Engine Rebuild

[druu]

Once my parts have arrived, I will be attempting to rebuild my engine from scratch. I've ordered a headkit from HKMOTOS which should be arriving this week which comes with a FCC and 14.5:1 head. I've taken my stock engine completely apart, etc.

A few things I'm not sure about:

1. I understand the crankcase will probably need modding to fit the new FCC, does anyone have pics of a modded case?

2. I noticed the crankcase has gasket strips on either side, the kit probably comes with new ones but are they relevant? I've heard of some crankcases not using gaskets at all.

3. Can someone give me some torque settings for the crankcase and head bolts? Cheers.

I'll probably have more q's as the thread progresses.

PS. I'm not worried about balancing stuff and whatnot and not looking to spend more than I already have on it. It's not going to be a bodge though (I am technically minded and pedantic). I think of it as a practice for a real engine anyway.

[Glen]

okay,

1) crank - no mods needed. you only need to mod if you get the stroker crank from the USA. the normal one pops right in.

2) the crank gaskets you must have! cut them out and use some hylomar gasket sealer to stick them on one half, then put some on the other side of the crankcase and shove em together. wipe off the excess.

not sure on the head torque.

but also replace the bearings and seals while your at it. one piece of crap in the bearings when your rebuilding or a leaking seal will ruin your day

[druu]

Thanks for the reply glen.

So the regular FCC should drop in, that's good to hear.

Crankcase gaskets, the old ones look fine but I won't risk it, if they don't have new ones in the kit then I'll make some up. Any idea how much torque settings for the crankcase bolts? I've read on an ADA PDF that head bolts should be 6, 8 then 10lb. Crankcase torque?

The stock bearings in the crankcase are NSK's and are still in very good condition (the stock engine was barely used). Seals are also in very good condition.

[mac90]

nsk bearings are a better quality (french) aftermarket bearing so must have been replaced before, flush them out with fresh fuel & inspect for damage or play

as for seals if you pop one out you will find most industrial supplies stores will keep a seal to suit tho they may look good they could still leak or be brittle

everything else is fairly simple (arrow on piston pointing toward the front of the engine) just relube each moving part with some straight 2 stroke oil as you assemble
i myself use a dab of engine assembly grease & 2 stroke oil on all internal seal bearings & just oil on the bore & rings

[druu]

The bearings haven't been replaced as I've owned the bike since new (only about 2-3 months old). It's one of the latest Lammas Group bikes with hydraulic brakes, etc.

I was suprised when I saw the NSK in there, was expecting an unknown chinese brand as I did with the wheel bearings and head steam. Unless of course, it's a fake NSK. But the quality was much higher than the other bearings.

Seals are still fine. As I mentioned earlier, the bike is only a few months old.

Still unsure of torque settings for crankcase bolts, surely someone knows?

[mac90]

just tight is the usual standard for chinese stuff as the alloy can strip easy
i suggest not over tight, with a small dab of lock tight on any essential ones your worried about coming loose

[druu]

Cool, thanks Mac. I guess now it's just a waiting game until the parts arrive.

Oh, any advice on porting? Common areas, etc?

[mac90]

id only de bur any rough edges or leftover dags from casting

[Glen]

theres a sharp step where the crankcase enters the side boost port thats very rough. i got bored and attempted to mill that off then smooth it out with sand paper to smooth the flow ALOT but never got into it properly.

but id imagine aside from that theres not much you can do to those motors porting wise. just have to fiddle around with squish settings.

[druu]

Ok, will keep that in mind, cheers guys. Also, I understand these *should* come with squish preset from factory (insert type head). Ideally, would 0.7mm be an optimal setting for squish?