Freestyle Need some advice on building a stroker motor

[BlessedYamahaSJ]

Roseand, i will call zack too. i appreciate the people on here who give constructive criticism.

atomic punk, i have done a few top ends, and i know that doesnt make me a pro. but i know there are people out there who just throw motors together, dont run the right oil mixture, fry cranks, and sell their garbage online.

 

[Big Kahuna]

The problem is, you cannot just start sourcing the parts until you know how you are going to build it. None of us can give you those answers....... There are two ways to build a stroker using stock cases and cylinders. You either use a spacer plate (Above or below the cylinder) or you take care of the extra stroke by cutting the domes to allow the longer stroke (Called a Pop Top by some)......... Next, you may have to deck the cylinders to get your port timing exactly where it needs to be or add a thicker base gasket if need be........ Before you even go this way, you got to know what crank you are using to determine what way to go, how thick your spacer needs to be vs your port timing and how much to cut the domes..............

 

[BlessedYamahaSJ]

Thanks Kahuna, that is more what i was looking for. i appreciate it.

 

[bungeeguy]

Well if you are stuck on doing it yourself get at least 44mm carbs and a msd enhancer. BUT, I think because you are even asking such obviously basic questions says that you may be in way over your head on this. Not trying to rain on your parade but I really think you would be way better off just saving each month so that you can get a good motor from a respected builder.

 

[Half flip95]

generally speaking you need the crank, core cases, core cylinder, and girdle head to get started

 

[Big Kahuna]

Pop Top, is with the spacer above the cylinder.

 

[Half flip95]

what do u do for a gasket on the bottom of the spacer plate?

 

[waxhead]

The spacer plates are normally cut for orings as well so you have two sets of o-rings.
personally I set up all my strokers with a positive deck and run the piston out the top of the block, Still not ideal but way better than a spacer on the cylinder.
You can space up your cylinder but it will crank up your transfer port timing alot and this drops your blow down alot. it would be so bad on a triple exhaust port engione as it has more exhaust port but on an old nail yamaha setup not a great thing at all.
There is so many way to do it and most of them not right, be careful as you may end up with something that just doesn't go as well as you hoped.
If you do the stroker run it for a few tanks and then pull the head off and have a look how much exhaust gas is going down the transfers. If you do not have a blow down the pressure in the cylinder is to high and it stalls the transfer flow and blackens the port. if this you can either raise the exhaust port to give more blow down or lower the transfer timing, by lowering the cylinder

 

[wanderer1]

Here is my dumb 2 cents. Buy a cylinder/head already set up for the stroke you want to use. eliminates spacer plates, girlded head, porting, port timing and dome guess work. Unless you have (not implying you don't) very good understanding of the effects of port timing, squish, dome design- squish band, divergence etc.- you might end up with something less than desirable. Good luck.

 

[Half flip95]

There is so many way to do it and most of them not right, be careful as you may end up with something that just doesn't go as well as you hoped.

yuppp. best to write one of the pros a check and say call me when its done.

 

[Matt_E]

The problem with doing it yourself on a budget is that you, more than likely, end up with a motor that costs way more than your standard 701, but has a power level not at all congruent With the increase in cost. And worst case, you will get he reliability of an eBay special to boot.
I wish you luck, but will also caution you that I have been there, done that (albeit with a stock stroke big bore and not a stroker). Eventually I paid a pro to do it. It would have been cheaper to go that way to begin with.

If you are determined, do plenty of research on port timing, ignition setup, compression, rod length and angles, etc etc ad nauseum

 

[BlessedYamahaSJ]

Thanks Matt. That was my plan. I appreciate all the info guys. Yes I am on a budget, but I DO want to do this right. Motor may not even be ready for next season. I love learning about this stuff and I will do as much research as I possibly can before I start cutting, grinding, and bolting together.

Edit: just being vague ^^^

I am wondering on these spacers and will be looking into the advantages and disadvantages of how and where they are installed with what size stroke.

I DO appreciate any advice, either on ignitions, porting, dome sizes, anything besides that I should have a professional do it. That has been made clear

 

[Half flip95]

If I had that itch and had to scratch it, I would try stick a 61x on a 5mm. take up half the added stroke with a spacer plate and the other half with recessed domes. make the ports wider. ignition should be programmable, look at some curves being used in the "curve thread".

but thats just a stab in the dark if i had to start somewhere

 

[grezzmky]

For those of you who know everything and feel like mocking me, i am not disregarding peoples advice. I am just trying to get peoples perspective, opinion, and advice on this. i might not have made this clear, i do NOT know how to build this motor. I am not building it tonight. I have already contacted someone who can build this motor for me. (i will continue to contact more builders to aquire different perspecives on the build too) I am not worried about machining, or porting at this moment. I am just trying to find out what PARTS i need. have people had bad luck with a certain product? have you found something to be bullet proof?
.

Yea, we have (mostley) all had bad luck piecing a motor together and learned to not build a garage stroker motor and expect it to be worth a crap or last.
Maybe you should save up for a total loss or mag pump and do a small port job and hone if you have to do something yourself... my 2cents

 

[Big Kahuna]

If your on a budget. Forget a stroker. That not a budget motor.

 

[BlessedYamahaSJ]

Lol thanks y'all. Decided no stroker this year, just goin with a 61x/62t motor maybe with a port job and some new pro-x pistons

 

[Roseand]

What head/comp are you going with?

Sent from my XT907 using Tapatalk

 

[BlessedYamahaSJ]

Got an ada head with 35cc domes right now on my stock 61x motor. Not sure what compression it is running, don't have an accurate compression tester.

 

[Schmidty721]

I'd sell you my 5mm for $1k

 

[kwakhead]

For those of you who know everything and feel like mocking me, i am not disregarding peoples advice. I am just trying to get peoples perspective, opinion, and advice on this. i might not have made this clear, i do NOT know how to build this motor. I am not building it tonight. I have already contacted someone who can build this motor for me. (i will continue to contact more builders to aquire different perspecives on the build too) I am not worried about machining, or porting at this moment. I am just trying to find out what PARTS i need. have people had bad luck with a certain product? have you found something to be bullet proof?

I am thinking running stock carbs for the 62t case. and thanks for the advice on the MSD. i will look into it.






Chadman, i appreciate it. i already contacted PHP about their lightweight 4 mil stroker crank. I think i will be going with this one as well.

sorry to say it man but there are alot of aholes on here that talk too much...