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Post by dev150cc on May 19, 2014 0:53:29 GMT -5
Weekend update.... Well, I picked up a few jets and jetted up from 102 to 115. The carb is super-clean, no debris, and checked the pilot jet while I was down there. Float height looks good, given an eyeball inspection. Did a mild suction on the petcock to make sure it's triggering gas flow. Took the gas cap off to make sure it's not suction locked. Checked the gas tank overflo hose going to the little emissions do-hicky to make sure extra gas wasn't going into there.Checked all the vacuum hoses, intake manifold, etc. All looks perfect. I did a compression test and got a rock solid 140 PSI (I had PSI but forgot to open the throttle). Supa! For all intents and purposes, these scoot should be all systems go. I took it back out for a spin after the 115 jet install. What I thought before was overheating re-manifested itself leaving the neighborhood for the test ride, right from the get-go. And I know it wasn't overheating. If I try to give it any throttle at all, it just misses. But it doesn't feel like a lean/rich stumble, just missing. If I go nice and easy on the throttle, it will ease its way up, but I dare not goose it whatsoever or it will so that "miss". Makes me wonder if I have a spark issue at this point, because everything else looks great. I bad spark plug boot would be plausible, if not the coil. I've never had a CDI go, so I'm not sure how it feels, but that's a possibility as well. I'll go spark plug back to the CDI tomorrow with spares and the new 12 gram variator setup. If it's not spark, I'm going back to the old variator with the heaviest weights I have - 13 gram. The old 17 grams were too worn to reuse. So for all intents and purpose, I have to say carburation is not an issue. Compression is not an issue. Air intake is solid. Vacuum hoses and connections are all new/sound. Exhaust checks out. Gotta be spark or variator I figure. Keeping in mind, none of this occurred until last week when I lost a belt and decided to try the Koso variator and 12 gram rollers from the stock 17 gram rollers and variator.
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Post by dev150cc on May 17, 2014 9:06:04 GMT -5
Good question John. Yes it's clear, connected solidly and no leaks. I checked it out with the PDI.
I have a 102 main jet - just pulled it off. I have to work on a rental property today but will find a m/c shop in the area and pick up a few extras. I figure a 110 and 115 would be good for experimenting with first.
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Post by dev150cc on May 17, 2014 0:02:09 GMT -5
I'm planning on pulling the carb out and doing just that. Aside from somewhat low PSI, everything else checks out.
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Post by dev150cc on May 16, 2014 20:56:10 GMT -5
Regarding PSI, this bike fires right up, and before my belt loss incident, was running fine. I had driven it 25 miles to work that day before the belt blew.
edit - I forgot to hold the throttle wide open while testing. I'll have to re-run that test.
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Post by dev150cc on May 16, 2014 20:54:58 GMT -5
So I got home and checked all vacuum hoses - Aok, they all look fine. Fuel hoses too. And nothing kinked. But, I did a compression check just using the electric start (*see below) and it read PSI tested 3 times. I rechecked the valves - 004 and 005 just right already. Could be a crapping out coil, which is easy to test with a swap. So, I'll read up this weekend on compression and see if being at PSI is a showstopper and time for a rebuild. I hope not, but it wouldn't be the end of the world on a small cylinder. May as well order an aluminum intake as well if I'm going to tear into it. *I attempted to use the kick starter to check any additional pressure with the CV cover off. Apparently that's a no-no because I broke the kick starter off. Looks like it's in there with a short piece of aluminum sleeve on the engine side, and supported on the outside by the cover. One more project to fix....
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Post by dev150cc on May 16, 2014 16:25:28 GMT -5
Hi guys,
Yeah, I can tell you for sure it's a short block 157QMJ running a 743 belt with 10 inch tires. Meiduo md15o-t4 (same as Tank Viaggio, roketa sicily, etc).
Alleyoop, I was thinking the same think about running lean, but the spark plug doesn't show it. And I attribute the top end gain strictly to variator. Recall it's rotating at substantially fewer rpms now with the new variator/weights. I may get a richer jet just to try, but I'll go through valve adjustment and track any possible vacuum leak first. I just checked the valves 200 miles ago, but it certainly warrants another look.
I'm running a stock air box with stock type filter that looks nice and clean. I'll check for an intake crack as well (you never know, it coulda snuck up on me since last ride)
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Post by dev150cc on May 16, 2014 12:45:25 GMT -5
As far as I've seen, the 743/20/30 is the stock belt for a lot of short case gy6 150's. It is the size of Gates that was on previously as well. As I recall from hours of scouring various forms, the short engines don't have much option to increase belt size.
And I could be wrong - perhaps the engine wasn't overheating, but the symptom was increasing stuttering the closer I got to bringing it home. Maybe belt slippage? I had to carefully feather the throttle on those last couple of miles home just to keep smoothly rolling at a lower speed. I know it could be a dozen different things coincidentally going south at the same time I'm performing this maintenance. Tack readings and getting a sharpie marking on the variator travel will help there as a first step.
