MY THOUGHTS (and there ONLY MY thoughts) is there are pro's and cons with running the stiffner plate... There really isn't much advantage to useing the stiffner plate as far as I can tell.. The TORQUE (or twisting) doesnt come into play until the crankshaft turns the reciprocating motion into ROTATING MOTION..Therfore, there really isn't any need to keep the cylinders from moving around independently of each other.. I could see from an aluminum density standpoint that the stiffner plate would keep the jugs from moving around,,,but,,,as far as making more horsepower,you'd have to find out if the INCREASED HEAT of the heads actually HELPS YOU or HURTS YOU!!! Naturally, thicker aluminum has a tendency to hold heat moreso than thinner aluminum. BUT,,, The STRONGER aluminum expands differently than "cast" or "POT" aluminum... Lets say (FOR EXAMPLE ONLY) that the "jugs" expand .004 and the headplate expands .002. Well, there is a PROBLEM THERE and the jugs are going to cool and adapt to the discrepancy... The adapted jugs are now GEEKED .002 which puts them in a "bind" promoting unnatural wear...... There have been tests done PROVING the headplates ACTUALLY HELP,,, but,,, there is a JETTING AND TEMPERATURE concern that could produce the SAME RESULTS!!!! As far as the theory of the cylinders FLEXING,,, WELL<<< if we were talking MOTOR MOUNTS I would agree.. but the motion of the cylinders and pistons have LITTLE if any effect on the torque of the motor...
It does look pretty cool though!!!
Mac
Member
ExpertX - I had my domes opened up from 700 to 780 cc. Maybe what you are seeing is the larger overall diameter. MrViper helped me out with the machine work. ExpertX are you building a trail motor? You should check the cc and measure PSI. I'm going to break in my engine on the weekend and expect the compession to climb into the 150's.
vipertripplexxx
New member
Good point. Yamaha's don't need the plates on trail motors. Unless you run ultra high compression, it's a waste of your $$$$$$$$$$$.
Mac, What squish are you running? I run my STD. Bore 700 mega's at .045".
With the big bore widening the band do you increase squish slightly?
Mac
Member
Mega squish
XXX - Squish is .051 to .053 Your opinion it should be higher? Is it possible to go less squish running pump regular and still be safe?
XXX - Squish is .051 to .053 Your opinion it should be higher? Is it possible to go less squish running pump regular and still be safe?
vipertripplexxx
New member
I would think that would be about as close as you want to go with pump gas. I figured you would bring it out a little since the squish width is actually larger.
Thanks for the reply, Steveo
Just because the band is wider really has nothing to do with you needing to go more squish clearance, the optimum squishband width is 45-55% of the bore! Some race engine will use up to 60%, some less then 40% of the bore. Its all about engine application(more precisely the load in which the engine carries) as to what band width you use. You can run .035" squish on premium pumpgas if you change things, it all has to do with squish angle,radius and the dome cc. Your controling the flame front travel on the piston dome, or the combustion control, a wder band aloows you to centralize the combustion on the crown so if you have a large squish clearance you create a larger spot for stagnent fuel mix to create hot spots and form detonation under the edges of the cyl head and piston top. If you ever study a burn down sled engine youll find the piston to have the edges taken off or pitted badly, you seldom ever see the middle damaged.
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vipertripplexxx
New member
More squish clearance generally is safer as far as detonation goes!
Do you mean a wider squish band?
Wider squish band + same fuel = more squish clearance needed.
"Megas can run very tight squish clearance because the band is narrower than the stock squish band" Dave Trygstad proffesional race engine builder.
By the way Daves wife passed away recently, say a prayer for his family.
Actually its just the opposite. Tighter squish is safer as far as detonation goes, it matters on what the dome size is and the angle in which the squish is to the piston angle, the tighter it is the less wasted charge is trapped on the piston edge and not burned till AFTER TDC and is wasted energy, causing hot spots and loss of combustion efficency- A Grahm Bell, author of 2 stroke performance Tuning book!!
