Thudding-vibrating By epdowd (Read 784 times)

[epdowd]

I have a 150cc Znen Pacifica. It has begun to what I would call a thudding or heavy vibration. It starts up and idles fine but as I give it gas to take off it starts this thudding at about 3800 to 4000 rpm on up. Then as I go on up in rpm's it seem less but I think it is because it is more noticeable at low rpm. However after it has run for 15 or 20 minutes it almost acts normal, very little vibration-thudding.. New spark plug, good gas. Could it be Engine misfire as in "missing" only under a load???. Any of you fellows had this happen or have ideas ?.. Thank you..

[crwford]

I would check the CVT transmission and belt and all nuts and bolts also check inside of unit and check the rollers for flat spots.

[epdowd]

I'll do that and thanks for the reply.. It is usually more work taking all the plastic off to get at the problem versus the final fix..

[epdowd]

OK, I screwed up when I was trying out the different slider weights. I put some 18x14 instead of the proper 20x15 for this 123mm Variator. I have 12 gram Mr. Pulley. Now it works OK but I do have some vibration at low rpm take off. Nothing like it was..
Any ideas ??.

[epdowd]

I have 12 gram sliders in the variator. Could my problem be lugging at the low rpm take off ?. Do I go with lighter or heavier sliders to help the low end ?. I'm about to blame the variator.

[cyborg]

I would think it's all in the drivetrain,,, if you have it open check the clutch and contra spring as well

[epdowd]

Thanks cyborg. I put a new clutch on it last year trying to find the cause of this vibration at low rpm on take off only. It idles fine.
So I have a new clutch, proper sliders and still basically have the same problem.

[rks]

Thudding, or heavy vibration on take off....sounds like clutch chatter to me. Clean the drum, and deglaze the pads with sand paper.

[epdowd]

I'm running out of options other than the sledge hammer,, I'll try that rks, Thank you !!..

[epdowd]

Well, I hope this is my problem - not betting.. I took the variator off and looked it over very carefully, looks good, then I stuck my finger in the sleeved bearing that the boss fits through and as I rotate it, it feels rough !!. Not bad but I'm sure it's not proper. I've had some low rpm vibration since I bought this scoot six years ago, it got worse over time and I hadn't found the problem. I'll get another reliable variator from one of our sponsors.
I'll let you know..
cyborg,, you have the 123mm variator and use 12 gram 20x15 sliders ??.
Thanks,, Harv

[epdowd]

Wow, , I put in a new variator and That was my problem all along !!. Runs smooth as silk on take off rpm's..I used the same 12 gram sliders I had in the old one. So it did have a rough spot in the Boss area or it was just out of balance. So - all is good !!

[cyborg]

Bingo you win ,,,, there's a piston right there as soon as I get to a computer

[epdowd]

Thanks cyborg !!. It's sure a relief to have the P.I.B over with..