one more

Once i have the other number i can look at blow down and intake duration for additional data entry and pics.
then maybe some port timing etc. you can coose. Even D for carb sizing correctly

Then a discussion on recommendations with your Engine builder and add on choices.

Adnoh

Top of intakes to tops of cylinder measure 64.75 average +/- .5mm across them all.

Adnoh,

Can you please post those figures again with a 47cc dome please? I see you used 55cc. I am interested in CR here and do plan to run C12 fuel. This K-Fab head has a 47cc dome in it. Also I have an aftermarket chamber and exhaust not sure the brand but its pretty nice.

Is this spreadsheet somewhere?

I'm on the hunt to replace my PE34 with something like a PWK 36 or larger, but they're dang expensive even used. Also the pilot did run awesome on the PE34 before takedown so I'm kind of fine with staying on the PE34 for break-in until I have time to tune in a replacement.

Thanks

What head gasket?
Also must likely the top of cyinder has been decked a toucb since it's sleeved .
So after you put on clinded and torgue roll up to TDC (Top Dead Center) and use a feeler guage like in one of my pics for a final number. Also have you cc'ed the head. I would bet it's off.
If memory serves the CC's include a stock head gasket.
Maybe the k- fab is spot on.
I'll try to work on. Tommorow night.
I used stock as a base line so you could evaluate the diff combos.
I used cometic since your 81.5. the stock I'd is 81.13.
Don't want that hanging inside.
Not sure if k-fab uses an o-ring style.
Thought I seen a gasket.
I'm sure you noticed the uccr. You can much higher with fuel. Also make sure your not going to starve at high rpm.
In decrease in primary may help. Maybe a spacer. Help hit like a hammer.

I'm going to use a stock head gasket since I have one; and I've already enlarged it some to clear the 81.5 bore. Its measuring at 0.7mm thick.

Squish-wise I know this is going to be pretty tight. This pilot HAD 39 thousandths before rebuild! With that being said, piston top to top of cylinder at TDC (Top Dead Center) *SHOULD* measure out to FLAT, as the gasket measures 10 thousandths, and the edge of the dome is measuring 30 thousandths. 10+30=40 thousandths - exactly what my squish measured before rebuild.

I'll get a more accurate number when I got the piston up in there with the new crank/rod, but for now with 0mm of piston at TDC (Top Dead Center) using the following:

Dome - 47cc (Measured with the plug installed and windex/water which has reduced surface tension)
Stock gasket: ~3.75cc
Piston dome volume: 16cc
Over-all combustion chamber volume: 34.75cc

Exhaust top to cylinder top (Assuming piston top as well): 45.5mm

Static "trapped" compression ratio: 7.83:1
Dynamic at "blow down" compression ratio at 65.5mm top of intake ports: 10.83:1
Total dynamic compression ratio (Full stroke at 79mm): 12.86:1 This must be your UCCR figure. See, my combustion chamber volume is pretty tight!

Hopefully that's not too much for this thing. As noted before tear-down, the unit has some signs of pre-ignition peppering of the dome on pump gas. I'm going to be running VP C12 110octane with Klotz R30 oil at 40:1. I run my jetski at about 13:1 Dynamic but that thing only sees short throttle bursts.

In other news, I know this stock PE34 is going to be a bottleneck (understandably its a bottleneck in STOCK trim, and I'm not quite stock here). I've got my eye on a PWK 41 Airstriker Pro carb with JD Jetting - comes with 2 needles and several jets to get tune started. This seems like a good deal, in fact the 41mm pro carb is actually less cost right now than JD's PWK 38 with the same needle/jet setup.

Seems the KTM300, CR500, and KX500 guys like their PWK 41. Perhaps this 412cc monster would be OK on a 41 too.

The piston I have's final is measuring 3.205", and the bore is 3.209". These are the numbers I received back from my Engine builder who did the bore/hone.

Thank you

Sounds like your all over it. The only thing I'll check is. Blow down degrees.
The head for ski and pilot should be diff in way of area ratio and squish and maybe bowl shape. Still should be fine with fuel. Raising the exhaust will increase slow down time in degrees. So that will or should be keep in check. I may also do a mean line for you. Then you can push ring down to match and get idea of available port area see where you at. Most likely on the way up the oval. Then area decrease rapidly as the mean line goes up with port height change.
Thank you for posting information I find it fun and interesting.

Also yes uccr is un-corrected compression ratio.

What’s mean line?

I’m still not sure if or what I can possibly do for cylinder porting. I would take your advice though- port shape, height, width etc.

