Question-------------------------
Thanks for being a smartass. That's really helpful. Do you have any advice regarding the proper jet size? or baffling. For you info, the bike was a recycle job... the original pipes were rotten through & the air box was smashed- I had to replace the wiring harness etc. so these parts that are missing are missing because they were un useable, not because I was trying to improve performance. I cant afford (& it wouldnt make sense) to replace all of the stock components... I made the pipes myself & a lot of the other parts I needed... So a real answer or some advise on how to "tune" it properly would be appreciated. I want it done right & I want to do it myself... thats why I "asked the expert".
Followup To
Question -
Hey Chris, I have a 81 xj 650. I have removed the airbox & added slip-on aircleaners - I also, for the moment am running un-baffled straight pipes... the idle is super high... how can I dial it down. Do I need to turn each of the pilot screws? Thanks! ADAM
Answer -
Hi Adam.
Well, if you did not retune the bike for the changes you've made (which I suspect is the case), then you've just screwed up your bike.
Not completely, so there's still hope if you undo all of the things that you did to it in the name (name only, to be honest) of performance.
The changes that you've made require retuning of the bike in order to not ruin the valves and performance. Sure it SOUNDS fast, but you, in fact, have made the bike slower as well as harming performance and possibly a dozen other things on the bike.
The bike was designed to run with everything balanced to certain components. The factory exhaust produced back-compression that prevented burning of the valves as well as a proper level of pressure in the engine exhaust side. Have your pipes turned blue near the exhaust end of the exhaust pipe yet? It will, and there is no fixing that color change in the chrome. Also, your hearing will soon suffer as well from the noise. All researh indicates that loud pipes do not save lives, but look on the bright side; they do annoy the neighbors and draw a ton of unwanted attention from the local cops.
The air filter box and air filter was designed to allow a proper level of air into the carbs to allow for correct mixture. The bike runs either too lean (whitened electrodes on the spark plugs) or too rich (blackened or wet plugs) now, doesn't it? That is because of the change in the mixture.
As far as the idle, there is an adjustment screw between the carbs on the underside of the carbs between the #2 and #3 carbs. Adjust it out to reduce the idle and in to increase the idle.
Good luck and ride safe.
FALCON
AnswerHi Adam.
Well, you should have said that your issue was related to a restoration. That is a completely different thing.
As far as the baffles, just get an aftermarket set of exhausts. Either aftermarket factory spec (pipes and all), factory (also pipes and all--plus more expensive) or, if the pipes that you made are the same size as a factory set, slip-ons (mufflers only) for your bike. Those are available through any decent bike shop or online at www.jcwhitney. com or www.denniskirk.com (there are hundreds others, but I have used these 2 before and am pleased with what I got from them).
You may have to go to a cycle junkyard for a replacement airbox if a dealership or local shop cannot get one for you. Also, it is a real pain in the butt to install the airbox, so be ready for a very frustrating experience; possibly more so than the retune If you retune it rather than finish restoring it to factory.
Jet sizes and other retuning specs are best left to someone who makes performance mods to bikes as a matter of course. They do retuning so often that they have those specs on hand. If you ask nice, they may even print the info up for you (but don't hold your breath on that one). I, myself, do not do that type of retuning or performance changes, so I won't have any of those specs.
Good luck and ride safe.
FALCON
