Why only CG builds?

[FurryOnTheInside]

I'm not sure what clutch bearings FNTPuck is referring to, the clutch shaft support bearings I suppose.
Which on mine I just gave a generous squirt of axle grease into the area underneath the clutch cable stop post, it's made it's way to both sides of the output and clutch side bearings and they're both running smoothly. I don't know how you could easily press apart the clutch assembly with basic home tools.

I was wondering about this too. I never run the engine with the clutch disengaged; but I have to pedal my bike on public roads, plus I like to use the engine to get up to speed then try to keep the speed up with just pedalling, so I want mine to roll better with the clutch pulled. I know it's possible to replace the main clutch shaft bearings but I would be very interested in improving the clutch hub bearings (as I call them) too.

 

[Spare_Parts]

The clutch can be pressed apart and back together. I have run across people talking about it in old posts. Never had an issue other than noise from it. Do have a few laying around so maybe I'll give it a try. May be something that can be done in a vice....

 

[MotorBicycleRacing]

the worst part really is the poor clutch.

Doug Owens on Facebook has a real bearing fix for the Chinas gal clutch and better pads.

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[FNTPuck]

The awful lack of clutch quality, ( no more bearings on the inner clutch body with these Ebay/ Amazon cheapy 48 cc engines..) which I see as something in favor of these, as long as you can spray some lithium grease into the steel to steel wearing surface. I try to avoid running the engine much with the clutch pulled in, it clatters a lot. I'm not sure what clutch bearings FNTPuck is referring to, the clutch shaft support bearings I suppose.
Which on mine I just gave a generous squirt of axle grease into the area underneath the clutch cable stop post, it's made it's way to both sides of the output and clutch side bearings and they're both running smoothly. I don't know how you could easily press apart the clutch assembly with basic home tools.

Nah not the clutch shaft bearings, the actual hub bearings. Stock takes 57 of the 3mm bearings, and they use crappy soft chrome plated bearings. You can clean the race and instead run 54 slightly larger 1/8" bearings instead. It will take up the extra slop, stabilize the assembly, and last longer since the outer bevel gear won't bounce around so much which beats up the bearings.

I've done a bunch so far with G25 stainless bearings, and used G5 ceramics on my personal bike just for fun since they theoretically will last longer and roll even smoother. I honestly can't tell much of a difference on the bike, so usually just recommend the MUCH cheaper stainless (its like $2 vs $10 worth of bearings for stainless vs ceramic). Have one on the bike of a guy who does 20mi per day, and I pulled it after ~200 miles to inspect and it was just as good as when I installed it with no noticeable increase in slop or wear. Just make sure the surfaces are cleaned, burrs sanded down, and you use a quality grease. If its a used clutch there will be grooves and burrs in the race, especially if you are rebuilding a failed one.

Top are the stock bearings, bottom are the G5 rated silicon nitride ceramic. Now I mostly use G25 stainless since there is no real noticable difference and I can get 500 of them for half the price of 100 of the ceramics. Note it will use 54 bearings instead of 57 since they are slightly larger diameter.

This is installed on the race. Much better fit than the stock ones.

Not as good as that badass sealed bearing setup above, but easier for someone to do themselves at home and still a big improvement over stock.

 

[FNTPuck]

The clutch can be pressed apart and back together. I have run across people talking about it in old posts. Never had an issue other than noise from it. Do have a few laying around so maybe I'll give it a try. May be something that can be done in a vice....

Yep, it can be done in a vice.

I was "lucky" enough to get 5 of the defective CDH/Zeda clutches back in October of last year, and before the issue was realized 4 of the 5 grenaded themselves within the first 100 miles. One barely made it to 10 miles before turning the bearings to dust. First we thought they were coming from the factory dry, but when I ordered old stock clutches to compare them and took apart a new one, I noticed both were well greased but the older clutches had way less slop(both up/down and front/back) than the new ones. Not sure if it was due to a poorly machined race with slightly larger diameter, or a bad batch of slightly undersized bearings but someone mentioned trying larger bearings so I decided to be a guinea pig and gave it a shot. It worked perfectly.

Now I keep a few as spares for local repairs, and to offer as upgrades on my own motors.

 

[JerboaJohn]

cool! I'll have to try that this summer. I thought I had a decent clutch getting 850 miles on it before it ate the bearings. they are soft. some were not round anymore. probably they started going at 5-600 miles.

 

[mark20]

main reason i switch to 4 stroke as it fits my needs better.
the CG 2 stroke worked flawlessly, but its just not the right engine for me. (i dont really want to smell like 2 stroke every time i go anywhere lol)
is the CG a perfect engine, hell no, is it a simple engine, yes.
just my opinion. everyone gets them because its dirt cheap. its easy enough to assemble (no welding required or drilling, unlike my 4 stroke lol)
and its fun! i tinkered with mine, planning on putting on a big bore kit. (go big or go home)
but if you want one, go out and get one (for people just viewing these forums, and dont have one)

 

[LewieBike]

Yep, it can be done in a vice.

I was "lucky" enough to get 5 of the defective CDH/Zeda clutches back in October of last year, and before the issue was realized 4 of the 5 grenaded themselves within the first 100 miles. One barely made it to 10 miles before turning the bearings to dust. First we thought they were coming from the factory dry, but when I ordered old stock clutches to compare them and took apart a new one, I noticed both were well greased but the older clutches had way less slop(both up/down and front/back) than the new ones. Not sure if it was due to a poorly machined race with slightly larger diameter, or a bad batch of slightly undersized bearings but someone mentioned trying larger bearings so I decided to be a guinea pig and gave it a shot. It worked perfectly.

Now I keep a few as spares for local repairs, and to offer as upgrades on my own motors.

Has anyone done a step by step of how to do this? I have a big vise so pressing isn't a problem.

 

[Spare_Parts]

If @FNTPuck doesn't do one I will when i do mine.

 

[FNTPuck]

Has anyone done a step by step of how to do this? I have a big vise so pressing isn't a problem.

I made a post-mod comparison video that shows an old good clutch, a new defective one, and a fresh rebuilt/upgraded bearing one side by side but never did a step by step. Once you get it apart its all self-explanatory though. Clean the race/backing plate, if its a blown clutch you may need to gently sand out any bumps and grooves, lightly grease the race to hold the BBs in place, then use tweezers or clean hands to place the bearings back on the race 1 at a time, keeping it all as clean as possible.

Putting it back together isn't hard, just hold the bottom part in the vice and use a pipe of the same diameter as the outer ring on the race and tap it in with a small hammer. If you don't have an identical sized pipe, in a pinch you can use just a flat square bracket like from the U-Bolt mount to tap it in an "+" pattern (first tap it spread across top/bottom, then across left/right). You need something that will only push on the race on the left side in this pic - the race sits inside the bevel gear then gets pressed on the backing plate. You can also see the damage on the backing plate from the bearings that turned themselves to paste within 50 miles.

This is the back of a bevel gear with fresh bearings in it. They don't actually touch the backing plate, but that plate still needs to be sanded and cleaned to not get junk inside the nice clean new bearings. The race and backing plate stay connected while the bevel gear rotates around it.