32mm Polini PWK Carburetor experiment
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Apologies for the state of the bike, I've not had the best of conditions or time the past few days I've been off work for testing.
I raised the needle one notch this morning, which seemed to help a lot with the throttle response, no bog when going from idle to wot
I also tried a step leaner pilot and main jet, upon riding around my drive it seemed to of made no difference to the spluttering issue I was having, so I then went up two sizes of pilot jet to see if it prefered the richer pilot, after about 50m up the road I went back home and swiftly removed it, spluttering worse than ever and barely wanting to run anything less than high rpms with wot
I then fitted the standard size pilot the bike came with, which is the smallest pilot jet I have and went for a ride. The bikes going allot better and seems fairly happy through most of the rpm, top end seems great and it's idling/cold starting nice. However I still have the spluttering issue under load, I've narrowed it down to roughly 1/8th throttle to about half throttle bad splutter, I'm guessing this is the crossover from the pilot to the needle jet? I'm unsure where to go from here, should I try lean off the needle again now I have a smaller pilot than before? The bike is practically unrideable through town behind cars doing 20-30mph, have to keep whipping the clutch in as it's spluttering so bad. -
Apologies for the state of the bike, I've not had the best of conditions or time the past few days I've been off work for testing.
I raised the needle one notch this morning, which seemed to help a lot with the throttle response, no bog when going from idle to wot
I also tried a step leaner pilot and main jet, upon riding around my drive it seemed to of made no difference to the spluttering issue I was having, so I then went up two sizes of pilot jet to see if it prefered the richer pilot, after about 50m up the road I went back home and swiftly removed it, spluttering worse than ever and barely wanting to run anything less than high rpms with wot
I then fitted the standard size pilot the bike came with, which is the smallest pilot jet I have and went for a ride. The bikes going allot better and seems fairly happy through most of the rpm, top end seems great and it's idling/cold starting nice. However I still have the spluttering issue under load, I've narrowed it down to roughly 1/8th throttle to about half throttle bad splutter, I'm guessing this is the crossover from the pilot to the needle jet? I'm unsure where to go from here, should I try lean off the needle again now I have a smaller pilot than before? The bike is practically unrideable through town behind cars doing 20-30mph, have to keep whipping the clutch in as it's spluttering so bad. -
@NINJA not as far as I'm aware, no power jet on this carb and no leaks from any breathers, float height is good, both brass nossles either side of slide are breathers as far as I'm aware? I've just got the pipes open
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@Glynn123 More tuning required then, is the PV opening correctly, as that may be a hindrance and what's that big silver round thing on the right???
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@NINJA pv is on the same settings it used to run on, cleaned and setup it all about a 1000 miles ago roughly so shouldn't be that.
Silver things a plug for the emmisions bottle that usually goes in the airbox -
@Glynn123 Would putting the bottle back on not be worth a shot? As that may be affecting the mixture ratio, I know my bike ran better with the bottle on rather than with it removed.
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@Glynn123 Would putting the bottle back on not be worth a shot? As that may be affecting the mixture ratio, I know my bike ran better with the bottle on rather than with it removed.
@NINJA possible but I don't see a blanked out airbox causing issues, just a smooth run through a new filter.
Yeah that top bolt is missing, its been like that since the previous owner rebuilt it, I've got a bolt kit on order which hasn't arrived yet but I'm certain it doesn't leak, tried spraying isopropyl on it while revving etc in past
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@NINJA possible but I don't see a blanked out airbox causing issues, just a smooth run through a new filter.
Yeah that top bolt is missing, its been like that since the previous owner rebuilt it, I've got a bolt kit on order which hasn't arrived yet but I'm certain it doesn't leak, tried spraying isopropyl on it while revving etc in past
@Glynn123 OK as you've increased the airflow with the larger carb, then I would look at the other 2 elements aka fuel and spark. If there is sufficient fuel reaching the carb & barrel with no blockages, then perhaps a different plug may help? What's your current plug like and have you performed a plug chop since you installed the carb? Maybe doing that will give you some clues in which direction you need to go???
