Here would be a good one for dyno drags, take the weight factor out see what they do motor to motor, and shifting ability.

 

This question has been beat to death. Every time it gets answered, it pops back up. The 730 kit will suffice as a good race motor but IMHO it is a play toy that is relatively affordable. I liked my 730 for duning. It made so much power so early in the rev range. It was a wonderful upgrade for guys who want more grunt that is bolt on without machining. The peak hp may only be 10 or 11 including the bump in compression but the average hp increase from bottom to top is the real advantage.

Choose, you are a racer. That bike of yours hauls but it isn't set up for a weekend of play. Don't buy a 730 kit for strictly racing. Buy a stroker. It will rev quicker, you aren't limited to 13.5:1 compression. I guarentee you that a 715 w/ 15:1 comp stroker will outrun a 730 big bore at 13:1 at the races all other things being equal. It may post almost identical peak numbers but they way it makes power, especially topend is more appropriate for race applications. The reason you don't do a stroker for duning is the cost. The crank itself (8mm) is over $1500 plus all the labor involved in splitting the case. It might cost twice as much as a 730 big bore when you are done.

If you want to approach 80 hp before NOS, the 730 is actually a pretty affordable way to get there. I think if 80 hp is the goal, it is the cheapest way next to NOS but that has tradeoffs to. Thanks to average hp a 70 hp 730 will outrun a 70 hp 650 by a lot. I bet with equal weight machines a 70 hp 730 will outrun a 75 hp stockbore and stroke motor.

ERBE, you forgot one other group and that is the ones who would rather save a few bucks than build a fast motor. By and large you get what you pay for.

Stroker is the fastest by far.

Ron

 

There is being thrifty and being cost effective, again its only a toy and if you can build up to a 70hp machine or a dune sheadding monster that is reliable and fun to ride without being Donald Trump, then I dont whats wrong with that.
(ERBE) Smiles and waves back at DSnut[img]i/expressions/face-icon-small-happy.gif[/img]

 

hey arachnid are you afraid of sporting that hpr sticker on the bike? well im here now doing a west coast call out there is no phobia of spiders out here. i cant wait to place that sticker on your pretty little bike of yours. im still waiting[img]i/expressions/face-icon-small-happy.gif[/img]

 

I'll let you decide how well your gonna beat this spider after the clash.....we are expecting an HPR 800, [img]i/expressions/face-icon-small-wink.gif[/img]

Oh yeah, then I'll let you know if the 800 is worth the money......[img]i/expressions/face-icon-small-shocked.gif[/img]

 

i did not know rwr made an 800 oops[img]i/expressions/face-icon-small-smile.gif[/img] is that there stage 3 or is that the glamis one

 

 

ERBIE -- I am not sure why you are waving at me. I wasen't referring to you, just agreeing with you and adding to your list. We were both referring to "most people". There is nothing wrong with that, I am simply saying that in most things you get what you pay for. Btw, it takes way more than a big bore to get 70 hp out of DS. It isn't as easy as putting on a big bore and calling it a day. It is easy to make 55 hp with a big bore but 70 takes some real knowledge and/or money.

Nothing personal.

DSNUT waves at ERBIE from the top of the hill.....

[img]i/expressions/face-icon-small-wink.gif[/img]

I am glad you took an interest in me ERBIE. thebigshow and AZsand have been playing with other guys lately so I have been bored. This is more like it! [img]i/expressions/face-icon-small-happy.gif[/img]

 

Here is a dyno sheet a forum member posted of a HPR730 with single carb Dyno Sheets I would like to see what it would pull with dual lectron carbs.