Break In Port timing suggestions?

DirtyBum

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Hi this is my first post!

SO I am fairly new to porting, I built a piston port 80cc which blew up (spun the bearing which in turn destroyed my piston and cylinder). I bought the cheapest cylinder, new piston, bearings, rings, slant head, reed valve, jets and a new sparkplug from Amazon and I am cracking my case today to clean out the residual bearings and such... I'll be balancing my crankshaft and planning down the mating surface while I'm at it. Parts won't be in until tomorrow and I'd like to port my engine for optimal performance at low rpms/climbing hills and was hoping someone could just give me some decent ballpark port durations for running a reed valved engine uphill, I've got a lot to do and I'm honestly just not trying to research and understand why exactly those port durations do what they do. I will be windowing the piston and I'm open to putting a trench/boost port in but I want to do this in under 6 hours as I am damn tired of working on the engine.

I'm going to be taking this baby on a road trip through the Appalachians (about 900 miles) in a week or two so not trying to do anything extreme or wonky which will make it unreliable.

Please limit answers to port duration suggestions as I already know it's not the best idea to go on a road trip that soon, I'm cold and the bike has been pretty damn reliable until the bearing finally gave out (modded too hard, I know what I did wrong and I don't wanna talk about it 🤣) and I am heading for greener pastures.

If I don't get an answer soon I'll keep my durations and just do a little cleaning and up and widening of the ports, that got me 35 mph before and was great going uphill until the cataclysm.

Thank you!
 

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@ImpulseRocket or @Mike Cyanide are the most knowledgeable on porting.

That's some impressive carnage btw. Good job lol.
Thanks 😅 felt funny for about 5 miles then it made this crazy noise like suddenly lost compression *ZOOOOT* and cut off, started up about 5 more times did the same. Probably could've avoided some of the damage, but I was on my way to grandmas house!!!

So far raised the exhaust and lowered the intake about a mm each, and put a boost port just under the transfers. I'll probably ride it like this if it does well at least for a few days.

Here's a few pics of the new stuff and my bike which is almost entirely made of trash. I started with a bmx and a friction drive weedwacker setup, so I kept the crank and handlebars from the original bike.

Also the old cylinder, which was already scratched up this bad aside from the head being all chunked up bearing needles (and would still hit 34 on nice hills)

I ran her on 93 non ethanol for the majority of the thousand or so miles she was running, lesson learned. I've only got about 150 bucks and 100 hours (atleast) in it as of yet so not too shabby in my opinion. It's been a fun learning experience.

The transfers are totally different and I have to get some studs to bolt the head on, which I thought would be ideal for opening her up to see how it's going inside (also decking the cylinder for compression and squish gap) but I'm hoping she will still be good at climbing hills and run similar??? There was no squish in in the previous head, but had those open transfers with two channels which I have no idea how it works.

Unfortunately, I left my puller tool up the road so I didn't crack the case, just washed the hell out of it with mixed gas. I "ran" it over and over with a strong magnet submerged, upside down, backwards, any way I could. Until I was positive the needles were all out and most of the steel "glitter" was removed. I'm thinking to run the old cylinder a bit to try and blow out the remaining residue without contaminating the new head too much? Any thoughts? And thanks for reading.
 

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Hi this is my first post!

SO I am fairly new to porting, I built a piston port 80cc which blew up (spun the bearing which in turn destroyed my piston and cylinder). I bought the cheapest cylinder, new piston, bearings, rings, slant head, reed valve, jets and a new sparkplug from Amazon and I am cracking my case today to clean out the residual bearings and such... I'll be balancing my crankshaft and planning down the mating surface while I'm at it. Parts won't be in until tomorrow and I'd like to port my engine for optimal performance at low rpms/climbing hills and was hoping someone could just give me some decent ballpark port durations for running a reed valved engine uphill, I've got a lot to do and I'm honestly just not trying to research and understand why exactly those port durations do what they do. I will be windowing the piston and I'm open to putting a trench/boost port in but I want to do this in under 6 hours as I am damn tired of working on the engine.

I'm going to be taking this baby on a road trip through the Appalachians (about 900 miles) in a week or two so not trying to do anything extreme or wonky which will make it unreliable.

Please limit answers to port duration suggestions as I already know it's not the best idea to go on a road trip that soon, I'm cold and the bike has been pretty damn reliable until the bearing finally gave out (modded too hard, I know what I did wrong and I don't wanna talk about it 🤣) and I am heading for greener pastures.

If I don't get an answer soon I'll keep my durations and just do a little cleaning and up and widening of the ports, that got me 35 mph before and was great going uphill until the cataclysm.

Thank you!
900 miles... hope you have alot of spare crap lol cuz that optimistic to say the least. 165 to 170 exh 115 to 125 trans you have a pic of a reed so no point in intake. Not sure I'd use a reed on a road trip bike. Hope that loctite 518 or dirko ht red on your intake. Those numbers are ovb lower for lower rpm higher for high. DONT EXCEED 70% BORE WIDTH on porta
 
Thanks 😅 felt funny for about 5 miles then it made this crazy noise like suddenly lost compression *ZOOOOT* and cut off, started up about 5 more times did the same. Probably could've avoided some of the damage, but I was on my way to grandmas house!!!

So far raised the exhaust and lowered the intake about a mm each, and put a boost port just under the transfers. I'll probably ride it like this if it does well at least for a few days.

Here's a few pics of the new stuff and my bike which is almost entirely made of trash. I started with a bmx and a friction drive weedwacker setup, so I kept the crank and handlebars from the original bike.

Also the old cylinder, which was already scratched up this bad aside from the head being all chunked up bearing needles (and would still hit 34 on nice hills)

I ran her on 93 non ethanol for the majority of the thousand or so miles she was running, lesson learned. I've only got about 150 bucks and 100 hours (atleast) in it as of yet so not too shabby in my opinion. It's been a fun learning experience.

The transfers are totally different and I have to get some studs to bolt the head on, which I thought would be ideal for opening her up to see how it's going inside (also decking the cylinder for compression and squish gap) but I'm hoping she will still be good at climbing hills and run similar??? There was no squish in in the previous head, but had those open transfers with two channels which I have no idea how it works.

Unfortunately, I left my puller tool up the road so I didn't crack the case, just washed the hell out of it with mixed gas. I "ran" it over and over with a strong magnet submerged, upside down, backwards, any way I could. Until I was positive the needles were all out and most of the steel "glitter" was removed. I'm thinking to run the old cylinder a bit to try and blow out the remaining residue without contaminating the new head too much? Any thoughts? And thanks for reading.
Hope you got a new bottom end using that one would foolish to say the least. Atleadt replace the bearings maybe check crank for true. With the damage ya did there's no way you didn't fill the bearings with trash.
 
I can suggest port figures, but knowing what I would be starting with would definitely be nicer. Do you want to run piston port, reed valve for windowed piston or a boost port? Max RPM?

My ultra generic recommendations, if low rpm power is what you desire then....
keep the blowdown to about 20 degrees, maybe 22 tops.
For Piston port, 120-125 degrees of duration on the intake port.
Transfers 120-122 degrees
Exhaust: 160 degrees, give or take.

These are numbers for an engine with a power peak around 6000-7000rpm

A critical component of port work isn't just numbers, but shape as well. Making sure the transfers open and close at the same time is critical, and the upper transfer roof is parallel to the top of the piston and pointing the flow path to the intake side as much as possible.
 
I know you don't want to hear it but use more oil next time. Try 25:1. That looks like an over heated, lean fuel, oil starved situation. Let me guess, ran like a bat out of hell until it burnt up?
 
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