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dont know what to do, HELP


jay793

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If those pistons were for a longrod, they would not be sticking out above the deck !!!!

They would be below the deck by 5mm

The wrist pin bore for a 5mm longrod is 5mm closer to the crown.

 

There is something else going on there.

And if he does try to use blaster pistons, they will not come up far enough in the bore.

That picture he showed only looks loke 2mm over the deck. 5mm is .200 (almost 1/4 inch.)

 

For some strange reason, someone must have milled the base of those cylinders. Or, there is a 4mil crank with stock rods in there.

 

Why dont you measure the cylinder height from base to deck and I'll tell you if it is short.

Like someone mentioned here earlier I would not use a base spacer. Get some domes cut for a 4mil stroke.

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I have seen people shave the jugs to lower exhaust port timing for more bottom end power. You cut the head to make up for it. Maybe thats what he did. You can measure the jug length base to top and maybe someone else can give you the number off a stock jug thats not shaved.

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If those pistons were for a longrod, they would not be sticking out above the deck !!!!

They would be below the deck by 5mm

The wrist pin bore for a 5mm longrod is 5mm closer to the crown.

 

There is something else going on there.

And if he does try to use blaster pistons, they will not come up far enough in the bore.

That picture he showed only looks loke 2mm over the deck. 5mm is .200 (almost 1/4 inch.)

 

For some strange reason, someone must have milled the base of those cylinders. Or, there is a 4mil crank with stock rods in there.

 

Why dont you measure the cylinder height from base to deck and I'll tell you if it is short.

Like someone mentioned here earlier I would not use a base spacer. Get some domes cut for a 4mil stroke.

 

 

Brian is dead on. Blaster pistons on a stock rod banshee crank would be 5mm below deck. Keep in mind that we put in the blaster piston to compensate for the extra 5mm of a 115mm rod so the deck would be nearly even. I agree that the total cylinder height needs measured as well as actual neg piston travel past deck. This helps narrow it down. Trinity very possibly decked the bottom of the cylinders to correct an over ported cylinder. This can have bad effects on the bottom of the ports and cylinder flow will suffer big time. You also need to measure the stroke of the engine to rule things out. buy a digital caliper and go to work.

 

With this strange deal, I HIGHLY recommend you have a porting expert inspect to see what has been done and what is the right setup for those cylinders!! You may also call us and we can tell you what to measure to find out what is going on.

 

 

Brandon

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Thanks for your help I think im going to take it to a shop and have them look at it and tell me whats going on, I dont want to throw it all in the trash by doing something stupid like a spacer or anything. I have jeff from fast cuting me domes for a coolhead to match these pistons, should I tell him to hold up on it or will i need them anyway?

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