XJ750P

Hi , I was on this site several years ago . whilst renovating an xj650 and an xj900 . Well the 650 has been finished a while but the 900 had been put on hold while restoring a '62 Honda C92, so 900 will be finished shortly ,BUT , I got hold of an Xj750P , the one off model made especially for the West Australian police force. I am having a great deal of trouble identifying the actual frame it was based on ( it seems more like the xj650 frame than anything else ), as it seems to match nothing I can positively identify. It also seems to have been fairly heavy "de-policed " by several previous owners . I gather that they were pretty much put together out of the spare parts bin , containing elements of both Seca and Maxim models . Any info or suggestions would be greatly appreciated , cheers , Murray
1986 XJ750P 37H 000418

 

Welcome back Murray
@chacal or @hogfiddles should be able to help you with that. There is a list in one of the forums that has all that information. Based on Seca body but wheels and engine Xj750rl in appearance.

 

MODEL NAME: XJ750P
STREET NAME: 1983 XJ750 Police Special
MODEL ID CODE: 37H
FRAME ID: 37H
SERIAL NUMBER STARTS AT: 000101
NOTE: this model is a Western Australia Police Special model. White painted swingarm and steering crowns, may have used 900 cams.
NOTE: the 1983 version had a white frame and a black frame on the 1985 models. Uses XJ900 anti-dive forks and XJ750 Maxim brake calipers

 

Thanks for the reply guys . I also believe that they used the 650 turbo rims on the 750P. Still need to identify the frame ,so to know what back end to put on it . hope the photos will help someone to give a positive id (frame and engine numbers match by the way ) , cheers

 

what number is stamped into the headtube?
The tail light not the right light for the fender.... and I don't believe the fender is the right fender to begin with, either.

Notice how the light housing has been notched for the wire? That light harness doesn't exit there.... it goes through the fender under the housing. See the hole with the grommet for a wire harness? Xj's didn't have that... the wire harnesscwas underneath the fender.....

 

Hi Hogfiddles , no number on the headtube , just the australian compliance plate ..... 6/86 37H 000418 , matches the eng. number . Also the forks are 37mm anti dive units ( disconnected )as per xj900 , but the calipers are xj650 turbo . the mounting points are different . I have a spare set of 650 turbo forks , if these match out in other ways , I will substitute . Proving to be a bit of a frankenstein bike . Being an ex police special it,s hard to say what was modified as a one off order , the wiring has been severely interfered with to cope with extra police demands ( the alternator was beefed up I believe ) It's possible that Yamaha had run out of normal xj750 frames by then and used some sort of hybrid unit , maybe parts from the XJ750D , cheers

 

No number seems to indicate that it's factory replacement frame.or at least the tube was----lol. Check over the frame carefully and see if you can find anything that might look like parts of the frame were grafted together

 

No obvious signs of molestation of the frame , the compliance plate is usually the frame no . Found the following pics on a web site . It would seem that the frame may be a one off police special , it is very heavily built . My impression is that the frame is thicker . I will put calipers on it tomorrow ,

 

Hi murray I seem to remember you here .. member cds1984 in WA has a police bike and is quite knowledgeable on them, you could try contacting him via the site. Yes they are a bitsa bike and at it's age may well have been bitsa even morer . From what pics I've seen of them they seem 750 seca and 900 mixed. Good luck with it.

 

The pics appear to show an'83 xj750 frame, various bits on it confirm that. There are other pics online to show that the 750p did use that taillight and fender. But I still am not convinced about the routing for that wire. I am also wondering about lack of numbers stamped in the head tube. From my experience, all head tubes had the serial in it, except for factory replacement frames.

 

Thanks for the input guys , will contact cds1984 to chase up more info , cheers

 

Hi , trying to identify carbs on xj750P the head side outlet is 38mm OD and airbox side 50mm OD . The only symbol I can see is this one

 

They are the same carbs as used on the standard 650/750 Seca and Maxim.
Hitachi HSC32
Jetting may be slightly different on the police 750 than it was for the standard 750, but I'm not entirely sure.

If you are lucky the ink on the bottoms of the float bowls will still be there to confirm.

 

Yeah those are hitachi carbs.

If the numbers are faded, sometime you can read them if

1..you play around with reflected light on the surface

2. wet them and dry them

3. Read a few numbers/letters on one bowl, a few from another, a few from yet another, etc

Most important would be the group of three---- like: 5v2, 4h7, 35a, etc.....

