661 Stroker

[Mastermind]

Shaun, can you make me some bushings to allow me to run a 394 piston in one of these?

 

[Redfin]

Jawney, did you do anything to the floor of the exhaust port?

No Sir.

 

[Redfin]

You’ll need to check that the bottom of the transfers are not above the piston at TDC. That is often the case with strokers.

At TDC?

 

[Mastermind]

At TDC?

No. At BDC

 

[srcarr52]

Shaun, can you make me some bushings to allow me to run a 394 piston in one of these?

Sketch something up and I can make whatever you need.

No. At BDC

Yes, at BDC. I shouldn't post before I'm properly caffeinated.

 

[Redfin]

Yes, at BDC. I shouldn't post before I'm properly caffeinated.

Are you talking about the bottom of the upper trans?

 

[srcarr52]

Are you talking about the bottom of the upper trans?

Yes, the bottom of the upper transfer port opening are often still above the piston at BDC when you increase the stroke.

 

[EvilRoySlade]

Yes, the bottom of the upper transfer port opening are often still above the piston at BDC when you increase the stroke.

I’m curious, are you saying this in the sense that they should be opened to take advantage of the space? But you say it more like a warning.

 

[srcarr52]

I’m curious, are you saying this in the sense that they should be opened to take advantage of the space? But you say it more like a warning.

They'll need to get ground on so a pocket of exhaust isn't left on the top of the piston.

 

[Mastermind]

Sketch something up and I can make whatever you need.

Is is possible to find a wrist pin bearing that is the width of the 661, but the inner and outer dimensions of the 288?

 

[EvilRoySlade]

Is is possible to find a wrist pin bearing that is the width of the 661, but the inner and outer dimensions of the 288?

Someone once gave the tip of using dirt bike bearings. KTM makes a lot of mini bikes and their parts are pretty easy to search. I just search the dimensions that I want and go from there.

 

[Wonkydonkey]

Koto bearings is what I’ve been told, and yes just get the sizes and put in evil bay the correct fashion, it will give you a head start

 

[Mastermind]

Not having any luck.

 

[psuiewalsh]

I tried looking for 13X17X13mm . Is that correct? If so will 12mm wide be too loose or could you have a shim washer(s)?
https://www.123bearing.com/bearing-RS131712-KOYO.php

 

[Mastermind]

I tried looking for 13X17X13mm . Is that correct? If so will 12mm wide be too loose or could you have a shim washer(s)?
https://www.123bearing.com/bearing-RS131712-KOYO.php

12 would be too narrow. But could work with the right thrust washer design.

 

[srcarr52]

12 would be too narrow. But could work with the right thrust washer design.

We can make thrust washers with a step to center the bearing.

 

[Mastermind]

We can make thrust washers with a step to center the bearing.

We can probably make them to work with the 288 bearing really. Thoughts?

 

[srcarr52]

We can probably make them to work with the 288 bearing really. Thoughts?

I would think so, is that a 13x17x17.5 wide? What size do you need for a 661?

 

[Mastermind]

I would think so, is that a 13x17x17.5 wide? What size do you need for a 661?

Correct.

I'm thinking of using a 394 piston in the 661 stroker.

 

[srcarr52]

Correct.

I'm thinking of using a 394 piston in the 661 stroker.

What is the bearing size in a 661?