Could it be a choke problem?

[kevino]

The Ice Bear will start instantly and idle slowly.  If I try to tease the throttle  I might get the engine to rev but not consistently.   Because it starts  can I assume the choke is doing its job?    I don't know much about scooters.   But I've had 30 years practice  working on  air-cooled engines, specifically VWs.    VWs have a relay that sends 12V from the coil to the carb.   Looking at a Haynes Chinese scooters book I don't see a similar relay in  the schematic.   Any suggestions what to do?

TIA,

kevino

[aeroxbud]

The choke gets 12V. There should be two wires going to it. One is a ground the other a constant live. No relay.
As the choke heats up the needle inside expands to block off a port. Cutting fuel.
You can take the choke off. Then connect it two a 12V source. You should see the needle move out.

[TheScooterJesus]

I have assembled brand new ice bear scooters when i worked at a scooter dealer and i can speak from experience when i tell you the carbs, and exhausts, are usually complete garbage, as well as the head is usually NOT TORQUED to spec.

My first recommendation would be to get a replacement carb (such as a you-all or blue line carb for 150cc gy6) and an aftermarket cheap exhaust from amazon. The stock icebear intakes are also super terrible and i would recommend the NCY intake filter and tube kit made for gy6. This will fix most of your issues until your stock cdi and ignition coil go out, at which point you should upgrade those to higher quality ones.

Ice bear are really terribly scooters unfortunately. Even brand new out of the box. However if you replace most of the standard parts, they can be very reliable.

[kevino]

www.ebay.com/itm/145018264986?chn=ps&mkevt=1&mkcid=28&srsltid=AfmBOorNURt9PBj_4mDB0npvGX_xhFbWbUyNUFpHIj_W4-EbpvygMB9nWp8

Thanks for the replies. I found this one for $60 and similar models for $20. Is this a direct replacement for the original carb? Don't understand why a 49cc motor can be replaced with a much larger carb?

[kevino]

www.scooterworks.com/products/ncy-coated-intake-manifold-non-egr-28mm-gy6-scooters?gad_source=1&gclid=CjwKCAjwnv-vBhBdEiwABCYQA-6qnUg-NptKew0nCbQtqGLY0h_J_89GEfMlhDQ1I_nEbMivwnkU6BoCcNIQAvD_BwE

Why is this (expensive!) manifold better than the original?

[kevino]

I over-torqued the head bolts and stripped at least one of the four. My history is with air-cooled VWs. It was common to strip head studs and need to tap in new threads to save an engine. Is the same process available for these 49cc motors?
TIA,
kevino

[GrumpyUnk]

Did you strip the threads in the base/block of the engine? If so, you will have to search for a thread repair kit, or tap for the next larger size. I think the timesert(?) brand is a bit more functional if you end up having to R&R the cylinder a few times. Maybe use a torque wrench next time.
If the 'byvalve' is working properly, the cold engine rpm at startup will be over 2,000rpms. It will remain high for around a minute at least, maybe more, and then should settle down to around 1500 rpm. If you remove the black plastic cover, then the two Philips screws & retainer, you should be able to pull the byvalve from its perch. Inspect that the brass-looking plunger is not extended. WHen the engine starts, it produces voltage that is applied to the wires, and causes the byvalve to heat up, which then slowly pushes the plunger into the carb to cut off flow. As the flow lessens, the rpms will drop to normal idle rpm. It is difficult(IMO) to get one of these to start if the byvalve is not working. I assume newer models are different, but I don't have any to fiddle with, in the case where the black plastic cylinder is not longer on the left side of the carb.
tom

[kevino]

Thanks for the help. I confused nM with Ft/lbs when trying to torque the new big bore kit.

I think the head material is a softer metal than the steel threaded rods. That was the case in the dozen VW engines that I rebuilt. Some years were worse than others.

I'm wondering whether fixing the block is worth it versus buying a new one. This is just a toy, something to work on when trying to learn scooter mechanics. So now I have to decide if I want to tear the engine down and put in thread inserts or just buy another block.

kevino

[GrumpyUnk]

Maybe I don't get it, but I thought all you had to do was remove the head & cylinder, drill the threads for the timesert, and put back together. Or was that tearing the engine down???
tom

[kevino]

Mar 27, 2024 12:15:52 GMT -5 GrumpyUnk said:

Maybe I don't get it, but I thought all you had to do was remove the head & cylinder, drill the threads for the timesert, and put back together. Or was that tearing the engine down???
tom

Thanks for the reply.  I'm still in the 'thinking about it' stage.   Again, my experience is with VWs.  I  assumed  putting in a case saver insert helicoil means taking the engine apart.  OR buying another block and add the BBK kit,  carb, starter, etc.   

I'm also not sure what a 49cc short block, long block is.  In VWs the short block is crankcase only while the long block is crankcase plus pistons, connecting rods, cylinders and heads.   Like the photo:


www.scooterworks.com/products/gy6-engine-long-case-short-block-gy6-150?gad_source=1&gclid=Cj0KCQjwqpSwBhClARIsADlZ_TmZ4CFCmtVQkQv8Kyxbgr6LJBxwcEdOB_QZ-N-LcEqGLHb_yE2ZynkaAiejEALw_wcB

[TheScooterJesus]

did you strip the actual stud or the hole on the block/case itself? cuz you can most likely just replace the stud and cylinder/head and be good to go. Otherwise, these engines are extremely cheap and scooterworks USA sells left and right hand cases for very very cheap

[kevino]

Mar 29, 2024 17:58:44 GMT -5 TheScooterJesus said:

did you strip the actual stud or the hole on the block/case itself? cuz you can most likely just replace the stud and cylinder/head and be good to go. Otherwise, these engines are extremely cheap and scooterworks USA sells left and right hand cases for very very cheap

Thanks for the note. One head stud no longer accepts torquing.  The other three are still good.   So far it's usable but I realize this can't continue.    I may opt to put a helicoil into the head just for the experience.   And look into finding a cheap replacement.  

[GrumpyUnk]

Helicoil or Timesert. If you plan on doing any work beyond the BBK, and possibly be removing installing, the Timesert may be the better option. When doing the initial bore, blob a bunch of grease onto the drill to catch chips/bits. If you are careful, you could actually(possible?) stuff some greasy paper towels into the crankcase alongside the connecting rod to place it under the hole you are working on. I think they are through holes, not blind, so when you drill you will likely poke through. A piece of greased paper towel should catch anything the grease on the drill misses. Beyond that, it will flow to the screen. The oil circulation only pumps oil to the rocker arms atop the cylinder head. Likelihood of getting to the ball bearings via splash should be pretty low if there were any chips.
Personally, I do NOT want to split a case. Not the difficulty, but the time it takes to separate without breaking the casting(glued gaskets) and then once apart, cleaning the glued gasket bits from the sealing/joining surfaces. Ugh.
Maybe I did not get it, but you would not be putting anything into the head. The stud screws into one of the case halves. The barrel is lowered onto the case, with the base gasket already in place, next is the head gasket and then the cylinder head, followed by the cam followers/rocker arms. A side bolt on the timing chain side, and the 4 stud fasteners are it. I think. I have seen multiple values for the stud torque prescribed. Around 10-15 ft-lb is about it. I think from memory.
tom

Added:  There are shop manuals on site that will give the procedure and the torque specs.  Poke around a bit.
tom