SEDUCED BY THE DARK SIDE!!!
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@Glynn123 OK as you've increased the airflow with the larger carb, then I would look at the other 2 elements aka fuel and spark. If there is sufficient fuel reaching the carb & barrel with no blockages, then perhaps a different plug may help? What's your current plug like and have you performed a plug chop since you installed the carb? Maybe doing that will give you some clues in which direction you need to go???
@NINJA I'll try a different plug and maybe go for a regular 15 minute run with varied rpm tomorrow to get a baseline, hadn't tried a new plug yet but bought a set of four BR8ES to play around with, I'm thinking of dropping the needle again to test but its a ballache with the split cables etc haha
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@NINJA I'll try a different plug and maybe go for a regular 15 minute run with varied rpm tomorrow to get a baseline, hadn't tried a new plug yet but bought a set of four BR8ES to play around with, I'm thinking of dropping the needle again to test but its a ballache with the split cables etc haha
@Glynn123 I'd look at your plug first before changing any of the jets etc. As the colour of your plug will indicate which direction you need to go in. Maybe even try a colder grade plug or an Iridium one and see what occurs with those???
SEDUCED BY THE DARK SIDE!!!
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@Glynn123 I'd look at your plug first before changing any of the jets etc. As the colour of your plug will indicate which direction you need to go in. Maybe even try a colder grade plug or an Iridium one and see what occurs with those???
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@NINJA been running it on an iridium for a while now, bought the standards just for plug chopping
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Finally getting somewhere with this carburetor, sorry for the wait, had a little incident with buying a car I definitely shouldn't of bought haha.
Was having severe spluttering with the DT all the way to main jet, the bike would literally barely run under load unless you were flat out. Narrowed this down to the needle and invested in a polini needle kit. Currently running a 140 main and 42 pilot, along with the standard N68E needle. The bike actually fouled it's plug after trying to startup again after a 5 mile ride, it was running allot worse in the 15 degrees weather we had compared to when I last played with it in around 5 degrees weather. I tried the leaner JJK needle and found it was bogging on big throttle inputs, so raised it a notch to find the bike had transformed. I just went a short 10 mile ride and the bike is a totally new beast, miles better than standard carb, loads of torque from idle. The only issue I'm finding now is a splutter at low throttle say 1/8th under, so I'm guessing the pilot is rich. However upon checking the new plug I fitted the bikes running abit lean, so tonight I fitted a JJN needle, which from what I can gather will give a leaner low end with richer mid and top, I've left it in the mid position for now. Once this weather clears up Abit and I'm back off work I'll give the bike another shot and post an update, but I'm finally glad to be getting somewhere with this bike, as it was proving a minefield a while ago. -
@Glynn123
Be careful of the float level, the angle of the inlet isn't suited for most carbs. It's a real pain in the ass to setup.
I ran a Mikuni TM32 with a WR200 Inlet manifold and it was good but always had trouble with float control.
The Mikuni TMss with angled venturi design just works for me.
The WR200 had a TM30ss, I've used a TM34ss from a Suzuki RGV 250 VJ22, which worked well,
Keep it real
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@Glynn123
Be careful of the float level, the angle of the inlet isn't suited for most carbs. It's a real pain in the ass to setup.
I ran a Mikuni TM32 with a WR200 Inlet manifold and it was good but always had trouble with float control.The Mikuni TMss with angled venturi design just works for me.
The WR200 had a TM30ss, I've used a TM34ss from a Suzuki RGV 250 VJ22, which worked well,
@Darty ah right cheers, I've had no issues so far on the standard float height the carb came with, what symptoms should I be looking for? Just a bog when holding bike wot for a while? Had bike flat out for a good minute or so in 6th and never seen any issues?
