Exhaust and rebuild ??

Hi, I have a few questions about doing an exhaust kit and motor rebuild on my 82 xj750 maxim. First, I'm wanting to put a Mac 4-1 exhaust, but I have no clue of the jet sizes I'd need. I plan on keeping the stock airbox, mainly because I hear it's a real b**** to tune these style carbs with pods. Now for the fun part: the rebuild. This motor has a little over 35K on the clock and it's showing. Fires right up, but cylinders 1 and 2 are close to dead. 3 and 4 fire right up, but it's not until after 15-20 seconds after, then the first 2 fire up. Not sure if it's the carbs or what. Either way, what would I need to do to rebuild it? I'm wanting new pistons, if not possible, definitely rings. But I'm worried there's a ridge on the cylinders. If there is, then what would I have to do? I'd also like to change rod bearings of there are any? (I only know mainly truck motors) I just need sort of a guide from someone that's done this before, lol
Thanks

 

If the factory exhaust is in good condition, keep it (even if you want to go to a 4-1, keep it in storage for later).

Carbs need refreshed; a full teardown, and cleaning, along with new throttle shaft seals and mixture screw o-rings.
IN THE CHURCH OF CLEAN
Setting the fuel levels


There is no need to even touch the engine internals unless the starter clutch is slipping, or the alternator chain guide has broken apart. These engines are easily capable of 200,000 miles before rebuild (if not more).

An exhaustive intro and how-to guide can be found in my signature.

Shops are not your friend.

 

Take it to a shop, or do it myself?
Zen answer: Become the shop and do it yourself.

 

Actually just took a screenshot, and going to print that for my wall

 

Thanks for the info. Had no idea that these engines were capable of that much, lol. The stock exhaust was chopped and left with straight pipes. Might just order a stock exhaust online and see if backpressure changes anything, which it will. Straight pipes are nice and all, but I'd rather have it done "right" instead of the most common way these bikes are straight piped. I'll post a picture of the exhaust

 

There's very little back pressure, if any. The xj is a very free-blowing engine

 

You're just missing the mufflers. Nothing was cut from your system. It looks like the gaskets are even still in place (though fitting new gaskets is a good idea).

 

Well, now knowing that a rebuild isn't necessary, how about an exhaust? I've looked on eBay, and the only one I can find to fit is the Mac 4-1 that sounds like a Honda Civic with the same can. Any suggestions? Edit: not really looking to spend over a few hundred, that's just ridiculous, lol

 

The chrome shield is cut

 

I ended up putting a small flexible exhaust from the collector to get the correct angle needed and fitted Harley pipes . this was a temporary measure but now i can fit any muffler i want.

 

Yeah, I cut those off because no matter what, they rattled. You could only imagine how irritating that was

 

I was also kinda thinking if getting just the header from Mac, then using an adapter if I needed one to fit a small glasspack. Then I could run a tip if I have room for it, lol. If you can't tell already, I work on mainly vehicles, not bikes

 

The rattle can (well, could. no going back now) be fixed with two quick tack welds.

 

A vehicle is a mobile machine that transports people or cargo. Bikes are vehicles.

 

Ya know...I've never thought of that till now

 

Yeah, I realized what I said after I posted that, lmao. Trucks mainly, bikes being what I'm learning on working on. That's why I was thinking I was close to a motor rebuild, since I've been told that's pretty high miles for a motorcycle, at 35K.

 

35k is only high in that some people don't ride enough due to limited riding season, and so they don't see the odo get that high. These 4 cylinder engines can easily handle triple that amount!

 

I'll leave this here, and point out that the Evolution engine in the FXR is a steaming pile of crap in comparison to the XJ engine (I'm not H-D Bashing. the EVO is a good engine, just not nearly as good as what Yamaha was making at the time).
https://recordsetter.com/world-record/miles-ridden-motorcycle/585

 

Damn. Never realized that bikes were capable of that and more. That's actually really useful information. That bike was in rough shape when I got it, is why I was thinking it needed rebuilt. Long story short, I got it for $250 at a scrapyard in running and rideable condition with a clean title. Since then I've put a choke cable, clutch cable, new clutch (kg powersports), new stator, new regulator, and I'm working on getting a new petcock since mine drips fuel when shut off, and getting a new valve cover gasket. It's one hell of a project, but man I love that bike.

 

Chacal has rebuild kits for the petcock in stock (and everything else that's still available, and that actually fits correctly).
Rebuilding the Yamaha Vacuum Fuel Valve w/pics
The pics are being held hostage by Photobucket (for now), but the descripion is thorough.