... is a pain in the ass.
Got my PWK28s setup on my LC with specs suggested by a friend down in SF with the same setup.
45 pilots, JJH needles @#2, 145 mains.
Lots of clutch slipping to get off the line, but idle isn't hanging, so i assume the pilots are close enough.
It runs better when cold and gets worse as it gets hot, so I can only assume the needles are lean and need to raise up a clip or two.
Would be nice to have a warm dry day, coz chipping away at this between rain showers is slow going.
Bacon :bacon:
That says to me It's rich to start with when cold.
Start by getting the main jet near enough, if it idles ok the move to looking at the needle and jet assembly,
Quote from: Barrie on December 01, 2020, 02:04:06 AM
That says to me It's rich to start with when cold.
Start by getting the main jet near enough, if it idles ok the move to looking at the needle and jet assembly,
I've always done the reverse.
Get the idle/pilot and air/fuel screw dialed in. Then move on to the needle. Then the main.
All the jets are flowing when on the main, so no use worrying about it, until everything else is right.
I've also come to read "The general consensus is use JJH needles with the airbox and N68A needles with foam filters".
So, I'll stick the N68A's in and see if that helps. :metal:
OK. if you know WOT is about right, then decide whether your rich or lean in the middle, from your description it sounds rich when hot, so the needle needs to dropped a couple of notches . Your right about it being the sum of the pilot and the main , but if it idles with around 1 turn out on the air screw the mid range only is your problem which is only controlled on the needle up to 75% throttle, after that it's main jet to fine tune again
Quote from: pdxjim on December 01, 2020, 02:43:48 AM
I've always done the reverse.
Get the idle/pilot and air/fuel screw dialed in. Then move on to the needle. Then the main.
This is the correct procedure :twocents:
pilots big. I think its affecting needle. 42 pilot, 1 rich needle, 150 mains to start. :twocents:
I found a pair of 42's in my stash.
I'll put those in when the N68A needles show up.
I have a good stash of Keihin jets if you need something. KTM, you know.
Quote from: 85RZwade on December 01, 2020, 07:46:59 PM
I have a good stash of Keihin jets if you need something. KTM, you know.
Polini jets are cheap and readily available here in town, as the mopeders and scooter bois all run PWKs or clones.
I've not used them, or compared the Polini to genuine Kehin, but I expect they are good quality.
Scored a pair of 38's and a pair of 40's from the scooter bois for $10 total. :whoop:
Polini jets, but beggars ...
I dropped the 42's in anyway, coz lots of guys in the UK use 40's with the airbox so ... I gotta be bigger than that with pods, right?
Gonna change the needles out to N68A middle clip.
On second thought, it's not the jetting itself that's a hassle, it's taking everything apart right after I just put the damn thing all back together. Over and over.
... and spilling gas all over my brand new build, and huffing gas fumes, and ....
(https://i.ibb.co/NpxtYZJ/3-B3996-F6-FF52-4764-ABF4-82949-AA72168.jpg)
I will say, I'm pretty impressed with this PJ1 Engine and Case paint I used. It's holding up surprisingly well.
Go to the local model shop and get some 2 part fuel proofer , matt and gloss is available , over here we call it Aerocote
(UK).Spray a light coat over the finished paintwork, spilt fuel will then not affect the paint finish.
Ok.
Swapped in 42 pilots. All else the same.
Still won't pull itself off the line and just basically bogs out and dies. Won't idle. Unrideable.
Totally rideable, and runs pretty good with chokes on, tho.
Sounds like you are too lean.
Setting pilot, needle and then main works if you are already jetted close to perfect.
New build with new carbs, I would be starting out with getting the main jet close first.
Although the pilot does theoretically affect the entire throttle opening range, it is soo small that I just ignore it to start.
Everybody may not agree, just my :twocents:
Quote from: rodneya on December 03, 2020, 07:21:01 PM
Sounds like you are too lean.
Setting pilot, needle and then main works if you are already jetted close to perfect.
New build with new carbs, I would be starting out with getting the main jet close first.
Although the pilot does theoretically affect the entire throttle opening range, it is soo small that I just ignore it to start.
Everybody may not agree, just my :twocents:
That's the way it feels to me too. It running better with the chokes on kinda confirms it.
It pulls great on the mains, it's just getting there that's bad.
I'll probably throw the 38's in just to be sure, then see if the scooter bois have any 50 pilots :eek:
I only have four 50s. Less than two hours ride (brrr) or a couple days by mail. I'd send the shiny ones.
(https://i.postimg.cc/QNJq2K7Q/image.jpg)
I thi k you're compensating the needle position with the pilot :twocents:
Well, raising the needles is certainly easier than changing jets, but it won't even idle with the 42s.
That shouldn't have anything to do with the needles.
