Torgo
03-07-2016, 08:40 PM
As I'm coming up on 1k miles, I've kept the bike stock except for a 17T front sprocket. We've had a couple of warm days around here, > 80F, and the carb has started to act up at full throttle. Bogs and starts to stutter. If I go half-choke, it smooths out with OK power. I ended up pulling the plug, and it's white, so it's been running lean as expected. It's a little counter-intuitive since I would expect higher temperature to run richer, but I guess there's some interaction going on with the dialed-down EPA setup.
So I've been getting the idea to do the standard mod around here and get a Mikuni installed, with a jet set for around here and another one for West TX with the higher altitude, if needed. Before doing that, I figured I get some quality wrench time and see what's going on in the PZ30.
First of all, it's not actually riveted. It's actually screwed together with break-aways. Instead of drilling them out, I drilled a start hole, then crammed in some small torx bits from one of my many Harbor Freight collections into a drill and reversed them out. All 3 came out with not much effort.
http://chinariders.net/attachment.php?attachmentid=4846&stc=1&d=1457400230
The needle is not adjustable like a Mikuni - it has one setting for the c-clip. I guess you could do the old trick of adding a washer or two under it to make it richer if you wanted to adjust it.
http://chinariders.net/attachment.php?attachmentid=4848&stc=1&d=1457400230
The mixture screw has a black plastic plug installed preventing access. This is easily removed by making a small hole with a hand-turned drill bit and popping it out with a jeweler's screw driver . It's only backed off a single turn.
http://chinariders.net/attachment.php?attachmentid=4847&stc=1&d=1457400230
The slow and main jets are right there and easy to find and remove. The main is a 'K 98' and the slow is a 'K40A.'
The main looks standard and looks like you can easily match it up to OEM or aftermarket versions that are available all over the place. Not so for the slow jet - it's some kind of EPA monstrosity.
The slow jet is a non-standard 28mm and has 4.4mm threads at the bottom of it. There's a threaded cylinder that looks like it was pressed into the shaft to engage the threads of the slow jet . The flare towards the top of the jet then seats at the top of the shaft. I was unable to find any standard jets that match up.
Best I can tell is that you would have to thread the shaft itself if you wanted to use more common 28mm Keihen jets. Somewhere I read that folks sent theirs in for modifications - seems like a lot of effort when it's so cheap and easy to just swap out. So if you want to adjust that, I think you'll have some difficulty.
http://chinariders.net/attachment.php?attachmentid=4849&stc=1&d=1457400230
While I had it open, I figured I'd hack away a bit, without the effort of spending any extra money since I'll just put that towards the Mikuni if I end up doing the swap. I did two things:
1) Backed off another half turn to the mix screw.
2) Used a scriber tool with a very tapered point to pound into both sides of the main jet to increase the diameter. (My smallest drill bit on hand was 1/16", so that would have been too much.) What did this set it to? No idea, just a little bigger than '98.'
http://chinariders.net/attachment.php?attachmentid=4850&stc=1&d=1457400230
Big difference: it idles better, jumps now, and has more power available through the full throttle range. Actually felt close to popping a wheelie and I wasn't really trying. Now, flat out, it pushed above 60mph. Still have the rear 50T. It had never gone above 55-57 previously. I'll need more time on it to get a better feel overall, but that's the initial impression.
After playing around with this, I still think going with the Mikuni and pod filter is the path of least resistance. Still, you can crack the PZ30 open without too much difficulty and fiddle with a couple of things if you want to try to squeeze a little more out of it. The mix adjustment almost seems like it should be a requirement now that I've done it, and for $5 or so, you could actually increase the main the right way. The pilot is another story - look like you're stuck with that if you run out of room with the mix screw.
So I've been getting the idea to do the standard mod around here and get a Mikuni installed, with a jet set for around here and another one for West TX with the higher altitude, if needed. Before doing that, I figured I get some quality wrench time and see what's going on in the PZ30.
First of all, it's not actually riveted. It's actually screwed together with break-aways. Instead of drilling them out, I drilled a start hole, then crammed in some small torx bits from one of my many Harbor Freight collections into a drill and reversed them out. All 3 came out with not much effort.
http://chinariders.net/attachment.php?attachmentid=4846&stc=1&d=1457400230
The needle is not adjustable like a Mikuni - it has one setting for the c-clip. I guess you could do the old trick of adding a washer or two under it to make it richer if you wanted to adjust it.
http://chinariders.net/attachment.php?attachmentid=4848&stc=1&d=1457400230
The mixture screw has a black plastic plug installed preventing access. This is easily removed by making a small hole with a hand-turned drill bit and popping it out with a jeweler's screw driver . It's only backed off a single turn.
http://chinariders.net/attachment.php?attachmentid=4847&stc=1&d=1457400230
The slow and main jets are right there and easy to find and remove. The main is a 'K 98' and the slow is a 'K40A.'
The main looks standard and looks like you can easily match it up to OEM or aftermarket versions that are available all over the place. Not so for the slow jet - it's some kind of EPA monstrosity.
The slow jet is a non-standard 28mm and has 4.4mm threads at the bottom of it. There's a threaded cylinder that looks like it was pressed into the shaft to engage the threads of the slow jet . The flare towards the top of the jet then seats at the top of the shaft. I was unable to find any standard jets that match up.
Best I can tell is that you would have to thread the shaft itself if you wanted to use more common 28mm Keihen jets. Somewhere I read that folks sent theirs in for modifications - seems like a lot of effort when it's so cheap and easy to just swap out. So if you want to adjust that, I think you'll have some difficulty.
http://chinariders.net/attachment.php?attachmentid=4849&stc=1&d=1457400230
While I had it open, I figured I'd hack away a bit, without the effort of spending any extra money since I'll just put that towards the Mikuni if I end up doing the swap. I did two things:
1) Backed off another half turn to the mix screw.
2) Used a scriber tool with a very tapered point to pound into both sides of the main jet to increase the diameter. (My smallest drill bit on hand was 1/16", so that would have been too much.) What did this set it to? No idea, just a little bigger than '98.'
http://chinariders.net/attachment.php?attachmentid=4850&stc=1&d=1457400230
Big difference: it idles better, jumps now, and has more power available through the full throttle range. Actually felt close to popping a wheelie and I wasn't really trying. Now, flat out, it pushed above 60mph. Still have the rear 50T. It had never gone above 55-57 previously. I'll need more time on it to get a better feel overall, but that's the initial impression.
After playing around with this, I still think going with the Mikuni and pod filter is the path of least resistance. Still, you can crack the PZ30 open without too much difficulty and fiddle with a couple of things if you want to try to squeeze a little more out of it. The mix adjustment almost seems like it should be a requirement now that I've done it, and for $5 or so, you could actually increase the main the right way. The pilot is another story - look like you're stuck with that if you run out of room with the mix screw.