Bansh-eman Posted May 11, 2009 Report Share Posted May 11, 2009 IMO Those parts will be affected very little if any by changing the rod angle. The biggest relief is going to come from the decreased force on the cylinded wall/piston. These parts are absolutely affected. When you apply force to a solid object on one end where does that force transfer? The other end.... and what is the softest component between those two points? Those listed. If you lessen the angel that the force is being applied, then less of the actual force is being driven directly at those areas, thus improving life of them Quote Link to comment Share on other sites More sharing options...
shanYE west Posted May 11, 2009 Report Share Posted May 11, 2009 These parts are absolutely affected. When you apply force to a solid object on one end where does that force transfer? The other end.... and what is the softest component between those two points? Those listed. If you lessen the angel that the force is being applied, then less of the actual force is being driven directly at those areas, thus improving life of them Its not solid.. its a rotating assembly. When force is applied.. it spins. Are you forgeting that there is a piston attached to the end of the rod? That aluminum piston sure is alot softer then them steel needle bearings.. As far as wear goes.. the biggest advantage from the reduced rod angle is the piston/cylinder wall wear. once again.. IMO bearing wear is minimal.. if any. If your worried about loads on the bearings.. dont up your compression.. because upping your compression 10psi will increase the load on the bearings ALOT more then decreasing rod lenght 5mm.... Needle bearings have a very high load range. Hence people running 200psi compression. Quote Link to comment Share on other sites More sharing options...
Bansh-eman Posted May 12, 2009 Report Share Posted May 12, 2009 Its not solid.. its a rotating assembly. When force is applied.. it spins. Are you forgeting that there is a piston attached to the end of the rod? That aluminum piston sure is alot softer then them steel needle bearings.. As far as wear goes.. the biggest advantage from the reduced rod angle is the piston/cylinder wall wear. once again.. IMO bearing wear is minimal.. if any. If your worried about loads on the bearings.. dont up your compression.. because upping your compression 10psi will increase the load on the bearings ALOT more then decreasing rod lenght 5mm.... Needle bearings have a very high load range. Hence people running 200psi compression. The rod is a solid material, there for the force does transfer. It does not matter if it is rotating or not, there IS force applied to it. The difference is the amount of force being applied directly downward on the material. Because the piston, rod, bearings and everything else have tolerances and are not formed as one uniform piece, they all are affected by the amount of force. Just because I didn Quote Link to comment Share on other sites More sharing options...
2strokesmoker Posted May 12, 2009 Author Report Share Posted May 12, 2009 The rod is a solid material, there for the force does transfer. It does not matter if it is rotating or not, there IS force applied to it. The difference is the amount of force being applied directly downward on the material. Because the piston, rod, bearings and everything else have tolerances and are not formed as one uniform piece, they all are affected by the amount of force. Just because I didn Quote Link to comment Share on other sites More sharing options...
shanYE west Posted May 12, 2009 Report Share Posted May 12, 2009 The rod is a solid material, there for the force does transfer. It does not matter if it is rotating or not, there IS force applied to it. The difference is the amount of force being applied directly downward on the material. Because the piston, rod, bearings and everything else have tolerances and are not formed as one uniform piece, they all are affected by the amount of force. Just because I didn Quote Link to comment Share on other sites More sharing options...
swrbansheeboy Posted May 12, 2009 Report Share Posted May 12, 2009 (edited) Fellas, Fellas, Fellas, this is getting way too deep. I had a simple question in the beginning of this thread. I was only asking the simple question is there a way to measure the rod length? The motor is assembled and waiting for some other odds and ends to get her fired up. This got way too deep. I appreciate everyone's input but im not to keen to all these term thus this information is not doing me any good. lol I might sound like a idoit but it takes time to learn all this shit. I knw the basics of rebuilding a two stroke motor, but when it comes to these mods thats were i start to get kinda lost. Anyway like I said I appreciate all the info posted but thats not what I was looking for. No biggy. Hopefully she runs strong! i may be wrong (and i'm sure someone will let me know i am) but i'm pretty sure you can figure out what you have with the engine assembled. now i'm no expert at this so bear with me but i have watched my engine builder do this once or twice... you need a dial indicator (a digital one that does mm would be a bonus since you can run it to bdc and then zero it out), extend the end of the dial indicator out and drop it into the spark plug hole then roll the motor to find bdc. now roll the motor till you hit tdc on the dial indicator. now as to how to decipher the overall stroke number you get and compare it to stock stroke vs. stroker crank vs. long rod i cant tell you, maybe someone way smarter than me can give you this information. i just know that it can be done and i'm not smart enough to tell you exactly how to do it... i would assume that a long rod would be something like +5 over stock at bdc and also +5 at tdc where a 4 mill stroker crank would be -4 at bdc and +4 at tdc and a 4 mill stroker crank with long rods would be +1 over stock at bdc and +9 at tdc... regardless you will need to know what stock is to compare what you find against that, i personaly have no clue as i've never done it myself but you get the idea.... i've probably got it wrong but it's just some food for thought... Edited May 12, 2009 by swrbansheeboy Quote Link to comment Share on other sites More sharing options...
