I have a 61x/61x motor I'm running a mod b pipe Ada head with 35cc domes lightened stock fly wheel. I took the top end off and there is some light scoring on the cylinders and piston. Compression before I took it apart was 150 in each hole. I'm porting it my self and am wondering if it's worth to go to a 83 or 84 bore since it's already apart. Any input appreciated, thanks
701 bore
- Thread starter 800750
- Start date
cookn
Kamikaze
- Location
- where you live
I wouldn't go as far as saying a larger bore wont make any difference or else why would they offer big bore kits , a tuned motor will make small gains as it steps up its bore to a larger size but some peoples motors are tuned so poorly they would never noticed the difference. Its my opinion that the yamaha motors really come alive when you bring all the little things together such as porting, larger bore, higher compression and advanced timing. Its just my personal experience from tinkering over time that alot of the small mods added together is what makes a good performing package. I know of people that have taken the 61x cylinder out to 84mm and seen performance gains.
I didnt see he was planning to port. I agree, the right parts and setup will make a big difference. I notice a decent difference from my ported 84.5 to stock 81. Simply going 81 to 84 without changing anything else is only a 7% increase in CC's, and the only feeling most would get is the placebo effect. In which case I would say keep the available bores.
SUPERJET-113
GASKETS FOR CHAMP BRAP!
- Location
- Lake Havasu City, AZ USA
701's start to wake up @83mm IMO. If you have to bore go for it for sure.
bored&stroked
Urban redneck
- Location
- AZ
Pretty sure 10 out of 10 84mm bore 701's will out perform 81mm bore 701's with all other things equal. How much, that's the debatable part. I'll be going to 84mm next time I need a bore just cause it makes me feel cool if nothing else.