Tri Z Engine Build

[aramid]

Both great ideas guys THANK YOU!!!! CCing is still pending.

yeah, the mold idea is cool to, good suggestion . . If you use the mold idea, you can also use plaster of paris instead of silicone if you want . . the plaster is easy to sand if needed plus you only need to wait 30 minutes for it to dry instead of 2 days.

You can spray some silicone on a piece of metal in one area and put wax like turtle wax in another then put a dab of plaster on it then try to pull if off when it dries and use whichever one works to put on the head . . then just fill the head up with plaster.

If you want you can color the gasket surface of the head with felt pen before adding wax and plaster then after the plaster dries you can put a piece of 180 orange sand paper on flat surface and carefully sand it until the plaster is flush with the head . . the felt pen mark will be your guide so you dint sand the heck out of the head by accident.

You can put a line over the top of the plaster at the half way point then cut it just on the outside of the line with a cut off wheel . . then lay a piece of around 180 - 220 orange sand paper on a flat surface and sand it up to the line.

you can now use the plaster mold to trace out your tracing paper and save 8 bucks on a pin gauge that you may use again however, the pin gauge can be used on the piston top too then you can lay the finished tracing paper over the paper from the head shape and get a visual perspective of what's going on.


as far as measuring the head volume . . if you don;t currently have a plate you can just use your least favorote cd . . the size is perfect pluss it already has a hole in it . . if its something good like ozzie, you can just clean off the greae afterwards and it will be just as good as it ever was . . i think.

[onformula1]

yeah, the mold idea is cool to, good suggestion . . If you use the mold idea, you can also use plaster of paris instead of silicone if you want . . the plaster is easy to sand if needed plus you only need to wait 30 minutes for it to dry instead of 2 days.

You can spray some silicone on a piece of metal in one area and put wax like turtle wax in another then put a dab of plaster on it then try to pull if off when it dries and use whichever one works to put on the head . . then just fill the head up with plaster.

If you want you can color the gasket surface of the head with felt pen before adding wax and plaster then after the plaster dries you can put a piece of 180 orange sand paper on flat surface and carefully sand it until the plaster is flush with the head . . the felt pen mark will be your guide so you dint sand the heck out of the head by accident.

You can put a line over the top of the plaster at the half way point then cut it just on the outside of the line with a cut off wheel . . then lay a piece of around 180 - 220 orange sand paper on a flat surface and sand it up to the line.

you can now use the plaster mold to trace out your tracing paper and save 8 bucks on a pin gauge that you may use again however, the pin gauge can be used on the piston top too then you can lay the finished tracing paper over the paper from the head shape and get a visual perspective of what's going on.


as far as measuring the head volume . . if you don;t currently have a plate you can just use your least favorote cd . . the size is perfect pluss it already has a hole in it . . if its something good like ozzie, you can just clean off the greae afterwards and it will be just as good as it ever was . . i think.

I have never used plaster of Paris, but it should work fine, I use silicone because it lasts forever I have molds that are 25 years old and they still work.

I don't have experience with plaster of Paris, does it hold up for the long haul?

I use a 3/8" piece on glass with a small hole in it because its heavy & you can put the hole on the outer edge so the head can be carefully rotated to get any air bubbles out. Regular water with a few drops of food coloring helps as well.

[cr480r]

I always just used a tiny angle finder.. Plenty accurate to measure differences between the dome and crown.. Even checking squish with solder will tell you if the squish band is positive, parallel, or negative.. Or you could even leave the head and base gaskets out for mock up and use plastigage.. Don't over think it. I've always cut squish parallel or 1-2 positive if the piston has a lot of crown, use torqsoft calculator to figure the band width needed for desired msv. Squish clearance has quite an effect on msv. Then last work the bowl to get desired volume. Always works for me. I repaired a friends cr250 head that had a damaged dome. I had no way to weld it, so i took a generous cut. He wanted to run pump gas no matter what so I reduced it to around 14.7:1 CR.. To get the chamber large enough i had to use a toroid/bathtub design. It ran fantastic, he didn't trust the funky head so he later bought a oem head for it. It lost power everywhere even with more compression. Most people just bolt them on and go, but the head plays a big role on performance and should not be overlooked.

[Billy Golightly]

Billy, I can't tell from the picture, you didn't cut the piston to the edge correct? can't tell if there is one or to cuts on there.

In other words you didn't effectively raise all the ports including the exhaust port correct?

No, I didn't do anything with the edges of the piston. I basically flat topped part of the piston, and left sort of a reverse squish band on the exterior edges. Lowered compression and lightened the piston. I went in about a half inch from the sides, and then machined flat straight across to the center. Thats why I was saying when I did this, it was kind of the opposite of working on the outside edges only.

