ratdog
Scoot Enthusiast
Posts: 342
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Post by ratdog on Oct 14, 2018 11:50:48 GMT -5
When we normally freshen up a worn engine, we hone the cylinder and put in new rings. It’s a cheap way to restore compression as long as the cylinder is not too warn. Of course if it really worn, we strip it all the way down and boring the cylinder and new pistons are on the menu. Installing a BBK is like doing the ring job except we are replacing the cylinder instead of just honking the existing cylinder, but we are not doing anything to the bottom end. It is so cheap to get a BBK, that it makes more sense then rebuilding the stock upper end.
Changing the weights should be used to adjust the RPMs when you accelerate. These engines are 3 hp at 7500 So we want the CVT to take the engine up to 7500 rpms while we take of and get up to speed. Heavier weights will move that rpm down. Unless your taking off at more then 7500 rpm, you should not be going to heavier weights. After you install a BBK, you might find your engine Erving beyond 7500 rpms and that would be the point where you might want to adjust the weights
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Post by Sir Scoots-A-Lot on Oct 14, 2018 17:23:21 GMT -5
I see. I currently have 5 gram weights that are nearly ideal for top speed acceleration and hill climb on my stock 139qmb from what I can gather from other people saying the peak performance should be like. I ordered the 6.5g sliders for if i ever install the BBK cylinder and piston I purchased. I will wait to put in the heavier sliders until I either install the bigger cylinder or if my cheap 5g rollers wear out and I need something. As of lately my rpms have been FEELING low as I keep the throttle way low and my engine is either tired out and or needs rejetting on the carb
Today was unfortunately another day I did about jack so far working on my scooter although I did start it up twice without issue for a 2.5 mile trip to the store and 2.5 miles home. I kept the throttle way down as either my engine is really tired as far as the cylinder may be worn or part, even most of the issues could be my jetting is way off. I am going to pul my carb and change jets either now or tomorrow sometime and give that a try. This cold weather has really been making me not want ot go out and work on it. When I move to FL it will be nice and warm...but I think they make you register mopeds :/ so i might not bother with having one for awhile
Well Thanks again for the answer Ratdog. I think Im going to order a new starter and as soon as that is in I will install the BBK cylinder. My current starter works but it is making some truly awful noises that I still havent found the root cause of, whether it be stripped splines, out of straight shafts or maybe the Bendix isnt getting out of the way of the bigger gear or isnt meshing with it properly when engaged to start could be the bendix end isnt sitting in the CVT cover properly and throwing off where it should be...I dont know for sure.
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Post by GrumpyUnk on Oct 15, 2018 14:24:52 GMT -5
To answer the question about the BBK being like a ring job, when you install a BBK, using the remainder standard OEM parts, you have replaced the piston, rings and cylinder. That means there are new sealing components, bringing the cylinder/piston back to original zero miles condition. The rest of course is whatever age/condition it was before. Many of the kits come with valve stem seals. If the seals are worn and hardened, as with a high mileage engine used daily, they could be considered 'rebuild' kits for tired engines. Removing the old seals to touch up the valve sealing surfaces at the same time the cylinder/piston/rings are replaced might damage the hardened seals. Putting new seals into the kit is a nice touch for those who want to clean up the valves at the same time, or replace valve components. If you get a new cylinder head, be sure to check the valve height on your current head to match, or order a rocker arm assembly that will match the valve length in the cylinder head you order. tom
Of course I posted before getting to 'the end' of messages...
