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  #21  
Old 06-06-2012, 12:04 AM
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Originally Posted by Fabroman View Post
Wow, you're getting quite a following.

What are your torque values in: Nm or ft/lb?

Remember, if you're not sure, look it up or ask; there are no silly questions
Thanks Fabroman. LOL. I just had a look at the 2 sets of torque values that I had posted (and queried because they looked different), and I see the one set is in Nm and the other in ft/lb. That is why I was getting confused.

Quote:
Originally Posted by r_chez_08 View Post
I would reccomend torquing any bolt going into an aluminium thread. I have stripped two on my gx160 shroud, I didn't even do them up that tight. I need to helicoil or keensert them now.

However, the only ones that are critical are the rod bolts and flywheel nut, as these can cause severe failure. I would also torque the side cover bolts because if you undertorque them they are likely to loosen and oil will leak. If you don't notice you can stuff the engine.
Thanks for the advice r_chez.

I took the head off last night when I got home, and was pleasantly surprised at how smooth the bore was. There were no noticeable scratches that I could see or feel. Yeah!! Here are some pics of it.

I was also wondering, how do I get rid/clean the black areas on the head, valves etc? Can I use a copper wire wheel, or do I need to use something else. I want to get it shiny again. Obviously I wount clean inside the bore.

I will be taking the flywheel of next. Just to make sure, will this be the correct way to do it:
  • undo flywheel nut, and then thread it back just on the tip of the shaft (so I don't damage the shaft)
  • Use a piece of wood over the nut and smack it with a hammer to break flywheel free (or should I just hit the nut straight)
  • pull the flywheel off and remove the key
Just keep in mind that I have already removed the side cover

Thanks everyone for the help, I appreciate it
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  #22  
Old 06-06-2012, 02:37 AM
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Yep, correct procedure for the flywheel.
That motor has definently been run for a while, but the bore isn't bad. If you need to replace the rings, I would suggest a quick hone with a flex hone if you can buy one reasonably where you live.

I use a wire wheel on the head. Probably not correct. While the head is off, I would grab some lapping compound and teach yourself how to lap the valves. They may not need it, but there's no harm in doing so.
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  #23  
Old 06-06-2012, 07:15 AM
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I was just wondering. Do I really need to lap my valves, or should they be OK?
  #24  
Old 06-06-2012, 10:29 AM
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Originally Posted by landuse View Post
Thanks Fabroman. LOL. I just had a look at the 2 sets of torque values that I had posted (and queried because they looked different), and I see the one set is in Nm and the other in ft/lb. That is why I was getting confused.
Glad I mentioned it then

Quote:
Originally Posted by landuse View Post
I took the head off last night when I got home, and was pleasantly surprised at how smooth the bore was. There were no noticeable scratches that I could see or feel. Yeah!!
Check around the top, you should feel a lip. A little lip is ok. too big & it may need boring (but, from what I can see, you should be ok)

Quote:
Originally Posted by landuse View Post
I was also wondering, how do I get rid/clean the black areas on the head, valves etc? Can I use a copper wire wheel, or do I need to use something else. I want to get it shiny again. Obviously I wount clean inside the bore.
What r_chez suggested will be fine.
Is that meant to be "won't clean inside the bore"? You can & should do that. Use 320 grit wet & dry paper soaked in diesel & work in a diagonal cross pattern (poor mans hone). Make sure you clean thoroughly when finished

Quote:
Originally Posted by landuse View Post
I will be taking the flywheel of next. Just to make sure, will this be the correct way to do it:
  • undo flywheel nut, and then thread it back just on the tip of the shaft (so I don't damage the shaft)
  • Use a piece of wood over the nut and smack it with a hammer to break flywheel free (or should I just hit the nut straight)
  • pull the flywheel off and remove the key
Just keep in mind that I have already removed the side cover

Thanks everyone for the help, I appreciate it
Make sure you screw the nut on so it's level with the end of the shaft.
It might be an idea to put the side cover back on while you remove the fyywheel, otherwise you will end up with parts flying everywhere.

