yes definitely 4L0-01s -are float heights set correct (21mm) on both? haven't set the height but they are not over filling. Could that cause spluttering? -needle jet seats correct?----Not sure what you mean -are main jets and pilot jets mikuni make?--------No -are both needle jets fitted? seen them without! Yes both fitted -have you balanced the carbs and the pips both show at same time in the sight glass (painting the pips help in misted glass) ------yes balanced -correct bowls fitted? LH carb one has the little hole, and check it isn't blocked -----yes it is Correct -are emulsions the correct ones (should be marked 345-P0 from memory)-----didnt see any markings on them so im not sure. -is choke plunger sealing correctly? (maybe swap that with your mates to eliminate) ------Put a rubber disc in to make sure it is closing but will try swapping it Thanks for your input it is much appreciated.
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Post by lcstevie on Sept 8, 2022 0:25:31 GMT 1
which model of carb is fitted ? - long before looking at the jetting, need to know which carbs are fitted The carbs are 4l0-01 Brass ball out clean New 22.5 pilot jet (not Mikuni) New main jet 220 (not Mikuni) New air screw (not Mikuni) set 1and half turns out
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Post by elsiefan on Sept 8, 2022 0:53:11 GMT 1
Usually in such situations, where one large component works and the other doesn't, the route would be to change individual parts of the main component, one at a time, and test to see if each change makes any difference. I guess that may not be possible in this case, or if it is, it would be a royal PITA to do. At least it keeps the costs of parts down, just the use of your time needed (and an understanding mate!) I did this once in a car to find a fault in the ABS system. My mate let me strip parts off his car and swap them over.
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Post by midlifecrisisrd on Sept 8, 2022 7:53:46 GMT 1
which model of carb is fitted ? - long before looking at the jetting, need to know which carbs are fitted The carbs are 4l0-01 Brass ball out clean New 22.5 pilot jet (not Mikuni) New main jet 220 (not Mikuni) New air screw (not Mikuni) set 1and half turns out If they are Keyster parts then bin them Steve
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Post by shaunthe2nd on Sept 8, 2022 8:04:36 GMT 1
From comments above, before you spend on parts, I would suggest checking the float heights and that the needle jet that sets the height is seated correct and seal around the needle jet housing is ok. Maybe causing fuel starvation if incorrect.
Whilst at it have another look at the emulsions, if you give them a clean you should see the faint stampings on them giving the ref number. Try swapping the choke plunger as suggested.
If still no luck, I'd be buying gen mikuni jets, mains and pilots and trying them.
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Post by muttsnuts on Sept 8, 2022 9:06:07 GMT 1
which needles are fitted ?
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Post by lcstevie on Sept 8, 2022 15:37:16 GMT 1
which needles are fitted ? Its got 5K1 Float height is set to 21mm from the casing base new float needle jets. just set these and tried it again to no joy AAAAAHhhhhhhhh tried some other needles which came in the jet kit (not 5K1) No joy.
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