Why wont it idle?
thats very odd. ive never seen one need over 45's on an rd of any kind. BUT, they are all different. i mean, stuff the 45's back in and richen the needle? also make sure the float level is correct, its very easy to get them off with the way the bowls come off. where is the air screw set?
Getting closer!
Raised the needles, and it's almost rideable.
Current setup: 42 pilots, airscrew 1.5 out. JJH @#4, 145 mains.
Pilot is clearly too small as idle hangs.
Once you get past the pilot the needles seem much better after moving from #2 to #4 so will leave them for now and go back to the 45 pilots at maybe 1-1.5 on the air screws. Polini bois have 48 and 50 pilots if I need them.
Biggest hassle of these PWK's is the idle screw and air screw is on the left side on both carbs, meaning you gotta pull the right carb off to adjust.
Only thing I can add is, if you are trying to compare jet sizes to what others use make sure that those aftermarket jets are indeed the same size and genuine Keihin parts. Number for number they may be different sizes.
It doesn't make any difference in the end when you get there but may make the road getting there a little more bumpy why you need a 50 when everyone else uses a 42.
Quote from: oxford on December 05, 2020, 08:22:37 PM
Only thing I can add is, if you are trying to compare jet sizes to what others use make sure that those aftermarket jets are indeed the same size and genuine Keihin parts. Number for number they may be different sizes.
It doesn't make any difference in the end when you get there but may make the road getting there a little more bumpy why you need a 50 when everyone else uses a 42.
True.
Only aftermarket jets I'm using are Polini, and they have the rep of being very consistent and as good as genuine Keihin.
Whether they flow the same as a genuine Keihin of the same number? Who knows.
Quote from: pdxjim on December 05, 2020, 08:30:45 PM
Only aftermarket jets I'm using are Polini, and they have the rep of being very consistent and as good as genuine Keihin.
Whether they flow the same as a genuine Keihin of the same number? Who knows.
this may very well be it. My pwk numbers i gave was from my lc topped motor from
way back with pwks and specII pipes, unported, so, very similar setup. I actually dynoed the bike, and the only jetting change was from a 152 to a 150 on the main and one clip richer (to 4). I also remember the airscrew seemed to respond best at 1.25 out. I put down 52 rwhp at that time back in.. 06 i think?
Ugh.
This is so weird.
Current setup is 45, 1.5 turns out, N68A #3, 145. Ed Erlenbach stage 2 port, squished head, vForce3 YZ85 reeds with spacers, Garrett's pipes.
It starts easily on one or both chokes. Idles easily when cold, and runsand revs pretty good when cold.
I can get about two blocks around my neighborhood before it starts acting up. Doesn't want to idle, feels very hollow down low. It starts bogging and missing and feeling like it's running out of fuel.
I'm about ready to decide jetting may not be the problem?
All electrical and charging system is stock original 40 year old parts. Timing is set to the factory marks, but since it's all new crank/rods/pistons/etc, I have a call out to a friend with a timing setup so I can verify it's correct at 1.8 btdc.
What else would cause shit running when hot? Bad coil maybe? R plugs and the wrong plug caps?
... and by hot, I really mean just warm. Like 2-3 minutes idleing on the stand and 2-3 minutes on the road it all goes to shit and I have to use the chokes to get home.
... but maybe the fact that it runs so much better on the choke means it really is jetting?
This fcuking thing is pissing me off.
Before it moves from jetting, can you just confirm that all the jets you are using are all aftermarket Poloni or are some of them genuine Keihin?
Are you getting fuel through? I have had a bad gas cap breather cause fuel starvation after a few minutes riding.
Loosen the cap and try ride a bit.
Electrical issues dont usually get better when the choke is on
Quote from: rodneya on December 08, 2020, 07:40:55 PM
Are you getting fuel through? I have had a bad gas cap breather cause fuel starvation after a few minutes riding.
Loosen the cap and try ride a bit.
Electrical issues dont usually get better when the choke is on
Clear fuel lines full of fuel.
No issue there.
Quote from: oxford on December 08, 2020, 07:39:31 PM
Before it moves from jetting, can you just confirm that all the jets you are using are all aftermarket Poloni or are some of them genuine Keihin?
All genuine Keihin jets from jetsrus.com in there now.
So far only the 42 pilots were Polini and they only lasted one test ride.
Lol ... to further confuse things, here are the plugs:
(https://i.ibb.co/qW6ZGft/6-A101014-EFD7-4609-9821-091-D6-CCB6910.jpg)
Ok, getting closer again.
Raised the N68A needles up to #4 and made it around the hood without resorting to the chokes to get me home.
Still hollow just off idle, but saved by the fat needles, I guess. Goes "Baaaaaa-whooom" when you whack the throttle, and hangs before settling down.
Going up to 50 pilots! :metal:
sounds electrical. id try a new coil.
