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| Not sucking https://www.ausmini.com/forums/viewtopic.php?f=2&t=31473 |
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| Author: | Rikki [ Sun May 06, 2007 8:51 pm ] |
| Post subject: | Not sucking |
Hi, I have twin SU carbs on my 1275 engine and at idle one of the carbs is sucking heaps of air and the other one isnt, i have got a colourtune and if your looking at the engine front on the 2 cylinders on the left are perfect (blue) but the two on the right are rich (yellow), the carb on the right is the one not sucking much air. Any ideas? ive tried adjusting almost everything on the carb. Cheers |
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| Author: | andbat [ Sun May 06, 2007 8:56 pm ] |
| Post subject: | |
something that lets air in is stuck for some reason. take it off and all apart and fidle with it put it back together after alot of swearing cause you forgot where it all went put it on the mini and... a: it will work fine. b:it'll be the same if not worse. i dunno, i just want to increase my thread count. 
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| Author: | Rikki [ Sun May 06, 2007 9:03 pm ] |
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andbat wrote: something that lets air in is stuck for some reason. Well thats stating something i already knew Quote: i dunno, i just want to increase my thread count.
Can you atleast say something useful, why does your thread count matter to you? it still doesnt make you smart. Cheers |
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| Author: | Hanra [ Sun May 06, 2007 9:05 pm ] |
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Did u back the linkage off between the 2 carbs to try and balance them? Ive got a carbalancer which makes the job easy as!!! If not grab some plastic tubing/hose and put one end to ur ear and the other to the mouth of the carb, u want to get the hiss sounding the same between the two carbs. At idle this is done by adjusting the idle screw in/out. If this is still not helping, u may have a worn throttle shaft or an air leak some where on one of the carbs. Ensure that the pistons are free to rise and fall, u should hear a clink sound if u raise the piston and then drop it. Or u may have a worn needle/jet or stuck choke... |
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| Author: | Rikki [ Sun May 06, 2007 9:11 pm ] |
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Yes i have the Carbalancer as well. I have tried to adjust the idle screw and the throttle linkage and still no luck, i can lift the piston and let it go and hear a click when if hits the bottom. Cheers |
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| Author: | Hanra [ Sun May 06, 2007 9:16 pm ] |
| Post subject: | |
Well it sounds like ur balancing the carbs ok then. So it will come down to needles/jets/and mixture adjustments..... Theres a pandoras box right there if u dont know wat ur doing.... U may have a worn needle, if u have a choke on the car, ensure that its not stuck on for the right carb. The right carb is running to rich by the sounds of it. |
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| Author: | Mick [ Sun May 06, 2007 10:23 pm ] |
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You are doing this as per the manual? I mean are you undoing the linkage between the two carbs? Because if you don't you will adjust them all day and the problem will remain. Check the butterfly spindles are nice and snug, rattle the shafts up and down to see if there is much play around the shafts, this will cause all kinds of problems if there is. BTW, if it was running lean and sucking air, wouldn't the colourtune show lean on the right carburrettor (which is also not sucking enough air a\ccording to the carb balancer)? Has the fuel bowl levels been checked? They may be obscenely high. |
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| Author: | 1310/71 [ Mon May 07, 2007 6:57 am ] |
| Post subject: | |
Never really mucked around with SU's (went to webers at an early age  ), but I hear a lot of SU problems can be not enough dashpot oil, or the wrong type. check the obvious above as people have said plus don't forget the dashpots.
KB |
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| Author: | AEG163job [ Mon May 07, 2007 10:27 am ] |
| Post subject: | |
recommend you FIRSTLY check 1) engine compression 2) timing 3) valve clearances. First you have to be sure you have the essentials right. Otherwise you are on a hiding to nothing, no amount of fiddling with carbs will get it right. If all above is OK, remove dashpot chambers & pistons & check for wear. Do the "vacuum" check as per Vizard. Then check throttle butterflies for synchronisation. Check for excessive wear in the spindles. You can get away with a little play here. Check the springs in the vaccum chambers to see if they are the same length. lastly, check for air leaks, make sure gaskets are all ok and smear with a little gasket goo-just a fine smear not like your'e icing a cake! Also, check the mating faces for the manifold to make sure they are flat. I like to true them up by using wet n dry and a flat pane of glass. Obviously, this means fully dismantling the carbs and checking everything, but nothing here is beyond the average person's ability. One last thing, check for air leaks wear at the manifold/head. The gasket should be renewed and the mating faces of the manifold should be trued up as above if necessary. Enough info here for 100 thread counts. 
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| Author: | simon k [ Mon May 07, 2007 1:12 pm ] |
| Post subject: | |
simple one.... just make sure you can push both pistons up in the carbs with your finger through the aircleaner trumpet - sometimes it takes me 10 minutes just to get my left hand one to fall all the way without sticking, and when it's all the way down it's really hard to push it up. The cover doesn't sit perfectly square and compresses a bit when it's screwed down, trapping the piston at the bottom... |
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| Author: | TheMiniMan [ Mon May 07, 2007 4:24 pm ] |
| Post subject: | |
Rikki, just bring your car around here & i`ll fix em for you easy-peasy just ring before you come tho 0407 135 656 Murarrie |
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| Author: | lil-ute [ Mon May 07, 2007 4:39 pm ] |
| Post subject: | |
weber |
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| Author: | Rikki [ Mon May 07, 2007 5:14 pm ] |
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TheMiniMan wrote: Rikki, just bring your car around here & i`ll fix em for you easy-peasy
just ring before you come tho 0407 135 656 Murarrie Thanks Matt ill prob do that just have to finish my dash, as without a dash it aint road worthy. Just curious as to know what the prob may actually be. Cheers |
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