Moderator Cynic Posted November 13, 2010 Moderator Posted November 13, 2010 Ok, i'm hoping a fresh approach might help. The 175 is being a bit of an arse, from cold she's fine and starts and idles perfectly with choke when cold and when she wont idle with choke its cos she don't need it and she will idle for 10-15 minutes happily. Thing is when your riding, she's a bit rich in the middle but leans off at the top end. Moving the needle up ruins the low speed (sub 5000rpm) manners and putting in a bigger jet and dropping the needle she just floods out and fouls the plug. Lower the needle without the big jet and she bloody near wont run at all. Add into this if i run her a touch rich but tweak the fuel tap it helps with the mid range but she still leans out up top. At least i think she's going lean, i cant say for certain as with the motor going rich in the mid range the plug is always shitty. I would expect het to be lean. I was thinking float height, but how when she's rich and lean at the same time. Its complex as the pipe is a gianelli after market pipe which messes with the jetting a bit. Stock carb settings just have her sulking and difficult to start so i have got to fine tune things to get it right. There could be a little ig error in there too but i don't want to mess with that as i don't think it will affect the carberation. She starts readily enough so i figure its near enough. Don't panic, she runs fine for trips to work and such its just she's just not running as well as i'd like but feel like i'm going in circles at the moment. Oh and its the stock 24mm carb not the 26.
Moderator Airhead Posted November 13, 2010 Moderator Posted November 13, 2010 Ok, i'm hoping a fresh approach might help. The 175 is being a bit of an arse, from cold she's fine and starts and idles perfectly with choke when cold and when she wont idle with choke its cos she don't need it and she will idle for 10-15 minutes happily. Thing is when your riding, she's a bit rich in the middle but leans off at the top end. Moving the needle up ruins the low speed (sub 5000rpm) manners and putting in a bigger jet and dropping the needle she just floods out and fouls the plug. Lower the needle without the big jet and she bloody near wont run at all. Add into this if i run her a touch rich but tweak the fuel tap it helps with the mid range but she still leans out up top. At least i think she's going lean, i cant say for certain as with the motor going rich in the mid range the plug is always shitty. I would expect het to be lean. I was thinking float height, but how when she's rich and lean at the same time. Its complex as the pipe is a gianelli after market pipe which messes with the jetting a bit. Stock carb settings just have her sulking and difficult to start so i have got to fine tune things to get it right. There could be a little ig error in there too but i don't want to mess with that as i don't think it will affect the carberation. She starts readily enough so i figure its near enough. Don't panic, she runs fine for trips to work and such its just she's just not running as well as i'd like but feel like i'm going in circles at the moment. Oh and its the stock 24mm carb not the 26. What makes you thing it goes from rich to lean Jason, I doubt that and would think it goes from rich to richer. If it was going lean at large throttle openings the only evidence you would have is a plug chop...I doubt you would know from performance until it holed a piston. But you would certainly notice poor performance by being rich. I have a gianelli on mine at the moment and it seems ok with a 140 instead of 130 (early airbox taken into consideration)
Moderator Cynic Posted November 13, 2010 Author Moderator Posted November 13, 2010 If i lean the mixture off by dropping the needle a notch or 2 the mid range is great but there is nothing above 6/7 grand. Go up from a 160 to a 170 and she wont run at all, but the inverse is true too, go to a 150 and you kicking till your leg practicall falls of just to get her to start. I have a feeling it could be something to do with float height but i have checked that till i'm boss eye'd and its definitely on spec. I might lower it a mm and see what gives. Like i say it goes well enough its just not 'nice' to ride, the throttle response especially is dull and you have to roll off the throttle in the higher gears to find the right spot to go faster then roll the throttle on very slowly or she fades out, this causes the idle to go high if you stop fast from this condition, which is what makes me think its lean. I do have some piston noise, maybe the bore is too worn to be serviceable. Its within spec but has got some slap.
Moderator Airhead Posted November 13, 2010 Moderator Posted November 13, 2010 why would going from a 160 to a 170 mean it wont run at all, thats not right. It should run with no main jet at all fitted shouldnt it? of course it would be drowned out at WOT without a mj but it shoud still run ok at up to around 3/4 throttle. Would it be worth checking your air jet isnt blocked.
Moderator Cynic Posted November 13, 2010 Author Moderator Posted November 13, 2010 why would going from a 160 to a 170 mean it wont run at all, thats not right. It should run with no main jet at all fitted shouldnt it? of course it would be drowned out at WOT without a mj but it shoud still run ok at up to around 3/4 throttle. Would it be worth checking your air jet isnt blocked. With a 170 in she is so rich the plug looks like its been dipped in fuel, with the 150 unless the needle is maxed on the bottom notch she will run really badly as well. This is why i posted. I'm missing something but i'm not sure what.
Moderator Airhead Posted November 13, 2010 Moderator Posted November 13, 2010 doesnt make sense does it so thats why I think it may have something to do with the pilot jet/air jet stuff, your bike is standard with a 160 so it should be happy with a 170 with the Gianelli. Looks like you have been trying to solve a carb issue with jet and needle changes when the issue is something other than jet or needle position. Also have you checked you have the right needle in it. If you cant sort it why not try your spare 3u500 carb I cleaned it up before sending it back to you
Moderator Cynic Posted November 15, 2010 Author Moderator Posted November 15, 2010 Found it, the floats i had used are actually heavier buy a couple of grammes. They feel like there is fuel in them which would screw up the float height just a little. Must be a pinhole in them or something as its been a very slight issue but getting worse:mellow: Anyhow, swapped the floats then she ran proper shite, lifted the needle a couple of clicks the higher it went the better it got, 170main and lower the needle and ta daaaa. 9000rpm anybody! and smooth as you like from 1500rpm to flat out in a full throttle roll on she's now as fast in 5 as she was in top the torque's back. I think i'd allowed for the extra fuel somehow messing with the needle at lower RPM where she was running on the other jets. Then when she's wide open there isn't enough gas cos the main was too small for WOT. Thank F for that. Happy now Oh the carb IS the one you gave me back og. Its now much nicer than my original
Moderator Airhead Posted November 15, 2010 Moderator Posted November 15, 2010 Good news, its great to hear her singing again eh
Moderator Cynic Posted November 15, 2010 Author Moderator Posted November 15, 2010 Good news, its great to hear her singing again eh Great , got that crisp cracking note you hear on the track, getting a bit bloody chilly now though in the mornings. Had ice on my visor today.
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