Thanks

The mean line is established in way port duration and is used for time area or what the port will support in way of rpm. As you raise the port roof the duration changes and the available area in mm squared decreases for port flow. This area is is all you have at a given rpm range. If done correctly the rpm range and torgue range can be increases/ altered.
As you raise the exhaust port the blow down changes and can go past maxium then you can run into issues with e-vac on cylinder and starve the stuffing charge. Major issue with the ody. You don't what that stuff charge to be weak or late in time. If correctly done it can act as a super charger and add pressure from static at port closure.
Maybe getting a little off track. If time allows I'll post up a pic tonight so you get the idea.
Once a mean line is established than the are of the port can be corrected for proper area for a given rpm.
Pretty sure bell address's this as well as the two stroke tunning hand book. The formula is not that hard. I built a spreadsheet to make it easy and give numbers for rpm.
Lee provided stock numbers that are a base line that my spread sheet confirms are real close to the books calculation. Since you going to be a short course Engine. The mid range is the focal point for angle area, controlled by mean line. Once you see pics your get it. Then a clutch set up to run with in that range and no one will take you out of a cornor.

here is a quick pic of an example
also I used a comet due it thickness and getting you closer to what you want not to mention ID
1.2 mm crushed

Adnoh,

I've created a map of this cylinder. Please see attached.

Boost port angle is about 33 degrees - pointed exactly to the middle of the top of the cylinder.

The transfer ports seem to have about a 0 degree, or 90 degree cut in relation to the bore.

I can feel with my finder that theres probably ~2mm of the original sleeve and casting that's being covered by the current sleeve. These are the secondary transfer ports next to the boost port (12.66mm and 12.48mm spaced from boost port). I've attached two pictures marked up with where the sleeve is covering.

That's strange on the boost port. Usually that mod is not done unless they matched the sleeve to what is there. If so the roof should have been higher. I will open my book on that one. From looking at piston I would have bet against that one. What I do is transfer those port angles to paper and look at the flow pattern from that. This is done for the side walls. So if the threre coming from inside port at 90 degrees then the line would be 90 across the bore for 1 and 2 closest to exhaust port there can be a change to an slight angle for exhaust push.this will provide a greater ibtuce angle for over lap from 3 and 4 then 3 and 4 can be matched in to achieve a better spread across piston top. With a longer blow down this will help create vacume in the cylinder at port opening. Generally with a center plug design yes the boost need to hit the plug and push down. So maybe the transfers change can aid this. Also a sympton of long blow down. The roofs of the transfers can have a slight angle usually toward the mean line then fine tune to LPP. Which in your case will be lower than normal so a longer blow down not so bad. So consideration of LPP, ex open and transfer angle keyy for you fuel based on UCCR.
Higher the UCCR, the e higher the LPP higher the roof angle. Remember not talking a lot. So on you paper you would make to lines to start. One being top of cylinder and one transfer roof angle if any. Then add mean line and estimated LPP or use a base line and Target that for LPP. Very important since it a short course mid range Engine. I'll paot up some port data I have for a close set up like your.
Again thanks for sharing and doing the work. Great info.
Adnoh

here is a pic of the port time area i was referring to
this is for angle area for given power range
If you stick with base line the power will flat-in out above listed rpm with a short over rev period with your pipe. as the clutch loads on top you lose acceleration.
with an alteration you blow down need to be in check most likely a roof change on transfer and boost to get around 31 for #1 and 30 for #2
look into max blow down for large bores and rpm

Again hacker math!

this is the area that the angle area is based off of
This area is above mean line

I have to admit I'm intrigued by your responses but I'm having a tough time understanding fully. Sucks because I am a very technical person at heart but this is scaring me. I have a $50 dremel that can can fix this cylinder but in the wrong hand I can get this a bit messed up.

I don't really understand the boost port, but understand it may be OK to raise it as well as transfer #3 and #4 to help with cylinder gas fill/evacuation - which is a decent thing - but in moderation and up to what - the mean line? I don't know where that is here honestly.

I like the chart showing #1 cut with a 184 degree duration on exhaust. That through some calculation could end in raising my exhaust port some which I know will help the top rpm hammer better -but again how much cut off - and I know that effects trapped compression - again I'm a n00b at figuring this out. Also not sure of the exhaust shape to make - maybe something like the attached port shape? Also I'm confident I can increase the exhaust width by about 4~5mm but again - angles are the confusing part. Also I don't understand the last chart other than the bottom where you've posted surface areas of the cut port.



