Inconsistent clutch performance on HT bicycle engine kit

[RoverGT]

Hi guys. I've done two builds so far, both HT engines (mega motors 66cc from bikeberry). On the first, I had no trouble with the clutch adjustment. It's fairly consistent. It gets a little tight when it's been ridden for a while. However, it never needs adjustment. On my second build (pictured), the clutch is a bit problematic. When the bike is cold, I'll get it adjusted right. When the clutch is engaged, the bike cranks fine. With the clutch disengaged, the bike pedals fine with no drag from the clutch. After riding the bike for 30 minutes to 1 hour, and then leaving it parked for an equal amount of time, the clutch performs as though the flower nut had been loosened on it. In other words, the clutch no longer produces enough drag to roll start the motor. I have to open the clutch cover, tighten the flower nut one "notch", and then I can crank the motor. However, now, the clutch is so tight that it's hard to pedal the bike. After the bike sits for a while after the mentioned adjustment, it becomes so tight that I'm forced to loosen it a notch, only to later tighten it. It's an easy enough problem to fix, but it's just annoying to keep doing it over and over. Anyone know of a potential solution?

I appreciate the help very much.

 

[Al.Fisherman]

Re: Inconsistent clutch performance on HT kit

Hi guys. I've done two builds so far, both HT engines (mega motors 66cc from bikeberry). On the first, I had no trouble with the clutch adjustment. It's fairly consistent. It gets a little tight when it's been ridden for a while. However, it never needs adjustment. On my second build (pictured), the clutch is a bit problematic. When the bike is cold, I'll get it adjusted right. When the clutch is engaged, the bike cranks fine. With the clutch disengaged, the bike pedals fine with no drag from the clutch. After riding the bike for 30 minutes to 1 hour, and then leaving it parked for an equal amount of time, the clutch performs as though the flower nut had been loosened on it. In other words, the clutch no longer produces enough drag to roll start the motor. I have to open the clutch cover, tighten the flower nut one "notch", and then I can crank the motor. However, now, the clutch is so tight that it's hard to pedal the bike. After the bike sits for a while after the mentioned adjustment, it becomes so tight that I'm forced to loosen it a notch, only to later tighten it. It's an easy enough problem to fix, but it's just annoying to keep doing it over and over. Anyone know of a potential solution?

I appreciate the help very much.

Could it be your clutch hub (57) bearings? Make sure you have the ball bearing behind the bucking bar...I'm sure it's there, but check. Otherwise it won't disengage at all...just a thought.

 

[fatdaddy]

Re: Inconsistent clutch performance on HT kit

Al just might be right. (good to see you on the other site Al.) The bucking bar and bearing come with very little or no grease on it. a lot of times the bar will wear down and throw off the clutch adjustment. You can check this by comparing the bar from your other engine to your "new" one. If you need to you can make a bar out of a smooth shank, grade eight bolt of the same size. (or order one.) Just make it as smooth as possible on the ends and grease it well before installing. And make REAL sure the bearing is there. Without the bearing the bar will grind down in no time.
This might be a silly idea, but you could try filing a notch in the middle of the two adjustments you've been using on your flower nut. This wont hurt the nut and they are not expensive anyway. It might just put it in the middle enough to get it working. Hey, I said it might be a silly idea.
fatdaddy.

 

[bairdco]

Re: Inconsistent clutch performance on HT kit

before you get involved with the internals, check your cable.

the stock cables are pretty lousy, and the wound inner metal part will sometimes push out of the plastic outer sheath. this would make the clutch act the way you describe. same goes for brakes.

 

[2door]

Re: Inconsistent clutch performance on HT kit

I'm wondering if there might be crud on the clutch friction surfaces that allow them to slip a little when cold. Have you tried cleaning them and the pressure plate surfaces with brake cleaner and seeing if that changes anything?

I'm speaking from the experience of having a clutch do exactly what you describe. I sprayed Brake Clean on the clutch pads, roughed them a little with course sandpaper, cleaned the friction surfaces and the problem went away. You probably know this but over lubricating the gears can allow grease to get into the clutch. Greasy pads can do some strange things when heated by friction.
Tom

 

[fatdaddy]

Re: Inconsistent clutch performance on HT kit

I'm wondering if there might be crud on the clutch friction surfaces that allow them to slip a little when cold. Have you tried cleaning them and the pressure plate surfaces with brake cleaner and seeing if that changes anything?

I'm speaking from the experience of having a clutch do exactly what you describe. I sprayed Brake Clean on the clutch pads, roughed them a little with course sandpaper, cleaned the friction surfaces and the problem went away. You probably know this but over lubricating the gears can allow grease to get into the clutch. Greasy pads can do some strange things when heated by friction.
Tom

2door, I've had to do this a lot on older engines. He doesn't say how long it's been up and running. I assumed it was a newer engine. If it has a little time on it then it is quite possible junk has built up on the pads and plate. Good catch.
Also, but not very likely, A bad crank seal will throw oil on the pads. Even a little bit will let the clutch slip, and slip even more when hot. I got a brand new engine with a bad seal one time and it acted about the same way the guy is describing. I didn't notice at first that there was a minute film of oil on everything.
fatdaddy.

