|
|
Post by fletche36 on Feb 1, 2021 15:02:45 GMT 1
Following on from the brass balls discussion ill give you a quick update and take a little more advice. right, i cleaned the carbs this morning and there was evidence of them being done relatively recent in that there was no varnish inside and witness marks of scraping etc. i didnt remove the balls as it looked like they have been done in the past ( little scratches around them) and i couldnt find a drill small enough! Thats my confession on not taking given advice. anyway what i found was firstly the clips on the needle were 2 from the top so i moved those down to 4 to richen it up as i felt leanness was an issue ( would only run on choke ). also whilst removing the pilots i discovered one was only in a few threads and hadnt been tightened in enough .i gave everything a squirt of carb cleaner and used the compressor to blow through all passageways. i then put them back together , refitted and went for a test ride.it definitey went better than on its maiden voyage and will run without choke and tick over nicely etc but there is a pronounced flat spot from 3k to 5.5k and after that it goes like i remember them doing !!! now im running swarbrick pipes but the road tune version which supposedly dont require a rejet and im wondering if thats kind of what lc s are like ( 30 years since riding one and my current other bike is a 300 2t enduro bike with the torque of a tractor). so has anyone got any good carb settings for these or is it worth a trip to a dyno ( i would use someone off here who knows his stuff) , i have never used a dyno so i dont know if the operator changes jets for you or just gives advice? Thanks in advance, and honestly i do listen to advice and am grateful for it even though i didnt remove my balls on this occasion  |
|
|
|
Post by lcmarky on Feb 1, 2021 15:42:29 GMT 1
Progress made then.
Get the bike to Dave @ Mutts Nutts for wisdom & a rolling road set up.
I think you've experienced why the YPVS was born!
|
|
|
|
Post by shaunthe2nd on Feb 1, 2021 15:49:26 GMT 1
If your bike revs clean from 5.5k through to 10k then its unlikley you have much of a problem with the brass balls, as dirt here usually prevents it clean revving up the range, so you probably ok in that respect.
All LC's seem to have a flat spot before 5.5k so what you describe isn't unusual but depends how pronounced it is.
You could try playing about with the size of the pilot jets (up or down one size maybe) and also the needle position and air jet screw to see if you get an improvement.
I usually try just one change at a time and make notes about how the ride changed to help home into the best set up.
The best way is to use someone with a dyno as its a lot more scientific. Most dyno guys will provide advise on set up and make changes to carb settings and jet sizes for you.
Normally several runs on a dyno would be needed to get it right.
If you are anywhere near Yorkshire then give muttsnuts on here a shout or go to his website to get a dyno appointment. Others on can advise on other dyno guys in other parts of the country who are worthy too, there are a small handful of them about.
Good luck with it.
|
|
|
|
Post by julianboolean on Feb 1, 2021 16:01:47 GMT 1
From memory of 1985 when I had a 250LC with Microns, you shouldn't need to change jets so long as you keep the airbox, the exhausts are probably the cause of the flatspot, changing the needle setting may improve it, the only way to tell is to move the clip and see what it does.
What are you bothering about the bit between 3k and 5k for, it's a small two stroke, you shouldn't be riding it at under 6k.
|
|
|
|
Post by 4lo4xvjohn on Feb 1, 2021 16:22:33 GMT 1
Have you checked the reeds also last time I jetted my carbs I tried three different jets to be sure what worked best after setting the needle and floats also I used to soak my carbs in petrol for a couple of days then use the air line on them, I was using power filters and microns so ended up slightly higher on the main jets , I also experimented on needle setting and found standard to work best with needles that are in good shape
|
|
|
|
Post by fletche36 on Feb 1, 2021 16:38:22 GMT 1
From memory of 1985 when I had a 250LC with Microns, you shouldn't need to change jets so long as you keep the airbox, the exhausts are probably the cause of the flatspot, changing the needle setting may improve it, the only way to tell is to move the clip and see what it does. What are you bothering about the bit between 3k and 5k for, it's a small two stroke, you shouldn't be riding it at under 6k. Because at the tender age of 56 i feel a bit of a hooligan if i rev it it did feel bloody good when it was in the power though ( nice light front wheel ) and it didnt drop out of the power when i changed gears . |
|
|
|
Post by fletche36 on Feb 1, 2021 16:47:47 GMT 1
