Wildcardracing

It's absolutely possible. I build them all the time and never run spacers. You will need to have your stock head rechambered or purchase a billet head and stroker domes. With the 115mm rods you will have to run the 795 series Wiseco pistons.

Welcome to the HQ :thumbsup: As for your question, we will need more info. What type of riding is the bike used for and what kind of a budget do you plan on for the build? Also, what is your elevation?

It is all going to depend on how tight the trails you ride are. If they are fast open trails then a mild dune port matched to some t-5's or CPI's would work out fine. If you are riding tighter trails then I would lean more towards an aggressive trail port and a midrange or low-mid pipe such as pro-circuits or fmf fatties. As far as your engine mods go, don't be affraid to ship your cylinders out to have them ported. Chances are you will get a better product than locally in many areas. There are a lot of good builders out there, get a few recommendations and make some calls to decide who you feel the most comfortable with.

What's your elevation? We run @310-320 at 4500' with CPI's and dune port.

What sprockets are you running? Could it be just geared high? What are all of your mods, elevation and jetting? Could also be a midrange jetting issue.

www.rockymountainatv.com will have the pro series boyesen reeds.

I have used both in my builds and acctually prefer the modquad over the pro-design. The new shafts on the modquad piece are good, just make sure to chamfer the end of it before you push it throught the seal or you will ruin your seal.

1.5 turns out is a good starting point. You should adjust the cables to where the reference mark on the slide is in the window when at wide open throttle. Use the tors (idle) adjusters to sync the carbs.

If your throttle got stuck then you are getting water into your carbs. If you have an open air filter you need to go back to the stock type air box or stay out of the water.

You would have to measure the bore to find out if it has been bored. Stock bore is 64mm, the next common size up would be 64.5mm and then every .25mm after. 66mm is the service limit of most banshee cylinders which is .080" over.

I'll join the choir here. I too would recommend the plastic, I've seen cases break with both styles though...just depends how bad the chain binds up. But, the platic gives a little more so it will better absorb the blow. One thing not yet mentioned is that the plastic are lighter, if weight savings are of any concern.

Sounds to me as though your carbs are out of sync, make sure both slides are the same height at idle and that the raise at exactly the same time when you push the throttle. Without a sync tool that's the best way to get them close.

I've never had an issue with the CPI's, I prefer them for an engine that will be dune ridden some. The Shearer's are worth some power but at a loss of low to mid power.

66.25x66.25x54x.0007854x2=372.2943cc

The 4mils best advantage over a stock stroke is the torque capabilities of the motor to be set up for a broad power band. Along with the stroke comes some extra displacement which in turn adds to the hp capabilities of the motor. Any time you set up a banshee engine for trail/woods/mx use you are going to be giving up top end power potential in favor of useable bottom end torque. It is almost always a tradeoff, most mods that add low end are going to rob you of some top end. The important part is making the power curve of the engine the most useable for the environment it will be use in. As far as a good port job doing the same thing, you are never going to achieve the same kind of low end torqe as a properly ported 4mil with a ported stock stroke.

You can realize the same power potential from either setup for very close to the same price, might as well go with the more reliable of the two. The ONLY advantage I can see in the 110 setup is that the 513 pistons are available in .010" increments whereas the 795's are only available in .020" increments.

Well...lol, the crank will be worth around $150(given it has new bearings maybe a little more) and the cylinders with new bore/pistons will be worth $250-$300. Your porting as it was a trail port may be coservative enough to be redone for the 4mil stroke. A new hotrods 4mil crank will run right around $450, 795 pistons will run @$170, seals will be $35, domes $75 and gaskets $45

You're going to want a port job that emphasizes on low to mid power for the riding style you talked about. If a builder tries to sell you on drag pipes and a dune port ect. just walk away.

what kind of riding do you use it for?? Suspension is always a real nice mod. If you are looking for more power:reeds, larger carbs and more aggressive portwork.

If the motor is set up right with a cut set of domes and no plate, with the right porting/pipe combination you will be just fine with a -1 swingarm. The porting/pipe combination needs to be set up for low end grunt with a smooth power band. I've built trail orientated 4mils for guys with stock and - lenght swingers and I've also built dune/drag 4mils that need +8 swingers. It's all in the setup.

I'm going to have to agree with dave on this one, the 115 is the way to go. Much less sideloading on the pistons=a motor that will last longer. IMO the best way to set up a 4mil is to run cut domes and have it ported for the additional stroke, spacer plates will raise your durations and be more prone to developing air leaks.

The most common places are the reed gaskets, base gaskets and crank seals...but could be leaking where the case halves seal, the head or have a crack somewhere in the case or cylinder. You need to have a leakdown test done to isolate a leak if you have one.

Ideal piston to bore clearance is .003 to .0035 inches with a set of Wiseco pistons, you may not need to rebore...you may be able to get away with a clenup hone and new pistons.

Just to give you a ballpark idea on cost, I charge $60 to true/weld cranks...but, I'm not in cali. What is your elevation?? 17's would be on the small side for a bike at sea level IMO. Also what kind of power gains are you looking for in it, high compression will hurt your over-rev and add low end power.

The porting should be matched to the pipes. That being said, every pipe has a given window of exhaust duration it will work best with...usually about a 4-6 degree window. The lower the duration the more low to mid power and less top end power. The higher the duration the more top end power and a little less bottom to mid. That is if the transfer ports are modified correctly to match the exhaust porting. One builders idea of what a dune port or trail port is may differ from anothers. A good builder will be able to match the porting to your riding style reguardless if they call it a trail or dune port at their shop. You should call some builders and get a feel for them, a good builder will ask you some questions about riding style, terain, weight, altitude and fuel choice...and should be able to answer any of your questions as well. Tell them what you want out of it and they will help you achieve that goal.