has anybody ever swapped out a motor on a 700 maxim? got a 82 750 seca motor being shipped right now, wondering what to expect in the swap. any comments appreciated.

I'd guess this one will be really easy... the 700 maxim was a detuned 750 maxim - the engines between the seca and maxim seemed to be the same.

The only differences I can think of might be the tach and oil sensors.

Don't know those two bikes well enough to say more than that...

I recall reading some where that the XJ900, XJ750, XJ650, XJ750X, and XJ700X are all swappable amongst each other. And maybe even the turbo. The best engine being the XJ750X from what I have read. I think there is an article about the turbo XJ Seca where they mention that the XJ750X engine would fit on the XJ CD.

Ditto on the oil sensor. I swapped my 83 750K Maxim engine for an 82 Seca engine. The oil light stays on now. This is because the oil level sensor for the Seca was monitored by the computer and needed a constant flow of current for the pc to monitor it and once it stopped the pc turned the buld on. The 750K had analog gauges so they only needed current to light the blub.
The Seca had an electric tach also. If yours has a cable driven tach that may be a problem. I don't know if the tach drive could be fitted to the cylinder head. I made no changes to the wiring harness. The Seca engine connectors matched right up. The Seca engine mounts differently but that is accomplished by the mounting hardware. Just use the bolts from your Maxim.
I was able to remove the exhaust as a complete unit but it may be easier to remove the mufflers seperately. Main thing to do is soak the header mounting nuts with PB blaster or Liquid wrench. They are notorious for breaking the studs off in the head.
OH Yea! Have a strong friend to help sit the engine in the frame and have a floor jack waiting to hold the bottom of the engine so you can position it to insert the mounting bolts.

thanks for the comments guys, hey Bluemaxim. I have read somewhere that the middle gear on the seca motors were different because of the smaller rear tire on the maxim. Did you have to swap out your middle gear and how big a job was that?
thanks,
kalani

As far as I know both are identical. I did not change out the middle gear. To do so would involve splitting the cases and I have never heard about the middle gear being different. I have put about 5K miles on my Seca engine this year and that baby is still going strong. I can't even think of a good reason for Yamaha to seperate the Maxim and Seca engine production line to accomodate for a 16 inch vs. 18 inch tire size.

With a few minor exceptions, the XJ750 Maxim's power plant is identical to the Seca's. The middle gear reduction ratio has been altered slightly to make up the difference between the rolling circumference of the rear wheels. The Maxim's gear sets are 48/37 tooth; the Seca's 49/36. Other small changes appear outside the power plant itself. First, carburetion has been altered slightly to accommodate the second change. The second the Maxim's initial advance begins 200 rpm sooner than the Seca 750RH's and full advance occurs 1000 rpm sooner, at 4000 rpm.

Well that's good to know. Thanks for the post. I missed the subject a bit because I forgot this started out about a Maxim 700. Does this gear change also apply to an 82 Seca vs a 82 Maxim 750?

Thanks for all the comments guys, i will keep you informed on the progress..
aloha,
kalani

I did a swap recently on my bike. But I swapped a 82 750 seca motor into my 81 650 maxim.
It all went pretty smoothly, minus a few snags. The previously mentioned oil sensor was an issue after I did the swap(light stays on). Another thing that was a pain was getting the motor in without binding against the driveshaft. For some reason, I thought it'd be a good idea to take off the boot where the drive shaft connects. Do NOT remove the boot! it seems to be impossible to get in and out of there without either removing the whole drive line, or pulling the engine back away from the shaft. The second time I did it, I just tied the boot back with some twine. I am not shure, But you might also have to swap out your jets. I did when I swapped. You might not have to considering your only going up 50cc's.