 

No sign of any numbers or letters on the bowls , long gone . Main jets marked #118 , slow jet #80 . Not sure how this compares to standard xj750 , cheers

 

Perhaps surprisingly, the 750P models used a smaller main fuel jet than standard XJ750 models, but used a "richer" main fuel jet needle, which probably reflects the intended usage characteristics for the bike:


HITACHI MAIN FUEL JETS:

ee) Aftermarket Hitachi brass MAIN FUEL JETS, sizes as follows, fits all XJ650 (except Turbo), all XJ750, all XJ700 (exc. "X") models, and all XV (Virago) models using Hitachi HSC40-series carbs.

NOTE: stock Hitachi XJ series carbs used the following original sizes:

#102: XJ750E-II models (cylinders #2 & #3)

#105: XJ750E-II models (cylinders #1 & #4)

#106: 1984 XJ750RL Seca models.

#107: all XJ700 non-X models.

#110: all XJ650 North American models (except 1982-84 Canadian models), all 1980-81 XJ650 UK/European (4K0 and 4K1) models, and all XJ650 Police (37G) models.

#112: all 1982-84 XJ650 UK/European (11N and 14R) models and 1982-84 XJ650 Canadian models.

#118: all XJ750 Police (24L and 37H) models.

#120: all XJ750 North American and UK/European models except the 1984 XJ750RL models.

#122: 1986 XV1000 models (on the #1 carb only)

#124: 1981-83 XV750 models (on the front cylinder carb only), 1986 XV700 models (on the #1 carb only), 1981-82 some XV920RH/RJ models, and 1984 XV1000 models (on the #1 carb only)

#126: 1981-83 some XV920 models

#128: 1982-83 XV920 some models, 1984-86 XV700 some models, 1984 XV1000 models (on the #2 carb only), and 1986 XV1000 models (on the #2 carb only)

#132: 1981-83 XV750 models (on the rear cylinder carb only)



HITACHI 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).

Replacement Hitachi main air jets are now available for these model carbs, in both their original sizes and in optional "tuning" sizes for use with pod filters or other special tuning purposes.


#50: all XJ650 models except Police models.

#55: all XJ650 Police (37G) models.

#70: all XJ700 non-X models, XJ750RL Seca models, and XJ750E-II models.

#80: all 1981-83 XJ750 North American models, 1981-84 XJ750 UK/European (11M) models, and XJ750 Police (24L and 37H) models.




HITACHI PILOT FUEL JETS:

ff) Aftermarket Hitachi PILOT FUEL JET, sizes as follows, fits all XJ650 (except Turbo), all XJ750, all XJ700 (exc. "X") models, and all XV (Virago) models using Hitachi HSC40-series carbs.

NOTE: stock Hitachi XJ series carbs used the following original sizes:

#36.5: all XJ700 non-X models.

#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 1984 XJ750RL Seca (Canada) models.

#41: all 1984 XJ750RL Seca (Australia), all1981-83 XV750, and XV920 models

#43: all 1982-84 XJ650 Canadian models, 1982-84 XJ650 UK/European (11N and 14R) models, 1981-83 XJ750 Maxim, Midnight Maxim Canadian models, 1981-84 XJ750 UK/European (11M) models, and XJ750 Police (24L and 37H) models.

#45: all XJ650 Police (37G) models.



HITACHI PILOT AIR JETS:

The pilot 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 "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).

Replacement Hitachi pilot air jets are now available for these model carbs, in both their original sizes and in optional "tuning" sizes for use with pod filters or other special tuning purposes.


#195: all 1980-81 all XJ650 North American models, all 1982 XJ650RJ and RJC Seca, all 1980-82 XJ650 UK/European (4K0 and 4K1) models, and all XJ650 Police (37G) and XJ750 Police (24L and 37H) 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.

#210: all XJ700 non-X models.

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



HITACHI MAIN FUEL JET NEEDLES:

Attached to the vacuum piston assembly is the MAIN JET NEEDLE, and as the vacuum piston is raised or lowered due to the vacuum signal through the carb throat, the main jet needle is raised or lowered into the brass emulsion tube (also described as the "main jet" or "power valve" in some technical literature). These jet needles control the overall fuel flow in the main jet circuit of each carb.

These precisely made aluminum replacement needles correctly replace worn, damaged, or incorrectly sized original needles in all Hitachi HSC32 or HSC33 series carbs. The needle "size" is inscribed on the shaft of the needle, just below the plastic head cap. Although all needles are interchangeable between any type Hitachi HSC32 or HSC33 series carb, their different "sizes" are designed to be used in specific applications as determined by factory design engineers.

