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[JamesButler]

I believe at one time there was a trend towards going with dual plugs when doing certain rebuilds.  The thought was that it was an effective way to prevent detonation, as well as being a greater efficient way to burn all the intake in the combustion chamber.  Has this theory withstood the test of time or not?  Specifically, would it be beneficial in a rebuild of a 80" evo to a 96" big/bore stroker, or is it not necessary? Anyone currently use them in their evo rebuilds?

[johnsachs]

NO...............unless you're going to use a turbo or nitrous.
John

[JamesButler]

John-
Thanks again for the input. I've had several others tell me the same thing.  But yesterday I  spoke with a guy named Perry from Flo Headworks in CA.  I specifically asked him about a 96" big bore/stroker build.  Sometimes I call around to see if I can get some newer perspectives on builds. Maybe I shouldn't do that anymore because now I'm really confused.  Anyway, no sooner did I get the words out of my mouth when he told me flat out to never increase the stroke in an EVO build because of the increased piston speed, it severely lessens the engines durability.   He then said that the best way to go was an 88" big bore build (3 5/8") with dual plugs. With their Super Port Flow headwork, Power Arc ignition, Axtel cylinders/pistons, Cycle Shack true duals exhaust, Crane cam .575 lift with performance springs and roller rockers to increase the lift to .600, re-jetted CV carb, he says would produce @ 100hp/105tq. With no durability issues.  All along people have been saying not to increase the bore of the  Evo because you never know if they'll crack, and now this guy is telling me to never stroke out an evo.   Any thoughts on this and an 88" big bore build?

[johnsachs]

You're confusing yourself way to much. 
Stay with Mikey,and go with his advice.He knows what's up.
I'll pm you.
John

[Gecko]

Shovels benefitted from dual plugs despite having essentially hemispherical heads because they had pistons with high crowns and the plug off to one side.  Flame travel wasn't good since it had to go over the crown (also made them prone to pinging and burning holes in the pistons).  Evos have bathtub combustion chambers and fairly flat top pistons so there isn't any obstacle in the way; dual plugs don't make sense unless you are concerned that one might not fire.

I'd be more inclined to go with a bore increase than a stroke for the same reason you heard - piston speed. 

[Bullwinkle]

>>Any thoughts on this and an 88" big bore build?<<

I'm not a big fan of strokers, either.  You get higher piston speed and increased rod angularity and pressure of the pistons against the cylinder walls.  They run good and the increased leverage (longer crank throw) has good torque, but my personal opinion is that the tradeoffs aren't worth it.  I might max out at about 4 1/2" stroke with good longevity, but the slight increase in displacement doesn't justify the cost to me.

If you are going to spend that kind of money, put a little more with it and go BIG.  By the time you buy the stroker wheels, rods, pistons, and do appropriate head work and cam to take full advantage of the increased displacement, you are well on the way to buying a 96" or bigger, -especially- if you have to hire someone to do the build for you.

With regard to cost, the same can be said of overbores as well as strokers.

What year are your engine cases?  If late evo (about 1996, 1997 and newer) should be OK with 3 5/8 bore cylinders.  1993 or so and older were weaker and I would neither bore nor stroke them if longevity is an issue.

Some years ago I had an 88" 3 5/8 bore Evo with Delkron cases, Branch heads, 44mm CV, E-Pipe, and a Crane cam similar to an Andrews 46 but with .550 lift.  It was -nice-.  About 88 HP, 90 torque, 50 MPG if I took it easy, and no real weaknesses.  I think it is a nice sensible Evo build.  I might have been tempted to put a JIMS 4 1/2" stroke crank in it and maybe 3 3/4" cylinders, but it ran pretty good as it was.  The only reason I changed it was that I got a good deal on a 111.

In the end, with stock cases and the expense of the whole package, I'd be tempted to buy a built aftermarket engine and be done with it.  If money is an issue, sell the stock engine to help offset the cost.

[JamesButler]

Gecko/Rocky-
Thanks for the input.  Sorry for not responding sooner, but stopped checking this thread regularly because it was getting little response. You both bring up great points, and because I am getting something done soon, I'm glad I checked this again.  I have an FXR3: '99 evo, therefore, should not have a problem with a reasonable bore (3 5/8"). Just thinking of the saying, "there is no replacement for increased displacement" and figured if I'm going to bore it, I may as well stroke it too to 4 5/8" and go with a 96" big bore/stroker build, and do everything else that goes with it, i.e., splitting the cases, new cylinders, pistons, and everything comparable that goes with the 80" hop up. Ofcourse, with the  chance of the evo bore issue arising, the extra strain on the valvetrain, and increased cylinder and piston wear (decreased durability and longevity), is 100+hp and 105+tq really necessary anyway? For me,probably not as most of my riding is done between 2,500 and 4,500 rpm, with an extremely rare redlining at 5,200. 

