61x cylinder to sleeve mismatch

[Polish jet pilot]

Guys I totally agree that listening to folks here is a good thing and I always do it and anlayze / compare. About "Race keyword': a guy who build engines for racing, or for whatever elese sets them up for racing by calculating port timing. He can time your engine as needed by doing some serious math (not my league at all). So he knows wehen and how power is delivered and how it should mix, burn etc (sorry for shortening all this). About sleeves: he is old school (really) and he said he could mahe a cylinder sleeve (he makes them for his boats, as well as cylinders, props, pumps, pistons, you name it...I was quite shocked) which would have the window lower and it would align with the cylinder just as it should...

So in his opinion all the imperfections should be removed, to increase flow. Obviously he is aware of things such as crankcase pressures, transfer duration, inlet duration, etc..

I asked previously about some tips from builders here, all I got is the info that I should be careful, blah blah..nothing concrete...

If this setup turns to be good I am going to post the dimensions of it so everybody can benefit from having a simple oem low cost setup.

 

[waxhead]

two stroke engines are two stroke engines , because he builds them for race boats etc doesnt mean he would have no idea for skis
So the guy that you are talking about should be able to do a decent job
Making a sleeve that drops the ports sown to match the cylinder mismatch is fine
R&D used to make a sleeve to do this and then run special domes to make it work
Nothing wrong with that, Its a lot of work for something that can be fixed on the oem sleeve
People on here have given you the right information you just have to sift through what is true and what is something they read on the internet that some one related to a two stroke porters uncle said so it must be the truth

 

[Polish jet pilot]

two stroke engines are two stroke engines , because he builds them for race boats etc doesnt mean he would have no idea for skis
So the guy that you are talking about should be able to do a decent job
Making a sleeve that drops the ports sown to match the cylinder mismatch is fine
R&D used to make a sleeve to do this and then run special domes to make it work
Nothing wrong with that, Its a lot of work for something that can be fixed on the oem sleeve
People on here have given you the right information you just have to sift through what is true and what is something they read on the internet that some one related to a two stroke porters uncle said so it must be the truth

Exactly - 2 stroke is a 2 stroke, especially for a guy who knows how they work. My point in all this was to find and use information. It seems that exact or at least more prcise info is not easily accessible. I know there is a lot people who would like to have porting done to their oem cylinder.. I want to help them (at least those who want to do it by themselves - maybe a small bunch of people here), thus if it works I will give the directives how to do it... Hopefully not taking away possible income from the guys who port and build motors in the US...

 

[SUPERTUNE]

How modified is your engine setup now?
Do you have:
Aftermaket ignition and flywheel
Factory 'B' pipe limited (we also modify them further for more torque and power)
Aftermarket head (ADA preferred / better squish design/ can also cut custom ones)
Better carb and intake system (I like Boyesen intake system/46mm Mikunis).
Skat Trak impeller with the correct pitch and matched to the pump.
Dual cooling and proper use of water control valves

Until you have all of this criteria done anything more than a sport port is really a waste of time, $$ and a lots of time a loss of power and ride-ability.
About making sleeves, if you go that route...use big bore sleeves this way you get a great power increase for bigger cc's.

 

[Waternut]

I'm not trying to bash this guy who does jet boat engines but there are plenty of people on here who have asked for freestyle engines from their "engine builder" only to find out that the guy could talk a great game and port like a retard. Math and calculations are good when done by someone who knows what they mean. If not, might as well give your cylinder to the bum on the street. It's not as easy as 1+1=2.

 

[Polish jet pilot]

My current setup:
- OEM engine
- removed chokes from oem carbs
- r&d angled inlet mani. spacer
- bpipe limited, bored exh. manifold and polished windows
- removed rev limiter

Willing:

- 82/83mm pistons (to be decided whether cast or forged pistons)
- cylinder porting
- cylinder matched to cases
- taper bored 38's with atomizer mod (riva powerbomb type)
- carbon tech Low Tension reeds
- OEM milled head (to be pump safe) or aftermarket head w/ girdle kit (preferably ATP Snake head)
- dual cooling (1 line for engine only, 2nd line for exhaust only ? )
- Ignition will be most probably left alone for now

The hull is defoamed and quite light. Pump is blueprinted, running oem 2008 prop, WW cone, and bored nozzle to 84mm

Andrew

 

[SUPERTUNE]

Take off the R&D reed spacer, your hurting bottom end right now.
GET SOME HEAD!! (you need some decent compression)

 

[SUPERJET-113]

Whats wrong with the R&D angled reed spacer?

 

[SUPERTUNE]

Whats wrong with the R&D angled reed spacer?

Without finger porting in the cases, still using stock carbs, not using a high performance reed system, has stock compression head and still running stock ignition... you just hurt the bottom end.
I've done it before so I know NOT to do it and was giving friendly advice on what I have learned for freestyle/freeride setup, now if your racing and running a more aggressive setup and turning over 7000 RPM's then that's were the benefits come into play with reed spacer plates.

 

[SUPERJET-113]

Ok, Ya, makes sense for a stock mild set up.

Now is that because on a stock set up with the spacer plate your just making more crank case volume and setting the carbs that much further back for a weaker signal and takes longer to get the fuel charge?

I have the RD angle spacer,but I have DASA engine, MSD TL, high comresssion head, B pipe, blah, blah, etc..
I like the 3 degree angle to help shoot the charge a bit more upwards and then help with the reed turbulence.

 

[Polish jet pilot]

What about if my setup will be different:

- head
- porting
- modded oem carbs (taper bored, venturi modified, no chokes)
- disconnected rev limiter
- bored to 82-83mm
- bored b pipe

I think it would be ok then?