Replace or repair accelerator cable?

[kevino]

I sent two photos. The second is soft rubber. It's been in my way since starting the tear-down. I'm guessing I need to remove parts to get these in?

[kevino]

BTW, the throttle cable went it magically easy. Now the engine starts and run, I left it idling for an hour to help break in the rings. Now my problem is figuring out how to assemble the plastic panels that surround the engine.

[kevino]

According to Haynes, on most engines the carb and exhaust must be removed. Some require the intake manifold to be removed also. So all of that just to replace the plastic cowlings?

[kevino]

Generally at the end of projects there's one or two left-over screws.....

[GrumpyUnk]

I don't see the photo so can only comment by using psychic powers that I do not possess.
You gave a zero-rated description, even omitting the color. And shape. And dimensions. And attaching points.

Maybe it is the panel that goes under the footrest/battery box.
Honestly I can't think of a plastic piece that goes under the engine. Newer, fancier models could have added a splash shield or an added air duct to scoop air up into the blower housing or onto the exhaust down pipe to reduce overall temperature. No. Clue.
tom

Finally saw the pics.  Top is the left side shroud that helps duct cooling air around the engine.  The ovalish opening is for the timing chain tensioner.
 The second picture shows the gasket that goes around the perimeter of the cylinder head.  It has a groove(tentative at best) that fits onto a protrusion from the cylinder head.  Worm it onto the head and try to keep it centered on the rim.  The shrouds will hold it in place once they are fastened tight.  Recalling, fit the one over the CVT side, over the tensioner, as mentioned aboe, and kind of slide it back towards the rear wheel.  It will then form the right hand side(looking from the cam cover end) of the shroud, and should hold the rubbery gasket in place.  The blower fan side fits from the left, and it will be the OTHER side of the clamshell that holds that rubbery one tight.  Without that gaske, lots of blower airflow can leak out past the plastic shroud.  That will increase operating temperature.  Best to get it in place.  If you wiggle it enough you will(should) find a position where all the bends conform to the shape of the cylinder head metal.  When aligned, the two shroud pieces should fit and hold it snug, sealing(mostly) the airflow.  It will feel kind of sturdy and firmly in place when fitted properly.  I have had one kind of destroyed that I used RTV to more or less paste it back together as I had no other.  Worked.
tom

[GrumpyUnk]

Jul 26, 2023 15:02:21 GMT -5 kevino said:

According to Haynes, on most engines the carb and exhaust must be removed. Some require the intake manifold to be removed also. So all of that just to replace the plastic cowlings?

 Well... Yes.  The shroud goes all the way around the carb elbow, the timing chain tensioner, and exhaust down pipe.

 Do not give in to just leaving parts off.  It will cause overheating.  Some 'genius' BBK installers convinced a 'friend' he did not need any of that crap.  He sold a Taotao to me for $50 with ~500 miles on the clock.  It has zero compression... the rings were not only toast, they were toast with the crusts cut off.  Useless.  I ordered a complete shroud for ~$20 to use after replacing the piston, rings and cylinder.  It was a NICE machine after that.  Almost brand new.  That was the one that had the CVT just work as designed.  Sold it too cheap, but the buyer was going to let his SIL father-to-be use it for transportation.
  Put it ALL back, and be sure to use all fasteners.  The Chinese designers don't put more bolts on than are the absolute minimum.  If they could use LESS they would.
 If you want to know if the shrouding is working, put your hand under the cylinder with the engine running at idle.  It SHOULD blow hot air downward as it goes over the head and cylinder.  Same as air-cooled engines on lawn mowers and garden tractors. 
tom

[kosmos]

Jul 26, 2023 13:30:26 GMT -5 kevino said:

BTW, the throttle cable went it magically easy. Now the engine starts and run, I left it idling for an hour to help break in the rings. Now my problem is figuring out how to assemble the plastic panels that surround the engine.

air shrouds on an air cooled engine are there to keep it cooled.  without it, your not cooling anything.  never leave those off except for a quick startup to make sure you assembled it correctly or something.  maybe only idling it didnt get very hot.  maybe you had it outside were air could breeze around it.  luck you didnt seize it.  

