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Post by chippy28 on Apr 23, 2011 20:28:02 GMT 1
Hi All,have been faffing about with jets and needle clips most of the day but stiil cannot get this thing to run right (1980 250 lc)
It will not rev past 6k so will not go into the powerband,the best it has run is on 190 mains and the needle clip in standard position.
I am running Microns which I bought from Billbot on here and have spoken to him about his setup which was fine on his bike but would it be ok for mine,ie my barrells have had some porting work done to the inlets and the outlets and also uderneath the barrells(Transfer ports sharpened the best way I can describe it)
So do I now go down another jet size or move the clip on the needle?will it be ok to do this with a tuned motor?
Also the airbox is all there ie snorkel and filter fitted and the bores are .25 over.
Hope someone can help/advise.
Cheers,Andy.
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Post by widget2k4 on Apr 23, 2011 21:50:46 GMT 1
I think you need to go up with microns or you will sieze your motor,I had 220 main jets in mine
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Post by chippy28 on Apr 25, 2011 20:02:45 GMT 1
Right done a plug chop today with the motor running crap but had to see what was going on in there,here are some pics   what do you think people? Also I think the needles are from a Keystar carb kit and I have compared them to one I have in a spare carb and they are totally different profiles ie the keystar one is alot thinner towards the bottom,should I be swapping these with some proper Mikuni ones? Any help/advice much appreciated as this is stopping me from riding the dam thing  Cheers,Andy.. |
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Post by LC'Adam on Apr 25, 2011 20:22:46 GMT 1
I think you answered your own question there mate, sounds like the keystar needles to me. The plug chop wont show in detail how the motor is running until your able to run it wide open in top i.e when the lumpy running is sorted. Its also better to use old plugs mate  Who did your porting?  Adam |
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paulo
Thrash Merchant
Posts: 406
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Post by paulo on Apr 25, 2011 20:28:23 GMT 1
I think a rule of thumb is up two sizes for microns.
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Post by chippy28 on Apr 25, 2011 20:34:57 GMT 1
Adam,no idea who did the porting mate,was like it when i bought it. New plugs from halfords are only £1.50 if you have one of there trade cards So do I now fit the needles from the spare carbs but are they the right ones tho ?? they have the number 4H16 on them,anyone know if these are the right ones  Cheers,Andy. |
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Post by chippy28 on Apr 25, 2011 20:37:05 GMT 1
I think a rule of thumb is up two sizes for microns. I agree with you and widget2k4 but it ran like a bag of T*TS |
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Post by oldelsieboy on Apr 25, 2011 20:48:56 GMT 1
they have the number 4H16 on them,anyone know if these are the right ones Cheers,Andy. 250LC (4L1) needles should be 4N10 OEB |
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Post by chippy28 on Apr 25, 2011 20:51:36 GMT 1
they have the number 4H16 on them,anyone know if these are the right ones Cheers,Andy. 250LC (4L1) needles should be 4N10 OEB Thankyou OEB. |
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Post by LC'Adam on Apr 25, 2011 20:52:02 GMT 1
250LC 4L1 STANDARD Main jet 190 Air jet 1.0 Needle 4N10 Clip from top 4 Pilot jet 20 Air screw 1.8 turns out float height 1.0mm I think I know what is happening, The Keystar needles are way to rich, main jets come in to play mainly at 6k RPM and above. Thats why coming down on the jets makes it slightly better. Basically, get yourself some standard needles and go to 210 mains. That should clear it up Also, the reason you use old plugs to chop is because they are easier to read mate. New ones take a long time to take on the running characteristics, if you get what I mean I assume you are running 4L1 carbs mate? |
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Post by chippy28 on Apr 25, 2011 20:56:51 GMT 1
Thankyou Adam ;D
Yep 4L1 carbs mate.
Thanks again ,Andy ;D
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Post by chippy28 on Apr 27, 2011 16:49:11 GMT 1
Hi All,Really need help with this now  fitted the new Mikuni needles today and still no good. The Bl**dy thing just wont rev when riding it but revs out stood still on the side stand it will get upto 6k when riding it but splutters and will not rev anymore. Any suggestions please before I take a hammer to this Bl**dy thing Cheers,Andy. |
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Post by LC'Adam on Apr 27, 2011 17:27:42 GMT 1
Bad news that mate I was sure that that would be the cause, is it any better now? If not I would be going down the electrical rout, my 125 had the same problem and it was bad connection from the loom to the coil. Mellow has a similar problem on his 125 (faulty stator). A weak spark can cause spluttering under load but can appear fine stood still. Check the coils have a good earth, check connection to coils, check stator to see if it is putting out the correct readings. There is a tolerance range in which the voltage should be, if it is outside then the stator is faulty and needs replacing/rewinding. LC's do tend to have allot of problems with stators so its worth checking mate. I'm sure others will let you know what the voltage should be and how to perform the test Adam |
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Post by chippy28 on Apr 27, 2011 20:25:05 GMT 1
Hi,will start pulling it apart next week now as i am away this weekend,have also found some figures to check the stator.
Another thing before I do rip it apart could this be down to timing because I followed the haynes book of lies to set it up but that was back in the day before unleaded fuel.
Cheers,Andy.
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Post by chippy28 on Apr 27, 2011 20:27:06 GMT 1
Adam,the only time time it did run slightly better was on a 210 main,needle clip one up from standard position and air filter removed.
Cheers,Andy..
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Post by LC'Adam on Apr 27, 2011 20:41:31 GMT 1
Only other thing I can think of is reeds Andy, or perhaps the port timing is out? They can be a pain in the ass but at least she looks the business Getting it to run right is just a bonus Only a matter of time before you find the cause, stick with it  Let us know your findings. P.S I didn't know the timing was adjustable? Adam |
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Post by chippy28 on May 3, 2011 11:47:20 GMT 1
Hi all,tested the stator this morning and found the low speed brown/black wires reading to be 230 ohm but the manual states it should read 271 ohm.
Would this cause the symptons I am having with the running of the bike?
Thanks in advance,Andy..
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Post by elsie1411 on May 8, 2011 12:22:11 GMT 1
don't know if this is any help but a couple of things checking is wether you have good compression on both barrels and if you can check that you haven't got a twist in the crank. i remember buggering mine up by tightening the nut on the flywheel up by hitting the spanner with a hammer to make sure it was tight, that exuberance of youth cost me a few quid so i've never done that again
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Post by mellow on May 8, 2011 15:33:56 GMT 1
Mellow has a similar problem on his 125 (faulty stator). Adam Id just like to clarify it wasnt my stator swapped to nikkon pipe n it runs fine ;D swapped back to my "modded "standard pipe today just to double check n yup ran like a bag of shite again |
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Post by chippy28 on May 9, 2011 18:47:12 GMT 1
Hi All and thanks for the replies,after swapping the whole of the ignition system from a known good running 350 it made no difference so went back to the carb side and it turned out the reason it was running shite was because i had the snorkel fitted to the airbox.
Now with this removed it revs out fine,infact up into the red and beyond.
Just got to fine tune the jetting now as I am pretty sure it is running a bit lean.
Cheers and thankyou,Andy..
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Post by t4vanman on May 9, 2011 21:04:18 GMT 1
Hi,
i'm glad to hear you are getting it sorted i know what you have gone through i've been there with my f2, just reminded me when you started reaching for the hammer!!!!
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fitted the new Mikuni needles today and still no good.
