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Post by endru on May 19, 2013 19:03:22 GMT -5
I'm getting ready to install my 50mm BBK from Scrappys. I have a UNI-style filter and will be using a derestricted exhaust. Now the question is main jet size. Can I get away with a #  ? I'd rather not burn up the new kit right after getting it, but that's the biggest size I have on hand. I've been looking at the websites of my favorite sellers, and many of them don't sell individual jets between and 100. The few that I have found were slightly high in price or shipping for my liking. Who would you recommend buying jets from? On a closely related note, I'm still using the stock carb, which I believe is 17mm. I don't feel the need to replace it until I get a performance head. Are the thread sizes on the main jets different for the 20-24mm carbs than for the 17mm that I have? I'm thinking maybe they just don't make main jets bigger than # for 17mm carbs. |
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Post by endru on May 17, 2013 18:10:34 GMT -5
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Post by endru on May 12, 2013 8:56:10 GMT -5
OP You have a good scoot there My Puma Was topnotch Yours Hank Thanks Hank, I saw those videos back on the old site back when I first got my scoot. Didn't yours get stolen or something? I really like my Puma. I wish it were styled more like the Angel, but I got a great deal on it and it's been really good to me. I like "Spectre" too. Maybe some day I'll be able have a list of mods like that on my Puma ;D I am waiting on parts coming in now for my bbk. If I were you I would wait to do the gears and instead do the a9 cam now while you already will have the engine apart. Good luck! That's a really interesting suggestion, I had forgotten that the a9 cam can improve top speed too, and that's what I'm looking for. I do subscribe to the 1 modification at a time principle though (easier to diagnose if something goes wrong), so I wouldn't be doing the kit and cam at the same time. I think I'll make the cam my very next step after the kit and gears. |
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Post by endru on May 11, 2013 14:26:59 GMT -5
Thanks for the feedback. Devo I'll send you a PM, I think for now I'm going to have to use the exhaust that I have. Larry I remember reading about Hank's builds on the old site, I'll have to check back on it again if I decide to pursue a stroker crankshaft.
Thanks again!
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Post by endru on May 10, 2013 21:57:16 GMT -5
I finally scraped together the funds to do some major upgrades to my Puma Amor 50cc, and I'd like to run them by you guys just to make sure I'm not missing something critical or wasting my money. I've done all kinds of minor things so far: valve adjustments, upjet, 1,500 rpm torque and clutch springs, iridium spark plug, pod filter, sliders tuned to my liking and orange coil. Here's what I'm planning to purchase: - 50mm BBK from Scrappydog's ebay store. 52mm would have been great but it's out of my price range. - #  and #  jets. Should I get one in between as well? I'm having trouble finding them, where's the best place to order those sizes? - Final gears: 16/50 from Scrappy's ebay store. Need a few more MPH top end. I'm still running a stock exhaust, which I know will restrict me some, but even ebay perf. exhausts cost more than the BBK. Might drill some holes in the exhaust to compensate. Sometime later I'll get that and also look into getting a better head, carb, intake manifold, variator, A9 cam and maybe even a stroker crankshaft. Are all my ducks in a row? |
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Post by endru on May 7, 2013 20:59:18 GMT -5
[replyingto=triker]triker[/replyingto]Thanks Triker, that's extremely helpful!
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Post by endru on May 6, 2013 21:52:51 GMT -5
[replyingto=teddy554]teddy554[/replyingto]Yeah I'm about  % sure that I have 69mm valves, just by eyeballing them from the side to see how far above the lip of the head they are. But I like cold hard measurements, so that would really be appreciated. Thanks! |
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Post by endru on May 6, 2013 19:54:35 GMT -5
Aha, that solves it, thanks Teddy. I wasn't thinking that you the rocker assembly from the original head. Makes perfect sense now.
So when I was investigating my stock head months ago trying to figure my valve length, it wasn't immediately obvious whether or not the valves were sticking up far enough to be 69mm. I wonder though if it wouldn't just be easier to measure the rocker arm lengths to determine the valve length.
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Post by endru on May 6, 2013 19:30:23 GMT -5
I'm having trouble wrapping my mind around the concept of 64mm vs. 69mm valves. The problem may simply lie in the fact that I haven't yet installed a BBK or performance head, so I haven't had the chance to see this stuff disassembled. But this is something that's been bothering me and I don't want to mess up when I'm ordering parts. My question is, why does it matter what the valve length is on my stock head? My only guess is that my 69mm head is in fact slightly taller (in addition to longer valves) and therefore going down to a 64mm head would make the crankcase bolts too long and the camshaft chain too long. And for those that have 64mm valves, the opposite would be true - a 69mm head would extend past the crankcase and too short of a cam chain. Is this where the problem lies, or am I way off?  |
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Post by endru on Apr 14, 2013 19:37:32 GMT -5
Hey everybody thanks so much for the valuable input.
I have had some luck so far with modifications. Everything is just so touchy - one poorly made modification will bottleneck the whole performance. Valve adjustments, variator weights, contra springs, jetting... everything has to be exact in order to get acceptable performance. My point is, once a get the BBK, I'm sure I'll see a significant power increase since I've become very comfortable with tuning the other things that would affect power. And the Pumas run on the same GY6 platform as every other Chinese clone scoot. So a Puma not performing better after a BBK install could be remedied the same way as the other brand scoots having that issue... we've seen plenty of that on here and the old scootdawg. Taller gears for instance would be in the plans shortly after installing a BBK.
The bar on the frame that goes over the valve cover is a real pain. Even a plug chop is cumbersome. Thanks for the advice on how to pull it apart.