You can go tighter on the squish with a angle change, correct dome size,running the same fuel octane and have LESS detonation! The squishband width all goes hand in hand to the amount of labor the engine is sustained to under load(meaning rpm level)
viper domes in mega inserts are thinner squish band, srx ones are not.
Sorry to hear about Daves loss!!
You can go tighter on the squish with a angle change, correct dome size,running the same fuel octane and have LESS detonation! The squishband width all goes hand in hand to the amount of labor the engine is sustained to under load(meaning rpm level)
viper domes in mega inserts are thinner squish band, srx ones are not.
Sorry to hear about Daves loss!!
Don
Hey I checked my squish on my mega set up, with center layer of gasket removed, and got right around that .059 to .060. Sounds kind of wide compared to others. I am going to run premium no matter what, but does this sound right to you. Maxdlx
Hey I checked my squish on my mega set up, with center layer of gasket removed, and got right around that .059 to .060. Sounds kind of wide compared to others. I am going to run premium no matter what, but does this sound right to you. Maxdlx
Paul, its wide but its runable. how much cranking compression does it have?
about 130, I need a new gauge though. i think this one was dropped, by a 3 year old
Don 110 on all 3 with a new kd tester. seems low for mega power and no center layer. Paul
vipertripplexxx
New member
To a certain point, but too high of an MSV, and your going to have detonation. M2C. There is a happy medium on this, too much either way and you will have problems.
Madlx, If you have .060 squish with mega powers your gonna be losing some power. those heads like tight squish .045". Unless you are running CPR pipes, then .050" would be better. M2C.
I'm running aaen pipes, and that was a cold test. maybe I'll try and warm it up and test it. I had someone tell me that the 8 inch hose on my new gauge will cause low readings. Those readings where after 5 pulls, with throttle open and closed, same 110 across the board. Maybe I can remove the hose and try it too. Maxdlx
skidooboy
New member
remember every tester is different. and you need a consistant test, to test guages to one another. so when doing compression test on EVERY MOTOR , with every tester it should be the same. my procedure is from bill cudney of cudney racing.
i do this for every test. cold motor, start and run for 5 seconds, pull all plugs, throttle wide open, 8 pulls. read read the guage. then i have an idea that i am in the ball park knowing how the gauge reads, high or low, motor to motor.
megapower recomends 2 layers of .010 gaskets for pipes and 1 for single piped vipers. your numbers are consistant from gauge to gauge (they read the same cyl to cyl) i am guessing your new gauge is reading low. i ran mine with 2 layers with a snap on guage i was at 130-135 on my viper.
but heed the warnings of the tuners here. squish and compression are all relative. EVERY TUNER has a different train of thought and methods to getting what they believe to be the best of what they know. loose/tight squish, hig/low compression, wide, narrow squish bands, ect... there is a give and take. too much too little or mixing them up might be super good, or super bad. seperates the tuners abilities. and this is a good thing, you find better ways to skin that cat.
and dont look at me cause it's all french to me. i tell em what i want out of the sled, and let the tuner tell me what to do. don has been very pacient with me as we have had some stumbling blocks with these heads. after buying a total of 17 new domes and selling 6 (including the set you have paul) gave 4 away, traded 3 high comp domes for 3 machined low comp domes, endless shipping back and forth, and dons hours on the lathe and in the machine shop. (thanks big guy, i'm trying to relax and not be so serious LOL) it has been along strange trip. but the sled is together and running and needing snow. i should be up riding right now but backed out. and some how i still have 7 domes sitting on the bench and 1 set in the sled. LOL ski
i do this for every test. cold motor, start and run for 5 seconds, pull all plugs, throttle wide open, 8 pulls. read read the guage. then i have an idea that i am in the ball park knowing how the gauge reads, high or low, motor to motor.
