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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 tvnacman on Jan 7, 2016 18:07:33 GMT -5
where is ignition timing at start up?
Is it kicking back or real sluggish at first compression stroke?
Some talk about an extra gasket, I'm not 100% sure on who what where.
John
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Post by rcq92130 on Jan 7, 2016 18:30:33 GMT -5
PM Dan at Dansgaragetalk.com. he or Pistonguy have great experience with this.
but your problem is almost assuredly NOT "too much compression" If you have an advanced angle (NOTE: NOT advancing angle) CDI, toss it in the trash and get either a stock CDI or an advancing angle CDI from tvnacman. The advanced angel units make starting very difficult.
More important: you HAVE to upgrade the wiring. Stock ChinaWiring simply cannot supply enough current to the starter. Some of us add second, parallel wiring from battery to solenoid and from solenoid to starter ... and from battery negative to frame ground. Others rip out the OEM ChinaWiring and put in heavy gauge stuff in the starter loop (including ground). Unless you do one of these you might as well figure out a way to make the kickstarter work (good luck on that) because no starter motor on the planet will solve the problem.
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Post by pistonguy on Jan 7, 2016 21:38:35 GMT -5
where is ignition timing at start up? Is it kicking back or real sluggish at first compression stroke? Some talk about an extra gasket, I'm not 100% sure on who what where. John Look into the Above First. Then Before you Take Anything Apart do a Compression Test. Here is a Stock Motor with a Stock Starter.  Get some base numbers before surgery. 60mm bore with a +1mm larger 61mm Head, larger volume will drop the comp. some, I don't know what mfg piston your using? Got Pics? |
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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 rcq92130 on Jan 7, 2016 23:07:05 GMT -5
It's not a volts problem but only an amps problem.
You have proven that with enough juice the starter works fine. The problem - proven by what you did - is the lack of current to the starter motor. you have also proven the starter motor is adequate.
Before going any further - never, ever again attach a 100A device. In only a few seconds that will seriously degrade the batteries. If you wish to jump start, without damaging anything, do so with a known good car battery - car engine not running. That provides an "infinite" amount of amps but only at 12 volts. No damage.
Sounds like the wiring is good. Still, of course, could be corroded terminals in the solenoid. That can easily be checked by jumping, with a screw driver, the 2 solenoid terminals.
I hooked up a dual battery system for my GY6 (now 190cc). Knowledgeable people advised this was a bad thing to do UNLESS the 2 batteries are identical, since (otherwise), one will continuously draw down the other. First check would be a car battery jumpered to the scooters battery terminals. If that does not work then to the solenoid upstream terminals, then if no good to the solenoid downstream terminal, and finally to the starter + connector directly. That way you can isolate the problem.
When doing all this clip the black jumper cable as much as possible right onto the starter motor case to avoid any ground connection possibilities (current flow problems can as much be a ground connection issues as a "red wire" issue).
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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 rcq92130 on Jan 8, 2016 1:11:19 GMT -5
Yippeeeee !
Sounds like a ground connection is loose or corroded. But - yea!!!!!!!!
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Post by pistonguy on Jan 8, 2016 7:25:39 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.  Good Job. Now Enjoy |
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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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