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Post by ricardoguitars on Jun 17, 2015 16:14:21 GMT -5
As some of you may know, I recently put a 59mm BBK and big valve head on my 125cc 1P52QMI GY6 engine as well as a 30mm carb, I've had troubles with it, the performance is very poor, it was a lot better with the stock 125cc bore, head and carb; I believed the carb was giving troubles, so I bought a new stock carb and try with that, still have poor performance. I'm out of ideas here, don't know what else to do to get this thing running better, I'm confident that I did a good job with the BBK installation, it is not overheating or leaking oil, valves where reseted and adjusted at .004 and .005, since this engine was a 125cc and now has a 155cc bore and head, I'm not sure if I need to replace the gears and/or the stroker as well?  |
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Post by JerryScript on Jun 17, 2015 16:19:55 GMT -5
Have you re-jetted the carb? You will most likely need to change your variator weights as well. What exactly is the issue? You should definitely have noticeable increase in power, but the CVT will need to be adjusted to take advantage of it.
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Post by ricardoguitars on Jun 17, 2015 16:39:09 GMT -5
Have you re-jetted the carb? You will most likely need to change your variator weights as well. What exactly is the issue? You should definitely have noticeable increase in power, but the CVT will need to be adjusted to take advantage of it. I had 12g sliders with the stock bore, performance was great, after installing the BBK it could barely take off, so I put 10g sliders and now it performs a bit better, take off is decent but it tops at 6000rpms going downhills, going uphills is very slow. The 30mm carb came with 125 main jet, the stock carb comes with 105 main jet, adjusting the A/F screw makes no difference until it is almost closed. The issue is general poor performance, instead of gaining power it lost it, cold starts are very hard, I have to let the start button pressed for a few seconds until it can idle on its own, but when it is hot it starts right away. I noticed that when I cold start it, I can't move the throttle or it stalls, I have to let it run for a few seconds until I can move the throttle without stalling. |
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Post by onewheeldrive on Jun 17, 2015 18:37:57 GMT -5
The gears are definitely not the issue--- but once you get it running right, it may be something to tinker with in the future. You should notice that your scooter has more balls, not less. With the BBK you shouldn't have to decrease the rollers' weight to get better performance, over the stock engine.
Something just isn't right whether it'd be the air/fuel mix, or I'm even wondering about a compression check in the back of my head. It's like you have no power.
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Post by pistonguy on Jun 17, 2015 18:51:00 GMT -5
She's got no Snot's, bummer.
How bout a Compression check to see were your at? please.
When I hear you have to crank it for awhile to start /keep it running I have some suspicions.
Including is better when hot.
Lest go thru a process of elimination
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Post by ricardoguitars on Jun 17, 2015 19:47:13 GMT -5
I don't have a compression gauge, I'll will get one and post the reading  If the issue is low compression, what could be wrong? what should I check? |
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Post by murkyapricot on Jun 17, 2015 20:12:53 GMT -5
Have you re-jetted the carb? You will most likely need to change your variator weights as well. What exactly is the issue? You should definitely have noticeable increase in power, but the CVT will need to be adjusted to take advantage of it. I had 12g sliders with the stock bore, performance was great, after installing the BBK it could barely take off, so I put 10g sliders and now it performs a bit better, take off is decent but it tops at 6000rpms going downhills, going uphills is very slow. The 30mm carb came with 125 main jet, the stock carb comes with 105 main jet, adjusting the A/F screw makes no difference until it is almost closed. The issue is general poor performance, instead of gaining power it lost it, cold starts are very hard, I have to let the start button pressed for a few seconds until it can idle on its own, but when it is hot it starts right away. I noticed that when I cold start it, I can't move the throttle or it stalls, I have to let it run for a few seconds until I can move the throttle without stalling. hmm well if it is not making a difference until the af is almost closed maybe you should try a 120 main also im thinking since it stalls when first starting up that it's too rich,and when the auto enricher turns off its not nearly as rich and that's why it doesn't stall when giving throttle |
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Post by ricardoguitars on Jun 17, 2015 20:19:12 GMT -5
I had 12g sliders with the stock bore, performance was great, after installing the BBK it could barely take off, so I put 10g sliders and now it performs a bit better, take off is decent but it tops at 6000rpms going downhills, going uphills is very slow. The 30mm carb came with 125 main jet, the stock carb comes with 105 main jet, adjusting the A/F screw makes no difference until it is almost closed. The issue is general poor performance, instead of gaining power it lost it, cold starts are very hard, I have to let the start button pressed for a few seconds until it can idle on its own, but when it is hot it starts right away. I noticed that when I cold start it, I can't move the throttle or it stalls, I have to let it run for a few seconds until I can move the throttle without stalling. hmm well if it is not making a difference until the af is almost closed maybe you should try a 120 main also im thinking since it stalls when first starting up that it's too rich,and when the auto enricher turns off its not nearly as rich and that's why it doesn't stall when giving throttle That makes a lot of sense, I guess I'm dealing with two issues here, carb adjustment and compression. |
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Post by murkyapricot on Jun 17, 2015 20:32:39 GMT -5
That's just my newbie observation don't know if it's right
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Post by onewheeldrive on Jun 18, 2015 3:00:33 GMT -5
It's probably not the compression (but you never know), unless there is an issue with your new head (valves/valve adjustment), rings or ring alignment, cylinder/piston, or head gasket you should be fine---just not sure I"d run out and buy a compression gauge yet, unless you have the money. Maybe the timing? Not sure.
