FlatTop Domes and Compression..

[Yamah0]

So i had 28cc domes on my setup and that gave me 150psi compresssion which i think was too low... so then i swapped to 24cc and that gave me
225psi which is too high for the gas im running, so i switched back to 28cc.

Then i was told that the numbers didnt make sense cuz the difference in psi was too big for just a 4cc difference, so that made me doubt the comp gauge i used when i checked the comp with the 28cc domes and thougt that my compression was over 150 with the 28cc, untill today when i rechecked the compression with a good gauge and saw 150 psi again.:banghead:

I checked everything, did a leakdown test and everything seemed fine.. soo did anyone run a 28 or 24cc domes on a Magoos flattop freestyle cylinder? What compression did u get?

If there was actually something wrong with my motor for it to get that 150psi... what could it be?

Dunno if this whole thread flowed but Im frustrated cuz i still havent got my motor to run right ever since i got it:banghead: :banghead:

Im gonna try some 25 and 25.5cc domes and see what i get... i was told i should be around 195psi with the 25cc domes, so we'll see.

 

[Flash-FX]

Zane..Just like everything ...there are lots..LOTS of variables. You should be able to get that thing running pretty good with only 150 Psi cranking pressure. Jr. Magoo's (Paul) Knows how to make low end HP with just about any cylinder. So, with that as a base you need to get that new carb dialed in. Those dam carb/s...
I've spent too much time messing around with jetting ..pop-off..:banghead: than I ever wanted to. (my buddy's are still busting my chops) Start with the idle and work your way up. Get or make a good pop-off gauge..you will most likely need it. Take your time..don't run it too lean. Sans...carpe piston $$.
High compression makes lots of heat that can destroy stuff real quick...Be cool..
That's a sweet boat, you need to enjoy it...:smile:

 

[waterfreak]

You should really check your squish clearance. I also run a 85.5 mm flat top motor with 26cc domes that yields 190 psi with .042 squish.

I also run a single 48mm freestyle carb that hits like a brick wall:banghead: :Banane01:

 

[Yamah0]

Ok found my problem:Banane01:

The supposedly 28cc domes that Jr Magoos sent me were actually 35cc. I just put in some 26cc domes and got 200psi... i was aiming for around 190-195psi, but thats cool.. ill keep it at 200 for a while tho...

 

[Jr.]

Were the 35cc domes marked incorrectly, or did I send you the wrong ones by mistake??................

In either case let me know & I'll correct the situation

 

[Yamah0]

Hey whats up Paul... Ya i pulled the domes out and the number on the was like y###35#.. so i assumed theyre 35.
Anyways, i put the 26cc on and now i need to rejet my carb and see where that puts me... I hope i can finally see what you cylinder really does:Banane01:


Zane...