XJ Specifications

Hi! I constantly find myself not knowing What I have in my garage Is it a 550 seca or a maxim? Is it a 550R or just a 550? What does the "R" stand for? Maybe a it's a noob question but it would make my life easier when ordering parts and asking you guys questions

The bike is a xj 550 4v8 -83 bought in Sweden. the chassi/frame number is 4V8231023

Is it possible to find out which model of carbs my bike is fitted with just by looking at the frame number? I know the carbs are Mikunis, but I don't see any modell number and I really need to know.

All my best!

 

Hard to say without looking at it. One can usually tell by looking at the styling, but there are other indicators.

A trailing "R" after the engine size indicates a Seca model vs a Maxim. Example: a 1982 650 Maxim has a model number of XJ650J. The Seca for that model year is a XJ650RJ. (To confuse things, the Seca Turbo model is a 650LJ... but I digress.)

They may be noob questions, but that doesn't mean they're not worth answering. You gotta learn somehow, right?

Indirectly. Looking up the frame number can give you the model of the bike, which allows one to look up the specifications, and those list the carb model.

The XJCD set has a file on it which lists all the XJ models, their frame numbers, model years, and intended markets. Your frame number says it's a European 550 model from 1983 (making it a 550K); lacking the trailing 'R', that means it's a Maxim and not a Seca. Regardless, I believe all the 550s used the Mikuni BS28 carb.

 

Close. There was no "R" designation on the European models; so a 4V8 will be similar in appearance to a 4U8 (550R) except they had the larger rear drum brake, swirly wheels and dual discs.

Yes, they all used the same BS28 carbs; the USA-market Seca (4U8) differs from the USA-market Maxim (5K5) in jet needles and pilot air jets.

Your 4V8 carbs are probably closer to the (4U8) 550 Seca's specs, except the Euro-spec bikes had fatter pilot fuel jets IIRC.

You might want to ask chacal (XJ4Ever) to be sure.

As far as the bike itself, does it look somewhat like THIS? (This is a USA market "4U8" 550 Seca, with a few non-stock items.)

 

Hi!

Thanks for your answers! I've been on the road for a couple of days and haven't got any chance to reply!

My bike looks exactly like the one on bigfitz picture, but mine has, as you said, swirly rims and dual discs.

So the frame number says "maxim", but the looks says seca? Am I right? Shall I look for 550R-parts when ordering from the US? Still a bit confused

Thank's for the carb model!

 

No, the frame number says "Euro-spec 550." The absence of the "R" in the model number only means Maxim here in the States.

Yes, when ordering from the USA, you're looking for "R" or Seca parts; except for your rear brake. I'm not 100% sure your calipers are the same, but I suspect they are.