 

[2door]

Re: Inconsistent clutch performance on HT kit

Fatdaddy,
I would agree with your assessment regarding the crankshaft seal except the he didn't say he was experiencing any of the typical symtoms of a bad seal. He'd most likely be seeing a high idle speed and possible hard starting and a loss of power depending on how much air was being drawn in through a defective seal.

Even when careful about lubricating the gears, over a period of time some of that slick stuff can find its way into the clutch. It will be interesting to see what he finds. I hope he comes back to tell us. We all learn from the experiences of others. One of the beauties of this form.
Thanks for your input.
Tom

 

[fatdaddy]

Re: Inconsistent clutch performance on HT kit

Fatdaddy,
I would agree with your assessment regarding the crankshaft seal except the he didn't say he was experiencing any of the typical symtoms of a bad seal. He'd most likely be seeing a high idle speed and possible hard starting and a loss of power depending on how much air was being drawn in through a defective seal.

Even when careful about lubricating the gears, over a period of time some of that slick stuff can find its way into the clutch. It will be interesting to see what he finds. I hope he comes back to tell us. We all learn from the experiences of others. One of the beauties of this form.
Thanks for your input.
Tom

2door, With a bad clutch side seal I don't think it's that air is getting in so much as oil coming out on the pads. On my last bad seal the engine ran great. He says that after riding for a while, (then sitting,) it gets "loose". Not saying I'm right, Just saying that an engine can "run" fine with a bad seal. The pads just don't do so well with oil on them.
And yer right, even if your carefull with lubing the gears, over time it's bound to sling a little carp on the pads. Either way, I think there is something going on with his clutch pads.
I've also had a bad experience with cheap pads from the factory. The pads tore up so badly it was letting peices of them jam up on top of the rest of the pads. There was no way to adjust it properly. As soon as I took the clutch apart it was obvious. But I tried to adjust it several times first couse I'm lazy and didn't want to take it apart.
I think yer right about another thing too. The first thing he should try is cleaning the clutch. The best way to do this is to take the clutch apart, pop the pads out, degrease them, (let em dry,) Then sandpaper them on both sides to remove glazing. Then degrease clutch assembly, (let dry,) and put together and adjust it up. If this takes care of his problem for a while, then happens again, I would be curious about what the heck is getting on his pads.
fatdaddy.

 

[Al.Fisherman]

Re: Inconsistent clutch performance on HT kit

The housing where the clutch shaft rides in the bearings have a seal but the housing won't leak fuel mix or cause a vacuum leak problem. The clutch section has has no effect on how the engine itself runs.You could take the whole cltch assembly out, mount a pull starter and operate the engine.

The picture below shows where the two sections are separate and the arrow is where the gasket seals the two separately. If it is oil getting on the clutch pads it most likely coming from the lube on the clutch hub or from the inner clutch shaft. Clean clutch, pull both clutch and chain sprocket/bucking bar/ball bearing and clean with a cleaner that has a nozzle.Something like Throttle body cleaner would work. Relube the hub and bucking bat/bearing with a little wheel bearing grease (won't breakdown due to heat) and re install.

 

[fatdaddy]

Re: Inconsistent clutch performance on HT kit

The housing where the clutch shaft rides in the bearings have a seal but the housing won't leak fuel mix or cause a vacuum leak problem. The clutch section has has no effect on how the engine itself runs.You could take the whole cltch assembly out, mount a pull starter and operate the engine.

Right Al, But the smaller gear is the crank gear and can, if the seal is bad, let fuel/oil mix through to the pads. You may not notice this in engine performance, but you will notice it in clutch performance. Oil on clutch= bad thing. This has only happend to me three times in about seven years or so, but it can and does happen. Your also right about a vacuum leak. Even if it COULD leak air, ( I don't think it can,) it would be so little I don't think you would notice a difference in engine performance.
fatdaddy.

 

[Al.Fisherman]

Re: Inconsistent clutch performance on HT kit

the smaller gear is the crank gear and can, if the seal is bad, let fuel/oil mix through to the pads. You may not notice
fatdaddy.

Point well taken.

 

[bairdco]

Re: Inconsistent clutch performance on HT kit

i'm still going with cable stretch. glazed or contaminated pads can be a problem, but if he has to keep tightening the flower nut, it sounds more like an adjustment problem.

if the pucks are covered in oil, adjusting the clutch constantly wouldn't help. it'd still slip.

i had a bike with the same problem, but i discovered it right away, because you could see the inner housing pushing out of the plastic sheath.

if the OP never replies back, i guess we'll never know.

 

[fatdaddy]

Re: Inconsistent clutch performance on HT kit

i'm still going with cable stretch. glazed or contaminated pads can be a problem, but if he has to keep tightening the flower nut, it sounds more like an adjustment problem.

if the pucks are covered in oil, adjusting the clutch constantly wouldn't help. it'd still slip.

i had a bike with the same problem, but i discovered it right away, because you could see the inner housing pushing out of the plastic sheath.

if the OP never replies back, i guess we'll never know.

