bicycle engine clutch.

[Jumpa]

are you sure you do not have 2 ball bearings in there before the rod? Sounds like there is something else in there. Also make sure the clutch cable is not connected when you put the cover on to eliminate any issues with that then hook it up after

 

[Shagasaur]

What you have shown in your picture is not the clutch. It is the transmission shaft with the clutch pressure spring still attached to it.
The clutch assembly is the large round thing with gear teeth all around it that is attached to the end of the transmission shaft. The puller tool removes it from the end of the transmission shaft.

Now...... on to the transmission shaft:

The assembly is installed into the case with an interference fit. The holes in the case, called bearing bosses, are machined at the factory to be a few thousandths of an inch smaller than the diameter of the bearings. This gives the bearings a tight, non-slip fit into the cases.
To remove the shaft and bearings properly you need to heat the case either in an oven to approx. 180F/ 200F or if you have the experience, carefully heat the case around the bearing boss with a propane torch before pressing or driving the bearings and shaft out. Aluminum expands more than steel and the heating process causes the bearing bosses to loosen up their grip on the bearings a little bit.

NOTE: When working on the bearings while still attached to the shaft, never put any sort of pressure on the shaft or inner bearing race. Only apply pressure to the outer bearing race. Use a properly sized deep socket or short piece of pipe to accomplish this.

To re-install the bearings and shaft back into the cases do the heating process to the case again, only this time you also need to put the bearings and shaft assembly in a zip-lock bag and place it in your freezer it for an hour or two.
Freezing the shaft assembly causes it to contract or shrink, heating the cases causes the bearing bosses to expand. As quick as you can, re-install the shaft into the case The assembly should nearly push into the cases with your fingers. A little tapping might be necessary. It needs to be done quickly before the hot case warms the shaft bearings and the frozen bearings cool the case. If this happens the assembly will become much more difficult to work because the bearings will have warmed up and the bearing bosses have cooled. You will have lost all thermal advantage to properly re-installing the assembly.

Ok.. Trying to put the clutch assembly on the clutch shaft and its not going all the way on. Its a new clutch shaft and a old assembly... Is the secret in cooling the assembly and shaft? So frustrating.

 

[MotorBicycleRacing]

Ok.. Trying to put the clutch assembly on the clutch shaft and its not going all the way on. Its a new clutch shaft and a old assembly... Is the secret in cooling the assembly and shaft? So frustrating.

The clutch slides on without doing anything.
Is the key way the same?

Manufacturers make the shaft OD and clutch ID in slightly different sizes.

Try the clutch on your Old shaft and measure both of them with a micrometer.

 

[Shagasaur]

The clutch slides on without doing anything.
Is the key way the same?

Manufacturers make the shaft OD and clutch ID in slightly different sizes.

Try the clutch on your Old shaft and measure both of them with a micrometer.

Just thought of that myself... Ran outside and slid the clutch on the old shaft, slid on no problem. Compared old and new shafts, its barely noticeable but the old shaft has a bit more taper to the shaft. Hmmm.. I think its time to break out the rotary tool...

 

[crassius]

also check the key width

 

[fredric3144]

I have adjusted my clutch , flower nut , cable , etc. and have gotten my bike going again BUT when I first start out leaving my house peddling down slight hill I release clutch it slips , engage peddle to get up speed again release it slips I have to do this about 5 or 6 times then it finally turns over and starts . I have no problems going up hills or any slippage after it has started . with clutch engaged and engine warmed up clutch will try to pull bike but easy to keep it from rolling . My question is if I rough up my clutch plate with sand paper or something will this cure my problem . I could just rough up the plate and try it but if that causes more problems it will be hard to unrough up the plate . Not a large problem when leaving my house as I have the long slight slopped hill but after getting to where I'm going I may or may not have a hill to help and it is a pita to get going . wearing my old a$$ out . Any suggestions please .

 

[crassius]

if the clutch pads are new, they may be slightly diff in thickness - they should even out in a short time

be sure they are loose enough in the slots to go all the way thru and contact the plates on both sides

redo your clutch adjustment often as they run in

last resort, adjust your inner spring tighter

 

[Jumpa]

I have adjusted my clutch , flower nut , cable , etc. and have gotten my bike going again BUT when I first start out leaving my house peddling down slight hill I release clutch it slips , engage peddle to get up speed again release it slips I have to do this about 5 or 6 times then it finally turns over and starts . I have no problems going up hills or any slippage after it has started . with clutch engaged and engine warmed up clutch will try to pull bike but easy to keep it from rolling . My question is if I rough up my clutch plate with sand paper or something will this cure my problem . I could just rough up the plate and try it but if that causes more problems it will be hard to unrough up the plate . Not a large problem when leaving my house as I have the long slight slopped hill but after getting to where I'm going I may or may not have a hill to help and it is a pita to get going . wearing my old a$$ out . Any suggestions please .

you may be hydro locking it...
try not giving it any gas at first also, make sure you shut off your gas at night or when ever your not using the bike.
Fred Does your bike have the 15 round or the square clutch pads?

 

[fredric3144]

now I have really messed up couldn't get the clutch to engage so tightened up on the flower nut and then something snapped inside now no clutch at all need to figure out how to replace the part the flower nut screws on to . I have and old kit to use for parts

 

[fredric3144]

Have decided on a cure gonna buy me a whole new motor for $89.99 on ebay not a kit just motor & clutch assembly only difference is the spark plug is straight up instead of slanted .

 

[crassius]

spark plug straight up - usually means 50cc

this can be disappointing if one is used to a 66cc, or if there are steep hills in the area

clutches can be confusing, but not usually hard to fix

 

[fredric3144]

thanks I double checked it is 80cc /66cc I did get the clutch fixed using parts from my first build a 50cc but the clutch parts were all the same . I am up and running again till the next problem LOL .

 

[Borderline]

Hi new here I need help I'm not very mechanical and the jargon confuses me so go easy please. I used the star nut to adjust the clutch, if I go any looser the motor won't engage at all and if I go any tighter I can't pedal so when the bike is cold it works just fine. The problem comes when I've been riding for awhile the bike just becomes rediculously hard to pedal and I can't walk it with the clutch lever pulled without the back wheel skidding like crazy.

 

[crassius]

go read the threads about adjusting cable & clutch - follow the steps there

 

[Poppajohn84]

So I stumbled upon this thread on a Google search, and I made an account for no other reason than to say thank you for this info. I'm Sure the way you explained and showed this, probably helped many people, including myself. So again, thank you for this.
**And just a little advice to anyone getting ready to post a question on this post or any other post, please read through the entire post, because more than likely your question has already been answered. It would help save some time on everyone's part. Please and thank you**

***Edit***
I think this will be my new go to for any motorized bike info I need .Thanks everyone for your hard work.

 

[Rusty_Nail]

I’ve been having slipping problems with my clutch too. I just put a new set of pads in on Sunday and since I put them in, no matter how I have the clutch adjusted it slips like crazy especially if I rip on the gas.

 

[Greg58]

Rusty did you shape the pads so they fit evenly in the clutch housing? I shape mine one by one so they fit well, some are larger and may not be allowing the plate to sit flush.

 

[Mossy]

To adjust the spring you remove the cable adjustment from the motor and with a slotted screw driver inside there's a slot to hold and rolling the wheel you can get the spring to tighten and there's a stronger spring available

 

[Rusty_Nail]

I did shave them so they would fit as best as possible. I used 320 grit sandpaper and very lightly sanded off a little bit of each side until it fit perfectly far as I could tell. Could it be because the pads need to break in and they don’t fully grab until they’re broken in? Thanks for the eBay link Mossy. I’ll check it out.