they are very competitive with 7's and even some 8's. Depending on what you would like it to do , the best mod is an 1 1/4 track. Clutching , gearing, and good maintenance.
I have an MBRP wide kit on the front end of my flatland HO and love it.
Ufo's have their good points and bad. Love the throttle respone, hate the gas mileage. Going to give them a go again with some changes and see if I can get the mileage up.
Even though it spots some 30cc's to the larger 700s, it is a really quick sled. On the bottom and mid-range, it really moves, but the top end suffers a little.
On my old 670, I had a goodwin performance clutch kit, and one tooth smaller gear (the small gear). It was studded with 144 studs, I had the shorter intake boots and had tried a couple of different rotary valves. I always did very well in grass drags with the machine, and even could beat SRX's up to about 75-80mph. After that, the top end would drop off.
I 'm sure it will but i dont want it to burn down after 500ft.The Crank S hop has dyno'd the 740 @145hp with 98ft lbs of torque,it sound's to me that the 740 is alot less radical than a standard bore 670 would be makeing the same hp as the 740.
If you bought it to ride it...then ride it. If you bought it to build out the motor, then that is another story. That motor is definately a drag race king, and will do well in that type of running, but if you want top end, the reed motors will develop more top end. But then, if you just want top speed, he with the most money wins...
Just remember, the more mods you do, the less reliable a sled becomes... (if you are just going to trail ride it).
Recently I spoke with a couple of the bigger rotax specialty shops, DNE, CrankShop etc. They would love to do the 740 bigbore but the they freely admit that the best bang for the buck is a tunnel and cylinder porting job with matched cases, slight bump in compression, timed rv and rv cover mod.
If your topend is ready to be redone the price isnt that bad. But if you have a good motor spend $900 Can or $600Us and send it to Don and let him do his thing.
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