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Post by wreckrat on Sept 10, 2020 16:34:15 GMT 1
Afternoon all,
Need some clarification from the gurus, i posted a thread about the left cylinder running rich on my F2 back in july and ive done a number of things to try and sort it, the main issue was rough running/misfire on slow throttle opening from off idle thru to half...ish throttle, between 4 and 6 thou rpm.
Ive done:
rebore, new pistons etc, new stator, plugs, banshee coils, carbs checked over by Dave muttsnutts, set up by dave on his dyno and fitted ignitec system to cure PV problem, now accelerates from idle to full throttle no problem, clutch slip stops play on dyno.
On the road the misfire is very prominent so i methodically reset the carb/oil pump synchronisation, carbs are standard F2 jetting/needle and with the left cyl/plug still running rich i went lower on the pilot jet from 27.5 to 25 and tweeking the air screw, had a run out and it seemed worse, misfireing/burbeling on opening throttle from off idle to around half throttle, left plug still black and slightly oily, right plug lovely tan colour then i did this,
I dropped the the needle in the left carb down to the top notch, rebalanced carbs and had another run and hey presto now pulls quite sweetly thru the throttle range and holds power quarter to half throttle and the left plug is now getting cleaner and similar colour to the right.
The question is, i havent found anywhere on this forum peeps who have different needle heights in their carbs..is this a done thing??
Next step is to do the clutch and its back to Dave for fine tune.
Cheers for your comments
Andy
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Post by midlifecrisisrd on Sept 10, 2020 17:15:29 GMT 1
I've heard of bikes running 1 size main on each side to fuel correctly
Different needle heights is kinda the same thing
I'd put the needles back the same but drop the main one size on the left and see how it feels on the road then on the dyno
Steve
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Post by wreckrat on Sept 10, 2020 17:54:20 GMT 1
Thanks Midlife, When the bike was on daves dyno the rich left cylinder was evident, the testing was done in 4th or 5th gear and winding the throttle wide open and the fuel curve was plain to see but seemed to produce good smooth power so we dropped the main jet in the left carb from 185 to 175...not a lot of difference, oily/black plug, on the road the issue is with gradual throttle opening from just off idle to 1/2 throttle acceleration, i have left the 175 main in for now as i havent done a WOT test yet but as i said just dropping the left needle made all the difference to the plug color and running...perhaps theres something amiss with the left carb...
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Post by rigga on Sept 11, 2020 9:42:16 GMT 1
Mutts will tell you this, each cylinder can be treated as individual air pumps, due to differences between them, from manufacturing to wear and tear, its not unusual to find that each cylinder requires different fuel requirements, hence jetting.
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Post by muttsnuts on Sept 11, 2020 11:17:18 GMT 1
um, not unusual for needles to be different heights, we can have a look at the next time its on the dyno, just be careful not to lean it off too much as otherwise you'll have issues higher up the rev range
Now that the clutch is fixed we will be able to fine tune it and see what its doing at lower rpm and steady throttle, slipping clutches just muddy the waters when trying to sort fuelling
Anyway, we can sort it for sure
I should be back up and running next week (workshop/dyno been down for nearly 3 weeks), so will start to clear the backlog and get jobs booked in once the workload has been reduced
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Post by wreckrat on Sept 11, 2020 18:43:13 GMT 1
Thanks Rigga/Dave, i just didnt think that different needle heights was a done thing but i couldnt believe what difference it made to the running, i even nipped out on it this afternoon to make sure i wasnt dreaming, i took it up about 1/2 throttle, smoothly opening the twist grip and it pulled strongly with no hesitation and held steady power in 5th cruising at 70ish....around 1/4 throttle...plug colour is...well not far off brown but funny looking...im sure you can read them when i show you dave.
Dave, as i said im near you monday afternoon so ill drop you a text on rough ETA and ill pick up the clutch kit and arrange some dyno time.
Bloody fantastic forum and info flying around guys.....Cheers..
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Post by muttsnuts on Sept 17, 2020 20:36:46 GMT 1
Thanks Rigga/Dave, i just didnt think that different needle heights was a done thing but i couldnt believe what difference it made to the running, i even nipped out on it this afternoon to make sure i wasnt dreaming, i took it up about 1/2 throttle, smoothly opening the twist grip and it pulled strongly with no hesitation and held steady power in 5th cruising at 70ish....around 1/4 throttle...plug colour is...well not far off brown but funny looking...im sure you can read them when i show you dave. Dave, as i said im near you monday afternoon so ill drop you a text on rough ETA and ill pick up the clutch kit and arrange some dyno time. Bloody fantastic forum and info flying around guys.....Cheers.. Hi Andy, yeah good to see you Monday afternoon, as usual manic as you saw ! I'll get you sorted and we will double check it all, but good its nearly there |
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Post by marrcel on Sept 18, 2020 6:55:22 GMT 1
Besides the fueling check for a weeping floath valve or stuck oil non return valve.
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Post by mouse on Sept 18, 2020 7:51:15 GMT 1
Besides the fueling check for a weeping floath valve or stuck oil non return valve. Yes, my 31k runs rich on the left hand cylinder, it fouls the plug every now and then. I spoke to 'Arrow' and he says it is the 'check valve' in the oil pump not shutting off the supply of oil to the carb when the engine is not running, it is no biggy, i just need to get the pump off and send it to the magician 'Arrow' to do his thing! Mouse |
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Post by wreckrat on Sept 23, 2020 15:48:46 GMT 1
Besides the fueling check for a weeping floath valve or stuck oil non return valve. Yes, my 31k runs rich on the left hand cylinder, it fouls the plug every now and then. I spoke to 'Arrow' and he says it is the 'check valve' in the oil pump not shutting off the supply of oil to the carb when the engine is not running, it is no biggy, i just need to get the pump off and send it to the magician 'Arrow' to do his thing! Mouse My bike runs rich on the left side all the time, mechanically I've done almost everything, arrow rebuilt my oil pump last year, top job, so really i can only think there may an issue with a 'worn' left carb...slide/emulsion tube worn where the needle slides up and down...dunno, just speculating, so in the mean time i picked up a new EBC clutch from Dave to fix the slipping clutch..just waiting for Norbo to send a pressure plate.....after i reminded him..then assemble in anticipation of getting the old girl on Daves dyno for a spot of fine fettling in november......cant wait.. |
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