670 mods 740 Big Bore??

[670Xpower]

I have a 99 summitX 670. 151X2.5 track 20 44 gears. I need more power Has anyone had good luck or info i a 740 big bore kit? Or should i just bore it .10 or .20 over and do more mods? I also want to put a real aggressive rotory valve. I ride 6500 ft and higher its a hill shooter Any info will be great. Thanks

 

[partsman]

I have a 99 summit X motor for sale.It would give you more power.It is a full port unionbay motor with bored carbs and union bay head.If intrested call.
Steve (604)816-5682

 

[9894doorider]

have you done anything to the motor? tried porting, shaving the head, pipe, boring carbs, what rotary valve is in the engine? have you messed with the cluthing at all, there's alot you can do, you can turn it in to a ho motor

 

[summer sucks 35]

can turn it in to a ho motor[/QUOTE]

99 summits are ho's

 

[Thunderguy BOOSTED]

I have a 1997 740 union bay in my S chassis! Based off a 670! Awesome motor! I Run 44mm carbs, kick a$$ air pods, P-85 primary, crank shop pipes, premixed on pump 91 oct! Have 21,42 gearing, and that thing pulls HARD!

 

[austinbrose]

I have a non HO and am very impressed with it, I can't imagine how powerful a big bore is. However, here are a few suggestions. The rotary valve to upgrade to is the 501, it came stock on some models, I don't know which. Adjusting belt deflection is important. Clutching is very important, but I can't recommend any thing specific. Losing weight makes a huge difference: lightweight trailing arms, lightweight hood, lighter can/pipe (however stock ho pipe very good), lighter seat (remove stock foam and stuff with swimming pool noodles).