Stroker Crankshaft &pistons

[duneslinger]

here's more questions on stroke cranks, is the wiseco 795 piston for use on a long rod crank and a spacer plate used for the difference on a 4mm stroke? would use of a spacer plate on a stroker crank motor keep the piston port timing same as a stoke crank on the down stroke? and if the piston moves 2mm farther into the case it would be 2mm below the tranfer port and ex floor then adding a plate would add to that 4mm total? would you have to rework the transfer floor or just run it? current set up is ..80 over, 4mm short rod, ported cylinders,ported reed cage, 35mm carbs,170psi, and t-4s has domes cut .80 to clear piston no spacer plate. problem is good pwr to upper mid then just stops reving wouldn,t wind up high main jets tried 350,340, 330 but i don,t think it's jetting thanks for any insight.

[fixitrod]

here's more questions on stroke cranks, is the wiseco 795 piston for use on a long rod crank and a spacer plate used for the difference on a 4mm stroke? would use of  a spacer plate on a stroker crank motor keep the piston port timing same as a stoke crank on the down stroke? and if the piston moves 2mm farther into the case it would be 2mm below the tranfer port and ex floor then adding a plate would add to that 4mm total? would you have to rework the transfer floor or just run it? current set up is ..80 over, 4mm short rod, ported cylinders,ported reed cage, 35mm carbs,170psi, and t-4s has domes cut .80 to clear piston no spacer plate. problem is good pwr to upper mid then just stops reving wouldn,t wind up high main jets tried 350,340, 330 but i don,t think it's jetting     thanks for any insight.

is the wiseco 795 piston for use on a long rod crank and a spacer plate used for the difference on a 4mm stroke?

 

Yes. The 795 series piston is offset for the difference in rod length. The spacer plate is used to make up the difference in 2mm stroke each direction... at least on a 4mm. I had the head cut and cylinder ported so I didn't need a spacer plate.

 

 

would use of  a spacer plate on a stroker crank motor keep the piston port timing same as a stoke crank on the down stroke?

 

Port timing should be modified for the extra stroke. It will not be the same.

 

 

problem is good pwr to upper mid then just stops reving wouldn,t wind up high main jets tried 350,340, 330 but i don,t think it's jetting     thanks for any insight.

 

If you added all the 4mm parts and didn't have the porting done for it, start there.

[H300F]

Did you have the porting done for a regular crank and then add the 4mm later on? You need the ports matched to the stroke for it to run correctly, adding cut domes or a spacer isn't going to elliminate the need for matched ports.

[duneslinger]

so if the motor was ported before i added the stroker crank and was using a cut dome insted of a plate, which ports need to bo moved and which way, up on the transfers and the ex 2mm?

[fixitrod]

You need a degree wheel to determine how much to cut. Don't guess.

[duneslinger]

is it true that if you install a 4mm stroker into a motor which was already ported you could run into problems with ransfer port timing and duration, I read it so where but lost it. Is there any kind of book or guide on the set up of a stroker crank? thanks

[shortys racing]

is it true that if you install a 4mm stroker into a motor which was already ported you could run into problems with ransfer port timing and duration, I read it so where but lost it. Is there any kind of book or guide on the set up of a stroker crank? thanks

think of it this way, a 4mm is 2mm further up and 2mm down..... so you'd have to cut the domes 2mm in the dome. Also the ports would be 2mm higher then normal since the piston is 2mm lower then normal. You would have to deck the cylinders 2mm and cut the head alot. Might as well sell the cylinders and start new. best way to get them right.

[fixitrod]

is it true that if you install a 4mm stroker into a motor which was already ported you could run into problems with ransfer port timing and duration, I read it so where but lost it. Is there any kind of book or guide on the set up of a stroker crank? thanks

think of it this way, a 4mm is 2mm further up and 2mm down..... so you'd have to cut the domes 2mm in the dome. Also the ports would be 2mm higher then normal since the piston is 2mm lower then normal. You would have to deck the cylinders 2mm and cut the head alot. Might as well sell the cylinders and start new. best way to get them right.

I don't think that's right shorty. The port timing will not be correct. Jim from passion has put this on a degree wheel. I'll search for the post.

[fixitrod]

Here it is shorty

 

http://www.bansheehq.com/forums/index.php?...&hl=4mm+stroker

 

If that's incorrect I'll be suprised, but would like to know. I was thinking the same until Jim explained it. Then it made a little since

[duneslinger]

ok my motor has a 4mm stroker short rod and cut domes .80/2mm for the piston clearance above the deck with no plate. i don,t have a dedree wheel yet but the ports measure ex-27.5mm from deck to top of port. the floor of the ports have not been dropped, transfer ports are 42mm from deck. intake ports are 67mm from deck. are these cut too much for this crank?? any idea what spec would i need for a good dune motor when i get a degree wheel thanks for the help

[PassionRE]

Those porting specs are quite tame in that build configuration, it has not been overported for a +4...Jim

[feature000]

I am getting a 4mm stroker 5mm long rod crank, with wiseco 795 series pistons I got my cylinders ported by LA sleeve for the stroker long rod crank. The problem I have run into is I wanna run a pro design coolhead what do I need to do? Do they sell some sort of spacer for the head. Please help.

[H300F]

You should ask LA how they set them up to run. You can run a deck plate or cut domes ("stroker domes"). I am assuming LA ported it for you to run with cut domes but they are the only ones who know so ask them.

[shortys racing]

I am getting a 4mm stroker 5mm long rod crank, with wiseco 795 series pistons I got my cylinders ported by LA sleeve for the stroker long rod crank. The problem I have run into is I wanna run a pro design coolhead what do I need to do? Do they sell some sort of spacer for the head. Please help.

we usually just run cut domes... We have some available.

[shortys racing]

is it true that if you install a 4mm stroker into a motor which was already ported you could run into problems with ransfer port timing and duration, I read it so where but lost it. Is there any kind of book or guide on the set up of a stroker crank? thanks

think of it this way, a 4mm is 2mm further up and 2mm down..... so you'd have to cut the domes 2mm in the dome. Also the ports would be 2mm higher then normal since the piston is 2mm lower then normal. You would have to deck the cylinders 2mm and cut the head alot. Might as well sell the cylinders and start new. best way to get them right.

I don't think that's right shorty. The port timing will not be correct. Jim from passion has put this on a degree wheel. I'll search for the post.

if he decked the bottom of the cylinders, then the timing would be lowered is what I was getting at. It is possible to fix it for a 4mm, depending on what port timing your looking for?? Drag, dune, ect. Bottom line, no spacer plate, and cut domes....you retain your crank case pressure and it will run like a champ.....