The starter Bendix has bushings on either end. One in the CVT cover, and one pressed into the side of the main case, right next to where the starter motor gear is situated. If the bushings are worn, the gears may not mesh well at either end. You can wiggle the Bendix out after removing the CVT cover, and stuff it into the cover. If it flops around a lot, you may need a new bushing. Same thing with the other end. If the big gear on the Bendix does not mesh well with the small gear on the starter motor armature, you may get noise and slipping gears. These bushings are often overlooked. Whenever I take the cover off, I make sure to dab a little grease onto both ends of the Bendix. Just enough to insure there is a thin coating of grease on the Bendix shaft area. If you remove the clutch bell(14mm) you can inspect the shoes and the inner bell surface. Both should be clean and dry. If you find you have slippage, make sure the surfaces are not lubed by anything. I swapped in some 7g sliders on a 47mm kit, and the rpms are going a bit too high as far as I am concerned. I took out 5g rollers, hoping to get the rpms to go lower. More fiddling needed. tom
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Post by Sir Scoots-A-Lot on Oct 15, 2018 16:46:47 GMT -5
To answer the question about the BBK being like a ring job, when you install a BBK, using the remainder standard OEM parts, you have replaced the piston, rings and cylinder. That means there are new sealing components, bringing the cylinder/piston back to original zero miles condition. The rest of course is whatever age/condition it was before. Many of the kits come with valve stem seals. If the seals are worn and hardened, as with a high mileage engine used daily, they could be considered 'rebuild' kits for tired engines. Removing the old seals to touch up the valve sealing surfaces at the same time the cylinder/piston/rings are replaced might damage the hardened seals. Putting new seals into the kit is a nice touch for those who want to clean up the valves at the same time, or replace valve components. If you get a new cylinder head, be sure to check the valve height on your current head to match, or order a rocker arm assembly that will match the valve length in the cylinder head you order. tom Of course I posted before getting to 'the end' of messages... The starter Bendix has bushings on either end. One in the CVT cover, and one pressed into the side of the main case, right next to where the starter motor gear is situated. If the bushings are worn, the gears may not mesh well at either end. You can wiggle the Bendix out after removing the CVT cover, and stuff it into the cover. If it flops around a lot, you may need a new bushing. Same thing with the other end. If the big gear on the Bendix does not mesh well with the small gear on the starter motor armature, you may get noise and slipping gears. These bushings are often overlooked. Whenever I take the cover off, I make sure to dab a little grease onto both ends of the Bendix. Just enough to insure there is a thin coating of grease on the Bendix shaft area. If you remove the clutch bell(14mm) you can inspect the shoes and the inner bell surface. Both should be clean and dry. If you find you have slippage, make sure the surfaces are not lubed by anything. I swapped in some 7g sliders on a 47mm kit, and the rpms are going a bit too high as far as I am concerned. I took out 5g rollers, hoping to get the rpms to go lower. More fiddling needed. tom I appreciate your reply Tom. My wonky starter is one main reason Im holding off installing the BBK cylinder/piston I have waiting. is the starter bushing on the CVT cover end supposed to be rempveable or is it built into the case? I see something silver in my CVT case there but it looks built in and maybe damaged, could be just part of my CVT case and could be I am missing that bushing. I have suspeceted for awhile I may be missing the starter CVT case bushing although I never used to hear/notice any electric starter issues until recently when I couldn't get my scoot started and cranked it way too many times---then after the millionth prolonged crank it started making intermittent on and off metal on metal grinding noises but still started within a couple tries the first time today and first try right away second time, maybe because engine was still a little warm Is the starter bushing on the engine side ---where is that located? Can I remove that bushing if I remove the Bendix and look behind it towards the engine? or do I need to unbolt the starter motor to remove that bushing? I wasnt aware there was a bushing on that end, although I havent taken the starter motor off or looked too closely at the Bendix. SO if I order a new starter motor and bendix do you know if the 2 starter bushings are included or should i probably order those also? The bushings arent mentioned in any ads I have seen on Ebay or Amazon I did recieve new valve stem oil seals...and I will look into that more but it seems if i remember correctly that you might need special spring compressor tools to change those? If its too difficult I might just try my stock head first after looking to make sure my stock head appears "OK" or order a new head for the $25 and 4-7 day wait
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Post by GrumpyUnk on Oct 16, 2018 11:16:29 GMT -5
The Bendix has bushings at both ends. The case and CVT cover are both made of soft metals. Without a bushing, the Bendix might wear excessively. You can order bushings from many web sites, but you'll have to search for them as they are not advertised much. A new CVT cover will NOT come with a bushing installed unless you order a 'loaded' CVT cover. A Bendix will not come with bushings. They are separate pieces. To change valve stem seals, you need to remove the valve springs to expose the seals. I have used a hammer to break the valve retainers loose from the stem, with the 'keepers' popping free all on their own(work where there are few hiding places as the keepers want to get away... and are SMALL). Once the keepers have loosened their grip(they will stick from oil chemical changes so need to be 'popped'), you can push on the valve spring washer to get the last keeper free. Remove the springs, washer, and shim at the bottom, and KEEP THEM IN ORDER. The valve can slide out, and the seal be pried from the top of the valve guide. You may be able to remove them without damage, but it is easy to tear them when trying to remove them. I set things back in place, put the washer/retainer atop the stem, put something under the valve to keep it from sliding down the guide, and set the keepers in place on top of the retainer. Pushing down on the washer, the keepers fall into place, almost, and may need adjustment using pressure & screwdriver, etc, to place them exactly. Once installed, I tap on the stem a few times to make sure the keepers are in place.
