7/11 concept?

[Anonymous]

hey all... i just had a very whacked out idea.
how the hell do you build a 7/11 motor? i have heard this phrase a time or two...
i am guessing it entails a 750 bottm, 1100 jugs, and pistons, coupled to a 750 top end. in my head this makes a high displacement, high compression beast.
i figure since i am on the hunt for a replacement engine (the one i am running needs a total tune up, and needs to be torn down to fix some stuff), and replacing would be cheaper than paying a shop to fix...
is there any way i could wedge such a monstrous beast into the cradle of a 78 GS550? maybe get the mounts modded (unless an earlier model 750 bottom would bolt in?), pods, 4-1, richen the jetting. would make that bike fly, i am also thinking using stock parts all around to maintain quality and economics.
also, if such a beast IS possible... what parts are required? what years and models are compatible? this may be an insane idea, but it is fun inside my head. motorcycles (let alone cheap ones) seem to be scarce in my area... i have not seen a single GS model for sale in my local classifieds, or even ones from the neigbouring counties. any info?

[Anonymous]

hmm... another thing that crossed my mind...
is the 7/11 a GS750 with an 1100cc powerplant? that would also make sense. although i like the idea of the hybrid built motor, this one is probably a little closer to the mark? someone fill me in please,as this topic is really a really interesting concept. and i want to find out what is meant by the mythical 7/11 phrase.

[Nerobro]

IIRC, there is no funny buisness with hybriding engines. you just throw the whole 1100cc powerplannt, crank,tranny and all, into a 750 frame.

As for your 550. Gimme a week and I'll tell you what you can do for additional displacement.

I'll give you a hint... the GS650 is a close relitive. And they're really 672cc, not 650.

The big benifits from a 7/11 come from weight reduction. You're effectively cutting eighty pounds off a 1100 when you put it in a 750 frame.

now with the 550 you have, you have the lightest 4cyl gs available. 430lbs claimed. With an anemic engine really... 49hp. heck the gs450 makes a claimed 42. The GS650 put out 72. And I've heard rumors of usign the 550 head on the 650 to make more comression and therefore more horsepower. But again... I haven't been able to confirm that.

I've also heard of using GSXR heads on 1100's... I was wondering if any of the GSXr's shared the same cylinder spacing as the 550. if not, the 83+ GS550's (think GSX, not GS) have 4 valve heads, and start off at 68hp? Something like that. 650 pistons with that head just might be something. :-)

If you have someone who has a 700-850 engine handy.. go take some measurements, see if you can wedge it into your frame. My first guess is no. The 550 is a terriably tight fit already. However, I do think you have a LOT of options to try out before we can say there's no more power to be found.

The number I've heard for the top that you can get in a 550 is 90 horsepower.... The first 72 is "easy" ;-)

[marcovandevelde]

You can also put an oil-cooled GSXR750 engine in it. Will make something like 100-110 horsies. You will need to fabricate you own engine mounts though, nothing straightforward. But not difficult either.

Marco.

[moto_dan]

...... someone fill me in please,as this topic is really a really interesting concept. and i want to find out what is meant by the mythical 7/11 phrase.

750 chassis
1100 engine

In the case of 16v GS's it is an easy swap.

[Anonymous]

well, that sheds a bit of lighht on the 7/11 idea. at least i have an answer for that one.
the whole basis of my hunt is:
the enging i am running requires much attention right now. i am still using it as a daily rider... but it runs like crap, and leaks oil. the friend i bought it from has like a 0 maintenance policy on things (mainly, changing the oil when needed). so it has never had a valve job, never been synched, and i am sure some of the ignition parts need replacing (points/condenser). on top of that, i have leaky seals that are a pain to get to replace, and have no experience splitting cases. so that would leave me with having to delegate the work to a shop.... which would be expensive, and time consuming. if i can find a powerplant to put in there, chances are it will be cheaper than the actual shop work (its somewhere between 75-85 an hour in my area). a GSX750 engine would be a hot ticket.... but where to mount the cooler? are there guys on here who have experience in fabbing engine mounts? would love to get the thing back into shape, even if it is a hot rodded one. if the price is right, i guess there isn't a whole lot to complain about, especially if i can get the pieces for less than what shop work would cost. probably just takes a bit of snooping around to find the goods, or maybe ebay, or some form of cycle salvage.