[MTS]

Your Sprock head photos are a little blurred, but it seems the width of your band is less than mine. The outer edge of the chamber to where the radius begins on mine is .450" (measuring the slope which is probably not the right way) Yours looks smaller in the photos. Same as the Tri-Z head. Could be my imagination, or maybe I have one of the newer domes
Attachment 209357

Sorry for the crappy old cell phone pics But i measured 12 mm, .475 , Cr480 seems to have a handle on this whole deal, im just working on a few other measurements trying to get this figured out, i Do have a Ronnie head sitting here, And it appears that the Angle of the Squish is the big difference, Just need to get a smaller angle finder to get a more accurate measurement. Must say this is One of the more intresting topics of late....good work

[ironchop]

El.....we use this stuff at work that's a two-part deal made by Plasti-guage (I think). You mix it up and pour it into whatever you want to make a mold of and its dry in an hour I believe. Works kickass and we frequently use it to take measurements of blind features inside of prototype parts to check difficult location dimensioning.

We get it from MSC Industrial Supply. I`ll look up the actual product name and get back with you

[Billy Golightly]

Would great stuff expanding foam insulation work also to get a good visual (assuming you had everything greased down good where it wouldnt stick)

[aramid]

Any of the expanding foams will work fir thus purpose . . A basic paste wax will prevent it from sticking . . Once it is poured into the head, a piece of plastic food wrap can be layed over it and slight pressure can be applied as it expands . . This will cause the foam to be denser and therefore more durable and easier to work with for this type of app . . Some hardware stores and of course amazon.com carry it.. . I have always used the 2 part foam, I have never used the single part spray foam but I guess it would work but I think it might be a bit less structurally strong . . Home Depot has some for 4 dollars but I seriously doubt it will work very well just based on the price.

http://www.homedepot.com/p/GREAT-STU...2848/100003351

http://www.amazon.com/Dow-157860-Tri.../dp/B0002YX9GG

http://www.uscomposites.com/foam.html

[El Camexican]

Thanks for all the suggestions guys. I ordered up the multi pin gizmo, should have it by next weekend.

MTS, I sure hope you can post up every detail possible on that head. It would be great compare it to the Sprock dome I have as well as use cr480's math to see how they compare. Maybe a small chamber Sprock dome can be cut to that profile?

Fabio mentioned the 490 earlier. Reminded me that there is still a guy up North racing them in the veteran class. I've never met him, but he's good buddies with the guy that sold me my Duck, so I plan to pick his brain before this is over. I'm told he has a few tricks for them that makes them purr.

Anyone recall reading of a 3rd Wrench Report? It's mentioned at the tail end of one of the Wrench Report articles that can be found on the internet. The same Ducati buddy raced quads in the mid 80's. He said the local Yamaha dealer had been campaigning a Tri-Z that they added a wheel to when the ban happened. He claims that Yamaha had offered the dealers kits and instructions that included the long rod. He's certain that that engine had it and said it was flat out the fast quad on the ice bar none. The dealership was Riteway Yamaha. Not sure who may still be around from back then, but surely if such a kit or instructions existed someone else has heard of them. Could this perhaps be the III Report?

[onformula1]

No, I didn't do anything with the edges of the piston. I basically flat topped part of the piston, and left sort of a reverse squish band on the exterior edges. Lowered compression and lightened the piston. I went in about a half inch from the sides, and then machined flat straight across to the center. Thats why I was saying when I did this, it was kind of the opposite of working on the outside edges only.

Got it, Thank You.

Very cool too.

[El Camexican]

Started documenting the ports tonight. Not as bad as I thought it would be. I still need to deal with radiuses and angles, but its a start. Was thinking of Tecati Dan while messing with this

[onformula1]

Hey, El Camexican want to have some fun? Check this out-

To reach 100% Volumetric Efficiency (Doesn't always happen, but you want to get close) The intake port or intake track should be 10% to 15% larger than the carb. bore.

So the question is what size carb. should I run?

Your intake port is 41mm X 48mm, add them together = 89 divide by 2 to get a average = 44.5

Most motors run best with a carb that is 15% smaller (good for all around use & MX, SX, Gp's, enduros)
Which is- 37.82mm or 38mm carb. size.


Some motors run best with a carb. that is 10% smaller (High speed desert, but gas mileage will be worse, Dunes, Drag racing, pin the tach boys)
Which is- 40.05mm or 40mm carb size.

[El Camexican]

Hey, El Camexican want to have some fun? Check this out-

To reach 100% Volumetric Efficiency (Doesn't always happen, but you want to get close) The intake port or intake track should be 10% to 15% larger than the carb. bore.

So the question is what size carb. should I run?

Your intake port is 41mm X 48mm, add them together = 89 divide by 2 to get a average = 44.5

Most motors run best with a carb that is 15% smaller (good for all around use & MX, SX, Gp's, enduros)
Which is- 37.82mm or 38mm carb. size.


Some motors run best with a carb. that is 10% smaller (High speed desert, but gas mileage will be worse, Dunes, Drag racing, pin the tach boys)
Which is- 40.05mm or 40mm carb size.

As luck would have it I have a 38mm Keihin for it. Do you count the boyesen ports in that number?

[El Camexican]

I was asked to post what it is I'm reading. I'll keep adding to this post as time goes on.

http://www.macdizzy.com/cyl_primer.htm

http://www.amrca.com/tech/tuners.pdf (thanks Beets!)

http://justyamahard350.com/articles/eric.htm

http://www.singaporebikes.com/forums...g-the-2-stroke

[onformula1]

No if you did you would need a Holley carb.