Engine swaps

It seems to me that a 750 engine would bolt right up to my 550 frame. I've rebuilt my share of engines and done a share of swaps - for track cars. My experience has always been, the cheaper route is always to swap in an engine then try to build power into the existing (in lieu of turbo).

What engines will mount into the stock locations, and what do I need to look out for?

 

what you gonna do about the shaft drive?

 

It won't work--your 550 is chain driven, the 750 is shaft-driven. There's a myriad of problems that you will run into if you try to do that.

I know that the 750 will bolt right into a 650 frame with the addition of a few spacers to get rid of free-play on the mounts. Those spacers can be simply a few stacks of washers. Other than that, everything is a direct hook-up. There is just slightly less clearance at the top of the engine but that's all.

I believe that the 550 frame is too small for a 750 engine to fit. Someone else can correct me if I'm wrong. I Don't think the 650 engine will fit, either.

But, if you want to take the extra time and extra effort, I guess you could make anything work if you really reeeaaaaalllly want to, and aren't afraid to use a sawzall, welder, torches, hammers, etc......and a lot of swear words.


Dave Fox

 

damn. I guess I'll have to hunt for bigger pistons and go the rebuild route... Or just sell and buy a new bike lol

 

Hey, so.... sounds like there isn't much to swaping a 750 into a 650 frame. Maybe I will try that.

 

What about a 900 or 1100 motor?

 

The possible bolt-in upgrade for the 550 is the chain drive 600, and there are a couple variations.

The 900 is slightly larger than the 650/750 due to the carbs and valve cover, but would be an easy modification- - except, the bike will be wheelie-happy without the lengthened swingarm.

Then there's the addition of the turbo, which requires the use of every turbo component to work correctly, such as the knock sensor, computer, sealed carbs, fuel regulator, hardened drivetrain, and many other parts.

 

900 and 1100 are still both shaft drives .good luck converting them even if you fabricated a swing arm with a drive shaft tube it wont be the correct length you will have to cut the tube and fabricate a new driveshaft

 

Just keep these points in mind:

Since one of the most popular engine swaps is putting an XJ750 engine into an XJ650 frame, we offer the following tips and guidelines regarding what issues you might expect to have to deal with in regards to this popular conversion. Also note that XJ750 Maxim/Midnight Maxim engines mount differently than XJ750 Seca engines, due to the lack of the rubber engine mounting insulators on XJ750 Seca crankcases.

* when putting an XJ750 engine into a 1980-81 XJ650 Maxim or Midnight Maxim frame, please observe the following changes:

- have to convert tachometer to an electrically driven version.
- the original XJ650 oil level sender needs to be retained (unless engine is from a 1983 750 Maxim or Midnight Maxim)
- the 650 shifter side cover and all internal components needs to be retained, unless you want to keep the 750 Seca style shifter. The 750 Maxim style shifter may not work.
- the engine mounting hardware for the XJ750 engine will need to be used (no rubbers on XJ750 Seca; XJ750 Maxim used the same basic hardware. Use the XJ650 front upper frame brackets when using a Maxim engine; the XJ750 Seca frame brackets when using a Seca engine).
- will need to use XJ650 airbox boots.
- will need to use XJ750 carbs (or re-establish the XJ650 carbs to XJ750 specs).
- need to retain XJ650 exhaust system.
- need to retain XJ650 wiring harness, except for the pick-up coils sub-harness. The pick-up coils on the XJ750 engines are different. Need to use the XJ750 TCI box.
- when using an XJ750 engine, be aware that there is a slight gearing difference----the XJ750 Seca used a 18" rear wheel, while the XJ650 Maxim models used only a 16" rear wheel, and thus middle drive gear ratios are slightly different inside the tranny. The XJ750 Maxim models have a slightly different gear ratio, also, even though they share the same size rear wheel as the Maxim. Thus there will be a difference in the acceleration of the bike, depending on which donor engine is used.


* when putting an XJ750 engine into a 1982-83 650 Maxim frame, please observe the following changes:

- the original XJ650 oil level sender needs to be retained (unless engine is from a 1983 750 Maxim or Midnight Maxim)
- the 650 shifter side cover and all internal components needs to be retained, unless you want to keep the 750 Seca style shifter. The 750 Maxim style shifter may not work.
- the engine mounting hardware for the XJ750 engine will need to be used (no rubbers on XJ750 Seca; XJ750 Maxim used the same basic hardware. Use the XJ650 front upper frame brackets when using a Maxim engine; the XJ750 Seca frame brackets when using a Seca engine).
- will need to use XJ650 airbox boots.
- will need to use XJ750 carbs (or re-establish the XJ650 carbs to XJ750 specs).
- need to retain XJ650 exhaust system.
- need to retain XJ650 wiring harness.
- when using an XJ750 engine, be aware that there is a slight gearing difference----the XJ750 Seca used a 18" rear wheel, while the XJ650 Maxim models used only a 16" rear wheel, and thus middle drive gear ratios are slightly different inside the tranny. The XJ750 Maxim models have a slightly different gear ratio, also, even though they share the same size rear wheel as the Maxim. Thus there will be a difference in the acceleration of the bike, depending on which donor engine is used.