Quote from: m in sc on December 09, 2020, 07:06:57 AM
sounds electrical. id try a new coil.
If you were to try a new coil, which one would you try?
There are options from $20 to $120.
I'd try a known good one before buying new; maybe the TDR could help out? Swapnostics, we call it at work.
I'll be replacing the coil and CDI (with an Ignitech or Zeel) eventually, anyway.
Prob not gonna spring for a new coil right away, unless it clearly isn't the jetting.
i played this game with the lightweight and pwks until i swapped the ignition. I even swapped carbs, jetted all over the place, etc, for like, a year. :bang:
Had a banhsee aftermarket ign in it, then went to an hpi (since i had the larger taper LC crank in the bike) and all of a sudden, no issues. turned out to be the box, i think.
my money is on electrical. any dual lead cdi coil with the right resistance will work.
:twocents:
Quote from: m in sc on December 10, 2020, 10:06:30 AM
i played this game with the lightweight and pwks until i swapped the ignition. I even swapped carbs, jetted all over the place, etc, for like, a year. :bang:
Had a banhsee aftermarket ign in it, then went to an hpi (since i had the larger taper LC crank in the bike) and all of a sudden, no issues. turned out to be the box, i think.
my money is on electrical. any dual lead cdi coil with the right resistance will work.
:twocents:
Ignition problems with aftermarket banshee ignition stuff is very common. the only stator that actually lasts is OEM and for CDI, OEM, Zeel or Dynayek.
All the other ones will leave you chasing your tail or stranded.
Vape and HPI seem to be doing it right though as their systems work really well.
agreed. it would work, but just ran like shit.
I mean, the stock stuff is now 35 years old. minimally. time to upgrade.
I had a 1980 rd400 that was running like crap around 4000 rpm and the more throttle i gave it the worse it got. I messed around so long with jetting and looking for this that and the next thing. One day i decided to put a timing light on it and i could see the mark perfectly... then i slowly revved it and all a sudden the mark started moving and appearing all over the place and sometimes not at all. Drove me mental... just talking about the effort i put into jetting and looking for air leaks makes me mad all these years later!
Jim, does that bottom end have new seals? I had an issue with my YZ this summer where it would run great until it warmed up then run pig rich. It turned out to be the wet side crank seal. The float stuck while parked in the garage and allowed fuel down into the crank and the seal softened. It would warm up and suck gear oil causing my plugs to look like your picture. Just a thought.
Edit: just saw your build thread and you rebuilt the bottom end. Might be worth taking a look anyway.
Quote from: Nkreig on December 13, 2020, 08:31:32 PM
Jim, does that bottom end have new seals? I had an issue with my YZ this summer where it would run great until it warmed up then run pig rich. It turned out to be the wet side crank seal. The float stuck while parked in the garage and allowed fuel down into the crank and the seal softened. It would warm up and suck gear oil causing my plugs to look like your picture. Just a thought.
Edit: just saw your build thread and you rebuilt the bottom end. Might be worth taking a look anyway.
Seals are all new. Not blowing white smoke at the right side, so pretty sure the wet side isn't leaking.
I didn't pressure test, so I guess a leak at the dry side crank seal, or intake is always a possibility.
Still chasing the jetting :bang:
Current setup is 52/1.75 airscrew/N68A#4/165
Today I raided the needles up to #4, and that helped pull away, but felt fat and not so clean thru the midrange as at #3. Not sure what to try next, but might try dropping the needles all the way down to #1 to see what happens. At least that'll tell me if I'm to rich or too lean.
Also have a Dynatek Banshee mini-coil on order. Not sure if they come with resistor or non resistor caps, but I'll get that sorted as well.
i also think you'll be chasing it w those needles. you say midrange. you mean 1/4-1/2 throttle or? if its fat at #4 but lean at #3, shim it @4 or try a different needle.
side note, do you have reed spacers in? might be that simple where the frequency is causing reversion at a certain rpm, and they may need to be added or adjusted.
or, drop back down to a 50 pilot set screw at 1.25 or so. the pilot may be artificially carrying the mid range up till the needle at the #4 position starts fueling, but was lacking at #3.
Jim, Out of curiousity how high are the hoods on the needle jets looking in at the cutaway on the slide? Lower, the same or do you have to open the throttle some to see the top of the hood? I got 4 PWK's from yz85's and got 3 different heights so I know they aren't all the same. On a street bike too tall can cause problems
Quote from: edgefinder on January 05, 2021, 04:55:10 PM
Jim, Out of curiousity how high are the hoods on the needle jets looking in at the cutaway on the slide? Lower, the same or do you have to open the throttle some to see the top of the hood? I got 4 PWK's from yz85's and got 3 different heights so I know they aren't all the same. On a street bike too tall can cause problems
Hoods on the needle jets?
Like the shroud that sticks up into the bore?