How to properly use a 5mm long rod questions.

[Full Throttle 11F]

At the risk of sounding like a retard and not wanting to waste time/money I have come to the all knowing Banshee HQ to find some assistance in selecting a crank for my shee. To start at the beginning I decided to throw a port job in my shee from trinity, after a season in the sand and a few TT races there was that distenct sound of a rod bearing. It was doing that nasty ticking sound it makes right before it lets go of the crank. I would like to use this repair to up the out put of the motor by running a stroker. This is where I run into my problem. I am told, that because cylinders have already been ported they cannot be port timed to a stroker crank. So instead I was going to put in a stock stroke +5mm long rod crank from hot rod. My question is do I run blaster pistons to off set the length of the rod or do I run a spacer plate under the cylinders? What are the differences, how is the port timming effected?

[Jereme6655]

Correct.....your old cylinders were ported for a stock stroke crank and if you were to go with a stroker crank you'd be seriously affecting the timing. With new cylinders on there and a 115 Long Rod crankshaft you will need to either run a spacer plate to make your stock port timing work correctly or you will need to get the new cylinders ported for the stroker crank along with different dones for both applications. You will also need to run a different piston.........it will need to be a 795 series wiseco piston to compinsate for a different stoke length

[bansheesandrider]

If you go with a stock stroke(54mm), long rod(115 mm) crank you can use the 795 series piston and NO other mods are required. If you go to a 4mil stroker(58mm) long rod you will need to use the 795 series piston AND have your dome cut to clear OR use a spacer plate. Cut domes are preferable over the spacer plate. Your port job may or may not be correctable for the stroker. The stock stroke long rod won't really add any power, it is more for reliability and less internal stress on the motor.

[jbooker82]

Throw the junk Trinity cylinders in the trash and build a 4 mill.

[camatv]

whatever trinity's porting is not that bad..

 

you need to measure the cylinder and then you can find out if a 115 rod +4 mill stroker will fit. most times buy bumping them up into the domes you can use the cylinders it just matters how much the trans ports were raised.

 

if you can measure from the top down i cna run those numbers and let you know your options. pictures of the cylinders themselves would be good also. using a spacer plate WILL not work on ported cylinders most of the time BUT creating+ deck height with the pistons will usually save them. at least thats my experience with them and not just second hand or backyard knowledge..

 

the long rod crak you probably wont see any real performance increase just mostly from it being a fresh motor i would say with high RPM racing the stock length rod crank nicely built and true'd/ welded with good bearings would be my second choice.

[Full Throttle 11F]

Thanks guys I really appreciate the info. I just have one last question before I make my purchases. Which is the better set up for the 115 long rod crank, running the 795 pistons or the spacer with the stock pistons?

[jbooker82]

You have to run 795 series piston with any long rod crank. Standard stroke or +4mill stroke. The conecting rods are 5mm longer and require a piston that has a 5mm off set wrist pin. When you run a long rod stroker you need 795 series pistons, and a cut cylinder head, or spacer plate. The cut head or spacer plate is for the extra 2mm that the piston will come up out of the cylinder.

[armyvet]

whatever trinity's porting is not that bad..

 

you need to measure the cylinder and then you can find out if a 115 rod +4 mill stroker will fit. most times buy bumping them up into the domes you can use the cylinders it just matters how much the trans ports were raised.

 

if you can measure from the top down i cna run those numbers and let you know your options. pictures of the cylinders themselves would be good also. using a spacer plate WILL not work on ported cylinders most of the time BUT creating+ deck height with the pistons will usually save them. at least thats my experience with them and not just second hand or backyard knowledge..

 

the long rod crak you probably wont see any real performance increase just mostly from it being a fresh motor i would say with high RPM racing the stock length rod crank nicely built and true'd/ welded with good bearings would be my second choice.

 

gonna have to agree here.a lot of times it just depends what was all done on the cylinder.My last banshee had a 4mil crank with yamaha rd400 rods which are 115mm,this was a ol'skool build.Anyway i replaced it with a stock stroke /rod length crank and it still ripped imo.Now was it optimum who knows but it still ran good.maybe it wasnt ported for the stroker crank to begin with but who knows,whenever you buy used its a crapshoot what you might find once you tear into it.i think too many people take what they "hear" on the web as fact.Me i tend to believe what i see and not hear as my eyes will never deceive me.