Pull Start Anyone with pull start installition experience ?

[Dilly Bar Rob]

Porkchop - I have a PK80 engine from zoombicycles (my second one on my second bike). For the first engine I had I also ordered the centrifugal clutch from zoombicycles. I had the same problem with the side cover rubbing on the clutch bell. I temporarily "fixed" the problem by putting 4 washers on the 4 bolts that hold the cover on - I put the washers between the "small" cover and the "big" cover if you know what I mean. This resulted in a gap between the two covers (duh) but it was fine for "testing purposes". In the end it did not matter as I had troubles with the the centrifugal clutch so I ended up taking it off again.

My problem with the cent clutch was this - I installed it and all was well apart from the bell rubbing on the cover. It engaged nice and smooth, no jerking or vibration whatsoever. However I kept wondering why the bell would rub on the cover, I thought that maybe I didn't get the "sleeve/bushing" to go on to the crank far enough resulting in the clutch "sticking out" too far. So the next day I decided to take the clutch out again just to check things out. When I took the "sleeve/bushing" out I immediately noticed a big crack going down the center of it, about 3/4 through it. Needless to say I didn't want to re-install it, so I contacted zoombicycles and sent them pictures of the crack. They replied to me that "this is a common problem, we are working with our manufacturer to find out why these sleeves crack". They also recommended that I grind out the sleeve some so it goes on farther and use locktight on it. They shipped me out a new sleeve for free. I ground it out some, installed with locktight. The clutch now engaged in a very jerky manor with LOTS of vibration, it also seemed to slip a lot. After 2 days I took it apart AGAIN. The new sleeve was again cracked, and this time it also showed signs that it was spinning on the crank (even though it was locktighted...). After that I just gave up on it, took it off and threw it in a box, didn't even bother contacting zoom. Looking at the design I see one MAJOR flaw - no key.... I mean, whats supposed to stop it from spinning on the crank, friction?!

I hope your experience is better then mine, and if you ever need a parts clutch just let me know...

 

[POPS]

Pops, I just got through tinkering. I like the way you break things down in your descriptions Makes this simple.

#1 There is a sleeve/bushing that goes over the crank shaft. The needle bearings ride on that sleeve. Not the crank shaft it's self. The only time those bearings should be turning is when the clutch drum is not. That being said, because the bearings actualy move inward and outward from the center of the crank shaft, they should have nothing to do with alignment of the race to the crank shaft. When the drum turns, it puts the bearings in a friction/wedge bind. I guess you know what I'm talking about. The sleeve that goes down and around the crank shaft will go down only so far. Mine appears to be all the way down. The sleeve also has 2 flat side on the top of it. I don't know the technical terms for that other than maybe a shoulder. When I install the clutch drum and clutch it's self, it all fits flush with the top of the shaft. Also, with or with out the bearings, something is alredy out of alignment because I already have weeble wobble in the clutch drum.
The gears appear to mesh properly. I don't recall if I mentioned or not that I spoke with zoombicycles and they told me they really didn't know what good that retainer clip was good for. I know I've talk to some vendors that sell parts but don't have the first clue about technical issues with them. Not saying zoom dosen't. But I know some are like that. Not trying to be contradictory, #2 but do you know what you've told me from experience ? #3 Bottom line, how do I get completley rid of the manual clutch an be able to peddle my bike or push it without turning over the engine ? Reverse the retainer clip direction ?
Thanks !

PC

Sorry for the delay in the reply but wireless key boards are great untill the batt's. die and you don't have any spares.

#1 You are Right and I stand corected that the rollers do not touch the crank. But if you take the rollers out than the bell wobles on the center sleve a lot. On mine I have no weeble wobble at all. I have 2 of them and they are the same same. Maybe move the rollers into different slots and that will stop the wobble.

#2 I have not installed my motors yet but I bet all of my 45 years wrenching that this is correct. It's only logic which anything that is mechanical is.
You can see that it free wheels when you preload it to the left. You are right in thinking that as the RPM'S go up the clutch will grab the bell and away you go.

#3 Yes...Reverse the spring and put a 180 twist on the top to hook into a hole in the bell so it preloads to the left and I know it will work.

Don't forget to greese the rollers and (blue lock thight that center bolt.)

