Take a look at my cylinder/porting...does this look right?

[MileHighJSC]

The sleeve is set to the deck height of the cylinder. The port timing is coming from the sleeve. Yes, if you want your sj 701 to run the way it was designed to, then you must match all aluminum casting to the angle and size of the sleeve. Yamaha is about profit. They are in the production business, They DO NOT BUILD hi performance out of the box race boats, Look at the stock pipe, What a POS. Almost all water craft motors are de-tuned so that joe shmo and every other knucklehead and his girl friend can't go out and F the motor up. I.E. 6 to 1 compression, rev limiter. The port mis-match enables the cylinder to go together fast, easy, and always in one try. It is easy for the factory to do on a production level and it kills horse power, a perfect de-tuning tool. The less horse power the longer the motor will last. Less warranty work and good word of mouth, "Man those super jets run forever"

 

[Polish jet pilot]

amen

 

[MileHighJSC]

The sleeve is set to the deck height of the cylinder. The port timing is coming from the sleeve. Yes, if you want your sj 701 to run the way it was designed to, then you must match all aluminum casting to the angle and size of the sleeve. Yamaha is about profit. They are in the production business, They DO NOT BUILD hi performance out of the box race boats, Look at the stock pipe, What a POS. Almost all water craft motors are de-tuned so that joe shmo and every other knucklehead and his girl friend can't go out and F the motor up. I.E. 6 to 1 compression, rev limiter. The port mis-match enables the cylinder to go together fast, easy, and always in one try. It is easy for the factory to do on a production level and it kills horse power, a perfect de-tuning tool. The less horse power the longer the motor will last. Less warranty work and good word of mouth, "Man those super jets run forever"

To follow up on my last post, 99.9% of people don't have the correct tools or the Mechanical savy to touch the intake ports. That is why the porting templates DON'T cover this area of the cylinder. For all you "nubes" It is extremely easy to F up your cylinder and or your port job, so be very, very carefull or better yet send it to a pro.

 

[haggis]

Just out of interest is there a freestyle sportport template for a 760 cylinder?

 

[Matt_E]

It uses the same template as the 701, as the template concerns itself with port width, not height.

 

[haggis]

right, I have a spare set of 760 jugs and might give it a go for fun, it dont matter if i f*** it up.

 

[Matt_E]

One of my best cylinders (that I ported myself) was a 760 cylinder.

 

[haggis]

Ive been slowly gathering parts for a stroker engine but that aint going to be ready until later next year so i was going to run my 760 for a while and thought it might be nice to give it a little wakeup without spending a fortune on it, again its a spare set of jugs so if i do make a bags up then i can still ride in january.