crankshaft play on new engine

weefek

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Hello everyone, completely new to this but I have a lot of mechanical / etc experience.

Due to medical reasons my drivers license has been temporarily revoked, and I live in a rural area. In order to get into town to buy essentials, I bought a bicycle. Unfortunately my being a fat ass for the last 5 years means that there's no way I can pedal all the way to town and back.

So I recently purchased a Grubee 69cc GT5B kit for my walmart special bike. I'm at about 20 / 30 miles so far and have worked out a lot of random issues on my own.

Not having experience with these kits or types of engines I'm wondering what all your opinions are on the amount of crank shaft / rod play. See the video below, it's quite audible. I can't imagine this is normal, it seems like a lot of play to me. Almost like someone forgot to install a bearing.



Let me know what you guys think.

Thanks!

EDIT: I realize most of you do this as a hobby, but for me it's for essential reasons. Any recommendations / ideas with regards to reliability? I already have an NGK spark plug to pop in the engine once I'm out of the break-in period and a spare chain. I will be buying a hub adapter for the rear drive sprocket soon as well. Also added picture of bike.
 

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DieselTech

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Hello everyone, completely new to this but I have a lot of mechanical / etc experience.

Due to medical reasons my drivers license has been temporarily revoked, and I live in a rural area. In order to get into town to buy essentials, I bought a bicycle. Unfortunately my being a fat ass for the last 5 years means that there's no way I can pedal all the way to town and back.

So I recently purchased a Grubee 69cc GT5B kit for my walmart special bike. I'm at about 20 / 30 miles so far and have worked out a lot of random issues on my own.

Not having experience with these kits or types of engines I'm wondering what all your opinions are on the amount of crank shaft / rod play. See the video below, it's quite audible. I can't imagine this is normal, it seems like a lot of play to me. Almost like someone forgot to install a bearing.



Let me know what you guys think.

Thanks!

EDIT: I realize most of you do this as a hobby, but for me it's for essential reasons. Any recommendations / ideas with regards to reliability? I already have an NGK spark plug to pop in the engine once I'm out of the break-in period and a spare chain. I will be buying a hub adapter for the rear drive sprocket soon as well. Also added picture of bike.

Remove the cover right in front of the cover you got off now, & do the same thing on the magneto rotor nut. Then see if you are getting the same type of noise. To me it sounds awful loose, but I have never tried your type of procedure either. The crankshaft is under the cover I mentioned over magneto.
 

weefek

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It's 100% crank to rod play. I first noticed it when I had the head off when I was putting lock-tight on the head studs and checking piston ring orientation before the first start.

The only reason I showed it that way was because I needed to get into town today and didn't want to disassemble it too far.
 

weefek

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I 100% agree, I do have a proper spark plug socket that works with the spark plug, but it doesn't work on the main drive sprocket because the wall thickness is too large. I can produce the same noises in the video by moving the bike back and forth, it's not the tool.
 

Chainlube

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I 100% agree, I do have a proper spark plug socket that works with the spark plug, but it doesn't work on the main drive sprocket because the wall thickness is too large. I can produce the same noises in the video by moving the bike back and forth, it's not the tool.
I was just being sarcastic, but these little motors have quite a bit of drive train noises. On the other end of the shaft that sprocket is on is another gear, so more noise. Pull the right side cover off and make sure it has a little bit, but not too much grease on the gears. That will quiet it down some, but won't make it stop.
 

weefek

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Yes, I've greased those gears. The noise from them is very loud at mid to low speeds. It's weird but everything seems happier the faster I drive this thing. I guess I'll just wait and see how long it takes to explode. Replacement engine isn't terribly expensive.

I basically took apart the entire engine before I started driving it just to make sure everything was ok... Gaskets, bolt torques, no machining debris, etc etc. This is the only issue at this point.

Thanks for the replies / interaction so far.

EDIT: I may be a new member but I've been lurking for a few weeks. I see you in here Damien. I respect your opinion very much, you seem like you know a thing or two about these kits. Please add your pennies (dimes these days?)
 

DAMIEN1307

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EDIT: I may be a new member but I've been lurking for a few weeks. I see you in here Damien. I respect your opinion very much, you seem like you know a thing or two about these kits. Please add your pennies (dimes these days?)
I can produce the same noises in the video by moving the bike back and forth, it's not the tool.
Its kind of difficult to know exactly what your experiencing without actually hearing it when your moving the bike back and forth, but it would also be good to hear it while riding it as well...Could you do a video of that as well and post it when you get a chance?

Pics of the bike at all angles and sides as well as close up pics of the bike motor the chain and sprocket assembly etc will also be of help just to see if anything obvious will jump right out at us...You would be surprised by how much we can help diagnose something just by pics and videos like what Im asking for...Makes things a little easier rather than just guessing...lol.
 

weefek

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Here's a few more pictures and a few videos. I have the bike apart right now so I'll try to get a video of it running / riding tomorrow. There's an audible 'pinging' noise (for lack of a better word) at low RPM / idling. I don't have a speedo, but I'd estimate at around 3/8 speed to maybe 5/8 of full throttle/speed the gears are audible. At full speed everything sounds good. Chain / drive sprocket noises are also a lot less now after maybe 30 miles.

So the main noise heard in the video from yesterday is actually just gear backlash (see first video in this post). I have no idea what the backlash is supposed to be but I'd assume since there doesn't look at any abnormal wear on the gears and the load is almost entirely in one direction it shouldn't be an issue. Not to mention the fact I can't see any way to actually adjust gear lash.

There IS crankshaft play (second video). Keep in my I have the chain completely removed while I filmed these, and also was looking at the piston from the exhaust port to make sure the piston wasn't moving. So I'm not entirely sure if the play is rod to crank or rod to piston.

Please ignore the messy garage :ROFLMAO:



 

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DAMIEN1307

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Please ignore the messy garage :ROFLMAO:
I would start with re-doing the clutch adjustment...Note in pic number #1 the postion on your clutch actuator arm.

20220516_172311.jpg


Now look at this pic below as to where my arm is located with the clurch lever fully released.

DSCN0186.JPG



Lets at least start with the basic clutch adjustment first...with the clutch lever totally released, do the cable end adjustment to match mine in the pics so it runs in a fairly straight line not so far inward as your is.

Now after that is done, Pull the clutch lever in and lock it in place whilst you adjust the flower nut on the right hand side of the engine where those clicky gears of yours are at...I ususally have it tight enough where the rear wheel won't turn freely at all and then back it off a notch at a time until the rear wheel will turn without any clutch resistence...Then put the lock screw back in place to keep it locked in place.

I know you said you had greased those two gears there but i do not see any...You should be using either white lithum grease or some Lucas red and tacky grease...Just a little though so the grease doesn't work itself underneath that clutch plate into the brake pads and cause slippage.

Be sure on the other side where the clutch actuator rod fits into the case cover that it is grease in its housing where it pivots back and forth as well and do the same with the straight bucking bar that the actuator arm pushes in...you want a dab of grease on both ends of that bar to minimise wear not only to the bucking bar contact point with the actuator but also the other end where it comes into contact with the steel ball bearing inside the casing...Now see if that doesnt help things out a little...Remember that when your done, with the clutch lever released, you want to see your clutch arm in the same position as mine in my pic.

Ps...I notice that the spring is missing on the exposed cable end between the cable housing and the actuator arm.
 
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