I took it a step futher and removed the clutch arm, rod, pin ,ball and put a stainless plug in the hole where the rod went. Than I took a blob of silicone and put it in the hole where the ball and pin were. I also removed the clutch cable holder and installed a greese zirt in there...POPS

 

[POPS]

Porkchop - I have a PK80 engine from zoombicycles (my second one on my second bike). For the first engine I had I also ordered the centrifugal clutch from zoombicycles. I had the same problem with the side cover rubbing on the clutch bell. I temporarily "fixed" the problem by putting 4 washers on the 4 bolts that hold the cover on - I put the washers between the "small" cover and the "big" cover if you know what I mean. This resulted in a gap between the two covers (duh) but it was fine for "testing purposes". In the end it did not matter as I had troubles with the the centrifugal clutch so I ended up taking it off again.

My problem with the cent clutch was this - I installed it and all was well apart from the bell rubbing on the cover. It engaged nice and smooth, no jerking or vibration whatsoever. However I kept wondering why the bell would rub on the cover, I thought that maybe I didn't get the "sleeve/bushing" to go on to the crank far enough resulting in the clutch "sticking out" too far. So the next day I decided to take the clutch out again just to check things out. When I took the "sleeve/bushing" out I immediately noticed a big crack going down the center of it, about 3/4 through it. Needless to say I didn't want to re-install it, so I contacted zoombicycles and sent them pictures of the crack. They replied to me that "this is a common problem, we are working with our manufacturer to find out why these sleeves crack". They also recommended that I grind out the sleeve some so it goes on farther and use locktight on it. They shipped me out a new sleeve for free. I ground it out some, installed with locktight. The clutch now engaged in a very jerky manor with LOTS of vibration, it also seemed to slip a lot. After 2 days I took it apart AGAIN. The new sleeve was again cracked, and this time it also showed signs that it was spinning on the crank (even though it was locktighted...). After that I just gave up on it, took it off and threw it in a box, didn't even bother contacting zoom. Looking at the design I see one MAJOR flaw - no key.... I mean, whats supposed to stop it from spinning on the crank, friction?!

I hope your experience is better then mine, and if you ever need a parts clutch just let me know...

Dilly

I think what happened to you is that you tightened the bolt down to hard and cracked the sleve because it is a tapered shaft and sleve and if you cranked too hard. It would crack the sleve at some point. When you ground out the second one it threw it all out of balance on the shaft....POPS

 

[Porkchop]

Thanks guys. I've got more experimenting to do yet. I'll get back with you.
Thanks !

..... PC .....

 

[Dilly Bar Rob]

Dilly

I think what happened to you is that you tightened the bolt down to hard and cracked the sleve because it is a tapered shaft and sleve and if you cranked too hard. It would crack the sleve at some point. When you ground out the second one it threw it all out of balance on the shaft....POPS

POPS - Yes it's quite possible that it indeed was my fault that the sleeve cracked the first time, I did torque it down quite a bit. But then as I say - how is the key-less sleeve supposed to NOT spin on the crank under load without being tightened a LOT?

Also possible that the second one was off balance because of me, but then again I have read (on here) that lots of people have problems with the cent. clutches vibrating & such when engaging - and they didn't grind anything!

I know for sure that the second sleeve didn't crack because of me - I put the sleeve on the crank first (with the clutch off of it) with some red locktight on the bottom of it and torqued down gently until it didn't seem to go on further. Since the clutch itself was off I could see that the sleeve was OK and did not crack. I then took the bolt out and installed the clutch on the sleeve (was tricky to do this way). Upon disassembly 2 days later the sleeve was cracked....I only weigh around 130lbs and the bike had a 44t rear sprocket so I doubt it cracked due to "undue stress".

Another thing Andrew from zoombicycles wrote in the email was "Some people continue to use the sleeve even though it has a small crack and don't seem to have any problems with the clutch working" - now there's a reply you don't want to hear from a vendor

I think I still have the emails but I deleted all the pictures of the cracked sleeves that I had. A few months back I ran into a thread from somebody on here that actually had the sleeve split in half after using the clutch for a longer period, he had pictures but unfortunately I can't seem to find the thread. There was also a picture in there of how the cent. clutch was "supoosed" to look in it's original form (maybe on a russian or first gen engine?) - it had a needle bearing instead of just the "sleeve" and the whole assembly ran in oil. The side cover looked the same (had the drain bolt just like the side cover from zoom does). Looks like somebody did a good enough job copying the cover but then decided to go rock-bottom cheap on the clutch itself.

 

[Dilly Bar Rob]

I found it!

