Another 4mm Stroker ?

[JasonGOSU]

Guys I'm coming to you because I'm sure you have the answer. I know some of you have a 4mm short rod stroker motor. Here's the dilema.

 

I've been told by the guy who is porting my cylinders that I need a spacer plate and can use the regular coolhead domes.

 

The guy I bought my short rod crank from tells me that the stock portiming should be left alone and all I need to do is use stroker domes. He also states that putting a spacer plate on top of the cylinders and using a regular 19cc coolhead dome will create detonation and usually eats through the seam where the head and spacer meet.

 

I've read in here that the port timing does need to be changed.

 

I need you guys just to tell me how it should be done so I can get it back together. Thanks for your help.

[Patriot Racing]

Custom domes are the way to go.

 

Your friend is correct, the port timing is most often more favorable with running the stroke out of the top of the cylinders. The spacer adds more potential failure points.

 

The cost of PD domes and spacers, we can getcha setup with custom domes. Shoot us an email.

 

Thanks,

Dan

[PassionRE]

Guys I'm coming to you because I'm sure you have the answer.  I know some of you have a 4mm short rod stroker motor.  Here's the dilema. 

 

I've been told by the guy who is porting my cylinders that I need a spacer plate and can use the regular coolhead domes. 

 

The guy I bought my short rod crank from tells me that the stock portiming should be left alone and all I need to do is use stroker domes.  He also states that putting a spacer plate on top of the cylinders and using a regular 19cc coolhead dome will create detonation and usually eats through the seam where the head and spacer meet.

 

I've read in here that the port timing does need to be changed.

 

I need you guys just to tell me how it should be done so I can get it back together.  Thanks for your help.

Using a spacer plate on top of the cylinder is a disaster waiting to happen. I use thicker base gaskets under the cylinder to maintain the use of off the shelf domes. Not only does this keep the piston top within the safety of the liners and maintain forced convection cooling charecteristics of a stock engine, it also enhances the port timing for a more performance oriented engine. If real performance is your game though, additional port configuring is needed to tap in to the full potential of a +4 engine...Jim

[The Rebel]

Guys I'm coming to you because I'm sure you have the answer.  I know some of you have a 4mm short rod stroker motor.  Here's the dilema. 

 

I've been told by the guy who is porting my cylinders that I need a spacer plate and can use the regular coolhead domes. 

 

The guy I bought my short rod crank from tells me that the stock portiming should be left alone and all I need to do is use stroker domes.  He also states that putting a spacer plate on top of the cylinders and using a regular 19cc coolhead dome will create detonation and usually eats through the seam where the head and spacer meet.

 

I've read in here that the port timing does need to be changed.

 

I need you guys just to tell me how it should be done so I can get it back together.  Thanks for your help.

Using a spacer plate on top of the cylinder is a disaster waiting to happen. I use thicker base gaskets under the cylinder to maintain the use of off the shelf domes. Not only does this keep the piston top within the safety of the liners and maintain forced convection cooling charecteristics of a stock engine, it also enhances the port timing for a more performance oriented engine. If real performance is your game though, additional port configuring is needed to tap in to the full potential of a +4 engine...Jim

Jim is shooting you right. Going with the spacer on top of the cylinders will make it more difficult to get the proper quinch area above the pistons. This creates potential (read garaunteed) detonation. Spacing the cylinders from the bottom is the best option, running short or long rod. The port timing does change with the +4 crank, depends on what you want to do with your bike as to what port configuration you need. With the long rod you are using a diff. pin height in the piston, port timing is the same, but your motor is a little slower revver. The trade off is better breathing in the top rs. Hope that helps.

[fixitrod]

Go to see your visiting us again Dan!!!

 

I used standard gaskets. I had the the domes cut to suit though. I also had porting done to match. I wanted everything to be as standard as possible and eliminate failure points as mentioned above. If my motor goes I can drop in a crank, pistons, standard gaskets, and have some domes cut and be good to go.

[JasonGOSU]

Guys,

 

Just wanted to thank you for all of you input, it has been much appreciated.

 

Jason