Got A Question For Passion,patriot,mpracing Or Equ

[Nightrider]

I was wondering as most Banshee aficianados do about increased power vs. crankshaft seperation.

 

As we all know,the "pressed" crankpins have reportedly worked there way loose on engines that produce alot more power over stock or are heavily abused.

But what I want to know,is how many engines have you guys torn down with the pins still tight and the cranks still in phase.

 

If a machine is strickly trail ridden vs competion use,is it neccesary to weld the crank beyond certain modifications.Also what would be the limit as far as compression and portwork?

 

I'm sure with the numerous amount of Banshee engines being rebuilt,you have an idea of possible limits.I'm sure with the owners feedback and taking into consideration the modifications.Is it possible to recommend a maximum level before its neccessary to tru & weld.

 

I only ask because I can't justify a major teardown with the low hours on my machine.

I will definitely get it done when its time for a rebuild,but can I get away with it and how much for how long?Can you give some feedback on engines you have serviced?

[PassionRE]

Crank seperation is pretty normal on Banshee engines regardless of compression and porting it seems. High RPM really isnt that big of a factor as much as jumping and sudden repetetive rpm fluxuations. Even with all this mind, after a couple of seasons on a crank they will start to seperate.

Welding doesnt cure this but does tend to slow it down. Many engines I've torn down that have been welded previously have cracked the welds and started to seperate anyway...a very old problem. Out of phase problems are much more rare but do happen.

If your engine is basicly stock and fresh, just ride it till you do upgrades and plan on welding at that time.

From what Ive seen, abuse is easily described as just riding the thing...I've seen how you guys ride!.....Jim

[Oilsmoke]

From what Ive seen, abuse is easily described as just riding the thing...I've seen how you guys ride!.....Jim

So is pinning better?

[PassionRE]

Pinning is better, more expensive, and makes rebuilds more tedious. It suprises me that the manufacturers havn't fugured out the cure.......such as pressed fit splines. No twist problems, twice the surface contact area, and no truing neccessary...maybe they will read this and save us all the pain....Jim

[checkster]

why can they use a 1 piece crank with a 2 piece rod, like a car? im sure they could figure out how to make a 2 piece roller bearing for the rod.

 

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[PassionRE]

why can they use a 1 piece crank with a 2 piece rod, like a car?  im sure they could figure out how to make a 2 piece roller bearing for the rod.

 

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2 cycle outboards are built that way and work great. I was thinking of a drop in replacement crank for Banshees with press fit splines. A billet crank with 2 piece rods would require tunneling the cases for clearance...Jim

[jinx44]

Plus more recipocating weight due to the extra metal on the rods and the weight of the bolts when using a 2 piece rod.

[checkster]

Plus more recipocating weight due to the extra metal on the rods and the weight of the bolts when using a 2 piece rod.

well my street bike doesnt have any problems going to 13 grand with two piece rods.

 

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[Nightrider]

well my street bike doesnt have any problems going to 13 grand with two piece rods.

 

Your streetbike also has more than 30 + horsepower.Extra reciprocating mass will eat horsepower.The banshee can't afford to give any more up.

 

Thanks for the info Passion racing.

[checkster]

LOL......I wish my street bike only made 30 more than my shee. that would mean my shee made around 110 hp. now that would be sweet!

 

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[yama-dude]

Would I be correct if I were to assume that "automotive style" or rods that have caps and tri-metal split bearings are superior to 1 peice rods with roller bearings?

Connecting rods don't rotate, they recipricate or swing back and forth. They swing to the right and then the left every revolution of the crank. The inertia of the roller bearing must also do this, correct??? It almost has to stop and change direction. If roller bearings were better you would think super bikes would have them. Those thing turn 14,000 rpm easy, and their made to do it all day long. The only advantage I can see with the roller bearing is its easyer to lubricate.

[Yaxy]

Are Banshee cranks really that bad? I hear allot of stories about cranks and rods going but have never had a issue with my 89 banshee which has probably 25,000 miles on it of fast roads some MX use and tight trails. I have never had a crank issue and went 10 years before taking the crank cases apart and at that point for proventive maintenace had the 2 outer crank bearings replaced and the crank trued. The shop here in Utica NY who does only R&D and building 2 stroke motors for 30 years said that the crank was fine, no major issues to worry about.

The banshee has been in full mod status for 8 years now, changing pistons every 6 years rings every 2 and I see virtually no piston or cylinder wear. This tell me that the shaft is working fine.

 

I want to buy a new banshee but all these crank stories make me wonder if quality in Yamaha parts are that much different then they were in 1989. I am a true 2 stroke fan and take good care of my stuff but do not want to put all kinds of money into a new machine and motor and after a few years it is junk.

 

 

Chris