Freestyle Ada head not sealing

S

Seas2699

Location
Redding
Have a 62t with blowsion 850 sleeves and pistons. Has an ADA superbore head with I believe 951 domes machined to fit. Ride the ski for about 10 minutes and then it will suddenly act likes it’s on one cylinder. Water coming from between head and cylinders. Is the head bad? Torques down fine and orings look fine but it only last a couple minutes before going down. If I do need a new head what are my options to fit?


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S

Seas2699

Location
Redding
Big Kahuna said:
Orangefinger asked because years ago there was a run of fake ADA years floating around that did not seem well. Or your head is worn out.
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I’m really not sure. The engine was built by a gentleman on here and I ended up with it in the ski I bought hahaha. Runs for a few minutes then no power at all. You can pull it out of the water and clear it out and it runs fine. Idk if the domes have just lost any squish from working into the head or what. Head is torqued down good and new orings were put in. I’m stumped. Seems like a very short time for the head to lose compression.


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S

Seas2699

Location
Redding
I’ll see if shimming the domes helps. Or I’ll just fill the whole ski with gas and see what happens


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cookn

cookn

Kamikaze
Location
where you live
I bet the shell is worn out because the domes should stick out a few thou to get the desired crush. try shimming them and see but a few years ago when i was looking at building the 850 the superbore heads were still available and if the domes are whats worn out im sure you could send the ones you have out to be matched by someone who cuts domes
 
S

Seas2699

Location
Redding
I’m thinking it’s the shell. The domes seemed fine. Replaced all the orings and didn’t help. If the shims work then it’s time for a new head. Ik the domes are 951 that have to be machined to fit. Ik blowsion makes domes but idk if they have to be cut or not and I think they only come in 50cc for some reason. I don’t think Ada even makes the superbore head with the girdle anymore so I’ll have to research what head and domes would work with the cr500 sleeves.


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Jr.

Jr.

Standing Tall
Staff member
Site Supporter
Location
Hot-Lanta
If you find its your headshell? I have a couple of ADA superbore headshells left over from when I built a couple of these jugs years ago? It has both ADA and my old JRM logos on them. Ill give you a Killer deal just to get it off the shelf!
My guess will be sleeve dropped? Or when they over bored for the sleeve, it touched into the waterjacket, thus allowing the water to seep in under pressure? Have seen both happen with this style superbore

Ski ya, Paul
 
orangefinger

orangefinger

Location
Reno,NV
there was another small tiny batch of ADA heads / domes where the groove for the O ring had been machined too big, do a close visual inspection and make sure the O rings sit nice and snug and don't have play...

The girdle bolts we tighten to 35 , that is not recommend specs from ADA but instructions from some engine builders thus some of these head had been known to improperly seal with 25 ...actual head screws stay with ada recommended specs... ( Yamaha )
 
S

Seas2699

Location
Redding
orangefinger said:
there was another small tiny batch of ADA heads / domes where the groove for the O ring had been machined too big, do a close visual inspection and make sure the O rings sit nice and snug and don't have play...

The girdle bolts we tighten to 35 , that is not recommend specs from ADA but instructions from some engine builders thus some of these head had been known to improperly seal with 25 ...actual head screws stay with ada recommended specs... ( Yamaha )
Click to expand...

I can tell you for sure the outside oring to seal the entire head doesn’t fit at all
The groove is much larger and the oring has to be greased to stay in. I’ll post up pics of inside and outside the head and see what you guys think.


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Quinc

Quinc

Buy a Superjet
Location
California
Seas2699 said:
I can tell you for sure the outside oring to seal the entire head doesn’t fit at all
The groove is much larger and the oring has to be greased to stay in. I’ll post up pics of inside and outside the head and see what you guys think.


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Click to expand...

Order new ada orings (From ADA) Some vendors are buying and re-selling mcmastercarr o-rings.
 
S

Seas2699

Location
Redding
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S

Seas2699

Location
Redding
e4266443ef758b95d7e6276a55e72959.jpg
it kinda looks like the domes aren’t sitting on the sleeves properly like they are pushed off to one side


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