Hey bairdco, The OP says he has to adjust in, then out, then in, then out, ect. The cable ain't gonna fix itself, then screw up again, then fix itself, then screw up again, ect. I've had a lot of cables push through the end caps and it don't fix itself. They just get worse untill you discover the problem. While oil on the pads can act differently depending on the engine temp. It may grab better when on cold oil, then when hot it may slip even more. I've been through this a few times. The engine will start and run for a while, then the clutch will start slipping REAL bad. If you adjust it when hot then it's too tight when cold. The first time this happend to me I kept adjusting the clutch back and forth untill I discovered the bad seal. Not saying that's his problem, Just saying it's a possibility
fatdaddy.

 

[RoverGT]

Re: Inconsistent clutch performance on HT kit

Thanks so much for all the info and ideas. I'm going to tear the clutch apart this weekend and go through it with a fine tooth comb. I don't think i'm missing the bucking bar or bearing, though I wouldn't bet my life on it. I was pretty careful putting it all together, and learned my lesson on the first bike when that little f'ing bearing went skittering across the garage floor to the most remote hidden corner under my work bench. I was pretty liberal with adding better quality high heat grease to the gear and inside where the bearing / bucking bar goes. It's highly likely that some grease is getting slopped around in there causing the inconsistencies, though I didn't consider it until you guys mentioned it. Though I did take the clutch plate completely off one time since the problem started happening to eye-ball the pads, I didn't take them out to inspect more closely. As I take it apart this weekend, I'll clean all existing grease out and regrease everything more carefully this time after cleaning. What should I use to clean it? I have some brake cleaner and some carb cleaner. I imagine the brake cleaner would be better, but I'm honestly not sure what the difference is. They're both solvents!?!

Just a quick comment about the cable. That was my first suspicion as well. It seems like it's in pretty good condition though. With the same kit I'm speaking of here, I did get a crappy throttle cable that I had to replace. It looked like it was from 1942. The cable would fray and crack, and within a day or two the ball end popped off inside the throttle handle. Again, that was the throttle cable. The clutch cable looks fairly new and SEEMS to work ok. The cable keep is firmly attached, and the arm seems to move consistently.

I'll let you know! Thanks again guys, I certainly appreciate it.

 

[RoverGT]

Re: Inconsistent clutch performance on HT kit

Here's the bike I'm working with the clutch issue on. Sometimes it's nice to visualize.

EDIT: Never mind, won't let me attach it. I'll get a link together soon.

 

[2door]

Re: Inconsistent clutch performance on HT kit

Rover,
Thank you for keeping us updated on your problem. It is very much appreciated when a member keeps us informed on the results of the help offered.
Thanks again.
Tom

 

[fatdaddy]

Re: Inconsistent clutch performance on HT kit

I'm just glad that with all the stuff we were throwing at you, ya got something out of it. Good luck this weekend.
fatdaddy.

 

[RoverGT]

Re: Inconsistent clutch performance on HT kit

Hey guys. So far, I've cleaned out the clutch very well and it seems to have made the clutch performance way more consistent. I took the clutch pads out, cleaned them until they sparkled with brake cleaner and a brush. Sprayed out the clutch and then reassembled. So far, the problem is resolved.

The pads were pretty dirty for the bike to be ridden only about 50 miles or so. I'm not sure so far if it was from too much grease on the gears, or if its, as you guys mentioned, from fuel leaking in, or perhaps another problem. There was quite a bit of grease sprayed around the inside of the clutch cover, so in all likelihood, that's the culprit. When the clutch is cold, it still gets a little loose and hard to start, but it's at least consistent to the point where I don't have to turn the flower nut. A little tweak of the cable screw usually does the trick now.

I'll keep you guys updated if the problem comes back, but I would count this one solved. Thanks again for the help. It's much appreciated.

 

[fatdaddy]

Re: Inconsistent clutch performance on HT kit

Hey Rover,Glad to see you got the problem mostly solved. A couple things though. You didn't say if you sandpaper'd the glaze off the pads. If there is still an oil or grease glaze on them it will affect the pads performance. And if it was more than just too much grease on the gears, a little oil too, then keep a close eye on it. Ride it for a few day's then check it again for grease and (or) oil. If you still have to adjust it, even a little bit, Then there is still something not quite right. I'm thinking a hot clutch just catches better on glazed pads. Like I said, Ride it a few days, and when you check it, deglaze the pads. you can't really mess them up doing this. I've even taken square pads and ground them round for the round clutch pad holes. (I was out of round pads.) Just make sure you do BOTH sides.
And personally, I NEVER adjust any cable from the lever side. Those things can strip back in and leave you with a loose cable at a critical moment. I leave the adjuster all the way in and adjust it from the other side. especially on the brake cable, but it could strip in on the clutch cable too.
Yeah, I know, Sometimes these things are a PITA. But they sure are a kick to ride.
fatdaddy.