Upgrading 650 4k0 to 750 11m

Hi all
My old 650 4k0 engine has around 90.000 Km on the clock, and is in need of some serius maintiance. Therefore I ask you all, if it is possible to change the engine to a 750 11m, widthout any difficulties, As I see it, the frame is the same on a 650 and a 750.

Am I right?

Greatings from Denmark

 

Hi TenKeys,
So far I've found the base engine, transmission cases that is (4H7), is the same from the 650 to the 900 and although your model codes are different than what I've been dealing with (Australian) I would think(depending on the level of my intoxication)you would have the same sort of situation in your part of the world!

I have successfully installed a 33F(XJ900RK) engine into a 37H(XJ750P) frame without even a slight problem... apart from TCI replacement, carb replacement and... well a few other minor things to us XJ fanatics , of course!

Although it might be a good idea to ask for some overall engine height difference between the 650 and the 750+ engines...

 

You will need to re-jet your carbs, and you should run the complete 750 ignition, however, you prolly could get by with running the original 650 ignition also.

I think there was an issue with the "oil" light switch??
The exhaust will bolt-up.

 

Happy new year all
Well now, it didn't go as planed(it newer does), I ended up with at 750 41Y engine insted.
I'm now searching for the jet size for a 4k0 carb working on the 41Y, I could't get the original 41y carb with the engine, any ide out there. And What about the ignition, can I reuse the one from 4k0. 8O :idea:

Gretings from Denmark

 

Some further questions to address - are you running the stock air cleaner and stock exhaust system??

Main jet for a 750 is "120" The jet next to it remains a "40" (unless you have a "43", because you are in Europe - 43 seems to work)

Quoted specs for Hitachi Pilot air jets - -
#195: all 1980-81 all XJ650 North American models, all 1982 XJ650RJ and RJC Seca, and 1980-82 XJ650 UK/European (4K0 and 4K1) models.

#205: all 1982-84 XJ650 Maxim North American models, 1982-84 XJ650 UK/European (11N) models, 1981-83 XJ750 Canadian models, and 1981-84 XJ750 UK/European (11M) models.

#225: all 1982 XJ650 UK/European (14R) models, all 1981-83 XJ750 USA models, XJ750E-II models, and XJ750RL models.

You need to change to 750 specs to match the Main fuel jet you choose.
The Main Air jet goes from a "50" to a "80"

Important - set float accurately with a clear tube 3MM below carb body.
- clean the piston-slider and bore with 1,000 grit sandpaper
- read "Church Of Clean"
Church of Clean
A different ignition box will have a different advance curve, but should otherwise work. As I said above - it's best to keep the whole ignition system all together, rather than mix parts.

 

Are we saying that the XJ650 will accommodate a 900 motor. If so, is this limited to the pre-Diversion XJ, or will a Divvy one fit?

 

Sorry guys - ignore that. I see this has been covered plenty of times before.

I now have the information...

Nige

 

Hi again
Further data.
4 in 1 exhaust system
Airfilter 4 times DELO Power-Luftfilter
http://www.louis.de/index.php?topic=art ... r=10050100
Carp is Hitachi 32mm
I can't seam to find the right size jets,
The Main Air jet
http://www.motorcyclecarbs.com/Hitachi_ ... _C2274.cfm
this is from 110 to 134 not 80 ?

The tube level I do not understand. I will return on that.

For now I wil clean the beast. Ultrasound bath is ok?(all apart)

Greatings from denmark

 

Hi all
Springtime is closing
The Carbs has been ultrasound cleened, after compleete disasemply.
I have found the data on the new jets, with 2 exeptions.

The two jet are best seen from air intake end.
One to the left and one to the right. see picture.(before cleaning)
I can't find any data on these.

The other jets are found to be.

