Chain make Snapping Sound Occasionally

GoldenMotor.com
fredgold52

fredgold52

New Member
Dec 3, 2009
156
0
0
Illinois
So far, the only problem my new 4G build is having is a snapping noise and corresponding jerking feeling. I've never seen it do it but it sounds and feels like the chain is getting caught on a sprocket tooth. Like it is trying to jump off the sprocket. However, that hasn't happened yet.

The rear sprocket is pretty true. Not perfect, but pretty good. I'll get it perfect tomorrow. The tensioner roller wobbles. It came that way. I'm thinking that can't be good but I don't know if it could cause this problem.

I have checked alignment. I should call it 'static' alignment as the bike is on the center stand not running when I check it. Are there things that can knock the chain out of line when it's under a load?

I don't want to ride it very far while it's doing this. More information about the bike:

Standard 4G belt transmission on an HS 49cc engine (love the engine)
11 tooth freewheel sprocket, 53 tooth rear sprocket.
Walmart Murray bike maybe 15 years old

Any help/ideas greatly appreciated.
Fred
 
2door

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
Rough edges on sprocket teeth can cause your problem but if the tensioner wheel is not running true that's probably the culprit. Many of us who run a tensioner replace the kit supplied wheel with a skate board wheel with bearings. You'll need to cut a groove in the wheel for the width of the chain. Skate board wheels come two ways. Some are a two piece affair with and inner core and an outer layer. Those won't work. look for a good quality urethane wheel that is one piece.

Other reasons for uneven chain travel could be binding links/rollers and incorrect tension. Too tight or too loose can cause a chain to run rough.
Get that rear sprocket as close to perfect as you can get it. That's critical.
Tom
 
fredgold52

fredgold52

New Member
Dec 3, 2009
156
0
0
Illinois
Big improvement today. My strategy was simple. Since I didn't know for sure what the cause was but I did have some excellent input from Tom, I took everything apart.

First, took the 48 tooth sprocket and carefully ground the edges off the teeth. Mounted the sprocket according to illustrated instructions found here. Carefully trued the sprocket to approach zero run-out. Took the transmission off the engine and disassembled it. Even took the belt tensioning cam out of the housing and cleaned it. There's some darn fine machining in these little engines. Kind of surprised me to see it.

Took the tensioner roller apart to try and fix the wobble. Some careful dremelling helped it. Positioned the tensioner to minimize the effect of any wobble left in it. Workin good.

With everything back together went for a ride. Rode about 20 blocks (it's only like 40 degrees here). No snapping, no popping. Everything smooth and nice. Can't leave it alone though. Tomorrow, I'll grind the larger sprocket and mount it. The clutch works less hard with the bigger cog. I'm a big guy (300 lbs) and that little clutch needs all the help it can get. Speed isn't that important to me. It's just fun to ride around.

Thanks for the help, Tom.
 
Texhun

Texhun

New Member
Aug 2, 2011
322
0
0
Rosebud Texas
Hey fred before you grind off all your teeth. Put it all together and look down the chain and make sure your wheel isn't pointing to the side any. It's happened to me many times I'll put the wheel on crooked and the chain will start popping. The sprocket can be perfectly true and the tensioner can be right on but if the wheels on the frame crooked and it's not running true with the engine sprocket, the chain will to go on the edges of the sprocket causing popping and so-on. Just something to check.
 
Last edited:
F

Fugi93

New Member
Dec 30, 2011
144
0
0
illinois
fredgold52 said:
Tomorrow, I'll grind the larger sprocket and mount it. The clutch works less hard with the bigger cog. I'm a big guy (300 lbs) and that little clutch needs all the help it can get. Speed isn't that important to me. It's just fun to ride around.
Click to expand...
It is probably that clutch slipping too much on it own. I'm at 17 to 1 gearing and mine took off with a 260 pound guy like child's play. If you have a 5 to 1 gearbox and a 48t, you should not even notice your weight, imo. Looks like you're at around 22 to 1 right now. I'm just saying this because my clutch was slipping way too much also. Now she engages at 4 to 5 mph (was 14 mph) and my motor thanks me every day. I couldn't just cruise at 8 - 10 or 12 mph without it slipping all the time, minimun speed had to be 14. That sucked.
 
fredgold52

fredgold52

New Member
Dec 3, 2009
156
0
0
Illinois
Texhun, I have a large steel carpenters square that I hold against the side of the large sprocket to see what the alignment looks like. Right now, it's within 1/16 inch and working well.

Fugi93, The more i ride it the better the clutch acts. I still have the 48 on it. I may take some brake cleaner to the shoes in the clutch as there is some chattering going on when I take off. I handled the clutch alot during the assembly process. It probably got some lubricant on the shoes at some point. If it could lock in at a lower speed, that would be good. But the snapping is gone with just a bit of clutch chatter and I believe that's going away with use.

I'd ride it more but it's getting kind of cold here. It is February you know.
 
The_Aleman

The_Aleman

Active Member
Jul 31, 2008
2,653
4
38
el People's Republik de Kalifornistan
hey Fred, if you have a Napa near you they carry a little black bottle of "Marvel Lubricating Oil", it's ~$2.

IMO, that's a 4G owner's best friend. Apply it once a week on the bearings and shaft flange and you should be good.
 
