putting a 87 250R cylinder on and 86 bottom end

[sx250heath]

I have an 86 bottom end and 87 cylinder that has been ported by Paul Turner. Since the two year have the same stroke will it work or will I need a long rod crank and piston?

[pcs]

just measure the height of the cylinders, if they are the same then you should be good to go, if you add a long rod, then you will need to run a spacer.
http://www.eddie-sanders-racing.com/product_p/spacer%20plate%20kit.htm

[82 250r]

You may want to call Duncan Racing. The port timing may be different on an 87 and the rod length has nothing to do with it. The cdi's from 86-87 have different timing curves so i assume the port timing with the cylinder is different as well. Don't know for sure.

[KASEY]

ALL 250r cylinders have the same stroke and are the same height,, the problem is if you stay with a short rod you will have to run the wrong piston,,, if you go to the long rod cranK then all will be right with the world and NO YOU WON'T NEED A SPACER PLATE. the only case where you woud need a spacer plate is if you ran a short rod piston on a long rod,,,,, PLEASE if you don't know for sure don't comment,,,, all it does is add to the confusion!!!!!!!!

[KASEY]

just measure the height of the cylinders, if they are the same then you should be good to go, if you add a long rod, then you will need to run a spacer.
http://www.eddie-sanders-racing.com/product_p/spacer%20plate%20kit.htm 100% wrong!!! You don't know don't add to the confision!!!

[KASEY]

You may want to call Duncan Racing. The port timing may be different on an 87 and the rod length has nothing to do with it. The cdi's from 86-87 have different timing curves so i assume the port timing with the cylinder is different as well. Don't know for sure.

PLEASE DON'T ASSUME!!!! don't know don't post!!!!

[sx250heath]

Thank you very much kasey.

[82 250r]

PLEASE DON'T ASSUME!!!! don't know don't post!!!!
Kasey, I'm not trying to get into a pissing match and I have no doubt you know your stuff. :)

My post was directing him to call someone who knows for sure...Duncan Racing...then i gave a reason why.
I was not stating that i know...therefore call someone who does...Duncan Racing. You helped him just the same so done and done.

"don't know don't post!!!!"

Really?
I gave the OP a solution to finding the right answer even when i "don't know". That's what the forum is about.
No hard feelings.

Marc

[MyMistress86R]

Piss in the AM Wheaties Kasey?

[KASEY]

i don't eat breakfast... i just can't stand all the wrong info and the well i think it will work or my friend might have done that,,,, CRAP .. when people ask a valid question ONLY people who know the answer should answer .. can't build much on I THINK IT WILL OR I ASSUME IT WILL.............................................. .................. WELCOME BACK... NOW FIND SOMETHING TO DO BESIDES STIR THE POT!!!!!!!!!!!!!!!!!!! THANK YOU.

[Cave Rider]

@Kasey, Im having a problem with a mutt engine right now. It has a Long rod crank,86 cyl. 85/86 piston,and a spacer plate... Is the recipe correct ? Cant seem to get her to run "crisp"... Im usually a "stock" build kinda guy,so its got me twisted...thanks-Pat

[KASEY]

CHECK THE COMPRESSION.. that tells alot. the best way to find out is to perform a UCCR so you know if you need to use higher octane fuel or if its real low then you have other issues ,,

Get a small tube of White Grease, small bottle of Marvel Mystery Oil (or any other low viscosity or thin Oil), a plastic graduated syringe from a Pharmacy or Veterinarian (Horse syringe) 100CC capacity (or get two 60CC syringes), a $5 calculator and lots of patience…

· You need to set the engine on the bench, remove the head, gasket and make sure the deck is clean. This can be done with the engine in the chassis (more work), remove plastics, tank, ect…

· Level the top of the cylinder out using a small 6"-8" carpenters level…level in a crisscross direction between the cylinder head studs

· With piston ½" to 1" below TDC; coat the outer edges of the piston against the cylinder wall with White Grease…use a "Q-Tip" to spread evenly all the way around

· Bring piston to TDC…find TDC using your caliper end, the long blade end that slides out as you increase the caliper jaw opening. Set a steel carpenters ruler (thin edge down sitting on top of cylinder), sit the end of the caliper edge on top of the ruler edge, hold against the steel ruler and rest the caliper blade on top of the piston center as you rotate to TDC…find the point the caliper reads the shortest distance…this is TDC.

