83' GSX750E Engine upgrades- bigger engine or rebuild?

[BuckarooBanzai]

Greetings-

I have purchased a 1983 GSX750ES w/ a spun rod bearing for $150.00. The bike is complete although somewhat disassembled. I had originally planed on going crazy on my 1980 GS1000E, but since it is in such nice shape, decided to keep it as my stock daily rider. I purchased the 750 to become my "Fire Breathing Dragon" project. Originally I toyed with the idea of putting an 1100cc engine in w/ modifications. After reading a lot of posts here, this idea seemed like it may end up being problematic. The biggest issue was if the engine would bolt up or not & how many mounts would have to be modified. The second thought I had, was maybe I should concentrate on rebuilding the stock 750 engine & maxing it out as much as possible & skip the headaches the first would entail. Any thoughts or suggestions would be appreciated.

 

[Mark Harrop]

I'm going the 7/11 route myself...I spun my #1 (prob due to leaky petcock...filled my crankcase 4 or 5 times...)

I wanted a goal of 100 rwhp, and felt that, although it would be possible from the 750, If I spent the money on an 1100 I would...

1. Have the added benefit of more tourque

2. Only have to fabricate two brackets (I believe), and their template is on the internet...somewhere.

3. Have a more durable motor (less stress) than an overbored, cammed up buzz-bomb.

4. Be able to say 7-11 a lot.

 

[Busafied]

I'm going the 7/11 route myself...I spun my #1 (prob due to leaky petcock...filled my crankcase 4 or 5 times...)

I wanted a goal of 100 rwhp, and felt that, although it would be possible from the 750, If I spent the money on an 1100 I would...

1. Have the added benefit of more tourque

2. Only have to fabricate two brackets (I believe), and their template is on the internet...somewhere.

3. Have a more durable motor (less stress) than an overbored, cammed up buzz-bomb.

4. Be able to say 7-11 a lot.

Amen- exactly what I did this wknd to my 83, it is under the wrong heading of 1980 gS750 project below ..

 

[Big T]

No matter how much effort you put into a motor transplant, it will be a blip in comparison to hopping up your old motor. Figure on a minimum of $2,000 for a really hot street motor

 

[tkent02]

Just put a 1000 engine into my 750.
A nice improvement.
Those later 750 engines suck anyway.

 

[herostar]

Back from the dead! (that's why we have search...)

What year engines swap in easily?

Can most of the parts be swapped fairly easlily?

I think I just spun a bearing on my '83 750 and am looking to fix it with minimal cost...

 

[salty_monk]

I don't think the 1100 engine is such an easy fit on the 83 750's.....

Busafied is using a later engine which is smaller.

Dan

 

[Busafied]

Dan and I discussed this yrs ago on one of the central tx hill country rides.
I started to make it happen in 2008 for my wife Chantel who was a petite 5'3" 98# Woman.
Any of the slab side GSXR motors or GSXF (katana) 1127 or 750 motors will fit with mods.
I chose my old GSX1100F motor ;-)

The rear bottom bolts right in adjust the spacers I made from old GSXR750 ones in aluminum to align the sprocket using a laser.
The front ones off the stock 83 GS750 I re-used drilling new holes 3/4" I believe closer to the motor.
I still have to make some brackets for the top back motor mount, and the lowers, I will be using some flat plate stock I have and my drill press.
I found I had to use the breather cover off the gs750 motor on the gsxf 1100 motor to fit in the frame.
The stock gsxf1100 one made it just a tad too tall to set right in the frame.
The rubber mounts on the frame in FRONT had to be removed, I used some stock fuel line off my truck to slip over the nubs on the frame to stop the vibes.
I used some left over fuel line to sandwich between the valve cover & gas tank to isolate and stop vibes.The rear I used the STOCK bushings and bolts to mount the tank.

Using an old GSX1100F V&H header for the bike just barely clears the frame on the GS750.
The GSXR750 or 1100 exhausts as well as the Katana 1100 or 750 exhausts will work.
They will require YOU to spread the 750 to fit the 11's and visa-versa (push together) for the 1100 to 750
Fab'd up the rest of the exhaust hacked up a Busa stock can flange and made my own slip on.
Still going to redo exhaust with a shorty setup, possibly off a late model gsxr.

That's about it.
GL-
Ron

 

[Mark Harrop]

Back from the dead! (that's why we have search...)

What year engines swap in easily?

Can most of the parts be swapped fairly easlily?

