motor swap 850 to 1100

[roadflare]

After finding out the cylinder head has been fried, and confirmed it is beyond repair by a machinist, I have started looking for a new motor, keeping this whole issue as cost effective as possible.

The question:
Would an 1100 mount up to an 850 frame? Are the brackets the same? If so, I'll be back on the road in no time.

 

[Steve]

What year 850?

They answer is likely "yes", but you will need the motor mounts and driveshaft from the 1100.

If it's an '83 1100, get the final drive, too, it's a taller ratio.

.

 

[hillsy]

Don't know too much about the shafties, but in Katana world the 1100 motor slots into the 750 chassis with just the bottom engine mounts (the ones under the crank) needing to be altered. It's a minor change.

I'd imagine it's the same with the shaft drive models.

 

[roadflare]

It's a 1980 850 that I'm trying to save from the bone yard

 

[Steve]

What year is the 1100 engine?

As previously mentioned, use the 1100 mounts and shaft, it should be no problem.

.

 

[roadflare]

The 1100 is an 82. Sweet so that gives me a direction to go.

 

[roadflare]

I found an 82 1100GK complete and running on eBay for $399. Saving $250 from the one I was originally looking at and it's a lot cleaner.

 

[roadflare]

When you say taller ratio, can you break that down Barney style for me? I'm not quite sure what that means. I'll get one here soon once I recover from the motor purchase.

 

[Steve]

When you say taller ratio, can you break that down Barney style for me? I'm not quite sure what that means. I'll get one here soon once I recover from the motor purchase.

Going down the road at 70 mph, the 850 will be turning close to 5000 RPM. The 1100 engine has a taller ratio in the secondary drive that will lower the engine speed to about 4600 RPM. If you were to also install the final drive unit from an '83 1100, it would lower the engine speed down to about 4200 RPM.

.

 

[JTGS850GL]

Actually the 1100G motor will be a direct drop in except for the propeller shaft flange. The 1980 flange was smaller so you'll need the propeller shaft from a 1981 or newer GS big block. That would be the same propeller shaft used on an 81+ 850G or any 1000G or 1100G. Easy to find part on ebay.

The only difference in motor mounts is one of the rear mounts on that year but not sure why since, dimensionally, the 1100G motor is the same as the 850G. Later year GS850's shared all the same mounting hardware. All the engine mounting bolts are the same between the 850 and the 1100.

Kind of fresh in my mind since I just did an 1100G swap into my 1980 1000G and was thinking of what to do with my 1000G motor ounce it's rebuilt and the 850GL came to mind.

 

[roadflare]

@Steve Thank you! that makes sense in my brain.
@JTGS850GL Thank you too!

So the 82 1100GX will bolt right into my 80 850g frame. How friggin cool is that?
a quick google brought me to this:

http://www.ebay.com/itm/1983-1982-1...Parts_Accessories&hash=item46200d0971&vxp=mtr

Is this the whole shebang for the flange and drive shaft that both you and steve were saying?

 

[Steve]

Yep, that would be it. :encouragement:

Don't forget the 1100 uses larger carbs. It might run with the 850 carbs (but they would need to be re-jetted), but would be a bit strangled at top end. The intake boots on the 1100 are larger than the 850s, so they likely won't clamp down properly. The 850's boots might fit on the 1100 head if you slot the holes a bit for the larger diameter ports. You will have similar issues at the airbox, too. The basic airbox is the same, but the ports and boots are larger for the 1100.

.

 

[JTGS850GL]

If the engine doesn't come with carbs then just do it right and pickup a set of BS34SS carbs from a GS1100G/GL/GK. Don't use the carbs from a chain drive 16V GS1100E since the press fitted main air jet is too small (1.2mm v/s 1.7mm). They can be drilled out but it's just easier if you get the carbs that were intended for the engine. Trying to screw around with using the BS32SS carbs that came on the GS850 is going to be more work and frustration. Sell the GS850 carbs and recoup some or all of the cost.

 

[roadflare]

@JT i took that advice, i found a nice set of sonic cleaned, 34mm carbs off of a 1100gk for $250 on ebay. I didnt want to have to buy them, but This whole build is about doing it right, not doing it twice. The 1100 came the other day, and along with it was the drive shaft, the set back was one of the bushings for the motor mounts was missing from the transmission side. So i just went ahead and ordered all new ones for it, replace one, replace them all. so those will be here next week some time and my new carbs will be here around April 1st. then i just need 34mm pods and boots for the carbs.

It should be ready to bolt in once i get the bushings tho. then its minor mechanical work. I have a slow leak in my brakes somewhere, and i need to sync and do a tune up on the motor. other then those problems which arent that bad if you stop to think about it, it should be ready and waiting for the warm weather like a hot date.

 

[JTGS850GL]

Too bad you didn't post on the wanted section. I'd bet that some trusted member here had the carbs for less. Glad you ended up going the BS34SS route. It will make life a lot easier.

Pretty sure you didn't need to order anything. All of the mounts from the 850 should have been a straight swap for the 1100. Maybe I'm not understanding what was missing though.

Keep in mind that you'll need to re-jet the carbs for the pods. I'd get everything running using a stock airbox and then tune for the pods once you know everything is in good working order. If you plan on running the pods right away, then I'd pick up a Dyno-Jet kit and start with that. Tune should be very close.

Here's the link to my latest 1100G swap:
http://www.thegsresources.com/_forum/showthread.php?226675-Looky-what-folowed-me-home

 

[roadflare]

just a heads up,im not dead haha! I tried putting the motor in and as it turns out, The Motor i had was an 850 G, the motor i put in 1100 GK. the G has a simple bolt through mount on the motor side of things, where as the GK has opening for shock absorbing bushings. So the bike is up getting the motor put in at a shop, im tired of trying to get it to work, so i took it to a professional. once its in tho, i shouldnt have much issue getting it back together, i did end up cutting the exhaust to get a bolt out, but i found a nice 4 into one set that ill be picking up later on this month. ill keep you posted haha

 

[JTGS850GL]

The GK used isolators to reduce engine vibration. You could have simply swapped the mounting hardware from the 850 and everything would have just bolted right up. Hopefully you shop will do a good job and not charge you up the wazoo.

 

[roadflare]

im still using the mount bolts and have all of the brackets from the 850 frame, but that back set of tabs welded on the frame itself was just too dang narrow. many hours of thinkin' drinkin' brought me to the conclusion that i was over my head hahaha. its now going on week 3 and the shop still doesnt have my motor in. Now i do understand that there are plenty of other bikes in the shop that need tlc, but its got me worried to beat hell that im going to get my pants pulled down over the price. oh well, id rather eat this one and have a nice old bike, than buy any of this new stuff for more than what i paid for my car.

 

[roadflare]

Hola Amigos!

so i got the bike back from the shop, it was a grand total of 300 for everything, so not bad in my estimation. he had to redo all except 2 of the mounts .
Now that i have my bike back im working to get it back together. Its all pretty much ready to go minus the exhaust. Looking on the interwebs I found a 4-1 set from MAC that looks pretty nice, BUT, on their site it says it will fit 1100e with no mention of an 1100gk. to complicate this even more my 1100gk is in an 850gs frame haha!! so my question now is this: aside from the GK being a touring style, is there any differences that i should know about between the two engine wise? or will an exhaust from an 1100e fit on an 1100gk?

i really do appreciate the wealth of knowledge here. Cruising around the web i see this forum offered up consistently as THE go to for the gs.

 

[zuzu]

This set says it fits the 1100 GK.

http://www.ebay.com/itm/MAC-Street-...ki|Model:GS1100GK&hash=item2801875cce&vxp=mtr