· With piston at TDC, wipe the excess grease from the edges of the piston & cylinder wall…you want to leave a very small bead of grease sealing the edge of your piston to the sleeve

· Bolt head (with head gasket in place), NO spark plug and tighten down accordingly

· Take your syringe, fill to the 100CC mark…you want to fill to a known measured amount. If using two syringes, make sure you know the amount of oil in each…keep air out of the syringes.

· Take the filled syringe and fill through the spark plug hole up to the bottom most thread (the thread deepest inside the head closes to the Dome bowl looking from the top). Look at how much oil went into the cylinder-head by subtracting the amount of oil left in the syringe from the amount you started with. This is your Volume of Combustion Chamber at TDC…record this number.

· Add ½ a (.50)CC for the spark plug volume

UCCR = Volume of cylinder at BDC + Volume of combustion chamber at TDC divided by Volume of Combustion chamber at TDC)

Volume of Cylinder at BDC is Radius of Bore in MM x Radius of Bore in MM x 3.1416 x stroke in MM divided by 1000 = Volume in CC's

Example: 67MM piston & 72MM stroke: 33.5MM x 33.5MM x 3.1416 x 72MM divided by 1000 = 253.85CC's

Let's say the amount of Oil you measured or inserted into your cylinder/head at TDC with the syringe was 19.5CC's + .50 (spark plug volume) = 20.00CC's

Calculate: 253.85CC + 20CC = 273.85 divided by 20CC = 13.69/1

Your UCCR is 13.69/1

i know its alot of work,, but on trailprotrailprotrailprotrailprotrailprotrailprotr ailpro engines it really hepls to know what you have inside before you can resolve a problem,, them you can adjust fuel octane and start on jetting ,,, if its not crisp.. i would believe its real rich or low on compression..

[pcs]

ALL 250r cylinders have the same stroke and are the same height,, the problem is if you stay with a short rod you will have to run the wrong piston,,, if you go to the long rod cranK then all will be right with the world and NO YOU WON'T NEED A SPACER PLATE. the only case where you woud need a spacer plate is if you ran a short rod piston on a long rod,,,,, PLEASE if you don't know for sure don't comment,,,, all it does is add to the confusion!!!!!!!!

100% wrong!!! You don't know don't add to the confision!!!
so adding a long rod to a short rod engine with a short rod piston doesn't require a spacer is what you are saying...first you said to match the long rod with the long rod piston, which will work and you don't have to run a spacer. then you said its 100% wrong...make up your mind... look around and you'll find engines have such a combination so you are 100% wrong. so like I said if he threw in a long rod to an 86 motor, pistons are part of a motor, which is stating that he has an 86 piston, then he WOULD need a spacer plate so DON'T ADD confusion just bc you had a bad day and want to take it out on a forum.the last 250r set up i put together used a trx long rod, atc piston, spacer, and a ported cylinder, so i know that set up works and it is a set up that is commonly used. also, don't get so worked up over a simple forum conversation that you can even spell confusion correctly
confision!!! :lol:
here is a short vid that talks about an 86 motor using a long rod, SPACER PLATE, and an 86 piston.
http://www.youtube.com/watch?v=l3kYLJajA2o
watch and enjoy being 100% correct

[KASEY]

READ THE FIRST POST!!!! he has an 86 botton end.. and wants to use a 87 cyilnder,,, all he has to do is BOLT IT ON and ride... then he asks if he needs a long rod and piston,, the answer is NO!!! THEN TO MANY PEOPLE TRY TO ADD TO THE CONFUSION.. JUST LIKE YOUR DOING,,,,,,,,,,,,, Two simple questions and 2 simple answers,,,,

now YOU need to reread what i said,,,, oh here it is not trying to add wrong info!! to bad you guys can't read a post and get the info out of it that is already been posted....


the only case where you woud need a spacer plate is if you ran a short rod piston on a long rod,,,,, PLEASE if you don't know for sure don't comment,,,, all it does is add to the confusion!!!!!!!!

