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Post by flinntastic on Jul 22, 2023 1:47:10 GMT -5
I have been making sweet, sweet love to a 2011 Tao Tao VIP over several months. I bought it after a brewery abused the poor thing until the rear tire burst. I watched Brent’s amazing videos from project Tao Tao. The theme of the build is 50cc power so I kept it stock, new 18.5mm carb (80 main at 5300’), clutch springs, stock contra, 5g sliders, spark plug, new gear/engine oil with magnetic plugs, pod filter (the stock box was destroyed) and valve adjustment per 49ccscoot guidance. Great acceleration, gets right to 7,000-7,500 RPMs (verified with independent tach). The problem/ question is: My RPMs then continue to rise and will get close to 11,000 at which point I freak out and slow down because it sounds like it’s screaming. Is this normal? Should I just use throttle control? I plan on cracking open the CVT to follow up on the marker trick, drop in new belt as well as double checking a plug chop. I don’t think it’s a secret 63 but have not measured it and no B6 stamp.
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Post by aeroxbud on Jul 22, 2023 3:19:21 GMT -5
Could try heavier rollers and see what effect that has.
It might be worth checking to see what the gearing is. It could be headed very low for some reason.
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Post by classacted on Jul 22, 2023 10:43:57 GMT -5
if you have the fuel petcock installed (I got rid of that long ago and never regretted it), that could be giving you an issue, and the fuel cap could be causing a vacuum condition. when it's racing like that, remove the cap.
I always recommend to have at least one spare carb to swap off. in my experience carb issues are more likely than anything else.
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Post by flinntastic on Jul 22, 2023 10:52:47 GMT -5
I assume by your replies this is in fact not normal for a 139qmb and it’s best that I figure out a way to reduce RPMs. I forgot to mention the first thing I did was replace stock petcock with manual! Also, I have not checked the gearing but I am scared to alter the gearing as I’ve seen so many go wrong, has anyone done an up gear successfully with a 50cc 139qmb ever? If they have I would really appreciate hearing more about it!
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Post by aeroxbud on Jul 22, 2023 14:23:29 GMT -5
On Brent Tao Tao stock bike this is the RPM he was getting when trying out different jetting.
Speed.......RPM.......jet
33MPH.......6,820......72
36.45MPH....7,265......75
34MPH.......6,995......78
33.6MPH.....6,965......79
You get the idea.
Have you got your tachometer set to the right number of cylinders/strokes?
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Post by classacted on Jul 22, 2023 14:35:47 GMT -5
after reading your first post, I was under the impression that your engine was racing at idle. am I wrong about this?
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Post by flinntastic on Jul 22, 2023 15:51:25 GMT -5
Thank you AeroxBud! Reconsidering my tach, I had assumed per the instructions it was set to (1 spark per rotation? I can’t for sure recall). I wonder if that’s where my issue lies…Also I was under the impression my jetting was good as I am running at pod filter at high altitude (not sure what altitude the Project Tao Tao testing was ran at) but I have every intention of doing a plug chop ASAP! So on the list is check my tach, belt, plug, gear ratio and variator marker.
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Post by flinntastic on Jul 22, 2023 15:52:33 GMT -5
To clarify, I don’t seem to have any issues at idle or low throttle Classacted.
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Post by GrumpyUnk on Jul 23, 2023 10:27:43 GMT -5
I think you have a good running combination. Do not be surprised if things change when you replace the belt in the CVT. Belts seem to be like shoe sizes, not being the same even when marked as such. If you find a good length, try to get a brand name as you are much more likely to be able to replace it with one that measures the same when the time comes. Using Bob's Pizza and Belts products may lead to varying success with replacements when they come from different 'runs' of product. IOW, they are not presumed to be the same size from shipment to shipment no matter what the markings on the outer surface indicate. Getting one that is not the correct length will likely cause changes that are likely unwanted for the most part. OTOH, you might find a length that is wunnerful.
I have a bone-stock ZNEN that regularly runs up to 7800 rpm when close to 30-35mph. Given the accuracy of most speedometers, I have no idea of the actual velocity. I have seen 8000 when going downhill. I have not looked inside the CVT for any reason so far. Most times when opened for the first time, it is difficult and the gasket seems to be welded to both sides, so it is left as-is for as long as it works. I have considered doing a BBK to 72cc, but have held back because it runs so well.
If I flip the run/stop to run, it starts within the first few seconds, and I like that.
tom
ADDED
Do you reach 10-11,000 on level ground? If so, do you think the CVT/clutch is slipping or does it seem to continue to increase your speed at that rpm? I should look to see the rpms max reached. I think these will survice the rpms, but I personally don't care to have them that high.
You could change the final drive ratio by swapping gears in the final drive gearbox. There are two ways to change, one involves pressing a gear, the other changes the final drive output shaft/gear. Not too clear from memory, but you will likely lose acceleration in exchange for a higher top speed(lowered rpms too).
tom
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Post by flinntastic on Jul 23, 2023 15:33:08 GMT -5
I have had 10,000 to 11,000 indicated on flat ground, I could easily see this being the result of slippage and that’s something I’m going to look into. I have also considered a gear up at points, but want to really be sure that I’m getting power properly up stream. I am also super happy with the build so far, but until recently, haven’t had a phone mount for GPS speed tracking. I plan on posting on speed list at some point.
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Post by flinntastic on Jul 24, 2023 23:49:57 GMT -5
I finally got some time, checked the plug; powdery white so upjet it is… no time to check tach, CVT or anything else.
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Post by flinntastic on Jul 25, 2023 13:56:07 GMT -5
Funny enough I found the Project Tao Tao elevation was probably about ~46’ which is fascinating comparing my current jetting (80 main) at 5300’.
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Post by flinntastic on Aug 4, 2023 7:45:07 GMT -5
I’ve been occupied with getting a new triple tree installed since I had a slight bend in the handlebars and tried every other trick. I found one of the pinch bolts was hanging by a thread after it snapped off inside the triple tree. I attempted extraction but failed so I figured my sanity might be worth the $65 for a new triple tree. I did check the CVT, no obvious black marks from belt slip, the marker trick on the variator appeared to have about 3cm worth of space left! I bought and installed 6g sliders and installed new belt. Today I should get the triple tree in so I can start that process and then test drive.
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Post by flinntastic on Mar 2, 2024 11:25:17 GMT -5
I FIGURED IT OUT! I had at least one of the sliders in the wrong orientation and my slider plate spacers broke off. I replaced them and now I’m up to 40mph at ~8,000 RPMish.
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