OLD SCHOOL TRINITY HEAD

[BANSHEEFIEND]

I HAVE AN OLD TRINTY RACING HEAD THAT CAME WITH MY BANSHEE WHEN I BOUGHT IT. IT DOESN'T HAVE THE INTERCHANGEABLE DOMES. WOULD I BE ABLE TO PUT A SPARK PLUG IN IT, FILL IT WITH WATER USING A SYRINGE, AND DO SOME QUICK MATH TOO FIGURE OUT THE C.C.S? ALSO, WHAT IS THE SMALLEST C.C.S THAT I COULD RUN ON 94 PUMP GAS?

[ogre03]

why not just do a compression test? That's what you are wanting to find out right? If your compression is too high to run on pump gas.

 

Well first off I guess I should ask if it is on the bike...

Edited December 18, 2005 by ogre03

[BANSHEEFIEND]

IN THE PROCESS OF REBUILDING, HAD A STOCK HEAD. I TRIED MY IDEA AND CAME OUT WITH ABOUT 19.5 C.C.S PER DOME. PUMP GAS COMPATIBLE?

[itsaripper]

What you did getting the CC of the head wiil give you a ballpark idea of where you will be. If the head has Orings to seal it will be closer to the 19.5cc. If not and you use a head gasket then you have about .010 compressed space there. Your piston is not going to come all the way to the top of the cylinder, called deck hight. But you can ajust with bottem gasket,or machining some off. Brand new piston and ring will give you the max that you are going to get with that setup. The best way to know is bolt it on and take a compresson check.

McDizzie has a bunch of formulas that you could use to see what you have.

[BigRed350x]

OMG don't use water to figure it out. That will rust your cylinder walls. Even if you can't see the rust, as soon as water contacts that non-finished metal it will begin the rusting process. Use gas or alcohol if you are going to do that. You could even use two stroke oil. Just make sure your piston is at TDC before you go squirting anything in there or you will be pretty unhappy. lol

 

Just buy a compression tester.

Edited December 18, 2005 by BigRed350x

[locogato11283]

u need to doa compression check to see how many pounds of compressin you are running. that will determine what gas to run..if u are above 160 pounds 94 octane will be need to be mixed with something with a higher octane.

[BANSHEEFIEND]

BIGRED30X, I DIND'T FILL THE CYLINDERS WITH WATER. I JUST BOLTED THE HEAD TO A PIECES OF PLEXIGLASS, SEALED IT WITH CHAPSTICK, LEFT THE PLUG OUT, THEN USED A SYRINGE TO FILL TO THE BOTTOM OF THE SPARK PLUG HOLE.

[Ducman]

BANSHEEFIEND, the way you measured it sounds close enough. I would say that you could be off + or - 1cc. If your getting 19.5cc (probably 19cc with the plug in) I would say it would require race fuel mixed 50/50 with 94 pump fuel. 20cc dome would work with 94 if you run it at stock timing or if you are at 1500+ ft elevation. If you do install the head then measure compression you'll have a better idea as long as you have stock cylinders. 160psi or less will be ok on 94 octane. But, if you have porting with a raised exhaust port then you will read a lower psi with the same dome size, then you cant assume 160 psi is ok with 94.

 

It is best to meausre the volume with the plug in as it takes up about 1/2 of a cc. Just screw the plug into the dome, cut a hole in a cardboard box and sit the dome/head on the box so the dome is facing up and level. Fill it with a syringe using rubbing alcohol since it has very little surface tension. If you use water (high surface tension) it will form a dome of water (miniscus) before it spills over the edge so your number could be alot larger than the actual volume.

 

You can still have trinity or an machine shop that knows how to correctly cut domes, recut the domes to a larger volume.