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Originally Posted by landuse View Post
I was just wondering. Do I really need to lap my valves, or should they be OK?
Quote:
Originally Posted by r_chez_08 View Post
I would grab some lapping compound and teach yourself how to lap the valves. They may not need it, but there's no harm in doing so.
.. after you clean the head; the wire wheel may damage the valve seats
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  #25  
Old 06-06-2012, 01:44 PM
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Originally Posted by landuse View Post
I was just wondering. Do I really need to lap my valves, or should they be OK?
Not neccesarily, but it will be another skill to try. Look for any pitting etc on the seats.
And while your at it, you could get some little dremel sanding drums and have a go at some DIY porting! You can use the drums on a hand drill at full speed. Just smooth things out, especially the short side radius, on many motors this is a sharp 90* angle!

About the poor man's hone that fabroman was talking about- I have done that on my kart motor. Putting it back together now. What I did which worked pretty well- I got an old cloth/rag and put one corner in a hand drill. I then wrapped the cloth around the chuck, and put a strip of emery cloth over the rag. Slid it into the bore and shoved it in and out quite fast :O whilst the drill was running. Then put the drill in reverse and did the same. You want a 30-45* cross hatch. Bit bodge, but ok to seat the rings.
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  #26  
Old 06-07-2012, 12:14 AM
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Thanks again guys. You are giving me a lot of work, which I am not too sure if I am skilled enough to do. Could you maybe explain the poor man’s hone to me again? You talk about working it in a diagonal cross pattern. How would that work?

I will also see if I can purchase some lapping compound if it is not too expensive. I am trying to do this engine on a $0 budget, but I don't think that will happen. I am probably going to have to buy a few things anyway, and get the carb either fixed or get a new one.

Quote:
Originally Posted by r_chez_08 View Post
Btw- the spacing on the gx160 carbs is approx. 42mm
I measured the distance between the studs, and it is 42mm, so a GX carb should hopefully work

I think my carb is stuffed. It looks like someone tightened the bowl nut too tight, and stripped the threads in the carb. I will have a closer look at it though. I have included a few pics

R_chez, I think I will also leave the porting for now. I don't feel confident enough to do it at the moment, and will just keep the engine stock. If you could maybe indicate on one of my pics where you would do that porting though, I would appreciate it. You mention a 90* angle somewhere.

Fabroman, thanks for the info on the bore lip. I will check when I get home and see what it feels like. Thanks also for the tip of putting the side cover back on before I take the flywheel off. I was worried that not having it on could cause me problems when I whacked the flywheel nut.

EDIT: I just found out that a new side cover gasket is going to cost me $17.54. That is a whole lot of money that I don't want to spend. I am going to have to see if I can make my own. If someone could possibly hel me find out for me what the thickness of these gaskets are supposed to be? I just cannot seem to find out. If I know the thickness it would help me make my own
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  #27  
Old 06-07-2012, 02:39 AM
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Originally Posted by landuse View Post
Thanks again guys. You are giving me a lot of work, which I am not too sure if I am skilled enough to do. Could you maybe explain the poor manís hone to me again? You talk about working it in a diagonal cross pattern. How would that work?
When you use a honing stone to hone a bore, it's used as r_chez described his version. If you rub it down by hand (as I described) you need to rub on an angle so the "scratch" lines run down & around the bore, then you rub in the opposite direction to get a "cross hatch" pattern

Quote:
Originally Posted by landuse View Post
R_chez, I think I will also leave the porting for now. I don't feel confident enough to do it at the moment, and will just keep the engine stock. If you could maybe indicate on one of my pics where you would do that porting though, I would appreciate it. You mention a 90* angle somewhere.
We can't really see your ports in you pics but they are the "tunnels" that run between the carby/exhaust & the valve heads. they are usually "rough cast" which impedes flow. By smoothing them out you get better flow which improves performance. The 90* angle r_chez is referring to is in the bend in the port (see pic)
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  #28  
Old 06-07-2012, 03:43 AM
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Originally Posted by Fabroman View Post
If you rub it down by hand (as I described) you need to rub on an angle so the "scratch" lines run down & around the bore, then you rub in the opposite direction to get a "cross hatch" pattern
How long do you have to do this for? When do you know that you have honed enough?
  #29  
Old 06-07-2012, 04:30 AM
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How long do you have to do this for? When do you know that you have honed enough?
Until these marks are gone. But, you can't rub one area more than the rest, it must be even

Thanks for providing such a good pic of those marks, it helped me explain that a lot easier
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  #30  
Old 06-07-2012, 04:39 AM
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Until these marks are gone. But, you can't rub one area more than the rest, it must be even

