701 to 760 conversion???

[zimmy]

So ive been wondering what issues would come into play if i wanted to drop a 760 into a blaster.
Main issues i am curious about are whether or not its a straight drop in and how interchangeable are the 760 and 701 electrics.
If its not a straight drop in, how would i make the modification?
is it even worth putting all the time into it, what is the power difference, and can a B-pipe from a 701 be bolted straight onto the 760.
also, would the 760 jugs fit on the 701 cases?
can a 701 cylinder be bored out?

I know its a lot of questions, but its been chewing at my mind for a while and one day id like to get more power in my blaster.
if i had a 760 on hand id be out there with a tape measure, but im flying blind wondering how to do it.

if anyone has already done the mod please let me know how it went and what you had to do.

 

[meatball]

going from a straight 701 to a straight 760 would not be that big a difference, not worth it IMO. You only get a good gain if you get it ported. I think the exhaust ports are the same on a 760, so a FPP should bolt right up. Electrics all work the same. Only diff between a 701 is the cyls are different, and the head, also with the addition of dual 44's instead of 38's. Everything else, cases, elec etc. is the same. The rev limit may be a tad higher then a 701 but I really doubt it. The stator/flywheel is also different.

I would only drop in a 760 if I were going from unported-ported and the 760 cyl was a deal (and I had all the necessary bolt-ons, prop etc.). You cant bore a 701 61X cyl safely to a 760, but if you get beefier sleeves it can be done. 62T cyls are safe to bore to 760 I believe (never seen sleeve thickness) but they develope their max horsepower a little too late for flatwater riding, although that certainly doesnt stop people from using them.

If your looking for a step up you can probably do it elsewhere easier/cheaper.

If you still want to, a 760 will bolt right up. You do need the stator/flywheel with it though, as it is not a 61X or a 62T Flywheel. Elecs will work with it.

 

[Matt_E]

The stator and flywheel are different. The exhaust manifold for a 61x will not bolt straight up, the holes need to be enlarged.
Everything else will be the same.

 

[MADMAT]

So I can't use my 62t flywheel and stator on a 62t 760?

Whats the deal? The cases are identical except for dual pulse lines, right?

 

[WFO Speedracer]

The stator and flywheel are different. The exhaust manifold for a 61x will not bolt straight up, the holes need to be enlarged.
Everything else will be the same.

Instead of enlarging the holes and buying the expensive azz Yamaha bolts to go with it you install timeserts in the holes to resize them to 8mm threads.

 

[SurfCrazed]

i have a 62T 701 cylinder and run a 61x exhaust all i had to do was drill the holes bigger and go to the local bolt store (York Bolt) up here in newport news and buy 8 new bolts total was about 2 bucks! cant beat that!

 

[keefer]

You can run the original Blaster electronics if you use the flywheel cover from the original engine. The 760 stator is in the cover of that engine. I would rather use the 61x style electrics anyway, the stock flywheel is lighter on the older setups.

I dropped a 760 from a B2 in my 94 SJ and it pretty much just bolted up after swapping to the SJ engine bed plates. I would go the time-cert route on the exhaust, drilling the holes makes the manifold very thin on some of the edges and keeping everything centered can be difficult. I have done it both ways and prefer the time-certs. Go ahead and port that cyl and run a girdled head to avoid future cyl cracking. I would get domes to make 180 psi for good power. Good luck.

 

[zimmy]

so if i buy and engine i should make sure it comes with flywheel and stator, that way all i have to do is change the bed plates and use time-certs for my B-pipe to mount it.
other than that its pretty much a straight drop in it sounds like if im correct?

what was your power difference in the SJ like after you put the 760 in it?

 

[ANT]

IMO it's not worth dropping in a 760. the only way it makes it worth it is if you get your 61X cylinder re-sleeved to a 760 and ported and get daul 44's and a girldled head. That is the only way you will notice big gains. The way you want to do it, with a regular 64X 760, you could probably make up the power difference by bolting on a head to the motor you have now. The reason is because the 760 has port timing that isn't conditioned for a bottom to mid powerband like you will want. the 61X is set-up stock like that and making the 61x a 760 and porting it will give you the power your looking for.

 

[keefer]

Ant is right, when I did mine I ported the cyl, added a Riva billet head and ran dual 46mm carbs. If you just drop in a stock 760 you will be disappointed. The 760 has higher exhaust ports, so the power will come in later with less off the bottom. If you already have a a 62T style 701 I would do like everyone is suggesting. Let LPW or Supertune port and / or big bore that baby and get a good girdled head with domes that make 180-185 psi with 44mm carbs you will notice way better power increase than a simple engine displacement increase.

 

[zimmy]

yeah i see your point, id be better to just work with what i have right now!
seems like it will be a lot cheaper!
thanks for taking the time to give me some input on the situation! i appreciate it!