Anyway, thanks again everyone, it really helps to have people who have more experience than me.
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Post by endru on Apr 11, 2013 11:52:17 GMT -5
[replyingto=maroluvr8569]maroluvr8569[/replyingto]My Puma Amor 50 had the same issue with dying at idle. Between a valve adjustment (they were very tight) and adjusting the A/F mixture screw, the problem is now solved. The mixture screw was only 1 turn out, way too lean. I needed to remove the plug covering the screw on the stock carb, but the 2nd carb you bought shouldn't have the screw plugged.
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Post by endru on Apr 9, 2013 21:15:25 GMT -5
On the old forum I got involved in a thread discussing some of the "anomaly" engines where the case bolts aren't spaced correctly for a typically bore kit upgrade. scootdawg.proboards.com/index.cgi?board=discussion&action=print&thread=55131. I wasn't really able to come to a solid conclusion though on whether an upgrade would fit my Puma Amor 50. I would really love to put on a 50mm or even 52mm kit this summer, and the kits are really affordable (especially from Scrappydog) but I'm afraid of buying the cylinder only to have it not fit. The best way to be certain is to remove the head and cylinder (and all the other stuff included in that process) and measure the spacing of the bolts. But man, that's a lot of work just to measure something... So I guess I'm just trying to reopen the discussion with the following questions. Has anyone had any updated experience with installing BBK's on znen (puma) 50cc engines? If I were to buy the kit and it didn't fit, is it feasible to drill new, correctly spaced holes to fit the kit? Any other relevant advice for me? |
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Post by endru on Mar 20, 2013 21:18:11 GMT -5
From what I've been told, it's a mixture of oil and a little bit of gas that makes it past the valves. Hence the light, frothy consistency and gasoline smell.
That being said, my original airbox was attached to the carb with a plastic elbow joint that had an unused nipple on it. When I got my free flow filter, I cut that joint off the old airbox and attached the filter to that. I rerouted the breather tube from the valve cover to that extra nipple, so it's recirculating the mixture back through the carb. It's not any better than the catch can or fuel filter ideas, so I'm not advocating this as scooter gospel, but it was an easy solution with nothing additional to buy.
There might be concerns from people about it fouling the plug or hindering performance. I've had this setup for about 500 miles now, and I recently did a plug chop and didn't see indications of fouling. I also haven't noticed any decreased performance or ignition blips which would indicate poor combustion. And after all, back when the hose was on the stock airbox, the gloop had soaked through the foam filter and was being sucked into the engine anyway.
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Post by endru on Mar 10, 2013 20:45:53 GMT -5
That is not an EGR system that is a PAIR system(Pulsed Air Injection Reburn) a EGR(Exhaust Gas Recirculation) is a valve actually on the pipe. Alleyoop I agree that it's not EGR. There is nothing tapped from the exhaust, so no exhaust gas being recirculated into the system. I'm skeptical though that it's a PAIR system, or at least that it is a true PAIR system. Like EGR, The PAIR system also has a valve attachment which is controlled by a vacuum tube coming from the intake. The oxygen rich air is directed into the exhaust manifold in order to heat up the exhaust and activate the catalytic converter. My bike doesn't have this valve, but I guess it could still be PAIR without it. Why even have a valve in the first place if the system is powered by the negative pressure created by the passing exhaust gases? If it's just putting extra air into the exhaust line, then I see no reason why this would hurt performance. And if it's making the catalytic converter work better, then I would consider it beneficial actually. |
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Post by endru on Mar 9, 2013 22:57:06 GMT -5
I'm wondering if I can plug the fresh air inlet hose for the EGR, and if that would even be advisable or beneficial. I've done a lot of research tonight so let me try to give everyone the full picture of what I know and don't know. First of all, I don't think I even have the full EGR system on my scoot. There is a thick black inlet hose (the one I'm thinking of plugging) that hangs out the back above the exhaust pipe. In-line on that hose is a one-way valve which I'm assuming contains a simple filter, which is contained within a small black cartridge. The hose continues to the valve cover, where it's connected to a metal piece that looks like a padlock. From the padlock (whatever that is) there is an S-bent metal tube that goes into the head. This is the part that people usually block off with a blocking plate. I'm guessing that inlet on the head directs the incoming cool air into the exhaust manifold or possibly the combustion chamber directly, I really have no clue. Either way, I don't believe this is a full EGR, because that would include exhaust gases being mixed with that cool air coming in, but there is no exhaust gas hose coming into the system, there is no sign of an EGR valve, unless it's that padlock thingy, and there is no 2nd vacuum line from the intake manifold, just the one which controls the fuel petcock. So what is all this that I have? Maybe the framework for an EGR system? If this little system I have is meant to cool the combustion chamber in order to decrease emissions, wouldn't it also be hurting performance? Like I mentioned, most people block off the EGR intake on the head using a plate that they either fabricate or buy. Why not just plug the inlet hose with a bolt or something? Before I went off and tried this, I thought I'd post to the forum to see if I understand this thing correctly and what the potential results would be. Oh and I googled this image of an EGR valve cover, which looks pretty much just like mine. Attachments:
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? I'd rather not burn up the new kit right after getting it, but that's the biggest size I have on hand. I've been looking at the websites of my favorite sellers, and many of them don't sell individual jets between 
and #
jets. Should I get one in between as well? I'm having trouble finding them, where's the best place to order those sizes?
% sure that I have 69mm valves, just by eyeballing them from the side to see how far above the lip of the head they are. But I like cold hard measurements, so that would really be appreciated. Thanks! 