Thanks for providing such a good pic of those marks, it helped me explain that a lot easier
Thanks Fabroman, I appreciate it. I am probably going to try do a lot over the weekend, as I just don't seem to have the time after work. I get home, go for a run, and it is dark already.
  #31  
Old 06-07-2012, 09:00 AM
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Pictures on google greatly help when looking at what hone marks should look like.
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  #32  
Old 06-07-2012, 09:51 AM
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Pictures on google greatly help when looking at what hone marks should look like.
That's true, like these:
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  #33  
Old 06-07-2012, 03:24 PM
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Yep. Mine's not that pretty, but it helps to hold oil on the bore which ultimately slows down wear rate.
I was at my local show today and passed a tool stand. They had a 3 stone hone for £25. I was soo tempted!
Came home, £18 on eBay! Trying to tell myself I really don't need one!

As for the side cover gasket, get some gasket material or cereal box. I would say in the .020" to .030" range, around .5mm
You need to have a little bit of endplay, I.e. You should be able to pull the crank in and out of the block a little, up to around .010. Not a lot, you should only just feel it.

I know you wanted to keep this a free project, but if you wanted I could strike you a good deal on a gx160 clone or genuine carb. If you want, get some internal measurements, I will tell you if they are close. I expect they would be.
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  #34  
Old 06-08-2012, 12:11 AM
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Thanks again for all the advice guys, I appreciate it. I would have thought that the bore would look smooth once you were finished with it. I didn't think you would actually see the scratch marks.

Quote:
Originally Posted by r_chez_08 View Post
I know you wanted to keep this a free project, but if you wanted I could strike you a good deal on a gx160 clone or genuine carb. If you want, get some internal measurements, I will tell you if they are close. I expect they would be.
Thanks r_chez, I will keep that in mind. Unfortunately the postage from the UK to here is a lot. My sister sent the carb that you donated, as well as a book to me, and that cost about 20 pounds. The pound vs rand conversion rate is about 14:1 at the moment, so 20 pounds is a lot of money. I will kepp it in mind though, cos carbs go for abo1ut 60 pounds new here. Secondhand is impossible to get.

So I took the flywheel off yesterday. I am definately learning the sequence of engine teardown....and the way I have gone about it is totally wrong. What you got to do is take the flywheel off before you take the side cover and the head off. If you don't, there is nothing to hold the flywheel still while you try take the nut off.

I put the side cover that I had taken off back on (thanks Fabroman), and then tried to remove the flywheel. I realised that I had to put the head back on so that I could stick a piece of rope down the plug hole for me to stop the piston from moving. If you don't do this it is impossible to take the flywheel nut off.

I got the nut loosened, and then whacked it with a hammer. The flywheel broke on the second whack. The flywheel key still lokks good, so no problem there.

Here are some pics of where I am at the moment.

I also phones a place that sells engine spares, and they are going to call me back today and let me know what the thickness of a side gasket is supposed to be.

The cam came out as well, but that is OK.

I also know someone who owns a torque wrench, so I will probably just borrow that when I need it. I also found out that the gasket is supposed to be 0.4mm thick
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  #35  
Old 06-08-2012, 11:25 AM
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Nice progress! You can take the flywheel off with an impact wrench if you have one.
Shipping isn't too bad for the carb, I will work it out for you if you want.
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Old 06-08-2012, 11:36 AM
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Nice progress! You can take the flywheel off with an impact wrench if you have one.
Shipping isn't too bad for the carb, I will work it out for you if you want.
Thanks rchez. If you could give me a price, i can keep it in mind if i need it. Shipping and the cost of the carb. PM me the details please. Thanks
  #37  
Old 06-08-2012, 02:26 PM
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PM'd I hope the prices sound OK. If not let me know.
What do you plan to do with the motor?
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Old 06-08-2012, 11:59 PM
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PM'd I hope the prices sound OK. If not let me know.
What do you plan to do with the motor?
I actually dont know what i am going to do with it. I think I might just sell it. I am trying to save money to buy a scooter for my daughter. She turns 16 soon
  #39  
Old 06-09-2012, 12:31 AM
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Come on buddy, you gotta make this thing run! Could you drill and tap larger for the carb bolt.
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Old 06-09-2012, 12:54 AM
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Come on buddy, you gotta make this thing run! Could you drill and tap larger for the carb bolt.
Oh, I am definately going to get it to run! No doubt about that. I will sell it after that. I have no use for another engine.

I was actually thinking about tapping for another bolt. Thanks
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