korky
L plate rider.
Posts: 26
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Post by korky on May 28, 2012 21:57:17 GMT 1
hi all
thanks for all the reply in lc250 carbs helped a lot,
bikes ticks over and runs well now!! BUT, and theres alway a but lol, it now pulls away well up to 5000 rpm then goes flat? it wont rev again till it gets over 6000 rpm! then revs into the red line, is this normal???
carbs now set as standard.
what i mean by flat is it seems to stop reving/pulling until it goes over the 6000 mark then takes off again, any ideas???
cheers john
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Post by spondonchris on May 28, 2012 22:58:10 GMT 1
Raise the needles one notch, that will sort it.
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btlc
Weekend rider
Posts: 74
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Post by btlc on May 29, 2012 12:34:23 GMT 1
Fit boyeson two stage reeds.
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Post by airbraker on May 29, 2012 12:46:25 GMT 1
Yea strange that I have a similar problem. Makes a little burble from pipes when it goes flat then enters power band and is fine. Needs encouragement all the time just seems reluctant ! Raise needles then  ? |
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Post by davey on May 29, 2012 17:31:52 GMT 1
This unless really flat was always a chracteristic of especially the 250,s.
one of the first road tests written described it as a hole at 5500 and at 6 took of like a cat that had been red hot pokered.
there are ways to minimise this as the guys have mentioned but i feel that it will always be apparent on the lc,s so try and live with it , keep it above the 6k mark and enjoy the expirence.
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korky
L plate rider.
Posts: 26
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Post by korky on May 29, 2012 20:34:20 GMT 1
hi all lifted the needles no change!!!! do reeds wear out?? been in there 27 years as the last owner had written most things down, could live with it but it spoils the ride, like you say above 6 its great fun, but not good if your overtaking and you have to wait for the power to make an appearance  any more ideas anyone??? korky |
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Post by 47x on May 29, 2012 21:00:21 GMT 1
change the reeds if you know they been in there that long for sure m8.but it is a trait of lc"s,up jetting or raising the needles usually sorts it tho.hth.
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btlc
Weekend rider
Posts: 74
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Post by btlc on May 30, 2012 14:04:20 GMT 1
Dont bother buying any other reed than boyeson for this problem as the thin small reeds open at low revs and the large reeds open at higher revs, the reeds are like a magic bullet for this and you should find that setting off will be far more responsive the flat spot is gone and when the power band kicks in its the just the same, i tried just about every thing then fitted these, end of problem.
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Post by arrow on May 30, 2012 14:38:46 GMT 1
Have you checked the emulsion tubes for wear around the tops. This could be your problem.
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korky
L plate rider.
Posts: 26
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Post by korky on May 30, 2012 21:33:16 GMT 1
hi arrow
have looked at and cleaned them, what kind of wear?? they are a tight fit in carb bodies, what else should i check? and where should i get new ones if needed? cheers korky
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korky
L plate rider.
Posts: 26
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Post by korky on May 30, 2012 21:35:53 GMT 1
hi again
yes going to change reeds, will look for boyeson then, just standard?
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Post by arrow on May 31, 2012 6:41:43 GMT 1
hi arrow have looked at and cleaned them, what kind of wear?? they are a tight fit in carb bodies, what else should i check? and where should i get new ones if needed? cheers korky The wear is around the top of the tube but is quite hard to see unless you have a new one to compare it to. If it were me I would just replace them, infact I replaced all the jets in my carbs, needles and float valves too. |
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btlc
Weekend rider
Posts: 74
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Post by btlc on May 31, 2012 11:13:30 GMT 1
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Post by airbraker on Jun 1, 2012 13:25:49 GMT 1
If your bike is totally standard check the main jets are 190. If they are that's what they should be it will be stamped on out side. If they are bigger your bike is over fueling. I just put my standard jets back in it had two sizes bigger in before to compensate for over size pistons. The flat spot seems to have vanished. If it is over fueling you will notice that it wont go over 8000 revs either. Mine just hung there not that I push it into the red all the time but I would expect to touch the red line occationally Trouble with these things is its all got to be just right or it wont do what it was designed too do. A mechanic mate of mine from the 80's told me that the needles and needle jets should be replaced at around 35000 miles as they wear an oval in the jet letting more fuel through that its supposed too. He knew exactly what the problem was as soon as he looked at the bikes millage. He also said that most of them never got that far as they were usually spread all over the road before they got there ! Plug check or dyno is the only sure way of checking the mixture as somebody already said and the reeds are a good idea too.
