First time engine tear down - veteran eyes appreciated

[cbrf23]

So I'm building a beer can, and I started tearing down my engine yesterday.
I've never done any engine work, so any veteran advice would be appreciated.
Was super pumped to get the cylinder off today; way less pumped once I did.

Anyways, here's what I found (all pics are as found, no cleanup).
Not sure how much carbon build up is "normal". Didnt think this looked all that bad:



Cylinder sleeve:


Further down, I see a little surface rust on the crank and con rod; again, not sure what is considered "normal":


Piston was a Vertex. Looks like there was some blow by at the bottom ring:



And then there was this.
Pretty sure this means the left side (stator side) of crankcase is shot. Bummer:

Also, some nasty looking pitting in the back corners on either side of intake. Not sure what this would be caused by, or if this is acceptable. Any advice here?

[AlisoBob]

And then there was this.
Pretty sure this means the left side (stator side) of crankcase is shot. Bummer:

Those "cracks" are totally normal. Every case has them, no worries.

Note: DO NOT LET ALL THAT GASKET DEBRIS GET DOWN THE OIL HOLES.

If you want to work on engines, you need to be a little more careful.....

[Roostius_Maximus]

Ya, those marks and the ones in the back are from casting, look away.
I'd get a real good look through the rod at the needled, see if there's pitting. Check the side clearance too, looks like it lapped that piston down with dust.

[cbrf23]

Thanks Bob and Roostius.

So are you saying that crank case half with the cracks may be serviceable? If so, that is awesome!

I am doing a full bottom end tear down also.
All parts are going to be inspected to ensure compliance with service limits, and I'll replace what I need to.
I was planning on testing (at least) case halves, conn rod, and water pump impeller with penetrating die.
What other parts should I be testing for cracks?

All salvageable parts are going to be cleaned with degreaser and then ran through my dishwasher before deburr and glass bead or zirblast, then they will be unltrasonically cleaned before assembly. This is why I was not very concerned about debris from gaskets/dirt.

I am going to replace all the bearings in the case halves, and all seals/washers/gaskets while I'm at it.

I will be reconditioning hardware as well (red wheel buff to remove corrosion, glass bead blast, ultrasonic clean) and will buy new hardware where ever I need to.

I can see some daylight through the reed valve so I was planning to replace that - I was looking at the Boyesen rad valve as a replacement, not sure if this would be a good upgrade for what I want to to with the bike. And any advice is welcomed!

I plan on installing a fresh new clutch pack, probably OEM as I'm hoping to re-use the stock basket (if its serviceable) and I've heard the carbon and kevlar discs tend to wear the stock baskets pretty quick.

This is for a super moto build, which I plan to plate and ride primarily on the street.
I would like to build the engine for good reliability and longevity, without sacrificing a lot of performance.
I'm looking at the pro racing "cool heads" and then I would like to find someone to tune the head and cylinder for my application.
I was thinking maybe lower compression a little and raise squish zone a little, try to make more street friendly and and get a little longer maintenance intervals.
I only have a BASIC understanding of the concepts of 2-stroke tuning, so I will be farming this work out.

Roostius, I've seen other posts from you about this kind of work - expect a PM from me in the near future

[freeride588]

What they are saying is that those "cracks" as you call them are actually casting marks and there is nothing wrong with your case.

[cbrf23]

Oh, ok thanks freeride.
Thats a relief.

Certainly look like cracks to naked eye

[freeride588]

Oh, ok thanks freeride.
Thats a relief.

Certainly look like cracks to naked eye

No worries man your not the first and you wont be the last to make that mistake. Glad I could help.

[cbrf23]

Crankcase splitter came in today.
Man, the front locating pin was STUUUUUCCCKKK!
Took a while, tried to be very patient and split as evenly as humanly possible.
It took a lot of "persuading", penetrating oil, and playing with tension (on/off) the splitter to finally get the front to split.
I must have looked over the engine at least 20 times thinking I had to have a missed a bolt somewhere!

Here is what I've been told I need to check, is there anything else you guys think needs to be added to list?
Check crank cases for cracks, esp around kick starter housing.
Cracks where the bearings sit in the crank case and surrounging area.
Wear on shift forks and dog legs.
Wear on the gears, look at 2nd and 3rd these are the ones that are usually worn.
Check dwangs on inside of gears, they are the slots that engage the gears.

[AlisoBob]

If you havent pulled the tranny out yet, you can wrap the thing together with big rubberbands to keep it all together until further inspection / breakdown is needed.

Reassemble the same way.

[cbrf23]

Got the cases split.
Ultrasonic cleaned all the insides.
I tumbled my shift fork rods with some 2mm porcelain balls to improve microfinish, and I cosmetically reconditioned some misc. parts with glass bead and/or zirblast.

Cylinder is getting bored/honed now and new piston to match.

I still need to inspect the OEM crank further...but i checked the gap between con rod and counterweight with my old set of feeler gages. and had over .058 clearance.
I will check axial and radial play and mic journals at work Saturday, as well as check gap with a calibrated set of feelers.

How do you guys feel about Hot Rods Cranks?
I can get a brand new Hot Rods crank for $108.

Still need to inspect transmission (also planned for Saturday) but here are some pics after ultrasonic.
Looks like some wear on the "darker" gears on both gear sets.
I took a pic here I think you can see what I'm talking about.
I tried to measure surface finish with profilometer, but couldnt get a good read cause of size of profilometer head and the measuring "point" is in the middle of the head so cant enough stroke over that face :/
Might be able to measure with indicator and height gage, probably try that saturday if I can find a sharp enough indicator tip...