Need porting

[FlyYoDreams]

Hey guys I’m new to the forum. I’m looking for a way to port my “80”cc Imaycc. I have some mechanical abilities but I’m not sure I can do it (sounds complicated with all the software etc). Can anybody give me some hints, tips and resources? Does anyone in south Florida port small engines?

 

[FlyYoDreams]

I have the same filter and engine as Damien, and yes it flows better than, and filters better than, any of the stock carb "filters"

It is also a washable and reusable K&N style cotton filter.

Awesome, kinda looked like that from the pic. I was hoping it would be

 

[FlyYoDreams]

There is a web site, https://lambretta-images.com/tuningh/port-timing-calculators/
this does not require a degree wheel just linear depth measurements using a veneer caliper.
Another online calculator for finding the equivalent dia of a square or rectangle is needed to properly port match!
Over widening and or altering port timings will not give the desired results if using a stock carb, the stock carbs are only 15mm at best with a few now being 16mm that claim to be 19mm, this is a problem since the port windows are 19mm equivalent dia and all ready over sized to a stock carb!
Port matching is taking the carb being used, lets say 18mm and then having a matched 18mm intake track and port window this includes the intake flange and track between it and the window so as not to change the velocity, the carb only meters for the flow through the body so being larger any where after it will just slow that flow down.
On the exhaust side a 19mm window is ok because at the flange is probably 20-21mm which allows for some expansion of the gasses into the head pipe.
Transfers are an issue in these engines as there is inadequate blow down period/duration and they are not shaped properly, so correcting the angles here is a big improvement along with increasing the blow down duration, keeping in mind that raising the exh port it still has to be the proper dimension, so this is what I look at first trying to get as close to 20 degrees of blow down and staying within that dimension.
The port timing calc is very accurate and allows you to play around and see what will work before hacking away at your cylinder saving you time and money and most of all not ending up with a dud!

Woah thanks for the wealth of information and the link. Sounds like you’re very familiar with engine science and I appreciate you taking the time to write such an informative response

 

[DAMIEN1307]

Well I just want to maximize power and efficiency. Nothing too crazy

One other thing I would suggest...Take that "Chinesium" Z-4 or Z-8 series spark plug and just chuck it in the trash...They have been well known to cause problems with some members motors..."Chinesium" quality consists of some 12 year kid saying its ok before dropping it on the floor and then packing it up in the kit...lol...lol.

Instead, get yourself the NGK-BR6HS spark plug to replace it with, that is what the majority of us here in the forums are using, they are a better made, consistant firing, quality spark plug.

 

[FrizzleFried]

 

[FlyYoDreams]

One other thing I would suggest...Take that "Chinesium" Z-4 or Z-8 series spark plug and just chuck it in the trash...They have been well known to cause problems with some members motors..."Chinesium" quality consists of some 12 year kid saying its ok before dropping it on the floor and then packing it up in the kit...lol...lol.

View attachment 189968

Instead, get yourself the NGK-BR6HS spark plug to replace it with, that is what the majority of us here in the forums are using, they are a better made, consistant firing, quality spark plug.

Lmao chinesium hahaha! I got one on the way!

 

[Mc2Stroke]

I don’t know if you’re still interested in porting a cylinder yourself but…

There are a lot of people that make it seem like you can easily screw up a cylinder if you don’t know what youre doing/ aren’t experienced.

The only way to gain experience is by doing it just make sure you do your research, and don’t go overboard. Maybe try making small alterations, it would give you a little hands on knowledge to do it in stages so you can see how each thing you change affects it.
*Before there were books telling people how to port engines written by people who’ve figured how to port by trial and error, or guys teaching others or whatever… there were the guys trying things no one had done, making mistakes and learning from them til they got it right. There is still guys trying different things no one else is doing, improving what’s already been proven to work.

If you’re serious about learning there are free pdf versions of books like “Two Stroke Tuners Handbook, Gordon Jennings”

https://www.rexs-speedshop.com/wp-content/uploads/2018/12/Two-stroke-Tuners-Handbook.pdf

“2 Stroke Performance Tuning, Graham Bell”

Graham Bell Two Stroke Performance Tuning

Graham Bell Two Stroke Performance Tuning

www.academia.edu

I believe those are the places I downloaded copies from but if you’re unable to just do a google search and you will find multiple places to download both books in pdf form.
There is some info on YouTube, most of the guys with really good information on 2 stroke porting are chainsaw guys but it still applies…
IronHorse is one, Tinman Saws is another, both have great information.
There are some others like:
2StrokeStuffing, AUmechanic, MichealForrest, 2stroke carb tuning porting information
These channels have some pretty good information, some pretty basic, others more in depth but quick and to the point.
Just what I have listed above will give you what you need do some basic changes to your cylinder, it’s no where close to everything but definitely somewhere to start your porting journey.

The information is out there you just have to put in the time and look for it… ( Ive saved you quite a few hours of looking already)
What I’ve listed above are great places to start,
Don’t be scared to try it out, just take it slow and go easy. A new cylinder is $25-30 so it’s not a huge loss if you do mess up, in fact buy a separate cylinder, one you can work on porting after you figure out what you want to do and lay out a template, the other you can use to keep the bike running while you try you hand at porting.