If your bike revs clean from 5.5k through to 10k then its unlikley you have much of a problem with the brass balls, as dirt here usually prevents it clean revving up the range, so you probably ok in that respect. All LC's seem to have a flat spot before 5.5k so what you describe isn't unusual but depends how pronounced it is. You could try playing about with the size of the pilot jets (up or down one size maybe) and also the needle position and air jet screw to see if you get an improvement. I usually try just one change at a time and make notes about how the ride changed to help home into the best set up. The best way is to use someone with a dyno as its a lot more scientific. Most dyno guys will provide advise on set up and make changes to carb settings and jet sizes for you. Normally several runs on a dyno would be needed to get it right. If you are anywhere near Yorkshire then give muttsnuts on here a shout or go to his website to get a dyno appointment. Others on can advise on other dyno guys in other parts of the country who are worthy too, there are a small handful of them about. Good luck with it. Thanks , that makes me feel better. im actually in Bury between lancs and manchester so Yorkshire isnt a bad journey ( dunno if i could class it as essential travel at the moment). if its dry tomorrow ill shake it down some more and get a few miles on it and see if i can gel with how it rides and if necessary ill book it in with mr nuts and take it from there. yes its very clean revving in the meat of the power and it comes back down to idle nicely too so its probably not far off.i guess i should have rode it first with standard pipes on and also i should have noted what jets were in there too but i was just giddy to go and test it . Thanks again for all advice. |
|
|
|
Post by shaunthe2nd on Feb 1, 2021 17:45:20 GMT 1
Make sure you do a plug chop just to be sure yr not running too lean which can eventually cause a seize or piston melt.
|
|
|
|
Post by fletche36 on Feb 1, 2021 18:27:48 GMT 1
Make sure you do a plug chop just to be sure yr not running too lean which can eventually cause a seize or piston melt. plugs are brand new so ill put a few miles on it to get some colour and then do a chop. ill probably never get into seizing territory as im not one for holding them wide open for ages. age has turned me into a pussy |
|
|
|
Post by beardy on Feb 1, 2021 18:50:25 GMT 1
I too have noticed as I’ve got older my bikes are getting faster. My zzr1100 above 8000 scares the c@&p outta me. Saves me buying the latest rocket ships 👍🏻
|
|
|
|
Post by muttsnuts on Feb 1, 2021 21:32:33 GMT 1
why oh why do people still beleive that the 250/350LC that has a stutter/flat spot between 3.5 and 5.5k is normal, it isn't, if the bike is setup right then there should be no stuttering/hesitation etc, now I accept that over the 40+yrs these bikes have been about they have had more than their fair share of different hands messing with them, plus a whole multitude of various parts fitted
Different setups on bikes give different results and some exhausts certainly do kill the bottom end (hence why the mid range pipes came into being)
If you ever get the chance to ride a well sorted stock 250/350LC you will see that it pulls from nothing and cleanly revs through to 9k, if it doesn't, then its not right, I've fixed an awful lot of bikes for people who have complained about this issue
It can be caused by various things, of whoch I reckon I can think of at least a dozen or more (no I am not going to list them !)
HTH
|
|
|
|
Post by earthman on Feb 1, 2021 21:43:57 GMT 1
From memory of 1985 when I had a 250LC with Microns, you shouldn't need to change jets so long as you keep the airbox, the exhausts are probably the cause of the flatspot, changing the needle setting may improve it, the only way to tell is to move the clip and see what it does. What are you bothering about the bit between 3k and 5k for, it's a small two stroke, you shouldn't be riding it at under 6k. Now I were told back in the day that the jets should be changed with Microns, even with the standard airbox, where as with allspeeds, no jet change were needed. I don't know any more because I picked the allspeeds over them anyhow. |
|
|
|
Post by fletche36 on Feb 1, 2021 22:00:34 GMT 1
why oh why do people still beleive that the 250/350LC that has a stutter/flat spot between 3.5 and 5.5k is normal, it isn't, if the bike is setup right then there should be no stuttering/hesitation etc, now I accept that over the 40+yrs these bikes have been about they have had more than their fair share of different hands messing with them, plus a whole multitude of various parts fitted Different setups on bikes give different results and some exhausts certainly do kill the bottom end (hence why the mid range pipes came into being) If you ever get the chance to ride a well sorted stock 250/350LC you will see that it pulls from nothing and cleanly revs through to 9k, if it doesn't, then its not right, I've fixed an awful lot of bikes for people who have complained about this issue It can be caused by various things, of whoch I reckon I can think of at least a dozen or more (no I am not going to list them !) HTH And if i cant fix it myself , which i like doing as i like a challenge, then i will be booking in with you for a tuning session |
|
|
|
Post by julianboolean on Feb 2, 2021 12:43:04 GMT 1