I think I just spun a bearing on my '83 750 and am looking to fix it with minimal cost...

Man, I still haven't got that 1100 in there yet.

From what I've read, I believe the 16v motors from 80-83 are basically the same size and you only need to fab the front-lower mounts to swap. I'm not sure about the post 83s....but I'm sure somebody here knows. I'm not sure what your definition of "fairly" easy is, but Suzuki kept the mounting points fairly close over the years, so its just a matter of making sure the new motor physically fits in the frame, then fabbing new mounts. I think removing the valve cover will be the main concern...hard to adjust the valves if you cant get the cover off...

Have you thought about just removing the motor, flipping it over, taking off the bottom and replacing the bad bearing? Strip all the bodywork, remove the forks/front wheel as a unit, the rear shocks/swingarm/wheel, unbolt the engine and lay the bike over then lift the frame off of it. If you have a welder or know a buddy with one, you can weld up an adapter to hang the engine in a cheap automotive engine stand. Just rotate it over and start unbolting...fix the bearing, then you can lube and clean all the other stuff as you put it back together. You are only out your labor and the price of a bearing.

I was tempted to go that route...but decided to start the 7-11 process. My biggest hurdle is finding someone to do the 1100 crank. I have a 5000 mile 83 1100 motor that fragged a starter clutch and a small-end 81 1100 motor that are both complete.

Too many unfinished projects....good luck with yours.

 

[herostar]

Swapping for a new bearing is a good idea. Wouldn't I need to get the block/crank surfaces checked out/machined before the new bearing goes in? It just doesn't seem as easy as you make it... Are motorcycles less precise than automobiles in this respect? I spun a crank bearing in my eclipse and I had to get a whole new bottom end...


I've swapped non-stock engines in cars before, but this would be my first motorcycle attempt. I can weld and fab pretty efficiently, so a couple engine mounts wouldn't be a problem.

 

[Mark Harrop]

I guess it depends on the extent of the damage. Is the engine out of the bike?
I know there are a few guys here that have dealt with the "high pressure" 16 valve engines, and don't have many good things to say about them.

I've never had mine apart, so I am only going on what I remember reading here.

You have to take it apart anyway, so might as well bite the bullet and crack that sucker open.
If you want to get some more responses, take some pictures and post them up here....everybody loves pictures!
You need to figure out if it is a bad crank or rod bearing, then go from there.

Sorry I can't be more help, I'm just a hack mechanic who's learned everything the hard way.

 

[salty_monk]

The 83+ "high pressure" models are meant to be better than the 81-82 models. It's a completely different generation of engine.

Dan

 

[Guest]

The 83+ "high pressure" models are meant to be better than the 81-82 models. It's a completely different generation of engine.

Dan

Mine has over 70K on it and about 600 or so dragstrip passes on it. The only parts in the motor that are not original are the cam chain (preventive maint.) and the trans due to a seized countershaft sprocket nut.

 

[salty_monk]

Nice to know Dee

 

[jetta90]

My 1984 GS 750 E is coming up to 44,000 miles and is showing no signs of dying. As far as I know the engine has never been opened up.
I like the bike and engine so much I bought another project 1984 GS 750 E to work on.
Mine has been solid, reliable and always runs strong.

 

[gearhead13]

My 2 cents:
The 80-82 750's can run a long time with proper maintenance, I took my '82 apart at 60,000 km and there was very little wear on the main and rod bearings, and the thing still had 140# compression, I rebuilt it with wiseco pistons and cams and porting and carbs and ran the **** out of it for a couple seasons, no problems at all
The '83 and up 750 frame is smaller and wont take the 80-83 1100 engine AFAIK. Only gixxer and oil cooled kat motors fit. My '82 frame took the '82 1100 engine real easy with only one motor mount needed, all the same electrical hookups.

 

[Busafied]

My 2 cents:
The 80-82 750's can run a long time with proper maintenance.
The '83 and up 750 frame is smaller and wont take the 80-83 1100 engine AFAIK. Only gixxer and oil cooled kat motors fit. My '82 frame took the '82 1100 engine real easy with only one motor mount needed, all the same electrical hookups.

Correct, I have had around 40 suzukis and about 10 others of various brands through the last 30 yrs.

The 83& up 750s wont take the pre 86 1100's too tight.
The 82 down we used to take the 85 and down 1100's and slam them in and leave the 750 markings in and own the street races.
of course they do the same thing these days too with the newer crotch rockets.