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Post by stellarfoxy on Jan 9, 2016 18:58:17 GMT -5
I sure hope so. I will do note investigating to see if there's any sign of what it was hung up on. nothing changed from before to now except removing the spark plug and pressure testing.
in all honesty, I think something broke internally. unfortunately that means removing everything to check it out if it's something serious. I'll update if I find out why this machine has to go and make everything personal.
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Post by stellarfoxy on Jan 7, 2016 23:31:24 GMT -5
Thank you for the ideas, but I think it's taunting me at this point. I put the stock starter back on with an extra jumper cable for the ground (can't have too much) and did a compression test- 180 psi. So it definitely isn't that (which someone mentioned before, I suppose I could have checked it before creating a post!) It suddenly didn't seem to struggle to turn over. In fact, after the pressure test, I put the plug back in and it started right up. go figure. Even started without the jumper cable ground. I wish I was making this up, it wouldn't barely turn over for ANYTHING the other day! I wish I knew what was holding it back before?! 
Thanks to everyone for your quick replies and helpfulness.
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Post by stellarfoxy on Jan 7, 2016 22:51:18 GMT -5
Thank you for the replies! the cam timing is accurate, I have an a9 cam. I did get rid of the advancing cdi box and put the stock one back on. it's not kicking back, it's simply extremely sluggish, like there's a lot of force fighting the starter. I have a 4ga wire from the battery to the relay, and from the relay to the starter. I have two 8ga wires from the engine to the ground terminal. They don't get hot, but a little warm maybe? If I advance the flywheel to beyond the compression stroke (VERY difficult by hand) it turns over a couple more times before voltage drops too much. it never really spins fast.
I'll try a compression test in a few minutes, I think it's together enough to do that.
Please keep in mind that with enough volts/amps thrown at it, it DID start up and run just fine, idled smoothly and so forth. It just really doesn't want to get going from a dead stop!
Thank you again! I'll return with results in 1/2 hour to an hour.
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Post by stellarfoxy on Jan 7, 2016 17:48:47 GMT -5
Hello again everyone! A few months ago I was struggling to get my 150cc started reliably again, and I thought to drop down to the stock cam. In the re-installation process, I broke a cylinder stud, so I decided screw it I'm going to replace the whole damn thing. I now have a brand new Taiwanese 60mm cylinder/high comp lightweight piston with 61mm big port head and 12k springs, complete with taida cylinder studs. It went together without a hitch, but I think I have too much compression...
My starter seems to really, REALLY struggle to get through the compression stroke. I bought a high torque starter, which got it started once, but it struggled a lot to get there- I had two batteries in parallel and a jump starter delivering 100a, and only then did it start, and it didn't really want to turn over still.
and woo did it run like when it did start! very exciting times!
That being said. Is there a way to reduce compression just a little bit to allow the starter to work better, maybe a small spacer or shim? or am I completely wrong in my diagnosis? with the same starter and only 1 battery, it had no problem turning over before the bbk/high comp piston setup.
Any help is greatly appreciated. Thank you!
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Post by stellarfoxy on Jul 12, 2015 0:37:06 GMT -5
man I hope so too. it's been over a year since owning it, probably 8 months fixing the engine and chassis, it's been awesome learning but I'm ready to ride more!!
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Post by stellarfoxy on Jul 11, 2015 17:07:05 GMT -5
good news! the stock cdi seems to have resolved the problem. it fires up very quickly, hot or cold. possibly there's a setting on the adjustable one that gets close to this because there seems to be less torque and it doesn't accelerate nearly as quickly, especially once the variator starts adjusting.
tightening the block bolts seems to have cured the oil leak.
thank you to everyone for help diagnosing this. it's all great information!
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Post by stellarfoxy on Jul 11, 2015 9:02:13 GMT -5
my compression is around 125psi, and I have a manual petcock already. in fact, with the pump carb, I have no vacuum lines at all, everything is internal on that. I seriously think the long bolts holding the crank case together just needed another little turn, I didn't see any oil underneath it yesterday but I may ride it around a bit today and see.
I'm going to try to tune everything with the stock cdi first then if I can get it nice and smooth I'll try to put that orange cdi back on and tune that, hopefully with better results.
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Post by stellarfoxy on Jul 10, 2015 16:03:48 GMT -5
    I think that's pretty much as timed as possible on these motors? I mean I checked it over and over and over, as timing being off led me to the complete tear down, didn't want to risk that again. That being said, I think I've found the culprit. That damn orange adjustable cdi box. I put the original back on and it seems to start much quicker and even start when warm, but until the idle enrichment circuit closes off, it idles funny, so it likely just needs tuning. revving to about 6000 rpm it starts choking out with either cdi, i did the kill-the-engine-at-WOT test and the plug is white on the tip. So probably need to up-jet from the 125 that came with it? I don't think this engine parts combo creates much vacuum and therefore needs a bigger fuel port to compensate. But I could be very wrong about that. I'll try a 130 and see if the float is horizontal. Also, while I had the covers off I removed the stator magnet and turns out every bolt needed a bit more torque, like a quarter- to half-turn per bolt, and the oil leak appears to be gone. I assume that's part of the rebuild break-in, but this is new to me and oil on the ground isn't ever a good thing. I'll update if I find anything new. |
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Post by stellarfoxy on Jul 10, 2015 9:09:57 GMT -5
also would a compression test show any indication of excessive pressure enough to blow a seal?
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Post by stellarfoxy on Jul 10, 2015 9:08:36 GMT -5
I've tried two different intake manifolds, the stock one and a 30mm aluminum one, I did the spray test on the new one without any sign of leaking. the oil is unrelated, just a new problem.
geh- I'll send pictures in a bit once I get it apart.
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Post by stellarfoxy on Jul 9, 2015 23:31:20 GMT -5
it was at one point, with the 24mm carb, but it wouldn't start after it got warm and it ran lean.
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Post by stellarfoxy on Jul 9, 2015 21:08:19 GMT -5
ok I'll try adjusting the valves again with it at the compression cycle tdc
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Post by stellarfoxy on Jul 9, 2015 21:06:11 GMT -5
wait I've been through this before actually. the original crank's timing gear was slightly off, I replaced it and everything was much better. it appears my reassembly was less than par. but I'm sure my tdc lines up with the lines on the cam and variator
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Post by stellarfoxy on Jul 9, 2015 19:59:28 GMT -5
ok. would the crank case pressure not be relieved by the pcv though? when I adjust valve lash, I usually turn the cam to where one valve is entirely open so that the other one is definitely closed, then the opposite. I figured that way it's definitely correct, as there's no way the cam lobe is interfering with the adjustment. is that incorrect?
also does that explain why it holds it's oil until right after it's not running? everything you're saying makes sense about excessive pressure, but wouldn't it be spewing oil while it was running also?
since you've mentioned pressure I'm wondering if some sealant got loose and is clogging one of the oil passages.
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Post by stellarfoxy on Jul 9, 2015 13:00:35 GMT -5
looks like around the starter (fresh o-ring) all the way down the back and underside of the main crank case separation line, and around a couple external screws near the drain plug. do these engines vibrate themselves loose? it only leaks after I turn it off, seems to hold it's oil fine until I kill it then it drips like crazy, yesterday I watched it lose a couple oz on the ground after a run
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