PassionRE

He pays me months in advance for 2 Cub motors I havnt even delivered yet, says he's not ready for them and I should knock out my other builds 1st....does that count?.....Jim

With simular porting styles on both engines you can expect 5-7 hp increase on 4mm engines and around 5 ft. lbs of torque increase over the simular 350 version. It can vary somewhat depending on pipes etc., but thats what Ive seen personally....Jim

To avoid confusion where slack in the cable and actuation point is concerned, remove cable from clutch lever, check that the marker on your top case halve is aligned with marker on clutch actuator when you move actuator in direction of travel with just slight pressure against the clutch assy(by hand).If they do not line up, remove clutch cover and loosen adjuster nut in the center of outer pressure plate. Adjust until these marks line up with slight pressure on actuator using your fingers, not the clutch lever, also make sure the actuator isn't bent or fatigued. After they line up, tighten lock-nut, put it back together and adjust slack out of cable with about 1/8-1/4" movement in clutch lever. If your clutch is assembled correctly and in good shape, it will operate perfectly....Jim

Chill out guys, no need for a cyber pissing match here. Ill be the first to admit that there is a ton of stiff competition out there. Fast. SSR, RDZ, Kurtz, etc. all build fast engines and the competition just gets tougher every year. Everyone has a choice and ultimately, they will make it. Kabina's motor was a personal project motor of mine and it's original design was governed by the fact that there were a few additions found in most drag motors that I was not willing to give on for reasons of affordability and reliability. In the end, affordability was thrown out the window but reliability wasn't. As far as being the fastest 4mm stock cylinder engine available, I doubt it, as far as being faster than engines it shouldn't be...definitely. I give this credit to Kabina himself. He listens to my every word, acts on it, and is honestly just relentless in his efforts to squeeze every ounce of power that is available. His efforts have allowed me to wade through many of the thoughts of conventional 2-stroke wisdom and disregard a lot of information floating around in the theory of performance design. Comparing his motor to other 12 ports I have built is a waste of time and oxygen. Not only is the motor itself one of a kind, without his efforts, it wouldn't run as it does. Needless to say his 06' motor will require the same efforts as the X3 did, and I can wait for the outcome. His partnership and results have sent me more work than you can even imagine....Jim

Old fart huh? Hey Im lost, can someone tell me which way is "Over the Hill"???..thanks guys!

As in any high perf 2-stroke, squish clearance is critical, especially when you have a design goal in mind as far as the type of power you are trying to produce and when you are designing a particular engine to refrain form detonation and piston breakage.. Generally accepted maximum squish velocity(rate of velocity of gases when squished based at engine peak rpm, given compression ratio,exhaust port height, actual squish clearance and actual squish band width) is 15-30 meters per second.15 m/s being a road race type engine or high perf snow-mobile engine, 30m/s being a high torque MX style or watercraft engine. Lower squish velocity's make best power at or near peak rpm and higher velocity's make best power at or near peak torque. Choosing your rate depends on what your after in style of power and your pipes and porting should definately be taken into consideration when trying to decide on this number. Experimenting can be deadly and expensive. Here are a few examples...REMEMBER, ANYTHING OVER 30M/S IS CONSIDERED RISKY BEHAVIOUR. Stock ported Shee with pipes that rev to 8K rpm on STOCK HEAD WITH MODIFIED SQUISH CLEARANCE. SQUISH CLEARANCE SQUISH VELOCITY .030" = 42.4M/S .040" = 33.5M/S .050" = 27.3M/S Stock ported Shee with pipes that rev to 10k rpm on STOCK HEAD WITH MODIFIED SQUISH CLEARANCE SQUISH CLEARANCE SQUISH VELOCITY .030" = 52.9M/S .040" = 41.8M/S .050" = 34.1M/S .060" = 28.3M/S As you see, pipes DO make a difference if they yield more peak rpm. In this case, with the higher revving pipes, squish clearance needed to be increased with the given squish band width. Keep in mind that narrowing the squish band width with a given squish clearance will drop the squish velocity. This is why builders modify squish band widths when milling stock heads. Increasing squish clearances will also lower squish velocity's as well. Likewise, wider band widths increase velocity with a given squish clearance, and decreased squish clearance will raise velocity with a given band width...hope that makes sense....Jim

On stock porting, the Shearers will hamper bottom end over a CPI and other pipes as well.. But if ported with Shearers in mind, you can have just as much bottom end as CPI's and just kill the CPI's in the high R's and in peak HP numbers...Jim