From memory of 1985 when I had a 250LC with Microns, you shouldn't need to change jets so long as you keep the airbox, the exhausts are probably the cause of the flatspot, changing the needle setting may improve it, the only way to tell is to move the clip and see what it does. What are you bothering about the bit between 3k and 5k for, it's a small two stroke, you shouldn't be riding it at under 6k. Now I were told back in the day that the jets should be changed with Microns, even with the standard airbox, where as with allspeeds, no jet change were needed. I don't know any more because I picked the allspeeds over them anyhow. I ran mine for months with Microns with no problems, I went back to standard pipes because I preferred the power delivery, but it would indicate 110mph with the Microns (big can) and 100 with the standard pipes - both plenty quick enough as I got nicked for speeding 3 times on that bike, all with the standard pipes. |
|
|
|
Post by fletche36 on Feb 2, 2021 14:43:27 GMT 1
bit more tinkering in the garage this morning. i have ensured that both carbs are synchronized and reset the throttle stop screws and have adjusted the air screws to get the best possible tickover so thats all good ( both are about 1 full turn out). i havent rode it today as its snowy in lancashire so its just been tuned "by ear"and i have also raised the needle one more clip, so its now on the bottom clip position and as rich as i can get on this needle,i also checked to ensure there wasnt an air leak. i did this because i found that i could induce a lean bog by whacking the throttle open from tickover which i have now almost eliminated. i know this isnt going to be tuned as well as on a dyno and i know that i need to give it a right good run but i think im going the right way :)Has anybody ever changed the pilots to larger ones because they felt the bike was lean? and if so what size did you go for?
|
|
|
|
Post by holty on Feb 2, 2021 14:56:53 GMT 1
first thing i would say is its not very easy to read the colour of a plug, i could show you a pic of my plugs 100 miles before i holed a piston and you would swear they were rich, the problem is its hard to get enough load on the engine for long enough, a straight uphill quiet road might help you, but my advise is the best money you can spend is on a dyno session with a good operator, as mutts has just said it should not stutter at any revs, mine doesnt and ive got microns on.
|
|
|
|
Post by julianboolean on Feb 2, 2021 15:01:32 GMT 1
The best way to see if you've sorted it is to ride it, I never changed the pilots, but in theory they only affect very low speed running with the throttle closed, your problems sound like needle as it's mid throttle running, generally I found if LCs coughed and spluttered they were running rich - this is the opposite of 4 strokes
|
|
|
|
Post by fletche36 on Feb 2, 2021 16:23:38 GMT 1
The best way to see if you've sorted it is to ride it, I never changed the pilots, but in theory they only affect very low speed running with the throttle closed, your problems sound like needle as it's mid throttle running, generally I found if LCs coughed and spluttered they were running rich - this is the opposite of 4 strokes its not coughing and spluttering but like its waiting to come onto the pipe.ill ride it as soon as its dry again and im sure its going the right way . Bikes are definitely a labour of love. |
|
|
|
Post by julianboolean on Feb 2, 2021 17:25:59 GMT 1
The best way to see if you've sorted it is to ride it, I never changed the pilots, but in theory they only affect very low speed running with the throttle closed, your problems sound like needle as it's mid throttle running, generally I found if LCs coughed and spluttered they were running rich - this is the opposite of 4 strokes its not coughing and spluttering but like its waiting to come onto the pipe.ill ride it as soon as its dry again and im sure its going the right way . Bikes are definitely a labour of love. You'll know if you've gone the wrong way. I don't mind fiddling with the carbs on LCs, they're pretty straight forward and easy to get at, my Kawasaki Z1170 is horrible to get the carbs on and off
|
|
|
|
Post by earthman on Feb 2, 2021 21:51:29 GMT 1
Now I were told back in the day that the jets should be changed with Microns, even with the standard airbox, where as with allspeeds, no jet change were needed. I don't know any more because I picked the allspeeds over them anyhow. I ran mine for months with Microns with no problems, I went back to standard pipes because I preferred the power delivery, but it would indicate 110mph with the Microns (big can) and 100 with the standard pipes - both plenty quick enough as I got nicked for speeding 3 times on that bike, all with the standard pipes. Always interested in hearing folks personal experiences with such like, I have no idea if the carbs should be touched on the 125LC for example, I just remember a mate having to do an engine rebuild after just bolting on a Micron, he certainly didn't change the jet, I know that much for sure. I really can't remember where I heard that the jets really should be changed, maybe it were via Stan Stevens?? Ideally you want answers to such questions from the company that actually makes the product,....so much easier to find out such like now we have access to email hey. |
|
