MZMiami 6.00CC High Comp Head and Spark Plug Reach

[SeanPatrick]

I posted part of this in my build thread but I wanted to make a separate thread to help anyone else who is using this head.


When I got this head I bolted it on and ran it without checking anything first. I figured whoever designed it knew what they were doing (I've learned to never assume that in this hobby).It felt like LESS compression than my stock slant head. Now I know why. After looking at it when I tore down my motor I see the plug was no where near deep enough.
It's this head from MZMiami http://www.ebay.com/itm/MOTORIZED-BI...item4198654527

This is with the stock equivalent plug. I took the picture with an NGK BR6HS installed.
You can't even see it down in there. This would seem to be where my low comp was coming from.


This is with an NGK B6ES installed. "E" is longer than "H"


for more reading on those plug numbers http://www.ngksparkplugs.com/techinfo/spark_plugs/partnumberkey.pdf

Hope this helps anyone else using this head or facing a similar problem.

 

[florida_rider]

after installing the E plug,did you notice a difference in compression?

 

[SeanPatrick]

I have not gotten around to trying it yet. I will report back with what I find. I would assume it would have higher comp. a half of inch of spark plug worth was removed from the equation.

 

[HeadSmess]

pretty typical...

you think if you were going to change from a standard plug, in any respect, you may as well go to a c or d series and utilise the extra space for more cooling fins...

that was just the way i saw it when i made a few myself...

the water cooled head did need an E thread plug...


you also gotta fiddle with the ideal heat ranges for a different head due to the extra heat being drawn from the plug. ie, go hotter... down in numbers for ngk.

 

[SeanPatrick]

you also gotta fiddle with the ideal heat ranges for a different head due to the extra heat being drawn from the plug. ie, go hotter... down in numbers for ngk.

Right before I found out about my reach problem, I had ordered a bunch of H plugs between 4 and 9. I'll be ordering more in E now.

Got any more pics of that sick set up? What pipe is that? I'm working on mounting an RM60 pipe right now.

 

[HeadSmess]

somewhere...i aint digging em up...i got threads somewhere

http://www.motoredbikes.com/showthread.php?40617-at-it-again-a-real-pipe-this-time
hard find...

handmade, did a few of them. port matched, tuned for the engine... huge difference. no wonder i bag out all these botched jobs


i could post the dimensions for the 8000rpm one i guess... you gotta do all the hard bits! but i made my first pipe with a fence stake and and a hammer as my "tools"... now i have a roller. pretty cheap the tapers are still hard though...

hint... download a program called "cone". make your mock ups in about 200gsm paper, its thick. almost cardboard i guess.. buy a ream at office supplies, that program "cone" is paper intensive!

from dimensions (ill post em eventually) you divide each section into easily managed lengths with 1 or 2mm increases in diameter per piece. then get some wire, mark the length of each piece on it, and figure out the bends, placing each one on a mark.

using cone, you then adjust the end angle on each piece to half the bend angle you desire...

the paper gives you an idea of the rotation youll need in each piece.... then its a matter of copying everything out in sheet steel and out with the stake and hammer...and tinsnips etc, of course.

also, try to make your bends small...it takes a lot of pieces. i tried doing one with about 6 joins through a 200 degree bend... really nasty, could feel the turbulence inside it fighting every step of the way... struggled to hit band, barely held it... but the exact same pipe done with a smoother 12 bend curve was perfect...

the carbon deposits inside are a good sign of any flow restriction...

 

[HeadSmess]

and as for water cooling...maybe, just maybe if i had thought of using a pulse pump/fuel pump off the crank pressure, it may still be in use... it had issues as a "thermosyphon" setup... i just recall one particularly chilly night, i had a tpiece as a vent on it...

it starts boiling, sprays some steam out, so i pop my finger over the tee...

and suddenly it creates a vacuum in the radiator, the waters flash boiling in the head, and recondensing in the radiator, my finger was sucked onto the tee piece, and it ran at about 70C or so at that reduced pressure...


basically it was fine from cold but if i stopped for even a minute it seemed to go vapor lock and overheat, spraying boiling water over everything vinyl hoses didnt help...

another thing to think of remaking thermosyphon would work if i had the outlet on top, and about 3/4 inch ID.

 

[SeanPatrick]

I got as far as a 2D model on paper and downloaded cone before I realized there was no way I could build one in my appartment. I settled on a suzuki RM60 pipe. I'm starting school in two weeks to be a machinist. So many I'll re-attempt later.

 

[HeadSmess]

determination never hurt...

small gas stove, blowtorch and start brazing

people have no ingenuity anymore

 

[butre]

brazing is a lost art, and even the people who know how to do it think of welding first. I'm guilty of it, all the time I go for the stick welder even when I should know that brazing would be more appropriate.