Newb ada head compression question for my SJ

OSA758

OSA758

Hey guys so ive had my 09 SJ for a year now and rode it all last summer no problems. But i did a compression test the other day cuz i was curious to see. I got 210 PSI each cylinder. Its an ada head i dont know if its a regular or
Girdle head or whatever you call it. I have a factory b wetpipe aswell.
The guy i bought it off ran pump gas so i am too but im pretty sure 210PSI should be race gas at least 100-110 octane. Should i be worried? Any suggestions?
 
Sasquachcrap

Sasquachcrap

Location
North Carolina
I would say thats a little high for 93. Are you sure your gauge is right. I dropped mine the other day and screwed it up. I tested it against a known good gauge, the broke one was 25 psi high. Do you know what size domes you are running?
 
JetManiac

JetManiac

Stoked
Site Supporter
Vendor Account
Location
orlando
As mentioned above, compression guages and procedures used can vary the results obtained alot. What is your dome size? I would assume you dont know since you bought it altogether.

If your reading is accurate, then it depends on your ride style. If you like to run WFO and race around, then definately you should replace domes with a larger size. If you do brapp brapp freestlye type riding with limited duration WFO, then 210 is just fine with 93 pump gas. My Own setups are usually 210-215 on pump gas and no detonation or issues but careful with the WFO and dual cooling.
 
OSA758

OSA758

JetManiac said:
As mentioned above, compression guages and procedures used can vary the results obtained alot. What is your dome size? I would assume you dont know since you bought it altogether.

If your reading is accurate, then it depends on your ride style. If you like to run WFO and race around, then definately you should replace domes with a larger size. If you do brapp brapp freestlye type riding with limited duration WFO, then 210 is just fine with 93 pump gas. My Own setups are usually 210-215 on pump gas and no detonation or issues but careful with the WFO and dual cooling.
Click to expand...
Yah i dont know the size dome but im assuming its 31-33cc.
I usually ride braap braap, once and awhile wfo for at least 15secs. And alot of times just ride a steady 1/4/ - 1/2 half throttle speed to get to other wnd of lake
 
OSA758

OSA758

SXIPro said:
How are you testing it? Warm? Cold? Throttle open or closed? What gauge and what tip on the gauge?
Click to expand...
It has been in a warm heated garage all winter, but it wasnt warmed up from riding if thats what you meant. So i dunno if thats considered cold.
I made sure i ran it first a little to clear any excese fogging oil from the winterizing. Checked it throttle open and checked it no throttle and same reading. Using a brand spankin new snap on gauge!
 
JetManiac

JetManiac

Stoked
Site Supporter
Vendor Account
Location
orlando
OSA758 said:
It has been in a warm heated garage all winter, but it wasnt warmed up from riding if thats what you meant. So i dunno if thats considered cold.
I made sure i ran it first a little to clear any excese fogging oil from the winterizing. Checked it throttle open and checked it no throttle and same reading. Using a brand spankin new snap on gauge!
Click to expand...

Try it again after you go run it. May be getting false high reading from the remaining fogging oil.
 
Quinc

Quinc

Buy a Superjet
Location
California
If there was water or oil in the cylinders it will read high. Try turning it over with the plugs out for a few seconds to make sure there is nothing in the cylinders and test it again.
 
OSA758

OSA758

Quinc said:
If there was water or oil in the cylinders it will read high. Try turning it over with the plugs out for a few seconds to make sure there is nothing in the cylinders and test it again.
Click to expand...
That was the first thing i did. Turned it over without plugs then put plugs and ran it for a bit then did the test again. Still the same.
 
OSA758

OSA758

SXIPro said:
You really want to test it when it is fully warmed up, not after thirty seconds on the hose. Ride it for a while, beach it, test it.
Click to expand...
Okay will do. Il let you guys know what i get after riding it for awhile. But i have to let it cool down because testing it warm would read higher. Then when its cool wouldnt i get same readings as i am now?
 
Last edited:
OSA758

OSA758

So....ive been busy and put this off, but i realiZe by asking a few other ppl that i have stock 701 case and cylinder because it has 62T on case and 61X on side of cylinder. Diametre of cylinder is 83mm.
I took off my ada head and it was a 37cc. Judging by ada specs 37cc should read 170PSI for 701 and if it was a 760 should read under 190PSI. Dunno y im getting 210PSI still.
 
OSA758

OSA758

Is it possible i the dome was shaved? I doubt the guy before me would do that. Or maybe high compression piston? I dont know how to compare the piston to see if its stock or high compression one
 
lanmine657

lanmine657

Location
fortcollins
Can you get a hold of the guy you bought it from? Who knows what's in there that's giving you high compression with out tearing it down, cylinder may be decked who knows. Ignition timing is another key factor for your fuel selection not just compression alone, I'd still try another gauge even though snap on is usually accurate before you spend money on domes or better fuel
 
OSA758

OSA758

lanmine657 said:
Can you get a hold of the guy you bought it from? Who knows what's in there that's giving you high compression with out tearing it down, cylinder may be decked who knows. Ignition timing is another key factor for your fuel selection not just compression alone, I'd still try another gauge even though snap on is usually accurate before you spend money on domes or better fuel
Click to expand...
I could probably find his contact info somewhere. And i just ordered new orings going to put head back on and check again with different guage. But snap on one is brand new havnt had issues with it. Is there like different adapters i need for the guages?
 
You must log in or register to reply here.
Top Bottom