[kevino]

"...When aligned, the two shroud pieces should fit and hold it snug, sealing(mostly) the airflow. It will feel kind of sturdy and firmly...."

Thanks for the help. Stumbling around in the garage I found the missing half of the shrouds under some boxes. Seeing it I think I can get it all together. I'm aware of how important air flow is on air-cooled engines; I know little about scooters but I'd owned over a dozen old (air-cooled) VW bugs in the past. When running the motor without the shrouds I'd stop to let it cool occasionally. Hopefully it was enough to prevent over-heating. Thanks again.

[GrumpyUnk]

Was there ANY shrouding in place when you ran at idle for an hour? The shroud around the flywheel & blower would have provided at least some airflow over the cylinder & head.
Breaking in piston rings can be done in about 10,000 ways. AFAIK, idling for an hour is not one of the recommended ways. Most ring producers/vendors have a suggested method.
New rings produce the most heat when they are first seating to the cylinder wall because 1)ring tension is at its highest, and 2)the two surfaces, ring/cylinder wall, are totally new to each other and have maximum friction.
You may have de-tensioned the rings by overheating. If you were lucky, you only decreased the life by 50% or so.(I made up the %) I do think it would reduce the usable lifetime of the new cylinder, and you will find out over time if that is true.
You could check compression to get an idea if the rings are seated or are losing pressure already.
I can state with confidence that riding a half mile or so will heat up the engine to full operating temperature, even when not using full throttle.
I can also state that most garden equipment air-cooled engine makers recommend running the engine at the rated RPM, and NOT idling the engine. Idling the engine slows down the blower on the flywheel reducing airflow over the engine and ALSO cuts down on splash lubrication. The splash lube in addition to lubricating the cylinder walls/rings, and the connecting rod bearing AND the main bearings, ALSO provides a good bit of COOLING as the splashed oil will absorb heat from whatever it lands on, and drain that heat into all the oil at the bottom of the pan/sump.
IOW, no splash due to low rpm leads to no cooling due to no splash. The only pressure lubed part of a 139qmb is the rocker arm assembly. All else is splash.
tom

[kevino]

The shrouds are in. But there's a hole and I don't know what covers or fills it. Hopefully the photo will show the hole.

s's

[GrumpyUnk]

If the hole is directly above and to the right of the black plastic tape covering the wire loom, then I would suggest getting a piece of plastic(milk carton/Coke bottle/microwave food tray) and gluing it to the shroud. I do not know what the hole is for as none of mine ever owned have a hole there. It appears there are ribs to make something stay aligned when fastened to the shroud. IOW, got no clue what goes there.
You could also use a screw, nut and washer to plug the hole. Put a screw with a large head on the inside, washer and nut on the outer, tighten. No or little impact on airflow inside, and it should stay in place and cut any leakage. I suppose a golf tee with the tip cut short, and some RTV would also do the job. Not much air pressure, so the main thing is keeping it in place, and RTV should do that fine.
tom

[kevino]

I found a photo of a cable guide in Haynes. I pushed the clip through the hole and screwed in a sheet metal screw to hold a cable retainer. Seemed to work.

[kevino]

Well it runs. But problems: Bad oil leak. No braking action in the right hand-brake master cylinder, I assume because it's empty. Idles too fast. When turning the handlebar left or right the engine races. I can't put the two Plastic Ice Bear panels on without first taking off the seat and storage compartment. I can't adjust the idle without taking the seat and storage compartment off. I haven't replaced the front plastic panel. But otherwise it sounds good in the back yard.

[aeroxbud]

The routing of the throttle cable isn't correct or it's pulling on something when you turn the bars.
If you take the seat off. It should be easily identifiable what the problem is when turning the bars.

[classacted]

you'll fix the cable issue, but the oil leak is bad news. it's a nice looking bike.