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Post by scooter7878 on Oct 31, 2021 6:16:59 GMT -5
Ok, so there's some good progress. My buddy Chad came over, who knows alot more about electrical things and found that the resistance on the ground was about 5 ohms. He says that's way too high. He has fittings, so we're going to do up a proper ground cable. But even when we bypassed everything and went straight to the starter it wouldn't start electrically. So he thinks the starter is hooped. I'll search for the high torque starter that james82nd mentioned. But we got it started with the rebuilt kick-start many, many times today. We're having trouble getting the idle and air-fuel dialed in right. We started with the 96 main jet installed and Chad felt it was running too rich. The scooter would sometimes try to run away on us. If you cranked the throttle it would just stay running fast, even when the throttle was completely released. We swapped out for a 90 jet and things improved a bit, but we still have to fight it to keep it running right. The other thing we noticed is that using the rear brake would act like a choke? Is that right? It would run OK with that on, but sometimes when we released it, the scooter would bog down or even shut off. I checked the idle jet, and it's a 34. So I think that's fine, based on Scooter7878's info above. Any other suggestions on this one? Thanks again! it sounds like the carburetor is getting stuck open a little I've had the little rubber boot on the cable sometimes slides down and after u open throttle it sticks under where the cable rides in the carb linkage. Or the cable or linkage is getting hung up some how. A main jet isn't going to give u a high idle and a rich idle jet is going to give u lower rpm or stalling a lean idle jet can make the rpm drop slowly after letting off throttle but really doesn't sound like a jet issue causing it to race like that. Something is hanging up in the carb or cable. Does it ever idle right or as soon u start it it's reving? If u have a 35 or 36 idle jet put that in and turn mix screw 2 1/2 turns out from bottom out. Back the idle adjustment out till it's not touching the lever than in till it just touches lever and once it touches go another half to 3/4 turn. That will give u a base setting if it still reving u got another issue causing it
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Post by GrumpyUnk on Oct 31, 2021 8:54:01 GMT -5
You have a carb that is running on the low end of the high-speed circuit. It is almost impossible to get it to run stably at lower rpms. I suggest that your pilot jet or low speed circuit it inop. Clean or replace the low speed/pilot jet. As far as the starter motor, unless it has been damaged, it should be able to handle the extra load without problem.
If your cables or relay are not working, the won't pass enough current to opearate properly. You can test using regular jumper cables to take the place of the scooter cables and relay. If the starter works by jumpering past the relay/cables, then the starter is not the problem. tom
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Post by epitome on Feb 25, 2022 21:14:51 GMT -5
Hey guys. After moving yet again, I'm still bashing my head against the wall on this one. I have replaced the starter with a high-torque version. I have replaced the two main cables with car battery cables. I have tested that the battery is outputting somewhere around 14v, and I have checked that at least 12v is reaching the starter when I try to start. I checked the ground as well, and still got about 14v. While it sounded like it was trying a bit harder to start, it was still just barely turning over one revolution before stopping. If I try to bypass the starter relay (using another battery cable from the battery side of the relay directly to the starter) I get very minor sparking and zero effort from the engine. Another friend of mine (Lyle) with some scooter mechanics experience has looked at it with me tonight and is just as stumped as me. For the last few times we've tried starting it tonight, the starter motor spins quite well, but it doesn't sound like the bendix is engaging, because the engine does nothing. I've pulled the bendix and looked at it, and it doesn't seem to be seized. I can operate it manually without effort. I tried greasing the post area that goes into the side of the engine in case it was having trouble turning, still no joy. We were able to kick-start the scooter a few times, and Lyle remarked that kick-starting it was harder than some 600cc's he's ridden before. We pulled the spark plug and found that it was MUCH easier to use the kick at that point. Does that indicate I've got really high compression? Could that be my problem with starting? I have a batch of idle jets coming in the mail that should arrive soon, and I'll try swapping out for the 35 like scooter7878 recommended. But this starting issue is really killing me. I even went as far as calling the two local motorcycle mechanics to ask if they'd look at it, and they both outright refused.
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Post by GrumpyUnk on Feb 26, 2022 12:14:09 GMT -5
Been too long... Have you re-checked the cam timing? If off a tooth or more, it can affect engine compression. Have you tried using car-style jumper cables from an auto / truck battery? Connecting the black to "-" and the chassis of the scooter, or the engine block(BEST), and connecting the "+" battery terminal to the large starter terminal(SPARK WARNING) there will be some sparkage, and then checking starter operation would determine if it is the starter(I know, replaced) or the connecting parts(cables, relay, grounds. There should be a cable from the cam cover bolt to the chassis that must be connected for the starter to operate. The "-" battery terminal must be connected to the chassis on a non-painted surface also. The Bendix will spin and fail to engage if the starter motor does not itself spin up the armature fast enough to force the Bendix to ride up the spiral and push its gear agains the teeth of the gear on the variator. The Bendix needs a good bang of juice, right now, to whirl fast and spin the armature before the Bendix gear can catch up. If it spins up too slowly, the Bendix will just go along for the rids, spinning up a bit slower than normal, and NEVER ride up the spiral to engage with the variator. tom
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Post by epitome on Feb 28, 2022 0:30:11 GMT -5
Thanks for that tip, GrumpyUnk. I spoke with another friend who used to be a heavy duty mechanic and he agreed with you that having my timing advanced by even one tooth can cause high compression and fast idle. So as soon as I have the time (and can borrow his torque wrench again) I'll take a look at that and see if all my problems go away. He also mentioned that if the previous owner had the scooter at high RPMs when he blew it up, it's possible I have a partially-sheared key, which could affect the timing as well. He says he has a special gauge I can use to physically measure the travel of the piston to determine TDC if that's necessary. But I'll try it the old fashioned way first. The new idle jets arrived today too, so I have those to try out if necessary. Thanks so much for your help on this, it's very much appreciated. I'll post here again once I've tried your suggestions.
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Post by epitome on Mar 4, 2022 22:34:08 GMT -5
Sad to say, after re-checking the timing marks it's still behaving the same way. Huge compression to the point I have to stand on the kick (I'm 200 lbs) and jump down for it to roll over. Frankly, I'm ready to just sell it for what I can and give up. Unless anyone else has any bright ideas? Does anyone know of any good scooter mechanics on Vancouver Island, BC Canada that will work on one of these? Looks like the big place in the bigger city an hour away from me won't do it, and neither of the local motorcycle mechanics will either. Should I make another post about looking for a mechanic in my area?
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Post by GrumpyUnk on Mar 5, 2022 9:19:45 GMT -5
Take off the blower housing and check for the TDC marks on the casting and flywheel. Put a pencil/probe in the spark plug hole, and rotate the crankshaft until the probe reaches its highest point. Note then where the marks on the flywheel are in relation to the casting mark. They should align. If not, then you can suspect poor quality or a possible damaged key. That would affect spark timing. It would also affect cam timing if used to set the cam/chain to the crankshaft position. With the timing mark at the TDC spot, the holes in the cam sprocket should be just about aligned with the top surface of the cylinder head. If you do not have a 139QMB service manual, check here(on site) and the web for a PDF download. They are out there, with pictures and all ... I have lost memory of the problem... so answers may be off the wall.. tom
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Post by steve1297 on Mar 8, 2022 6:55:03 GMT -5
Did the bushing that holds the tip of the bendix in the CVT cover somehow come out while you were working? That will really stress the bendix
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