vacationer
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Post by vacationer on Jun 29, 2021 14:50:52 GMT -5
Symptoms: - can't get above 20mph on flat road - kick start is a little unreliable (can't tell you about button start since it's disconnected currently) - covering airbox with my hand at idle lowers RPMs very slowly but doesn't kill the engine - removing the airbox entirely makes no difference whatsoever - adding starter fluid lowers RPMs instead of raising it (from what I understand, this is the opposite of what should happen) - changing main jet has no effect whatsoever on performance (went from 76 stock to 78 to 80, adjusting mixture screw each time to reach highest idle)
Notes: - exhaust is torqued to spec - all obvious leaks remedied at cylinder head, carb and airbox (used starter fluid to test - despite what I noted above, the results were still pretty consistent as far as leak testing) - airbox appears perfectly fine - carb float is level - pilot jet is stock - check all ports on carburetor. all seems clear except for the ones that don't go in a straight line. these were impossible to check - spark plug is a dry black, insulator tip is orange/white and the top of the center electrode is slightly white
What's the problem???
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Post by steve1297 on Jun 29, 2021 15:48:20 GMT -5
Check air pressure in tires. Low air pressure will Bog you down a huge amount.
Check variator and clutch. Go ahead and put a new belt on.
Other than that, just get a new carb. They are $20
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Post by scooter7878 on Jun 29, 2021 22:30:37 GMT -5
Can u post a good pic of plug bc dry black is usually rich but the white tip can mean lean I'd like to see the plug
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Post by scooter7878 on Jun 29, 2021 22:46:37 GMT -5
I dont rember if u have s bbk on but my buddy has a stock 50cc with just exhaust and hes running a 88 main if u have a bbk kit it would be even higher. As for the idle and idle jet not running turn the mixture screw all way in but not tight than back it out two full turns. Warm bike up fully and let idle adjust idle set screw to get idle a tad higher than it would normally be. Or atleast keep it idling. Now turn the mixture screw clockwise a 1/4turn give it 30 seconds to respond if idle drops turn it counter clockwise a 1/4turn past where u started. Wait. If idle goes up keep going till u get no response or it starts dropping than turn clockwise 1/8 turn. Blip throttle like a 1/4 throttle if it dosen't bog or stumble shut bike off. Now turn mixture screw clockwise counting how many turns till bottom out. It should be 2 to 3 turns. If it's in more than 2 turns u need a smaller idle jet. If it's out more than 3 turns u need a bigger idle jet. As for the main jet either post a pic of plug or just bang a 85 in and see my budds 50cc had same kind of issues till I bumped him up to a 85 or 88. U cant really hurt it by going too big and it's much better off that being lean. Any white on a spark plug is never good and indicates lean at some throttle position
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vacationer
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On Vacation
Posts: 239
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Post by vacationer on Jun 30, 2021 17:57:26 GMT -5
Spark: No BBK. I'll have to jetting and looking at the variator/clutch when the rain lets up. The kick start wasn't working and it was making a weird noise so I opened it up. Does something look wrong with this spring?
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Post by scooter7878 on Jul 1, 2021 0:15:58 GMT -5
Honestly I don't know abt the kick start bc I take them off right away but u can start it with the cover on with 2 bolts with electric start and carful pull the cover off while running. I do this by my self but a sec person may help u first time I use a long socket extension with a 10 mm socket once u got cover off hold the starter Bendix from vibrating into the varistor gear. With rear wheel off ground slowly work throttle till almost full and watch the belt move it should move all way to top of front pulley and back down smoothly do this a few times. If the belts not going all way up or down u got a cvt issues. As for the plug I'm not a expert on plug reading but the porcelain looks ok actually I see the white spot on the tip I'm not sure abt that u can Google plug chop gy6 and there's a lot of pics that explains it but it can't hurt to just try a 85 or 88 main see if it gets better. Give me more info on how it runs through out the throttle range does it have good power at take off and just doesn't get good top speed does it bog or sputter at any throttle or backfire or does it just lack top speed how does it feel my buddy's was kinda just not super powerful and only went about 30 mph I gave him a 88 and he said he's back up to 40 mph with good power
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Post by FrankenMech on Jul 1, 2021 1:52:30 GMT -5
You can make a bracket to hold the starter in place without the cover on. Plans are available on this site.
