larryhobman
Scoot Enthusiast
Posts: 117
Location: Delaware beaches
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Post by larryhobman on Sept 7, 2020 20:47:55 GMT -5
Looking for a little advise to see if an A9 cam is going to lower my compression or not when using a big valve head. My next build is a 52mm kit with a BVH, very open performance exhaust, A9 cam? . going to try a flat slide carb for better throttle response. I have 2 flat slide to try a 30mm and a 28mm. Let me know what you think I shoiuld try first? I currently run a 50mm set up, A9 cam, standard valve 50mm head and a 24mm cvk carb from a 150cc scoot.
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larryhobman
Scoot Enthusiast
Posts: 117
Location: Delaware beaches
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Post by larryhobman on Aug 15, 2020 14:09:16 GMT -5
I guess that we should just keep the 49cc scoot always a 49cc. No need for a bbk. Also we should keep the Chinese EGR valve crap too.
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larryhobman
Scoot Enthusiast
Posts: 117
Location: Delaware beaches
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Post by larryhobman on Aug 15, 2020 9:40:49 GMT -5
Get rid of the stock air box. That is the thing I trash when I upgrade. I run my 50mm with a 23mm carb from a 150 scoot and a 102 main jet. 41 pilot. Get a pod filter and #95. Stock cdi and coil are good to use. The performance ones are crap.
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larryhobman
Scoot Enthusiast
Posts: 117
Location: Delaware beaches
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Post by larryhobman on Aug 2, 2020 22:41:33 GMT -5
I run a gravity fed system on my 50mm set up A9 cam and a 24mm carb off of a 150cc. Runs great,
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larryhobman
Scoot Enthusiast
Posts: 117
Location: Delaware beaches
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Post by larryhobman on Jul 29, 2020 11:09:35 GMT -5
57.4
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larryhobman
Scoot Enthusiast
Posts: 117
Location: Delaware beaches
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Post by larryhobman on May 13, 2020 14:16:56 GMT -5
If you have a 'byvalve' or electric choke mechanism on your carb, it may be too big for the size engine, resulting in a rich mixture for the first startup and few minutes running. The pilot size seems a bit large. When you have a 4,000 rpm cold idle, you have a signal you have 'too much' choke. The byvalve is a a separate system to feed a cold engine. It has a pintle valve, a dip tube, and a well(reservoir) built into the float bowl(most). There is also a jet built into the wall of the float bowl that allows fuel into the well. Once started the fuel flow is limited after it has used up the fuel that filled the well during normal times, by the jet. Take a look. If it is too large for your engine (100cc vs 150cc..) you'll get too much fuel. You could also be into the 'mid-range' of the carb, which is hard to get to idle with stability. If the low speed system is marginal, you will have to open the throttle more, and get the flow into the mid-range, more or less. tom Hi Tom, I have it starting real fast now. I had to block off the auto choke. I have the A/F out 2.5 turns. An actual manual choke might be better but I do not ride when it is cold out. Attached a picture of what I made. It is a automatic choke with the top removed and drilled and pinned the plunger down to shut the circuit.
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larryhobman
Scoot Enthusiast
Posts: 117
Location: Delaware beaches
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Post by larryhobman on May 9, 2020 21:05:25 GMT -5
Hi Tom,
The carb is a standard 24mm 150cc with the automatic choke. I have a modified auto-choke which basically just plugged off the choke circuit. I will swap out the electric one for it tomorrow and see. If I get a PWK carb they come with a manual choke which want be good with weather changes.
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larryhobman
Scoot Enthusiast
Posts: 117
Location: Delaware beaches
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Post by larryhobman on May 9, 2020 18:03:56 GMT -5
Hi All
I am working hard starting, long cranking times. I have been changing pilot jets until I found one where it is good between 1.5 and 3 turns out, current setting 2.5 on a WARM motor. The problem is when cold it is still hard to start and when it does the rpm is high like almost 4000. When the motor is warm it fire up very quickly with no problems. Should I make changes to the needle clip height or just deal with the cranking.
I am thinking of going with a PWK 28mm or 30mm for better throttle response. Let me know your thoughts.
The set up is qmb139 with a 50mm piston and matching head with standard valves and an A9 cam. The carb is a 24mm off of a 150cc with a 102 main jet and now at 40 pilot. Standard cdi, coil and the free timing mod is done. Performance exhaust very open and an pod air filter. Valves are set to .003 and .004
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larryhobman
Scoot Enthusiast
Posts: 117
Location: Delaware beaches
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Post by larryhobman on Apr 20, 2020 8:43:46 GMT -5
Yes if you are only looking for speed but want a scoot then buy a large one 650cc. Do not bother with a 150cc you still have to pay the same insurance. I fool with the 49's for fun hobby and not for real speed. Where I live, if you are not doing 60 or more you will be run over.
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larryhobman
Scoot Enthusiast
Posts: 117
Location: Delaware beaches
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Post by larryhobman on Apr 18, 2020 21:30:54 GMT -5
Is your carb sealed that you keep looking for a new one? Does your current carb work well? You need to decide if you want a 50mm or a 47mm. For a new builder I might say the 47mm is best. I have installed both sizes and I am going with a 52mm on my next build, a Kymco that I should have soon if this virus crap get done.
I say to just get the 47mm kits and a jet kit. Look at air box mods or order a pod filter. Look up the free ignition mod on this site too. Get a set of sliders. After these are the way you like then look into springs, 1k contra and 1k clutch to start.
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larryhobman
Scoot Enthusiast
Posts: 117
Location: Delaware beaches
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Post by larryhobman on Apr 17, 2020 12:47:18 GMT -5
That is not a true 20mm carb. stick with stock but change your jets. start with a 90 or 95
Piston kit is okay check that you have a short case. 10" tire is a short case. 12" is a long case
That digital speedo is just like the one I returned. Did not do 1 cylinder motors like it says. only 2 or 4 cylinder. also was hard to calibrate for small scooter tires.
The belt you selected is for a long case. check your case size before ordering.
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larryhobman
Scoot Enthusiast
Posts: 117
Location: Delaware beaches
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Post by larryhobman on Mar 1, 2020 10:26:27 GMT -5
For me, if they have a title then fix it. No title I take them apart and use for parts. I just picked up a new scoot yesterday no title so more parts going in my collection.
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larryhobman
Scoot Enthusiast
Posts: 117
Location: Delaware beaches
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Post by larryhobman on Mar 1, 2020 10:21:30 GMT -5
Buy a 150cc if you want one. It is a lot of work to fit one in. Must be a good welder to do it.
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larryhobman
Scoot Enthusiast
Posts: 117
Location: Delaware beaches
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Post by larryhobman on Jun 14, 2019 17:47:38 GMT -5
Could be running lean and needs a 88 or 90 main jet. 85 mj is a little light.
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larryhobman
Scoot Enthusiast
Posts: 117
Location: Delaware beaches
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Post by larryhobman on Jun 7, 2019 13:20:54 GMT -5
Which wire is better to add a tach off of. The CDI Trigger wire or the CDI coil wire? Is it more accurate to hard wire the tach VS wrapping the tach line around the spark plug lead type? Let me know.
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