1981 Yamaha XJ650 Maxim Valve clearance/ carb issues

I agree ^.

 

Sorry for the late reply guys, but thank you for all the input! I think I figured it out. I had the screws set out way too far I moved them to about 3ish turns out and now she runs beautifully, I also had bad low end power when I was running rich, but not anymore! I got a new battery because the one I had on it before was dead. Now she starts with the push of a button. she might actually start if I have the enrichment circuit closed and give it just a little bit of throttle. I'll try it tomorrow. I should make note that I tested my battery when it was running at 3000rpm and I was getting about 14.11v I know that it should be 14.5v +- .3. so I might be having some problems with my alternator, but it's technically charging the battery... any thing to worry about there? Also I'm still working on doing the front brakes, but I got the rear pads and I want to switch them out since they're probably the original pads (they're worn all the way down and I hear squeaking when I push them). I was reading the manual and it says I need to remove the rear wheel which is all good and all, I just wasn't sure if i needed to drain the oil from where the drive shaft connects to the wheel. and if I do do i put 80w-90 back in it? also if there's a forum on how to change the rear brakes, could one of you guys send me a link to it? Thanks a ton!!!

 

You don't have to change the final drive to do the bakes but you should anyway. 80 gear oil from auto zone is what you want. There is a link somewhere but its pretty easy to do. Remove your license plate if it hangs off the fender. I forgot and creased it badly. Remove cotter pin and break free crown but on axle. Up on the center stand. Detach sway bar from right side. Detach the brake actuator lever, put the but back on to hold the spring in. Loosen the clamp on the axle and put a screwdriver through the hole there. Remove the crown but, the screwdriver is there to keep the axle from spinning with the but. Work the axle out through the right side, be gentle, use the screwdriver to pull, spin, gently pry. Put the bike in neutral and spin the rear tire and kick the bottom of the tire a few times and the wheel will work itself free. Work the wheel out, the shoe side of your brakes will slide out if the hub. Ckean with brake cleaner not air. Replace the shoes. Check your bearings and splines and replace your grease while its off. Reassemble and gently work your wheel back into place. Lift it up and slide back into the final drive, a bit of rotation makes mating every thing up easier. Slide the axle back through and get your spacers into place and loosely tighten your but. While you can rotate the hub reattach your actuator rod with the nut just barely on. Re attach the swing arm and put in a new cotter pin. Tighten your crown but, I keep the wheelk spinning to make sure every thing is mated and smooth as I tighten it down. Torque is 94lbs . new cotter pin. Tighten up the action on your brakes make sure they are not rubbing and you have a bit of play but not a lot of slop. Spin the wheel again and listen for anything rubbing and to make sure everything is is in true. Try it again. With the motor running working it up into fith with the throttle closed just to check for wobble under higher speeds, throw it in neutral and check your brakes out by how quick they kill the rotation. Put your license plate on and go for a genkte ride around the neighborhood and work them out adjust as needed and make sure your drum isn't heating from drag when your not applying the brakes. Remove the screwdriver you have been driving around with stuck through your axle.

 

Spelling mangeled by spell check. But was nut. Had to type that three times to get it to stop changing it for one sentence.

 

Alright! swapped out the rear brakes and got the new ones on! Not sure if the old ones were the original.. but that doesn't matter now haha. So I've got another question about fuel mixture again.. I didn't really think about it at the time, but it's recommended that you start the mixture screws out at 2 1/2 to 3 turns out, but that's with the stock exhaust.. the current exhaust on there is a lot more free flowing than stock, and usually with a more free flowing exhaust the mixture tends to be leaner right? if that's the case should I put my screws at 3 1/4 turns out? it has a hard time idling, even if I adjust my idle screw. it will idle at 1500rpm without any problems, but if I try to drop it any further, it will still run for a few seconds, but eventually if I don't give it any gas, it will die. I know when I was running it rich it would Idle at 1k just fine, that's what makes me think it needs to be a little richer.. what do you guys think?

 

I'll assume (without reading back through 10 pages of posts) that somewhere along the line, you got your valves in spec.

The next step, before trying to do any real mixture tuning, is a running vacuum sync; THEN start tweaking the idle mixtures.

 

You might want to go look through some of the modification threads to see what problems and solutions people have had with the lowered back pressure. I would check your plugs for your mixture reading though. Its been pretty cold here, with my idle set right for when its at temp it will not idle properly without the choke and occasionally bumping the throttle when it is first started. Every thing is in sync and properly adjusted, after five minutes of riding to the gas staion and its perfect.