[pcs]

read my post again...i never said he NEEDED a long rod to make his motor run, i said "IF" you add a long rod...if does not mean he has too, it means that he has a choice of adding a long rod to his motor. he mentioned adding a long rod so i said IF he added one he WOULD have to add a spacer , which according to you is 100% wrong but according to well known 250r builders its not. its just a matter of piston choices which both will work, run an short rod piston, run a spacer, run a long rod piston, no spacer. so i will be the bigger person and no lower myself to argue over you saying some posts are incorrect, or feed your need to try to flex your internet muscles over a simple forum question.its pointless to argue details online over a forum. have a great day.

[RIDE-RED 250r]

I have a question along this topic, if I may...

UCCR (un-corrected compression ratio) vs corrected compression ratio

Is the magic ratio for determining proper fuel octane rating the UCCR or CCR? Am I correct in my inference that CCR calculates actual running compression ratio taking into account compression lost while the exhaust port is still open on the up-stroke of the piston? If so, would the CCR be the ratio to pay closer attention to for fuel requirements?

I realize that calculating CCR is alot more involved since you would be taking into account port layout and timing... Assuming I am correct about how to determin CCR....

[KASEY]

just measure the height of the cylinders, if they are the same then you should be good to go,

just a note to end all the speculation and inaccuracies ... since some people DON'T KNOW ,,, ALL UNMODIFIED ATC AND TRX cylinders are the same height.... and will interchange all years........

[pcs]

I have an 86 bottom end and 87 cylinder that has been ported by Paul Turner. Since the two year have the same stroke will it work or will I need a long rod crank and piston? ..........

[MTS]

I realize that calculating CCR is alot more involved since you would be taking into account port layout and timing... Assuming I am correct about how to determin CCR....
Not really Just need to know your exaust port height, use that as your stroke in your Formula insted of the full, Kinda a Metric Japanes Thing...Like adding a long duration cam to a sbc to bleed off compression before it go's boom.. i run 14:1 or so UCCR and 7:7:1 CR (supposedly Stock) but im running 100L octane to keep it in one piece, most days... Just thought i would add, there are alot of things that go on in "that simple ass 2 stroke" :beer

[KASEY]

..........

post the answer!!! the answer is YES!! bolt the cyilnder on and ride the PCS out of it,,, you don't need a long rod crank or piston,,, see how simple it is??? no ifs ands or maybes about it...................................

[Rigaman]

Oh thanks Kasey. This thread has been a big help. I had SO many people telling me 88 and 89 were long rods, and you cant use an 88 or 89 cylinder on an earlier bottom end without a spacer. I think people confuse the spacers because the long rod big bore kits use spacers.

Since the later trx motors have longer rods, they have shorter pistons right? So if I wanted to use an 88 top end on an 85 bottom end, I would need an earlier piston? I cant use the 88 piston..

Which years were the longer rod motors? 88 and up?

[sx250heath]

The long rods were 87 to 89. From what I have gathered from this tread is an cylinder will work on any bottom end regardles of it's long or short rod. You need what ever piston goes with the rod (long rod piston on a long rod crank, short rod piston on a short rod crank).
If use a long rod crank and short rod piston you need a spacer.

[KASEY]

that is correct... I have been running an 88 cylinder on a 86 stock bottom end for several years without any issues,,

[sx250heath]

Thanks for clearing this up. I asked on a few sites and no one answered. I am thinking about getting a spacer plate using the long rod and a short rod piston.

[Dirtcrasher]

Kasey has probably corrected threads on this a few dozen times. Like he said, "I think" doesn't cut the mustard and you guys should feel fortunate that he corrects others replies and tells it as it is with his vast knowledge!!