Here ya go Big Blue....found it

Kotin, your going to need a manifold and cable as well, those 33's wont just bolt up. The stock manifolds will accept them, but will crack out in no time...and the stock cable will just not work at all. Shoot me a Pm if you need parts or help, more than glad to hook a Patriot and Great American such as yourself up with a great deal.....Jim

Yeah Tyler, I was a little concerned on that build, tried to go pretty conservative on everything where the head and timing were concerned...its not everyday somebody calls you up wanting a highway cruising Banshee with some real hit behind it. Your right, carbs might be in order....Jim

Seems like you were at 64.5mm so possibly 64.75 or 65mm ...look at the tops of the pistons and look at the last four numbers...that will tell you were you are at. .25mm will probably not clean it up depnding on exactly the type of failure, detonation, seizure, heat seizure etc etc. Drat, the only Passion street legal road race Banshee in Italy bites it...Jetting sound pretty close for dirt riding(on and off the gas), but on street application and highway riding(sustained rpm), prolly better rich it up some over the 360 unless your running the bowls dry and nothing is going to help that unless you go with different carbs with bigger bowls. Did it just fry the exhaust sides of the pistons or seize???....Jim

200.00 including piston sets(wiseco)... bored, honed and chamfered.....Jim

Its really not that tough. If you have even moderate mechanical skills you can handle it with good advice. You waterpump seal is probably bad if your getting coolant in the bottom end. What other symptoms make you think the bottom end needs rebuilding? If you decide to go in to the bottom end, just give me a call and Ill walk you through it.....Jim

Stock Banshee durations are exhaust 181.04 degrees and transfers 119.69 degrees. Durations are based on how many crank degrees in rotation from beginning of opening fo port to closing of the port. Widening or raising/or both of ports are the direction usually taken in mods except for where strokers on stock cylinders are concerned. Preference depends on flow requirements of the design where targeted HP is concerned, and in the style of power your looking for. Generally, low transfers make very peaky motors , taller tranfers make broader more torquey power, especially off the pipe. Exhaust area and transfer area must be mainained in balance for the type of power your looking for. Widening the transfers simply allows the transfers to operate more efficiently over the targeted spectrum of the power band your design calls for, and how much widening depends on exhaust area of the design needed to produce the style of power, and desired peak HP at a given RPM....Jim

Once old seal is removed, if you will spray the hole with carb spray or contact cleaner, and also spray the seal as well, you can push the seal in all the way with just your fingers without risking damage to the seal with a driver.....Jim

927 is probably the best oil available, Ive used it for over 20 years. Just make sure to keep your cans shaken before fueling(everytime) and if the cans sit for more than a week shake them extra good. It also helps to run your carbs dry after your done riding for the day, otherwise you will be extra rich on oil the next time you fire up. 40-1 is more than enough protection with 927...Jim

Dont go under at all and I wont run one with more than .0055". Pistons skirts really start taking a beating past that. Leave it, if you have even partial rear boost port opening youll probably never notice it on stockish cylinders. The stock transfers have more than enough area to cover whats needed for stockish Ex. ports,and will flow enough well past what rpm range most pipes will pull to...Jim

Dynos are going to vary bigtime. You wouldn't even believe where and how some the numbers that are floating around come to be ,or not to be, or wish to be, so lets just flush all of it. 421 Cheetah Cubs are a 193 BMEP@9700 RPM design... period(piped perfectly). Ive mapped several sets, averaged all of them ,and ran the maps through my programming and bone stock 421's will produce 95 hp(on gas) in a perfect world, with perfect jetting and perfect pipes....Jim

.003"

If you'll look closer tat that chart you''notice it says "lean mixture rating" , 99.5 octane. That is at stoichometric ratio...approx 12-1. 100LL jetted richer than stoicho is higher than 99.5...chart says like 130 or so on rich jetting, but that for aviation 4 strokes...you would lose alot of power running that rich on Banshee motor...Jim

Direct injection is a killer design, less fuel, more power, less emmisions. Originally developed for high performance piston aircraft in the 40's. Only snag in the design is that the fuel pumps that are required to overcome cylinder pressure at near TDC go through a beating....we'll see how they hold up over time I guess....Jim

Brian, you will also need targeted peak HP rpm, exhaust port height, desired compression ratio, and your preference on bottom end friendly or top-end friendly specifications in order to determine the desired squish velocity of your domes....makes a huge difference on how the 421's perform....Jim

BRAND NEW!! Shearer inframes in production chrome with silencers in the box. THE ultimate Banshee pipe...bar none! Also work fantastic on the new stock stroke and 421 CUB motors $469.00 SHIPPED.. in lower 48