megapower recomends 2 layers of .010 gaskets for pipes and 1 for single piped vipers. your numbers are consistant from gauge to gauge (they read the same cyl to cyl) i am guessing your new gauge is reading low. i ran mine with 2 layers with a snap on guage i was at 130-135 on my viper.
but heed the warnings of the tuners here. squish and compression are all relative. EVERY TUNER has a different train of thought and methods to getting what they believe to be the best of what they know. loose/tight squish, hig/low compression, wide, narrow squish bands, ect... there is a give and take. too much too little or mixing them up might be super good, or super bad. seperates the tuners abilities. and this is a good thing, you find better ways to skin that cat.
and dont look at me cause it's all french to me. i tell em what i want out of the sled, and let the tuner tell me what to do. don has been very pacient with me as we have had some stumbling blocks with these heads. after buying a total of 17 new domes and selling 6 (including the set you have paul) gave 4 away, traded 3 high comp domes for 3 machined low comp domes, endless shipping back and forth, and dons hours on the lathe and in the machine shop. (thanks big guy, i'm trying to relax and not be so serious LOL) it has been along strange trip. but the sled is together and running and needing snow. i should be up riding right now but backed out. and some how i still have 7 domes sitting on the bench and 1 set in the sled. LOL ski
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Mac
Member
Mega Power Domes?
XXX - What do mean when you say CPR pipes need .05 as opposed to .045? Not that I'm taking it personal but can SLP, aaen, or bender require less squish than CPR. Please elaborate on your train of thought. Ski you mentioned Big Bore domes in one of your posts. Are they still available and how many cc are they?
XXX - What do mean when you say CPR pipes need .05 as opposed to .045? Not that I'm taking it personal but can SLP, aaen, or bender require less squish than CPR. Please elaborate on your train of thought. Ski you mentioned Big Bore domes in one of your posts. Are they still available and how many cc are they?
warmed it up and well wasted my time 110 on all 3. It realy pulls hard so I'm giving into the poor tester theroy. Ran 65.3 mph in 500 ft, on dry grass. Not a record, but it was still pulling at the shut down point. this was on gps not speedo, can't see the speedo on the rough strip. has some 8 to 10 inch bumps in it. Maxdlx
Mac, LEAVE it alone!!
msv is easily controlled by the squish angle, radius and dome size. You might look into buying TSR racings head program, along with port 2000 software, will give you some reading material and let you play with numbers and see what happens when you properly set up a head.
There is nothing differnt between a mega head and any other head, except the fact the shell holds more water, the domes are easilt swapped out to differnt ones. The heads are all a squish design and there is no differance. All can be made exactly the same, so theres no reasoning to what a engine requires with a mega head versus a stock srx head, peak head, etc, if the dimensions of the dome, squish clearance, and radius are the same the engine will run the same. Cooling is the only benfit of the meag head versus any other aftermarket ones out there. The headplate was just snake oil, theres no advantage to indexing spark plugs on a 2 stroke.
Paul, how many layers of headgasket do you have in?
msv is easily controlled by the squish angle, radius and dome size. You might look into buying TSR racings head program, along with port 2000 software, will give you some reading material and let you play with numbers and see what happens when you properly set up a head.
There is nothing differnt between a mega head and any other head, except the fact the shell holds more water, the domes are easilt swapped out to differnt ones. The heads are all a squish design and there is no differance. All can be made exactly the same, so theres no reasoning to what a engine requires with a mega head versus a stock srx head, peak head, etc, if the dimensions of the dome, squish clearance, and radius are the same the engine will run the same. Cooling is the only benfit of the meag head versus any other aftermarket ones out there. The headplate was just snake oil, theres no advantage to indexing spark plugs on a 2 stroke.
Paul, how many layers of headgasket do you have in?
redsnake3
New member
just a quick ? not trying to steal the thread but what kind of effect will compression have on my jetting? if its leaner by how much approximately? are we talking 1-2 jet sizes or 5-10? im jumping from 130 to about 180. i will be running 110 race fuel if it matters.