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Post by arrow on Jun 1, 2012 15:37:23 GMT 1
The guy that runs Motocarb ( www.motocarb.co.uk/) told me that the emulsion tubes can wear in as little as 5000 miles. Don't shoot the messenger, thats what he told me. |
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Post by woodentopp on Jun 1, 2012 16:27:08 GMT 1
Allens performance were also very helpful with ordering of carb parts.
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korky
L plate rider.
Posts: 26
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Post by korky on Jun 3, 2012 12:14:29 GMT 1
hi thanks for all the feedback, it all helps, got new reeds fitting them after motogp!!! raining hard here so no testing today only changing 1 thing at a time to see what fixes it, lol carbs set as per standard still had dead spot at 5-6000 after that into the red!!!! this happens in ALL gears??? will change reeds then try, needle jets on order (3weeks from japan) cheers korky |
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korky
L plate rider.
Posts: 26
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Post by korky on Jun 3, 2012 12:16:25 GMT 1
ps forgot to say, needles were in middle clip and it was hard to pull away, now on 2nd from bottom pulls away nicely,
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korky
L plate rider.
Posts: 26
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Post by korky on Jun 12, 2012 23:19:29 GMT 1
hi all got emulsion tubes today.... 2 weeks early, will fit them tomorrow and try, thats if the rain stays away!!!!!!!!!!!! fitted new reeds then found a damaged main jet (cracked near thread) so fitted only spares i had 210's.. bike pulls away nicely, flat spot still there but seems better? ie does not last as long before reving though it, so a part result  , will fit new 190 main jets with tubes then try, will post results in the evening, cheers korky |
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Post by arrow on Jun 13, 2012 6:49:58 GMT 1
Yeh, keep us posted please, good luck .
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Post by lovelydog on Jun 14, 2012 0:36:59 GMT 1
Mine was crap until I disconnected the air filter,then it went ace.
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korky
L plate rider.
Posts: 26
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Post by korky on Jun 16, 2012 0:01:09 GMT 1
hi all, looks like its fixed.... ;D
put everything back to standard, new 190 main jets, and new emulsion tubes (£25 each from yamaha) had already replaced reeds (thanks btlc) made an improvement.
but think that arrow takes the most credit this time and his "change the emulsion tubes" good call and thanks,
bike is pulling very well now right though to the red line ;D with a nice kick at 5500 ish!!!
so i'll go and enjoy my first lc and finish my rd250d.
thanks for all your help hope to meet some of you soon,
korky
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korky
L plate rider.
Posts: 26
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Post by korky on Jun 16, 2012 0:04:02 GMT 1
btw, i'm not doing a runner!!!! this is a good forum, and i enjoy reading peoples faults etc may even be able to help someone one day lol
gt750's anyone??
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Post by arrow on Jun 16, 2012 0:06:28 GMT 1
hi all, looks like its fixed.... ;D put everything back to standard, new 190 main jets, and new emulsion tubes (£25 each from yamaha) had already replaced reeds (thanks btlc) made an improvement. but think that arrow takes the most credit this time and his "change the emulsion tubes" good call and thanks, bike is pulling very well now right though to the red line ;D with a nice kick at 5500 ish!!! so i'll go and enjoy my first lc and finish my rd250d. thanks for all your help hope to meet some of you soon, korky Thats what these forums are for mate, to help each other. Glad you got a good result in the end. |
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Post by airbraker on Jun 16, 2012 10:12:39 GMT 1
Good feed back I will save up for new emulsion tubes and needles cheers mate !
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?
any more ideas anyone??? korky
, will fit new 190 main jets with tubes then try, will post results in the evening,