I'm getting my crank back tomorrow, and am going to start building this Engine up as we have planned to go to Durhamtown very soon and I have everything I need to get it done.

Should I skip updating anything on this cylinder or is there something here that's honestly wrong that I can correct in a +/-30 minute port session?

I worked up a proposed change. still doing area numbers. I based this off of numbers i have. Just food for thought.
One thing for sure you need to fix those transfer open time. It hurt your low end and explains the look of your piston top.
the flow is jacked.Look this over there is a margin of error since I do not have a deck to top of piston for TDC (Top Dead Center). Once you get a degree wheel it can be fine tuned. I put up a washed piston that shows the flow change. kinda cool
As always consult your Engine builder.

The pic is of my pilot with port changes and comet gasket. just for testing. The intake was modified with boost post and raised and matched transfers.its a full dune/race set up. That pic is at 180 static compression.
it illustrates the flow and port balance using an over rich mixture for testing.

Adnoh

OK I see where you are going with this but have two questions:

From your 'change' items on the above left, and then a corrected-1 on the top right. The corrected-1 seems to be the direction right? That is, IF TDC (Top Dead Center) piston is 0.00mm to deck, right? I'll probably know that number for sure once I get this together.

Is the stock TDC-Piston-Deck normally 0.5mm?

Stock with wiesco .012 inch or .305 mm.
Your may not be that since sleeved.
When they sleeve it's close then they surface it down flat.
This is due to cutting top of Barrell for top of sleeve lip then press it in.

They best quick thing is match the transfer roof heights Most important for now

The corrected is based off what you posted to find the spot to start the degrees for adjustments.
As far as transfers and boost port when you match the heights radius them to what you have. Easy stuff.

In the last chart I gave the mean line to add to port map.
As a rule and on almost every pilot cylinder the best way to find BDC and then TDC (Top Dead Center) is the bottom of the exhaust port and transfers. The exception is a sleeved one.
When laying out out your timing limits I start with the cylinder on flat bench slid in piston. You should notice the crown edge right at bottom of ports. This is a very close BDC.
Then turn the cylinder over and move piston towards TDC (Top Dead Center). Then you can start setting the limits looking for ring lock pins if you marked them on top and bottom of piston and you can draw on cylinder the skirt layout. The only thing with with the ring pins is the amonut of twist for better word the assembly has
Here is where you find some power. And make sure your exhaust port floor is not expossed at TDC (Top Dead Center).

Any way match those transfer ports and run.
If so load your clutch for bottom end. If alt add one disc
If HRD add two. This will help on top check driven spring. If out of spec shim with carrier shims. This will help greatly. Don't over shim. You will now when you get it right.
If you start pushing hard out if cornor or lifting front back off one shim.
89 CDI (Capacitor Discharge Ignition), correct? If 90 tighten up your plug gap a touch as not to snuff the flame kernel. High pressure and fuel.

Enjoy your trip.

Port map now with extra mean lines in GREEN attached. I measured and put the lines in the spot as referenced. Is this what you were looking to see?

I'll check later when at home.
Mean while since I'm not the best at explaining my self, poor education.
Downoad the tuners hand book and go to Port timing. It will do what I can't.
Should be a link some where or CO will do it.
Two stroke tuners hand book, gorden Jennings. The only thing is the angle area. It old school timing.
Still relevant to the process.
Basicly area in time for RPM for air fuel delivery. Once you get an understanding of it then you will go ummm at the ody world as they over bore and put on adders.
Most of what I do is based off this book . It puts I hacker like my self in the right direction.
Really appreciate your work. Thanks for sharing

Appreciate it. Some of porting I understand is a little bit of experimentation.

You've given me a solid foundation to start to look at, and I've just picked up a degree wheel to start measuring and marking timing. I'll see how close I am or need to be to get 184ex, 124tx, and 30bd.

In other news, Fedex just dropped off my crank!

And in other, other news, I got my tank back from the radiator shop. Didn't like how the inside coating seems to have restricted the stock fuel pick-ups, but no issue. I've made a new fuel pickup at the bottom drain of the tank which has a new pickup filter inside of the tank - taken from an old petcock assembly I had lying around. Also integrated the new Polaris fuel pump. I'm thinking this may be the last ditch effort at continuing to use this tank - may need to look at Spun tanks if this doesn't hold up. Pictures attached.

Tank and crank

You plan on filtering the fuel before and after the pump? Not sure I have seen that before. I'm not saying it's a problem, but is is unusual. Just an observation.