 

I did do the valves and I've also done the vacuum sync. I think I'm where I need to be for the mixture now. I'll check my plugs, I've been riding around for a little while, so it should show me how it's running hopefully! I have to bump it a little bit with the choke all the way off after 2-3 minutes idling with the choke on followed by a 5-10 minute ride. if it's running lean the plugs should be white right? and if it's rich it will show them nearly black, so somewhere in between is what they should look like right?

 

So the very ends or my plugs (on the arm that goes over it) are extremely white.. around the base where it screws in it is relatively sooty.. I think that's a lean mixture.. not entirely sure though. I might try to clean them up a little bit, then take it on another good ride and double check them.

 

You want t look at the ceramic portion of your plug for color. Medium toast or light chocolate is good. Your right about lighter being leaner and darker richer.

 

Alright so new problem, and I figured I'd better address this before I try adjusting the mixture. first of all, it won't Idle at all unless i set the idle screw above 2k rpm if it drops below 1.5k even if I blip the throttle there is a very good possibility that it will die, it bogs down a little then will sputter and die. I took it on a 3 minute drive which I noticed when I got to third gear if I tried to increase the throttle (traveling at about 30mph) it would bog down and sputter like it was going to die, and I would have to downshift to second gear where the revs would jump to about 4k and I could then open the throttle, and the bike would accelerate wonderfully, then I could move into third gear without too much trouble (at about 35-40mph) for cruising. as I started going up a hill in third gear it bogged down again and so I down shifted to second and it bogged down again, then I shifted to first where it sputtered and died.. I tried to immediately start it (with the choke on) and got nothing, so I let it sit. about 3 or 4 minutes later I tried starting it, and i got a bit of a sputter, then a thrumping sound like it was trying to start, but it didn't want to just yet. let it sit for another 2-3 minutes, then cranked it over again, and with a little hesitation it finally started, giving it some revs I managed to make it home without too much trouble, at high rpms I have absolutely no problems what so ever, besides maybe a little backfire when I let off the gas. at low RPMs it struggles.. hopefully I gave you guys enough information on the symptoms I'm having. I think it's possible that I didn't get the carbs synced perfectly when I did them, so that's a possibility.. but I'm not sure if these symptoms show out of sync carbs, or plugged jets (again...) I've got an inline fuel filter on it now, so there really shouldn't be any foreign particles in the carbs, not saying it isn't impossible though.. anyways, thanks for reading all of this, and hopefully someone has had similar problems and managed to fix it! Thanks a bunch you guys!!

 

And you've accurately and individually WET-set the float levels to spec?

 

yup, I checked the wet float and everything... they were all pretty low, about where one on the bolts for the float bowl seated. I put them between 1 and 3mm from the top of the bowl.. I could try checking them again if you think that's what it is.

 

dID YOU CHECK YOUR PLUGS? ARE THEY BLACK LIKE TOO RICH OR WHITE LIKE TOO LEAN? whEN THE BIKE BUGS LIKE THAT, (sorry) it is not easy to tell if it is a rich bug or a lean bug. It alos could be ignition related

 

I haven't really tried to check them yet. I wasn't going to really bother with it until I could figure out the problem I'm having right now.. the bike should idle even if I have all the screws set at 3 turns out. I guess the thing I could do is run it for a little and when I have that problem again kill it, and remove the plugs to see see what it's showing

 

http://www.aa1car.com/library/reading_spark_plugs.jpg

 

Wet-setting floats: http://www.xj4ever.com/setting%20fuel%20levels.pdf

Your bike has a spec for its float levels. Put them in spec.

Did you replace the o-rings on the pilot mixture screws?

 

No I didn't replace those o-rings, I have no idea where you can get them haha. I did wet set them though, I believe the spec is 1-3mm and they are pretty dang close last time I adjusted them. I think I figured it out though... this is super embarrassing.. but.. I ran it out of gas... yup. go ahead and laugh all you want, when I realized that I *face palmed* pretty dang hard haha. I didn't even think that it was a viable possibility though because I had put about two gallons in it, and according the the tach, I've put maybe 40 miles on it. but now that I think about it I did let it idle a lot when i was doing the tests and everything, plus a decent amount spilled out when I was trying to sync the carbs, so it makes sense hahaha. So I put some gas in it and primed it, took a few tries, but it started with the choke on just fine. I was worried that I had picked up some debris from the bottom of the tank, but the inline fuel filter took care of that, and I didn't notice any major particles in it. I haven't really had a chance to ride it around and try to make some more adjustments, but I'll probably still have a problem with it idling, low gas shouldn't wouldn't cause idling problems would it?

 

and I'm pretty sure the reason why it was acting like it was out of gas and stalling on me.. was because it was.. hahaha so hopefully I don't have that problem again..