New project

[EE]

I'll be following this project! Nice choice Joe.

[teazer]

Excellent choice.  We have an FZR in the garage.  It sounds big and mean but only makes about the same HP as our RZ350.

Didn't Yamaha go to reverse cylinders specifically to reduce piston wear with large intake ports on the 250 models which ended up with huge intakes?

It's hard to get the pipes looking good on our old downward pointing exhaust ports.  I had a set from a Kart motor years ago but they could not be fitted to a bike as you can see. On the reverse cylinder models, the exhaust ports are completely different exit angles.

[Jspooner]

I never thought about the angled exhaust ports. I won't be doing that anyway. Don't like the looks at all.

[EE]

Not to sidetrack your thread Joe.. in 81 Yamaha reversed crankshaft rotation to allow for the still piston ported 250's growingly huge intake ports, by 85 they were on to case reedvalves so it wasn't an issue anymore by the time they got to the reverse cyl model in 88-90.

[teazer]

EE's right.  Yamaha had issues with piston life on the 250G with it's cavernous intake ports.

Just thinking out loud, but since we are now off topic, might I suggest an RZ motor in that frame with say a stroker crank and CPI cylinder for about twice as much power as a TZ top end. 

[Jspooner]

EE's right.  Yamaha had issues with piston life on the 250G with it's cavernous intake ports.

Just thinking out loud, but since we are now off topic, might I suggest an RZ motor in that frame with say a stroker crank and CPI cylinder for about twice as much power as a TZ top end. 

Sounds like fun but I've already got the TZ top end and I've got an LC bottom end on the way to use with it. But....................mounting will be the same so I could always change my mind when I get to that point of completion. 

[EE]

I like the TZ route. CPI's have been so done..and redone..

[85RZwade]

  stay the course

[m in sc]

I know not feasible.. but, could re-line add intake bridge? just spitballing.

[EE]

The problem wasn't the intake port size just look at the Portmap. The problem was the short skirt length and piston tech back then, Yamaha pistons were like teacups.. Joe I believe is running forged pistons he should be fine.. even if he replaces pistons slightly more often fun factory outweighs it to me. If his cyl needs a replate he could look at other single ring piston options before the replate n hone but I'd just run a good forged piston.

[m in sc]

got it. not being familiar with it is why i asked makes sense.

[EE]

It's not a bad idea mark just a lot of work for an arguable gain here. CPI runs a bridged cyl Reed intake BUT I think they gave up boost port efficiency by doing it because they bridged the boost port as well.. Honda is a great example of nicely shaped large cyl Reed intakes with an attached open boost port. Now if it were a piston port cyl I'd say yeah bridge it.

[m in sc]

thanks for the explanation Ed. 

[Jspooner]

Part 3

[EE]

Cool!