If you look into the side of the engine case, you can see the gear on the end of the starter motor armature. Next to the gear(to the left) you will see the hole the Bendix bushing rides in. To remove, you can use a puller, or a bolt threaded into the bushing material, or use the 'grease' method where you stuff the bushing full of grease and then attempt to thump a bolt that fits closely into the bushing. As you thump the bolt, it acts as a piston, and increases pressure inside the bushing. Pressure will bear on the edge of the bushing, and push it out as you repeat. The bolt or shaft must fit closely into the bushing to form a 'pump' with as little leakage around the bolt/shaft as possible. A new bushing is driven into place until it is roughly even with the edge of the case, and then is greased. Ditto for the CVT cover bushing. If the bushings are worn visibly oval, or the shaft allows a lot of wobble, the Bendix may not engage firmly with the starter motor gear or with the gear on the variator. Either can cause noise. Neither gear needs to be lubed at all to my knowledge. tom
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Post by Sir Scoots-A-Lot on Oct 16, 2018 12:00:59 GMT -5
The Bendix has bushings at both ends. The case and CVT cover are both made of soft metals. Without a bushing, the Bendix might wear excessively. You can order bushings from many web sites, but you'll have to search for them as they are not advertised much. A new CVT cover will NOT come with a bushing installed unless you order a 'loaded' CVT cover. A Bendix will not come with bushings. They are separate pieces. To change valve stem seals, you need to remove the valve springs to expose the seals. I have used a hammer to break the valve retainers loose from the stem, with the 'keepers' popping free all on their own(work where there are few hiding places as the keepers want to get away... and are SMALL). Once the keepers have loosened their grip(they will stick from oil chemical changes so need to be 'popped'), you can push on the valve spring washer to get the last keeper free. Remove the springs, washer, and shim at the bottom, and KEEP THEM IN ORDER. The valve can slide out, and the seal be pried from the top of the valve guide. You may be able to remove them without damage, but it is easy to tear them when trying to remove them. I set things back in place, put the washer/retainer atop the stem, put something under the valve to keep it from sliding down the guide, and set the keepers in place on top of the retainer. Pushing down on the washer, the keepers fall into place, almost, and may need adjustment using pressure & screwdriver, etc, to place them exactly. Once installed, I tap on the stem a few times to make sure the keepers are in place. If you look into the side of the engine case, you can see the gear on the end of the starter motor armature. Next to the gear(to the left) you will see the hole the Bendix bushing rides in. To remove, you can use a puller, or a bolt threaded into the bushing material, or use the 'grease' method where you stuff the bushing full of grease and then attempt to thump a bolt that fits closely into the bushing. As you thump the bolt, it acts as a piston, and increases pressure inside the bushing. Pressure will bear on the edge of the bushing, and push it out as you repeat. The bolt or shaft must fit closely into the bushing to form a 'pump' with as little leakage around the bolt/shaft as possible. A new bushing is driven into place until it is roughly even with the edge of the case, and then is greased. Ditto for the CVT cover bushing. If the bushings are worn visibly oval, or the shaft allows a lot of wobble, the Bendix may not engage firmly with the starter motor gear or with the gear on the variator. Either can cause noise. Neither gear needs to be lubed at all to my knowledge. tom Thanks for the detailed info Tom. I'm not sure if I will get so involved at this point in my life to try fixing the valve stem oil seal as I am fairly busy and a new head isn't all that much if I decide to go that route. When i have more time I would rather work on it than just waste money on a new part and i also dont like the idea of throwing out the old head if it is serviceable with parts i have because it seems wasteful even if its recycled for scrap metal As far as the starter goes it sounds like I need to do at least a little work there making sure the bushings are in good order. A few days ago I was distracted and accidently started my engine with the CVT cover off. The starter still made a bad noise so I must have some trouble on the inner side of the assembly. And it looks like I am maybe missing the CVT case bushing as well as it looks like there is "wobbly shaped" wear on the CVT case where the end of the Bendix sits. Another thing I was thinking about is I have serviced my variator, taken it off for roller changes and belt changes many times and depending on how its sitting and how tight I put the variator nut on affects how far in towards the engine or out towards the case that big metal variator starter gear will sit. I wiped out my kick starter a month or two ago and I think part of the problem was that big gear was sitting slightly in a different spot after service, which made the kick start gear not mesh entirley so part of it was hanging off instead of being fully engaged and I think that eventually led to the kick starter having many issues. I hadnt thought about that until now but am now thinking maybe I sould look at how tight the variator nut is and how the Bendix is meshing to see if that is a possible source of the noise. I will definitley also check both stater bushings. Thanks again for all the info about it Tom
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Post by Sir Scoots-A-Lot on Oct 16, 2018 15:36:58 GMT -5
its kind of funny when I just made another ride to the store it took a couple tries to start and if the engine doesnt catch quickly the starter will at first be spinning and engaged then it sounds like after a couple seconds it continues to spin but isnt engaged on one part or another as I can hear the elecric motor still spinning but it is no longer turning the engine over after a couple seconds. I am planning on looking at the whole starter assembly including the electric motor, Bendix and bushings tomorrow when I have the day off work and dont need it for transportation
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