Fairly new member, Fairly new XJ

Hey, everyone. I just bought a '82 550 Maxim. I couldnt believe it when i saw it. Only 4200 original miles, and get this, only $800. Runs like champ, but i just think i want to do some things to it to make it unique. I have already put 2k miles on it this summer. I think I am about ready to start adding some performance stuff. I am really wanting to know what to do about carbs. I live in Colorado at an elevation of 6500 ft; so that makes it a little more tricky when selecting jet sizes and such. If anyone has any tips, hit me up. Also, i was wondering if the 4-1 aftermarket exhaust systems are really better than the 4-2 stock ones? Input is greatly appreciated.

 

There isn't much you can do to it performance wise since it just and old school air cooled engine and a little 550 at that. You'd have to make it water cooled like a modern engine to be able to add more power which is probably not worth the trouble or expense. Also, anything you do to change the exhaust or intake will require rejetting. If you want performance buy a GSXR600.
However if you are at an elevation of 6500 ft it's probably running too rich unless the PO already had it rejetted so you may need to do that anyway. The 4-1 aftermarket exhaust systems don't have any advantages over the original unless you just like the look or sound or you need to replace the originals because they are rusted out. I replaced my rusted out stock exhaust with a stainless 4-1 from Super Trap that I was lucky to find on ebay and put on pod filters because it makes the carbs a lot easier to get to when I have to clean and adjust them every year in order to pass emissions but then I had to rejet to get it back to the correct mixture but it doesn't make much difference in performance.

 

I agree with Steve, stay with the original exhaust. First thing, get a manual, and I recommend the XJ cd(s) in their latest version. Welcome to the group.

 

The 550 does have a lot of power for an air cooled 550 but there isn't much that can be done to improve it except just follow the service manual to make sure everything is in top shape and performing like it was designed to do by the factory. On the other hand Dean used to take his to the track every weekend and he's a big guy!

 

I guess the whole more air+more fuel=more power doesnt apply with this small of an engine like it does with my big block Chevy. It doesn't really matter. I am going to enjoy riding it anyway. This bike really is a blast to ride, and i have no trouble keeping up with all of my buddies who have newer, bigger bikes. In fact, acouple of my friends that have stock 883 Sporties have trouble keeping up with me.

 

The only way the whole more air+more fuel=more power thing will work if if you turbo charge it but that's expensive and you can't do it for very long, maybe just for 1/4 mile runs then it would overheat (and you'll have trouble finding insurance). You can probably take most Sportsters in the stop light drag races as it is but you'll ruin 2nd gear if you do a lot of drag racing.

 

Cool, thanks for the tips.

 

Do a "Plug Read"
See how that thin Mountain Air is effecting the Pilot Mixture.

Since there is NO Air-Flow Meter to correct the Mixture, like a Fuel Injected System, YOU have to be the judge and adjust your Mixtures accordingly.

The correction can be made by either Adjusting the Pilot Mixture Screws or changing the Pilot Fuel Jet ... setting-up for the less air available at a mile high.

 

Does the "plug read" that you are referring to consist of pulling the plugs and physically looking at the color and condition?

 

Yes.
The coloring and condition of each plug will "Tell the story" about how the Cylinder is performing and the condition of the engine.

There are Plug Read Charts on the Web sites of most Major Plug makers.

You will get to "Eyeball" each Plug in turn, and determine what you should do ... Tuning Wise.

ColorTuners generally find their Plugs on the Lean side, initially, until they become familiar with the Colortune Plug and its window of Blue.

If the Ceramic surrounding the Center Electrode is Clean or shows very light brown coloring ... that Hole is too Lean and the Mixture Screw will need to be brought out to add some additional fuel to the burn.

Dark coloring can be a combination of ingredients ... Rich Mixture, Oil getting into the Combustion Chamber, etc.

You strive to set the Mixture at a ratio that will burn and cause the Plugs to have a Brown to Dark Brown tinge to them.

Rich enough to Idle and run the Bike ... with enough Richness to sustain the Throttle Response and not temporarily starve the bike when the Throttles are opened and the Bike comes "Off Idle" and transitions to Main Jet Supply.

Too little Fuel and the Bike will Backfire.
Too much and you Bogg-out, hesitate or foul Plugs.