However, as long as all four carbs on your bike are using the same size needle, you can swap needle sizes between different carbs. So, for instance, you can use the Y-20 size needle (XJ700 models using HSC33 series carbs) in an XJ750 engine (which normally used the Y-13 size needle in their HSC32 series carbs). This type of swapping of needles can be useful in situation where you may wish to fine-tune the fuel mixture in an engine, for instance when changing the air-flow through an engine using pod filters and/or aftermarket exhaust systems.

NOTE: original Hitachi main jet needles have a depression on the bottom of the plastic cap, and this should be oriented with the half-circle bump inside the diaphram.


Original main needle size configurations are as follows:

Y-10: used on all USA market XJ650 (except Turbo) models, 1982-84 XJ650 Canadian bikes, and 1982 XJ650 Euro (model 14R) carbs.

Y-11: used on all 1980-81 XJ650 Euro (model 4K0 and 4K1) and XJ650 Police (37G) carbs.

Y-12: used on all Canadian 1980-81 XJ650 Maxim, Midnight Maxim, and Canadian 1982 XJ650RJC Seca (non-yics) models.

Y-13: used on all USA market XJ750 (1981-83) models.

Y-14: used on all non-USA market XJ750 (1981-84, except XJ750RL) models and XJ750 Police (24L and 37H) models.

Y-17: used on all XJ750E-II models.

Y-18: used on all XJ750RL Seca models (1984) only.

Y-20: used on all XJ700 air-cooled models.

others: all other Y-xx size needles are used on other model Hitachi HSC series carbs, such as XV750, XV920, etc. models.


Original main needle size characteristics:

As noted previously, as long as all four needles are the same between all the carbs on your engine, you can swap around different sizes for "tuning" purposes. Although we have no guidelines nor experience available to assist you in your tuning exercises, we can offer these needle shape characteristics to help you in analyzing your needs. Be aware that the thickness of the needle at any position along its length determines the fuel flow through the main fuel circuit, and the rate of change of the needle thickness (the "taper" amount) determines when and how much the needle allows the fuel mixture to become leaner or richer.

- the Y-20 needles (XJ700 models) are "skinnier" at the bottom of their shaft than either the Y-13 (XJ750) or the Y-10 needles (XJ650). Thus the Y-20 needles are "richer" at higher rpm ranges than either the Y-10 or Y-13 needles.

- the Y-10 needles (XJ650 models) are "skinnier" at the bottom of their shaft than either the XJ750 Y-13 or Y-14 needles. Thus the Y-10 needles are "richer" than either the Y-13 or Y-14 needles, although the Y-20 (XJ700) needles are even richer, but only at wide-open throttle positions.

- the Y-11 needles (XJ650 Euro) are a bit leaner than Y-10 all the way through the rpm (needle position) range, especially at wide-open-throttle position. They are a bit richer than Y-13 needles, except at the wide-open-throttle position.

- the Y-13 needles (USA XJ750) are "richer" than the Y-20 needles (XJ700) throughout the rest of their overall length.

- the Y-14 needles (non-USA XJ750) are "richer" than the Y-13 needles (USA market XJ750) at 3/4-throttle positions and beyond; otherwise, almost identical to the Y-13 needle.

 

Thanks Len , a mine of much appreciated information as always , cheers

 

Once again , a big thank you for Len at xj4ever for the parts . It's nice to be able to start a new xj project and to have the confidence that you have a reliable and efficient source of practically any part you need

 

Here's my ex-Spanish police XJ650 from around 1984. These pics are from when I got it two years ago. It's now matt black and I love it! 78k kilometres on the clock.

 

As it is now. Although it has more modern front calipers from a ZZR600 fitted now.

 

Interesting that it looks like a 750 Seca but with a 650 motor.
Opposite of those 750cc 650 Secas from the Japanese market.

 

Yamaha was throwing everything at the wall back in those days, seeing what would stick...............

 

Numbers match up to the logbook but I'm guessing the swapping probably took place while in the police garage! They'd probably have spares back up from Yamaha undru contract anyway.

I would think that the police contract would be important to Yamaha for their public profile.

Thanks for your comments fellahs!

 

Here's a couple of pictures of my modified calipers...

 

Obviously I've tidied up the brackets since then, the brakes are a whole load better not surprisingly!

 

I have a question too about the digital police meter. Yamaha xj650p was the police bike here. I purchased it through a auction. How does the digital police meter work and how is the input given??

 

There is a reid switch in the Speedo that pulses once per rotation and feeds it.
Analogue to digital!

 

You sure the reed switch isn’t for turn signals?
Speedo is cable drive, and tach is electrical.
I’d like to see a pic of the cluster