* when putting an XJ750 engine into a 1982 650RJ Seca frame, please observe the following changes:

- have to convert tachometer to an electrically driven version.
- the original XJ650RJ oil level sender needs to be retained (unless engine is from a 1983 750 Maxim or Midnight Maxim)
- the shifter side cover and all internal components can to be retained if using a XJ750 Seca engine. The 750 Maxim style shifter may not work.
- all engine mounting hardware for the XJ750 Maxim engine will need to be used (no rubbers on Seca engines; an XJ750 Seca engine uses the same mounting hardware as the XJ650RJ Seca, except for the front upper frame brackets, the XJ650RJ Seca frame brackets should be used. If using an XJ750 Maxim engine, you'll need to be creative.............
- will need to use the XJ650 airbox boots.
- will need to use XJ750 carbs (or re-establish the XJ650 carbs to XJ750 specs).
- need to retain the XJ650RJ exhaust system
- need to retain the XJ650RJ wiring harness, except for the pick-up coils sub-harness. The pick-up coils on the XJ750 engines are different. Need to use the 750 TCI box.
- when using an XJ750 engine, be aware that there is a slight gearing difference----while both the XJ650RJ Seca and the XJ750 Seca models used a 18" rear wheel, the XJ750 Maxim models used only a 16" rear wheel, and thus the middle drive gear ratios are slightly different inside the tranny on some engines. Thus there will be a difference in the acceleration of the bike, depending on which donor engine is used.

 

Len, I hope the members appreciate what a font of knowledge you are, the quality of information you post is staggering, thanks. Wiz.

 

Thanks Wiz!

 

len glad you can type alout faster then me . it would of taken me an hr to type that much and i still wouldnt have known all the details. if this guy really wants to swap a motor he would be better to swap a motor from another make into it maybe an old oil cooled gsxr motor or something chain drive but it still wouldnt be easy to make brackets for it. wire in the computer and the rest of the wiring. but it would fly then. all in all would be better off getting another bike if he wants more power.maybe an xs1100 they make more performance parts for it then the rest of the xj family.
also another question for len someone told me you were in the atlanta area if this is true if i need something in a hurry and its a decent sized order could you package it up and i could pick it up. it will probably be a while when i finally get rid of all of my xv bikes and health wise lets me i want to start collecting and restoring them i would like to get a 1100 maxim 750 650 and a 550 for my collection. im to the stage in my life now where i think i am going to lay off buying fixing and selling them there are to many bikes i want to keep after fixing them up as you can tell by the bikes in my website those were just the bikes from 2008 and 2009. for the most part except for the z1 and fzr and the old black 350 honda they were a while back i kick my self for selling the 73 z1 that was about 10 years ago sold it for less then 2k now the prices are out of this world on them

 

Thanks for the fill-in, Len!

Dave Fox

 

Wow, every thing you need to known is known here. Thanks for all of that. I have been thinking about it a little. Some times when I am looking at parts bikes around here I end up finding more 750s than 650s. Thats what has made me ponder this. I thought there may be a little more to it than that. I haven't made it a sure thing, but If a parts bike comes up for the right price I may pick it up. The issue I am having is that when I find the 750s I rather restore them instead of rip them apart. I need one that has been wrecked. Other wise I would feel bad taking a good bike apart for my Frankenstein.

Thanks Chacal!!

 

On a slighty different tack, what is the level of difficulty in installing an XS1100 engine into a 750 Seca?

 

* when putting an XS/XJ1100 engine into a XJ650 Maxim, Midnight Maxim, or RJ Seca frame, please observe the following changes:

- put down the tools and the torch and back s-l-o-w-l-y away from the bike.
- 1100 engines are vastly different than the other XJ650/700/750/900 engines in design, style, size, etc., and attempting to put one of these engines into the smaller frames is likely to be a complete custom job. No other information is available. It would be wise to consider buying an XJ1100 model bike, and riding that, rather than trying to transplant just the engine.....

 

Depends how good you are with a hack saw, a welder, and metal fabrication to start with........................

 

I've got the idea that a 900 crank could be fitted into the 750 motor to make an 803 and you could put that into a 650 or 750 frame the 900 has a taller top gear (to save gas) or; keep the middle gear from a 650 or 750 gear the rpm's in gear would be the same as stock but you'd have a little more horse power and two fists full of torque at lower rpm's.