Do you have starting issues with both carbs? I know you said there wasn't a performance difference between carbs, but did the scooter start easier with one or the other? I mean are both pilot jets the same? You said you turned you mixture screw and it didn't do anything until it was almost all the way in?
What is your air filter situation? Stock, free-flow. Have you checked your plug at all?
I'm just thinking out loud here. I can't say I'd suspect the CDI or Coil going bad yet, but that's not saying much--I've never had a bad CDI.
Does your scooter accelerate smoothly or does it hesitate/jerk?
EDIT: I really can't think of anything else off the top of my head other than what I posted above, unless your air/fuel mix is way off with both main jets---- the bigger jet in the 30mm carb and the smaller main jet in the stock carb.
You may just have to play with the air/fuel mixture--- trial and error.
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Post by pistonguy on Jun 18, 2015 7:52:05 GMT -5
If your going to tinker with these builds a good investment is the Compression Gauge.
You will use it once you have it.
It sure would be nice to know right now what it is. Ay?
If good compression you've just eliminated the BBK as a problem.
Were just shooting in the dark right now.
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Post by ricardoguitars on Jun 18, 2015 10:06:57 GMT -5
It's probably not the compression (but you never know), unless there is an issue with your new head (valves/valve adjustment), rings or ring alignment, cylinder/piston, or head gasket you should be fine---just not sure I"d run out and buy a compression gauge yet, unless you have the money. Maybe the timing? Not sure. Do you have starting issues with both carbs? I know you said there wasn't a performance difference between carbs, but did the scooter start easier with one or the other? I mean are both pilot jets the same? You said you turned you mixture screw and it didn't do anything until it was almost all the way in? What is your air filter situation? Stock, free-flow. Have you checked your plug at all? I'm just thinking out loud here. I can't say I'd suspect the CDI or Coil going bad yet, but that's not saying much--I've never had a bad CDI. Does your scooter accelerate smoothly or does it hesitate/jerk? EDIT: I really can't think of anything else off the top of my head other than what I posted above, unless your air/fuel mix is way off with both main jets---- the bigger jet in the 30mm carb and the smaller main jet in the stock carb. You may just have to play with the air/fuel mixture--- trial and error. The plug shows it is running rich, that could explain the A/F issue, I'll try with a smaller jet, 120 or 115 perhaps; I didn't run it enough time with the stock carb to check if it was still rich or lean, I just put it on and checked if the issue was still there, it did have problems starting with both carbs. It accelerates without hesitation, just having a hard time going from 0 to 20kmph, then I can feel the light sliders kicking in and it starts to gain speed until it hits 5k rpms (flat surface), it tops there. I have the stock CDI and coil somewhere, I'll try with that as well. I'll definitely get the compression gauge, I'm still missing a lot of tools that I'll need to work on my car and scoot, I'm buying them when the need arises, a complete toolbox is a life time achievement, you are always missing something  |
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Post by geh3333 on Jun 18, 2015 17:28:57 GMT -5
When you install a bbk , you should not have to drop in variator weight. You should have a stronger running scoot , so if anything you should have to go up in weight. Your problem will be in the air/fuel system or the top end .
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Post by onewheeldrive on Jun 18, 2015 22:40:42 GMT -5
I hear you with the tools. I have a cheaper compression gauge and only have used it once, but it's nice to have just in case. Before I bought it, I went to an auto parts store but their gauge didn't have the right size adapter that screws into the head--- the adapters were all bigger than what I needed. That's pretty much why I bought mine.
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Post by onewheeldrive on Jun 18, 2015 23:15:17 GMT -5
I'm not sure what kind of airbox/filter setup you have, but some setups you can take the airbox cover off to get more air, and see if it runs better that way.
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