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Post by dev150cc on May 16, 2014 12:26:11 GMT -5
Everything else is in great shape. Just checked the valves last weekend and it's spot on. It would be coincidental, but I'll check all vacuum hoses to make sure I didn't accidentally pull something off when I was working in there. Other than that, I'm at a loss.
I'll get the tach on this weekend, and sharpie the pullies. Just don't want to risk burning up the engine testing things out.
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Post by dev150cc on May 16, 2014 12:16:29 GMT -5
Yeah, plug is a healthy toast/slight grey. Not rich, not too light. I thought maybe it was fouling out at the time, as that's how it felt, but no, it's good.
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Post by dev150cc on May 16, 2014 2:53:46 GMT -5
Ok, I cleaned everything out, including disassembling the clutch assembly and servicing it.
I installed the Koso variator with the 12 gram rollers (the originals measured 18 gram on my work scale - probably 17 but the scale only registers even numbers).
I installed the new Gates Prolink belt as well. It all went together smoothly.
Lost bottom end umph but gained quite a bit of top end - maybe 5-7mpg. I don't have a tach installed yet, but the RPM's are substantially lower at WOT. A lot lower. After about 10 miles, it started hesitating and cutting out. I think it was overheating. The outside temperature was around 78, so not too hot. I limped it home as it gradually started losing power - wasn't sure I'd make it home.
I noticed the CVT cover was fairly hot. I let it cool down a bit and took the cover off. I was expecting something bad, but nothing was out of place. I forgot to sharpie the pulley.
So to summarize: Short 150cc GY6 215 pound rider ambient temps 78 degrees Orig rollers 17g and I was topping out at about 50mph and felt the engine was getting toward red (no tach). It had decent jump off the line in original form.
After Koso variator and 12 gram rollers installed: Topped out around 60 indicated (was happy about that). Substantially lower top RPM - very noticeable, maybe too low? Lost quite a bit of bottom end, but I was happy with the topend tradeoff Oveheated engine I think (or something that felt like that, including progressively cutting out if I pushed it)
I'm at a loss. Ideas? I'll start by checking the plug tomorrow. *edit* I looked at the plug this morning and nothing notable, looks ok.
I have 13g rollers on order but won't be here for a few days. In the meantime, I may try my stock variator with the 12g rollers.
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Post by dev150cc on May 14, 2014 15:14:10 GMT -5
Thanks. According to USPS, it's already on its way and will be here tomorrow. The diligence is appreciate nonetheless.
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Post by dev150cc on May 14, 2014 13:36:07 GMT -5
Thanks for confirming you guys. It mechanically made sense, but it always pays to have someone validate your thoughts.
I measured my bad rollers - 18 grams down to 14 grams for that munched one. Total 100 grams. Going to 12 or 13, or a mixture, will put me in the 72-78 gram vicinity.
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Post by dev150cc on May 14, 2014 10:26:22 GMT -5
Hi John, thanks for the info. Yes, I pulled the clutch off and will open it up to check it's condition as well and clean/lube.
I appreciate the fast turnaround on my variator order. It will be here just in time for me to button it all back up after a property clean and inspection.
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Post by dev150cc on May 14, 2014 0:18:36 GMT -5
I had the variator cover off recently doing a PDI on my scoot with 3000 miles, new to me. I was pleased to see someone had installed a Gates Powerlink 743 belt and it was is good shape. Spec'ed the width at a tight 19mm, which should be good. Checked for cuts or other compromises, and gave the variator and clutch surfaces a feeling over for smoothness. A-ok. Rode the scoot to work yesterday 25 miles away. At 24.75 miles, the belt went - surprise! Tonight, I bought a electric impact wrench (my 6 gallon air tank won't pump an air impact wrench enough apparently) and made short order of removing the clutch and variator. Clutch looks fab, I'll just do a clean-up on it and re-install. The variator was a different story. I got the clutch off and pieces started falling out. Come to find, one of the roller weights had begun to disintegrate. See the one on top. Plenty of flat spots on the others as well. I already have on order a Koso variator from nycscooters and had them include 12g weights. I *was* going to compare them to the stockers, but that plan is out the door. I have a theory that the belt shredded because a piece of that roller got out and nicked the belt. Could just be coincidence though. Dumb question of the day (I'm entitled to one as a scoot newb): With a belt off, the variator assembly will be a bit "loose", correct. That is the ramp plate, rollers and variator itself will not be sprung because they are in a neutral position, yes? I was surprise, but shouldn't be, that it felt a little jangly when I took a moment to inspect it after the belt broke. Thanks all. Hope someone benefits from my experiences.
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