PILOT AIR JET

Now
HCP6293 Aftermarket Hitachi brass PILOT AIR JET #195,
original size for all 1980-81 all XJ650 North American models, all 1982 XJ650RJ and RJC Seca,
and 1980-82 XJ650 UK/European (4K0 and 4K1) models. Each:
$ 7.95


After
HCP6295 Aftermarket Hitachi brass PILOT AIR JET #205,
original size for all 1982-84 XJ650 Maxim North American models, 1982-84 XJ650 UK/European (11N) models,
1981-83 XJ750 Canadian models, and 1981-84 XJ750 UK/European (11M) models. Each:
$ 7.95


PILOT FUEL JET

Now
40: all 1980-83 XJ650 USA models, 1980-81 XJ650 Canadian models,
1982 XJ650RJ and RJC Seca Canadian models, 1980-82 XJ650 UK/European (4K0) models,
1981-83 all XJ750 USA models, XJ750E-II models, and XJ750RL models.
NOTE: the factory service manual references a pilot air fuel jet for the XJ750RL models as being either a #40 or a #41
size. We are not sure which size is actually correct.

After
43: all 1982-84 XJ650 Canadian models, 1982-84 XJ650 UK/European (11N and 14R) models,
1981-83 XJ750 Maxim, Midnight Maxim Canadian models, and 1981-84 XJ750 UK/European (11M) models.
HCP6320 Aftermarket brass #43 PILOT FUEL JET, each:
$ 6.95



MAIN FUEL JETS

Now
110: all XJ650 North American models (except 1982-84 Canadian models)
and all 1980-81 XJ650 UK/European (4K0 and 4K1) models.

After
HCP10609 Aftermarket brass #126 MAIN FUEL JET,
(4 i one Exhoust 4+, And 4 POD filters adds 4+ more, minus 2 makes 126)
each:
$ 6.95



The main air jets

The main air jets on all Hitachi HSCxx series carbs are located under the vacuum piston diaphram,
and are a small, brass "headless" screw-in jet. On some model carbs, these air jets live under a small,
curved flay metal "cover plate" which is retained by a special shouldered screw
(most later-model Hitachi carbs seem to have dispensed with this air jet cover plate,
although its threaded mounting hole still remains in the carb body).
NOTE: the Haynes workshop manual for the XJ650 and XJ750 models has the incorrect placement noted for these air jets
----the main air jet and pilot air jets are reversed in their picture and caption.
Just remember that the main air jet goes directly above the main fuel jet,
and is thus located in the "center" of the three holes in this area.

Now
HCP6307 Aftermarket Hitachi brass MAIN AIR JET #50, original size for all XJ650 models.

After
HCP6313 Aftermarket Hitachi brass MAIN AIR JET #80, original size for all XJ700 non-X
(air-cooled) models, XJ750RL Seca models, and XJ750E-II models. Each:
$ 7.95

Do any of the carp gods :lol: have any indput to this question

Greatings from Denmark

 

Your jet selections seem right, by the book, and perfect for "PODS" and 4 into 1 exhaust.

[ just a note that doesn't seem right - - the engine size is increased by 15% and many of the jets are increased this porportion, except the MAIN AIR JET which goes from a 50 to an 80, which is a 256% larger "area" inside the jet]

An article on wet-setting floats with pictures and lively discussion, and links to other threads - -

http://xjbikes.com/Forums/viewtopic/t=3 ... art=0.html

Now how about a picture of your bike??

 

Hi all

Now it's summer and I'm not driving yet..
I have just finished replacing the engine.
It fits ..
I have orderd a complete 41Y wirering, and ignition set(used)
and some used other spareparts.
The carb is redy. thanks to you all.
I have one hurdle. what to do with the gear box exthourgst(spelling)
I'm using POD filters for the carb. but the what to do with the exhourst(spelling). i have tried to attach a picture.

Greating from denmark

 

Just bang a "to-atmosphere" filter on the end of a short bit of pipe (as you've junked the airbox). They look a bit like a smaller pod.

Someone on here will have a pic if you need it.