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vacationer
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Post by vacationer on Jul 1, 2021 14:37:22 GMT -5
imgur.com/a/XvJ3ohIDoesn't quite look like it's getting all the way to the top, does it? This would make sense I guess since there seems to be no difference in RPMs between half throttle and full. Otherwise, the transition from idle upwards is pretty smooth. Switched to 88 and got no difference in speed but the engine does feel a little more powerful (could be psychosomatic though). Also, not sure if it explains the wonkiness of the kick start but I did just watch a video about scooter CVTs and his spring also looked janky. Must be standard.
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Post by scooter7878 on Jul 1, 2021 22:15:20 GMT -5
If that was full throttle it's not even close to full range take a sharpie marker and draw a line on the inside variater pulley from the bottom where the bushing is to top of variater and do that it will wear the marker off showing the belt travel
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Post by scooter7878 on Jul 1, 2021 22:19:31 GMT -5
At idle belt should be at bottom of front pulley and top of rear at wot it should be at top front pulley and bottom of rear pulley. If not either it variater is fucked or the rear pulley assembly is jamming up and not spreading allowed belt travel
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Post by GrumpyUnk on Jul 2, 2021 10:57:02 GMT -5
The kick starter gear is way past where it should be. Viewed from the 'inside', the semi-circle gear should be CCW of the gear with the 'cup', so it can be 'kicked' and rotate the 'cup' gear. As it is, it is too far CW. The spring around the base should be in tension. If you 'lift' the cup gear, you can rotate the circular gear back to where it belongs. The engine can be started using the starter and Bendix, but I do not recommend it. I have seen it done on a youtube, and it looked real janky to me. Most of the kick and Bendix pivots do not get a dab of grease, and are not checked or cleaned, and that can help them work properly. The CVT gasket is not necessary, but it will keep H2O from seeping in and getting things wet, to some degree. tom
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vacationer
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Post by vacationer on Jul 3, 2021 12:20:37 GMT -5
scooter7878 What exactly do you mean by "fucked"? @grumpyunk? Can you define CW/CCW?
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vacationer
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Post by vacationer on Jul 3, 2021 14:31:56 GMT -5
Well I was able to get the rear pulley off and drench it with brake cleaner. Upon inspection, I don't see anything obvious that would be causing my problem, but I also have never looked at a rear pulley before. When pinching the discs with my hands, the movement seemed to stick a little bit. Obviously, it took all my strength even to get it to budge but from there it still felt stiff past a certain point. I was able to pull the discs apart further than the bike is doing on its own. Not sure what that means.
A guy on youtube cleaned his clutch pads and scuffed up the inside of the outer piece the pads touch (not sure the name) since it had gotten too smooth. I did this as well but that didn't solve anything when I started back up again. Belt is a bit worn but I'd be surprised if it was enough to cut my top speed in half. I could be wrong.
Also, what kind of loctite should i use when I put this nut back on?
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Post by scooter7878 on Jul 3, 2021 15:58:58 GMT -5
The rear pulley should have a good bit of pressure to spread but should be smooth feeling. It should be taken apart and cleaned and greased it's very important there's videos on how too but the big but holding clutch needs come off and there will be spring load there be careful. Also what about the variater and rollers? That is what forces the belt to move so if there's a issue there the belt will not shift it's hole range I would take apart rear pulley and grease it and check the 3pins in the sliding pulley use a good grease made for high temp flat spots on the rollers will also cause that remove the variater and clean. Look at the rollers there should be no flat spots if there is replace the rollers at the very least but I would recommend a variater. Also check the 3 guides in the variater plate the plate should slide up and down the variater smoothly without much play in the bushings
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Post by scooter7878 on Jul 3, 2021 15:59:42 GMT -5
My guess is flat spotted rollers and or a jamming rear pulley
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