Last edited:
F

Fugi93

New Member
Dec 30, 2011
144
0
0
illinois
The_Aleman said:
hey Fred, if you have a Napa near you they carry a little black bottle of "Marvel Lubricating Oil", it's ~$2.

IMO, that's a 4G owner's best friend. Apple it once a week on the bearings and shaft flange and you should be good.
Click to expand...
I've read that there is a bushing in the 4g that is critical that it gets lubricated. Seems to mimic clutch chatter if not oiled. Is that true?
 
F

Fugi93

New Member
Dec 30, 2011
144
0
0
illinois
I just ordered a 36T. It just has too much power at low speeds with the 44T. Fully loaded curb weight with me on it is 198 lbs. I do like to peddal to keep the legs in shape and this current setup makes it too easy to get around that. I may have to drop down even further if this don't work.
 
fredgold52

fredgold52

New Member
Dec 3, 2009
156
0
0
Illinois
Marvel Oil , , , , , I hadn't thought of that at all. Thanks for the idea. There is a NAPA store close by. I'll check today.

I know about the bushing, but I haven't oiled it since the initial assembly. I'll get that done today.

You guys are great! Thanks alot.

Fred
 
maintenancenazi

maintenancenazi

New Member
Oct 22, 2011
157
0
0
Asheville
Fugi93 said:
I just ordered a 36T. It just has too much power at low speeds with the 44T. Fully loaded curb weight with me on it is 198 lbs. I do like to peddal to keep the legs in shape and this current setup makes it too easy to get around that. I may have to drop down even further if this don't work.
Click to expand...
I weigh 230 lbs, and at least for me I have found that a 32 tooth rear sprocket is just tall enough of a gear for me. And I live in a very hilly region. Also I don't mind peddling it up hills for assist.

Peace, James
 
fredgold52

fredgold52

New Member
Dec 3, 2009
156
0
0
Illinois
Well, so far with very little riding time, I'm thinking the 48t that came with the kit is good for hauling me around. (300 lbs. without the bike) If I can get the clutch chatter thing straightened out, this will be just fine.

I went looking for Marvel oil this morning. The NAPA store is a tiny thing that is just barely still in business. They didn't have it. So I went to the O'Reilly store and then to the Auto Zone store. Finally found it on Amazon. It'll be here Friday. I love small town America.

Good question about 2t or 4t. Maintenancenazi, the gearing we are talking about is for an HS Grubee Skything, 49cc four stroke. Darn fine engine by the way.
 
F

Fugi93

New Member
Dec 30, 2011
144
0
0
illinois
fredgold52 said:
Well, so far with very little riding time, I'm thinking the 48t that came with the kit is good for hauling me around. (300 lbs. without the bike) If I can get the clutch chatter thing straightened out, this will be just fine.

I went looking for Marvel oil this morning. The NAPA store is a tiny thing that is just barely still in business. They didn't have it. So I went to the O'Reilly store and then to the Auto Zone store. Finally found it on Amazon. It'll be here Friday. I love small town America.

Good question about 2t or 4t. Maintenancenazi, the gearing we are talking about is for an HS Grubee Skything, 49cc four stroke. Darn fine engine by the way.
Click to expand...
You should have got one with a good tranny!

http://
 
fredgold52

fredgold52

New Member
Dec 3, 2009
156
0
0
Illinois
maintenancenazi said:
No sorry, it's a 66cc HT with some mild porting, tuning, and an expansion chamber.
Click to expand...
Sounds like a fun motor. Two strokes are such a good time to mess with. Over on the Stellaspeed board it is often said,"Cheap, reliable, fast, Pick any two." I know that applies to 4 strokes as well, but things happen so much faster with 2 strokes.

One of these days I'll figure out why there is such a difference in gearing methods.
 
fredgold52

fredgold52

New Member
Dec 3, 2009
156
0
0
Illinois
Aleman and Fugi93, you guys hit it on the nose. I took the flanged bushing out if the clutch bell and lubed it thoroughly and reinstalled. The bike is smooth as glass. It's incredible. Unfortunately, it's like 30 degrees right now so once around the block was all I could do. But it is amazing the difference a little oil on that bushing made.

Thanks for the insight guys.
Fred
 
F

Fugi93

New Member
Dec 30, 2011
144
0
0
illinois
I watched one of Terry Blow's (blowbyu) videos and he said it should be soaked in oil for 24 hours.

I'm curious since I might be in the market for a 4g gearbox someday, at what speed does the clutch fully engage?
 
The_Aleman

The_Aleman

Active Member
Jul 31, 2008
2,653
4
38
el People's Republik de Kalifornistan
Soaking the bushing isn't really necessary - well _I_ haven't had to do it, but I'm using a real Oilite bushing. All I've needed to do is add a bit of Marvel Lubricationg Oil to the bushing flange while it's hot, like after a ride once or twice a week. I don't need to remove the gearbox to do that, just the cover.

Fugi, engagement speed depends on which 4G you would have. There are 2 of them, one is for "tapered shaft" engines and one is for "5/8 shaft" engines. The tapered shaft 4G engages properly out of the box, but the one-way bearing on the large pulley may be problematic. The 5/8 shaft 4G has a different clutch, one that engages too early (at or near idle). This clutch can be problematic and needs stronger springs immediately. With 60lb springs, it will engage properly (near 2800RPM). Stock springs are about 40lbs.
 
You must log in or register to reply here.
Top Bottom