85 750 maxim x - jets size?

Hello all, great site by the way. I have recently bought a 1985 750 maxim x, and am in the process of bringing it back to life. It has a beat up 4 in 1 exhaust and pod filters on it. Does anyone know what are the original size jets for this bike, as I am going to put the stock exhaust and airbox back in (if possible). I currently have the bike dismantled and wondering how do you determine the size of the jets in the carbs. I have the carbs removed from the bike but haven't got around to taking them apart yet. The bike was laid up for about 3 years so they are in need of a through cleaning. Any help would be appricited. Thanks.

Mike

 

Re: 85 750 maxim x

Jet sizes are stamped right on the jets themselves.

By the way, in 1985, the Maxim X was 700cc in the U.S. Is your model from Canada?

Main jet size for a U.S. model 1985 XJ700 Maxim X is 100.

 

Re: 85 750 maxim x

Yes my bike is from canada, it is the 750. I think that the stroke is a little longer thus giving it the extra displacement. I think that is the only real difference in the 700 and 750, so I would assume that the jets are the same, unless the compression ratio is diferent and the 750 has a different carb set up. Thanks for the info.

Mike

 

Re: 85 750 maxim x

Engine Type: 749 cm³ 4-cylinder In-line, 4-stroke
Cylinder Inclination: Forward 14°

Engine Model: 1MY
Engine Cooling: Liquid
XJ750X Displacement: (45.7 cu. in.)
XJ700X Displacement: 697 cm³ (42.5 cu. in.)
XJ750X Compression: 11.2:1
XJ700X Compression: 10.5:1
XJ750X Bore x Stroke: 68.0 x 51.6 mm (2.6772 x 2.0315 in)
XJ700X Bore x Stroke: 68.0 x 48.0 mm (2.6772 x 1.8898 in)
Combustion Chamber Volume: 18.4 cm³ (1.1 cu. in.)
Cam Arrangement: DOHC
Valves - Total: 20 total - 5 per cylinder
Valves - Intakes: (3) 21 mm per cylinder
Valves - Exhausts: (2) 23 mm per cylinder
Spark Plug Type4) NGK DR8ES-L or Nippon Denso X24ESR-U
Spark Plug Gap: 0.6 - 0.7 mm (0.024 - 0.028 in)
Carburetors: (4) Standard side-draft 33 mm Mikuni CV
Lubrication System: Wet Sump

 

Re: 85 750 maxim x

I have a Canadian XJ 750 Maxim X as well. Mine apparently has the wrong size jets in the wrong carbs. I believe the smaller ones are supposed to be in the two inner most carbs and the larger ones are supposed to be in the outer most carbs. Mine are one large and one small on each side. As for proper size, I don't know.

Steve

 

Re: 85 750 maxim x

???

That isn't right, is it?? I thought all XJ's were 2 valve per cylinder...

[edit] Wow, just did a quick google on it, proving my ignorance once again!!

That is very impressive, anyone got any pictures or drawings of the 5 valve cylinder head?? Way ahead of it's time I'd say...

 

The 5 valve Maxim came out the same year as the FZ750 5 valve sportbike engine. The Maxim X is basically a watercooled Maxim engine ( same bottom end as previous Maxim engines) with the 5 valve head. It lasted only 2 years, as it was replaced by the Fazer 750, with the 45 degree canted block, like the FZ "Genesis" engine. All FZ, FZR, YZF sportbike engines over 600cc have had 5 valve heads since 1985.

Too bad, the Maxim X was quite a speedy bike, and not nearly as "controversial looking" as the Fazer.

Original Fazer 750 (700):

Maxim X 750 (700):

 

Yeah the 5 valve per cylinder is definatly a peice of work. These bikes a notoriously fast aswell. I presently have mine pretty much taken down to the frame, with the engine and still in and wheels still on to move it around the shed. I will be digging into the carbs soon, and will keep you guys updated. And if anyone knows the proper size of jets for the 750 X could u let me know. Thanks again.

Mike

 

With all the weight reduction from removing the engine it must really fly

(DUCKS!)

Seriously - the X's are supposed to be some fast fast bikes...

 

This is from the XJCD: It says XJ750XN

Carburetor;
Type/Manufacturer/Quanity BS33/Mikuni/4
I.D. Mark 1FL 00
Main Jet #105
Main air Jet #120
Jet needle-clip Position 5FZ83
Needle Jet Y-2
Throttle valve #130
Pilot Jet #37.5
Pilot outlet size 0.8
Pilot air Jet #140

 

Oddly enough, around 1986 two guys I knew had a Maxim X and an XJ750R (the baby 900 Seca). The Maxim owner said the X wasn't quite as fast as the 750R, which sort of surprised me. Don't know if the 750R was tuned (it was abused however) or if the X rider was being hobbled by gearing.

750R (Canadian version did not have the chin fairing).

 

Yeah they are fast bikes. My buddy had one years ago and man she could haul ass. I haven't tryed mine yet, since I would like to check her out and get her back in working order first. They also sound really good, thats mostly the reason I'm going back to the stock exhaust, to get that whistling sound back. Espically when you rip it up around 9 or 10 grand. I used to have an 82 400 seca and a 84 vfr 1000 interceptor also, but the maxim x always was my favorite. Thanks for the info on the jets and carbs, I'll keep you guys updated on the progress. Thanks.
Mike

 

Hello The 4 into 1 system you currently have on the bike what make is it ?

 

Hey guys,
I have an 85 Maxim X (750) since new. It has sat for awhile and recently brought back to excellent running order. The only problem is that the idle set screw is siezed. The bike shop is claiming that even thought i had the carb completely redone i have to buy a new carb to fix this problem? Every single part in the carb is new and yet one screw is making the bike stall at idle?

any ideas?

 

Hey guys,
Just bought a 1985 Yamaha XJ 700 X MAXIM that im selling for parts. This is a USA bike. Motor is pretty much complete. If you need something just send me an email.

Thanks, webCHOPPERS

webchoppers@sbcglobal.net

Todays date Sept. 24th 2008

 

Re: 85 750 maxim x

By the way, in 1985, the Maxim X was 700cc in the U.S. Is your model from Canada?


THEY WERE IMPORTED INTO THE USA THAT YEAR (TECHNICALY) AS THEY WERE AVAILABLE IN HAWAII... MANY MILITARY PERSONEL BROUGHT THEM BACK TO CONUS....

 

Willing to part with the ignition switch and helmet lock? My lock was removed by the PO, and the ignition switch looks like someone took a screwdriver to it. Works fine, just a cosmetic issue.

 

hi mike why are you putting the air box back ?

 

If you with "the idle set screw" mean the throttle stop screw (the one with the curled knob positioned rear between carb 2 and 3 and which can be turned by hand to adjust the overall idle (as opposed to the idle mixture screws (of which there are 4))

- then it is a fairly simple working device and it shouldn´t be hard for anyone with metal working skills to either "un-seize" it or cutting/drilling/threading a replacement screw in there.

Either option probably requires the carbs to be pulled, of course and the latter may require further disassembling but - after all it´s only a partially threaded rod with a knob...

If the problem is one of the idle mixture screws, then matters become a little more delicate - still it can be done (and if everything else fails you´ll be searching for one out of 4 carb bodies and a replament screw set from Len/chacal).