Pre-Install Engine Inspection

JoeMetro

JoeMetro

Member
Got my kit at the door today! ($130 off eBay)
Decided to take a look before installing.

Here are my intake and exhaust ports, they look okay to me. What do y'all think?



I read somewhere on this forum that I should sand down this part of my engine (not sure what it's called, a bowl?)


I chipped off some of this very brittle gasket, I'm afraid some might have gone inside :/. I also though tmy piston rings were broken when I realized they're supposed to look like that haha

[URL=http://s1093.photobucket.com/user/mysterysandwich/media/OTB-piston_zpspwfaj1yg.jpg.html]

I want to give the engine a good rinse/clean and the author of this thread gave it a couple baths with WD-40 and one last one with 4-stroke oil. http://motorbicycling.com/showthread.php?t=45884


Would I just spray a whole bunch of WD-40 in the crevices between the piston and the body then shake it up?
Does anybody know if it'll be okay for me to use this "Mobil-1 10W-30, Synthetic, High mileage" as the last rinse?

Any help/input/advice is greatly appreciated!
 
the sanding of the "bowl" is called Lapping. and yes, do it. lap the head and the jug, so you have 2 good flat surfaces to join together via the head gasket. there is ideos on youtube how to do the process.

the jug gasket inside shouldnt be a big problem.. but try to get it out. and i hope u have a second one. because you need a gasket there!
 
Make sure the cylinder to case gasket is good before reassembling.

Use caution when putting the cylinder back on. Unless you have experience its easy to break the piston rings. They have to be compressed to slide back in the cylinder. DON"T USE FORCE or hammer on it. If the rings go back in right the cylinder should slide right on. The ring gaps must align with pins set into the ring grooves in the piston when compressing them.

I'm not sure about using WD40 to clean the case. Ideally you'll want a solvent that will carry away any debris, not stick them to things. As for lubrication after assembly just use whatever 2 stroke oil you plan to mix with your fuel. A little will go a long way. No need to saturate the insides.

Use a torque wrench on the cylinder head fasteners. 120 to 140 inch pounds tightened in an 'X' pattern. This would be a good time to get rid of the chrome acorn nuts and replace them with shouldered/flanged hex nuts. The acorns can be a source of trouble. Look for 8mm nuts, the thread pitch will need to be determined. Some are fine thread, some course. They'll be either 8mm X 1 or 8mm X 1.25

Use care when 'lapping' the cylinder head. It MUST be flat. Follow the instructions regarding 'lapping'. It's easy to sand an angle into the gasket surface. That you don't want. There is discussion on 'lapping' here. Use the search feature, key word, 'lapping'.

I never advocate a new builder begin by making modifications to the engine. Get some experience before worrying about hot rodding the thing. Unless you know exactly what you're doing you could ruin a brand new engine by grinding on things.

That will get you started. Good luck.

Tom
 
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Thanks y'all, I have done reading on port'ing and whatnot, I'm a little timid about it and afraid of ruining the engine. I will be as careful as I can when I put the cylinder back on...

I purchased new studs & nuts from SBP, and will be replacing everything. Although I don't have a torque wrench, is it worth buying or is one's best judgement sufficient?

As for the gaskets I'm thinking about going to an auto parts store -- Is there a thickness I'm looking for in gasket material? I was also going to use this Red High Temp RTV Gasket Maker on both sides of the gasket when I put it on. Orcan I just use the RTV by itself without any cut-outs?
http://www.amazon.com/gp/product/B0...3JZC1DK9TL57I&psc=1&ref_=wl_it_dp_o_pd_nS_img
 
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Joe,
A person who uses wrenches every day and has lots of experience can develope a 'feel' for tighteneing fasteners. Unfortunately over tightening is one of the biggest causes of fastener and thread failure on the Chinese 2 stroke engine. Many will blame "cheap material" and rush off to buy upgraded fasteners. Nothing wrong with that but often unnessessary if a torque wrench is used and proper torque values applied.

Not quite clear on your "as for gaskets" question. Are you referring to the cylinder head gasket? If not damaged you should reuse the head gasket that came on the engine. It is made from soft aluminum, not a fiber gasket material. No need for any gasket sealer on the head gasket either. Also keep in mind that most all RTV gasket searlers are not compatible with gasoline. Read the label on the container.

As for the intake and exhaust gaskets; I like a thicker gasket on the exhaust, 1/8" or so. You can go thinner on the intake, 1/16" or even 3/32" is good.

I don't understand when you say, "without any cut-outs". What's that mean?

Tom
 
2door said:
Joe,
A person who uses wrenches every day and has lots of experience can develope a 'feel' for tighteneing fasteners. Unfortunately over tightening is one of the biggest causes of fastener and thread failure on the Chinese 2 stroke engine. Many will blame "cheap material" and rush off to buy upgraded fasteners. Nothing wrong with that but often unnessessary if a torque wrench is used and proper torque values applied.

Not quite clear on your "as for gaskets" question. Are you referring to the cylinder head gasket? If not damaged you should reuse the head gasket that came on the engine. It is made from soft aluminum, not a fiber gasket material. No need for any gasket sealer on the head gasket either. Also keep in mind that most all RTV gasket searlers are not compatible with gasoline. Read the label on the container.

As for the intake and exhaust gaskets; I like a thicker gasket on the exhaust, 1/8" or so. You can go thinner on the intake, 1/16" or even 3/32" is good.

I don't understand when you say, "without any cut-outs". What's that mean?

Tom
Click to expand...

Sorry! I realized my questions were worded quite awkwardly -- thanks for your input however.
I did end up purchasing the torque wrench.

I was asking if I could just use the red RTV without an actual gasket. But I went out to an auto-parts store, bought some gasket material and made my own (crude) gasket.
 
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