blowit

Might need some tuning there. I would be curious to know the entire engine setup, fuel, timing, and maybe inspect under the head. You may need to retard timing a bit as it sounds like your MCP is happening well before 20*ATDC which for increase head temps and decrease pipe temps. If you install and EGT, I would know right off. It would be an EXCELLENT idea for you to get some really good plug pics and send them to me. I have seen plubs glow before but usually not when the motor is dialed in correctly. That heat should have converted to kinetic energy and/or go out the pipe. B

Timing between the boost and xfers needs a pretty close relationship. Raising the boost without the xfers will give you some problems. In some circumstances, it is easiest to put a plate under the cylinders and/or mod the timing edge of the pistons and correct things at the head rather than porting. This is the "poor boy" port job but it will help rather than doing nothing. B

Justification for modification I guess. :biggrin: B

breaking the sleeve and such are not typical of a lean condition (running out of fuel). Detonation, melted pistons, welded rings, etc, are common. It is possible if stock pistons were used that they shattered with violent detonation but forged pistons are much more ductile. B

Sounds like that motor was a bit loose and ready for the rebuild B

Mysterious math just means an answer without knowing how it was derived. No equation means we cannot use it. We basically had to go back through and "prove" some things for ourselves and learned a few things along the way. Understand that we were just educated in the aerospace world that everything (math) gets proved and checked. Our numbers do come out differently than Blair but that is because we caught some design issues. Math is right, geometry is not from our observation. Again, that is only our observation but it has not failed us yet. Not rewriting the laws of physics over here but do like to make sure 5+3=7.. :biggrin: B

Precisely my point. Many people rely on others math. I am just not comfortable with it. Not saying it is wrong but when I cannot see the equation, I am not comfortable using the data. Please feel free to visit any engineering firm with a "mysterious" calc and see how that works out... Just prefer to drive my own data. Again, there are some bright minds that come up with them though. Different strokes for different folks I guess... We have cut hundreds of Banshee heads for people all over the globe. Not sure what to say but we will stick with what works for us and our customers. :biggrin:

We have always helped out people that help us. Free parts is at the top of the list. B

I think there is a large discrepancy between power and the power surge common to two strokes. I don;t think the OP is suggesting that he has too much power, but rather does not like the way it is delivered. I know when I was 15-18ish, I used to think that violent surge of power was the "shiznat", but as soon as you get on a track and actually try and use it, that power hit will put you in the trees faster than you can scream "ohhh fucccc" I tried to ride one on a flattrack years ago and it was near impossible to put it in the "sweet spot". I was able to pass that fully modded Banshee with a stock TRX250R like it was sitting still. Remember dyno numbers for for people that want bragging rights, the curve that is created on a dyno is what wins races. There are things that will help with the power delivery of a Banshee like the single carb setup and 2 into 1 pipes, head rechambering, timing advance, etc, but port work will ultimately be the way to go. That being said, there is little one can do with a non-powervalve motor. The powervalve design allows for variable exhaust timing and will allow a two stroke to pull like a tractor on the bottom yet rev out to drag race timings at the top. A common mod for the banshee it to switch back to the RZ350 cylinders which are power valve cylinders, or go to a cheetah cylinder with powervalves. I honestly feel it was ridiculous that Yamaha removed the PVs for the Banshee build. It would have been a monster on every track with that addition. To reiterate, power and power delivery are two different things. A good built two stroke can have a 4 stroke type power band with all the power of a drag bike, it just takes the right tuning to get there. B

I just have my recorded figures in front of me but I am sure you are on the right track. :thumbsup: B

Personally, I think the term "roll out" is a bit retarded. Seems someone made that one up because the proper term "circumference" did not make sense. I think the proper term should be used but "roll out" seems the trendy phrase. B

Probably just what is input for oem port height. Banshees are supposed to be a zero deck height motor. Never are but that is theoretical.

Two different guys but worked on the same bike as I understand. Kevin Gigot and John Stallworth. Two different guys, two different places but both work a lot with Banshee stuff. Kevin is a good guy... Have not talked to John in years. B

Gunna have to share more about your engine setup to know if your situation is normal. I will tell you that if a rookie porting guy got a hold of it or it is jetted wrong, they can turn on like a light bulb. I have never liked it and much of our engine work has pivoted around smoothing the power surge in the Banshee. There are certainly things you can do if you do not like it but need to know what you are working with first. B

LOL :yelrotflmao: What is wrong with that one??? There are certain design limitations with that one but I will admit, it should be considered. The banshee plastics really don't help the situation either! B

I think that includes frame stripping, welding, and powder coating. I would think that is a bargain to get a frame done hands off for under 5 bills. I will admit that shipping a frame around though is not cheap. 2001 stroker, honestly, I think this job will take more than 30min. I would guess closer to 3 hours min to cut and trim all the gussets. Guess I thought there were pretty much in line on pricing. :shrug: B

With who's calculator? is 30s bad? One thing worth noting is gas speed is only one element of the equation. There are just many other factors at work. Any consideration for eddy currents in the chamber? B

Snop, we have looked hard ar the market but have not decided what would fit our business best. We have plenty of suspension design experience but there seems to be every top/dick/harry with a welder making the stuff. Shocks are a firm area of interest for us because of our experience in previous designing. I think we can make some fair improvements over many designs there. Regarding engine mods for them, we have not honestly looked hard enough to see our own path on that just yet. So many markets, so little time I guess. B

To be honest, I don;t know a damn thing about the certrain models of trucks, etc. We would be most inclined to build components that are interchangable between models. Do you have some example models to look up? I would have to go visit some dealers for sure I would think but that might be the way to go... Get the dealers involved. B

You might give me some more info on your truck markets. Not too familiar with them but interested. B

Stock is 176-178* open on exhaust. Brandon

Thanks for the reply. I would have to look at the market for such a thing. I will admit that those are NOT cheap pegs. We work with 17-4PH stainless a lot and it is one of the most structural stainless steals you can get. That being said, I have to wonder if we examined the material used, if it would actually BE 17-4... B

Figured I would throw the line out and see if any good ideas get reeled back in. We primarily engineer/cnc manufacture aerospace components and our racing/auto markets take a back seat but recently, with the "MF" economy, it has forced us to consider other possibilities. We are far from slow here but reading the writing on the walls is important. I am curious if you guys have any great ideas in the ATV markets? Our shop is geared for production so it does create problems in some "specialty" market, which means "not very many". We rarely run less than 500 of anything here. That being said, our ears are always open and ideas considered. Considerations for annual usage are important too... We have a couple new ATV products near release but willing to throw more effort into future ideas and engineering. If you guys have any solid ideas with marketing considerations, we are all ears. Hell, we are open to about any market right now. PM me of you like. Engineering and R&D costs are usually absorbed by us for new designs. Brandon

We have just had a few ideas over the past few months and were curious. By the numbers, the roller bearing on the PTO should hold WAY more radial load than a motor can make but they are not designed to handle axial loading very well. Straight cut gears can certainly cut down on axial forces but straights usually do not exhibit as good wear characteristics has helicals and they make more noise. Just pondering really. We are trying to build a map for new components this year but have to be cautious with the economic times. Our reduced work load here has allowed us to look at new parts innovations. We already have some fun stuff just getting finished up but will have room for more ideas it seems. B

If you can wait a bit, we have been cutting stock heads for many years. Just very busy this time of year. We don;t send them out as most do, and all our products are CNC machined in house. Several members run our heads. I can nearly guarantee you will be happy with our geometries. I will say that .032" squish is in the ballpark and will work great for a pump fuel 350 motor. The geometry of the head is what will make the difference in combination with the squish clearance. Brandon