I found the thread that I was referring to (with the clutch sleeve cracking). My bad- it didn't actually split in half but it did crack on both sides, most likely causing it to spin on the crank.

http://www.motoredbikes.com/showthread.php?t=4253&page=2

There are pictures of the clutch in oil setup in "funker's" post, it seems that the pictured engine has no manual clutch at all (allowing a oil bath to be used-see picture K800_P1010008.JPG ), it also looks like the shaft from the crank is a bit longer then on the average HT which allows the proper use of the key along with the needle bearing, a setup in my eyes vastly superior to the one from zoom (and other vendors).

Not meaning to go off topic with this, just wanted to throw all of that in.

Porkchop - if you are after a "centrifugal clutch only" setup maybe it would be worth to try and contact "funker" and find out what engine he had in those pictures. Perhaps you could still get one of those somewhere.

 

[Porkchop]

Pops, I have a question for you. I tinkered with my clutch for a few minutes earlier. The small gear attached to the clutch drum ia wider than the large drive gear on the engine. When the drum is installed, the back sides of both gears appear to be flush with each other. Does that sound correct ? Does it matter one way or another since the gear attached to the drum is wider ?
Also, the sleeve will not come off now without a lot of force. does that appear to be normal ? I still have weeble wobble in the drum. I think it's just poor workmanship. But I have big concerns about vibration on out of balance issues.
Thanks !

 

[POPS]

Pops, I have a question for you. I tinkered with my clutch for a few minutes earlier. The small gear attached to the clutch drum ia wider than the large drive gear on the engine. #1 When the drum is installed, the back sides of both gears appear to be flush with each other. Does that sound correct ? #2 Does it matter one way or another since the gear attached to the drum is wider ?
Also, the sleeve will not come off now without a lot of force. #3 does that appear to be normal ? I still have weeble wobble in the drum. I think it's just poor workmanship. But I have big concerns about vibration on out of balance issues.
Thanks !

PC

#1...Yes ,That is the same on mine.


#2...No..Not IMHO


#3...Yes.. It's just setilling in on the tapered shaft like it is supposed to.

Try moveing the rollers to different slots on the bearing race. It might take out any wobble it has....POPS

 

[POPS]

POPS - Yes it's quite possible that it indeed was my fault that the sleeve cracked the first time, I did torque it down quite a bit. But then as I say - #1 how is the key-less sleeve supposed to NOT spin on the crank under load without being tightened a LOT?

Also possible that the second one was off balance because of me, but then again I have read (on here) that lots of people have problems with the cent. clutches vibrating & such when engaging - and they didn't grind anything!
#2 I know for sure that the second sleeve didn't crack because of me - I put the sleeve on the crank first (with the clutch off of it) with some red locktight on the bottom of it and torqued down gently until it didn't seem to go on further. Since the clutch itself was off I could see that the sleeve was OK and did not crack. I then took the bolt out and installed the clutch on the sleeve (was tricky to do this way). Upon disassembly 2 days later the sleeve was cracked....I only weigh around 130lbs and the bike had a 44t rear sprocket so I doubt it cracked due to "undue stress".

Another thing Andrew from zoombicycles wrote in the email was "Some people continue to use the sleeve even though it has a small crack and don't seem to have any problems with the clutch working" - now there's a reply you don't want to hear from a vendor

I think I still have the emails but I deleted all the pictures of the cracked sleeves that I had. A few months back I ran into a thread from somebody on here that actually had the sleeve split in half after using the clutch for a longer period, he had pictures but unfortunately I can't seem to find the thread. There was also a picture in there of how the cent. clutch was "supoosed" to look in it's original form (maybe on a russian or first gen engine?) - it had a needle bearing instead of just the "sleeve" and the whole assembly ran in oil. The side cover looked the same (had the drain bolt just like the side cover from zoom does). Looks like somebody did a good enough job copying the cover but then decided to go rock-bottom cheap on the clutch itself.

Rob

#1...The crank is a tapered shaft as well as the bearing center.
Many clutches out there are tapered shaft press fit.

When they are seated on there you have to use a puller to
get them off! They are tight and will not slip on the shaft.

#2...Because of the way you installed the clutch that time it's
my guess that you did not get all of the rollers seated right
into the slots and if 1 was just a little out it would have
cracked again when you snuged it down.

I have no ider how you got it back together like that...POPS

 

[Porkchop]

Batteries

Pops, thanks again. Remember a couple of day ago your key board batteries bit the dust ? Well, I went to take photos of my gears, and lo and behold, batteries were dead in both of my cameras. Luckily I have rechargeable batteries with a 15 minute quick charger. Maybe I'll get some photos posted so people can see what we've been talking about here with the centrifugal clutch issues.