Bansh-eman Posted May 12, 2009 Report Share Posted May 12, 2009 that will give you the stroke, but not the rod length. If you know what kind of pistons you run then it would make it ez to figure out. The most simple way is to simply look at the side of the rod it should have markings on it. Go on the Hotrods website and they used to have a PDF file and you could pull it from there. Is there a specific reason your more worried about the rod length and not the stroke? Quote Link to comment Share on other sites More sharing options...
Bansh-eman Posted May 12, 2009 Report Share Posted May 12, 2009 (edited) I stated my opinion.. You got yours.. I still think bearing wear is minimal if any. I'll leave it at that. This could go on forever.. Physics and trigonometry is not my opinion brosif. Agree to disagree. Edited May 12, 2009 by Bansh-eman Quote Link to comment Share on other sites More sharing options...
dajogejr Posted May 12, 2009 Report Share Posted May 12, 2009 Guys, Guys, Guys....you're both right. Longer rod does put less stress on the pin, bearings, etc., but...it is really designed to cut down on the piston trying to thrust itself through the cylinder. As said, adding 10PSI of cranking compression will do as much or more pressure on the assembly. You have to measure center of both big and small ends to get the rod length. Or....get a part number off the rod. H121 is the standard rod, 110mm H158 is the 115mm long rod. Quote Link to comment Share on other sites More sharing options...
shanYE west Posted May 12, 2009 Report Share Posted May 12, 2009 Physics and trigonometry is not my opinion brosif. Agree to disagree. tell me this... whats the load capabilities of the needles bearings... how much force is placed on them in a stock configuration.. Then tell me the load on them in a 115mm rod setup.. Tell me how much longer bearing life is extended.. YOU DONT KNOW!!! therefore its your opinion. Changing the rod angle will affect the bearings life VERY LITTLE. Until you can prove otherwise... its a matter of opinion. brosif.... I'll stick with my opinions.. Last time I checked.. My bikes have ran like tops so they must be working. You can keep your physics and trig. I'm done here. Quote Link to comment Share on other sites More sharing options...
dajogejr Posted May 12, 2009 Report Share Posted May 12, 2009 whats the load capabilities of the needles bearings... how much force is placed on them in a stock configuration.. Then tell me the load on them in a 115mm rod setup.. I bet there are a small handful of people that could answer that truthfully...without BS. Firehead...this sounds like something up your alley....you got any comment? Quote Link to comment Share on other sites More sharing options...
2strokesmoker Posted May 12, 2009 Author Report Share Posted May 12, 2009 Guys, Guys, Guys....you're both right. Longer rod does put less stress on the pin, bearings, etc., but...it is really designed to cut down on the piston trying to thrust itself through the cylinder. As said, adding 10PSI of cranking compression will do as much or more pressure on the assembly. You have to measure center of both big and small ends to get the rod length. Or....get a part number off the rod. H121 is the standard rod, 110mm H158 is the 115mm long rod. [/quote Well went over my buddys last night and stuck my dial indicator down his jugs and sure as shit I have a different stroke than a stocker. Now the my motor is assembled what do i do? I got 795 series pistons that came with the bike when I bought it in pecies......Is this correct? I turned the motor over and it dosent hit the head. Is there a way to check this? Thanks guys and sorry for the can of worms. Quote Link to comment Share on other sites More sharing options...
dajogejr Posted May 12, 2009 Report Share Posted May 12, 2009 The piston refers to the rod length, NOT the stroke. If you have stock cylinders and a longer stroke crank, you either have a spacer at the bottom of the cylinders or a head/domes that are cut recessed for the added stroke. The 795 series, or racers choice series, have the wrist pin hole moved 5mm closer to the crown of the piston (top). The 795 series dome also has the same profile as the standard banshee piston (513 or 573 series, I forget...someone correct that) Do a search on a squish test. It involves a piece of solder through the spark plug hole, smashing it down with the piston (against the head) and measuring that thickness. From .040 to .060 is the norm, depending on your setup. A mid 40 to low 50 number is the average... Quote Link to comment Share on other sites More sharing options...
shanYE west Posted May 12, 2009 Report Share Posted May 12, 2009 he probably could.. But there is alot of variables for him to calculate in there also.. I know there is stress releif on the bearings in a long rod setup.. that was never questioned.. All I was saying is that extended bearing life is not one of the key advantages of the long rod setup. Extended bearing life will be minimal (meaning you'll never notice it) You'll see more stress on the bearings by uping compression 10psi. Its like saying buy a cool head for its cooling capabilities.. Quote Link to comment Share on other sites More sharing options...
BellicoseBanshee Posted May 12, 2009 Report Share Posted May 12, 2009 I would think end-side shake and dragging rollers should be of more concern than rod length when it comes to the life of the lower bearing. Quote Link to comment Share on other sites More sharing options...
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