So, maybe the safest way to go is with an 80" hop up...  Ported heads and manifold for better flow, re-jetted CV carb, with K&N air cleaner,  Supertrapp 2 into 1 exhaust, inc. comp ratio to 10:1, Axtel domed pistons, Dyna 2001/ Crane Hi 4  igniton module, V-thunder 3010 or 3020 cam, adjustable pushrods, stiffer valve springs, and add a TP oil pump and compression release valve for safe measure.  Been told that similar builds have yielded @80+hp and @ 90tq with no compromised engine longevity, durability, reliablity or tractability. Also, the integrity of the FXR3 and the evolution engine would not be compromised. 

Maybe further down the road I would go big via the third option, e.g., Ultima 107 or 113.
 

[Bullwinkle]

What I would do depends.  I -like- the S&S 111.  It has long connecting rods for good rod/piston angle, a slightly shorter stroke than an Evo, big bore so you can cram bigger valves in it, and a good oiling system including piston oilers, etc.  Some were on eBay a while back for ~$3K.  The motor is -strong-.  I bought several sets of fork seals with mine before I decided that it was easier on my pocket to keep the front tire on the road.  <grin>  Gas mileage is pretty good and it is reliable as an anvil.  A good exhaust like D&D or RB Racing is important with a big engine.  A Supertrapp is at the top of the list, too, no matter which engine you end up with.  Buy some extra end plates if you go 111.  <grin>.

I think you are right on track for decent torque and reliability.  For budget heads, maybe Big Boyz (http://www.bigboyzheadporting.com) Hillside Cycle (http://www.hillsidecycle.com) great work.  If you want to get tricky, R&R Cycle (http://www.cart.rrcycles.com) or Johnson Engine Technology (http://www.johnsonenginetechnology.com) do very nice work and they weld the exhaust ports and do some pretty fancy things for an advantage over regular porting.  R&R and JET charge more, so it is up to you to decide if a bit more performance is worth the extra money.  Not to slight other head porters, there are plenty of good ones out there and Evo heads start out pretty good, so not a lot is necessary.

If it was me, I'd either do one of two things:  Find a good 111 on eBay, or a build something exactly like you are thinking about.  I read good things about the V-Thunder 3010 and 3020 cams.  I am running one of their 5010 cams with a set of worked over SE heads in a 1999 FXR and it is pretty strong.  Also, give some thought about Andrews EV-27 or EV-3.  The  Wood cams W6 is very good, but they move the valves quickly and I'm not sure that is good for the long term with the lifters.  Woodcarbs.com has a lot of dyno sheets posted to give you some idea of what you can do.

Crane is out of business, but Daytona Twin Tech makes a very good ignition module.

Anyway, a little more homework and the fog should clear up for you.  You have a good foundation and whichever way you go will make you happy.

[cahdbiker]

JamesButler, Hi James I read your post and a lot of the other responses. I have been down this road before. I highly recommend a completely new  engine instead of trying to make your evo what it is not really meant to be. There are a lot of good deals out there on EBAY etc. Just make sure you get a good warranty including parts and labor. I happened to put an S&S 107 in my 95 Heritage. The engine I got from S&S (thru a company called Parts Direct in Las Vegas) was a lemon and had to be completely rebuilt once after two thousand miles, and then the top end(pistons rings and cylinders) had to be done again after another two thousand miles. Thankfully I had the S&S IST ignition which gives you a 3 year warranty so almost all of the expense was covered. If you go the new engine route whatever brand it may be check the manufacture web site for certified repair centers near where you live in case you have warranty issues like I did. If you decide to keep your evo I would upgrade the ignition, get an Andrews 27 or 3 cam. (call them and they will tell you how much to shave off your cylinder heads to get a little more power without having pinging issues), get a good flowing exhaust and intake and don't let your compression ratio get too high. Also, the stock carb can be modified for a small amount of money and it will be more than sufficient for the changes I mentioned. I would keep the changes to your evo engine basic, or else just get a bigger engine. Just my 2 cents. Let us know what you  do and how it works out. CAHDBIKER

[HILLSIDECYCLE.COM]

I believe at one time there was a trend towards going with dual plugs when doing certain rebuilds.  The thought was that it was an effective way to prevent detonation, as well as being a greater efficient way to burn all the intake in the combustion chamber.  Has this theory withstood the test of time or not?  Specifically, would it be beneficial in a rebuild of a 80" evo to a 96" big/bore stroker, or is it not necessary? Anyone currently use them in their evo rebuilds?

They do not need dual-plugs unless your looking for it to be used in maximum effort application, ie drag racing.
We HAVE dual-plugged them upon client's request, and have had the opportunity to witness dyno results. Virtually nothing was seen.
One thing that we have seen, when increasing compression/cylinder pressure, is to gap the plugs(we like NGK's) at .035".
Scott