85 xj700n no fire

Hey guys I have recently acquired a 1985 xj700n maxim. I am very new to street bikes and didn't even know what I was looking at when I went and looked at this bike. They made me a deal I couldn't refuse. Anyway it only has 7800 miles been setting for about 8 years. Although it was inside I knew there would be a few issues. I changed the oil and filter and put a new battery iv bottle some gas and she fired fairly easy. Problem is after you shut it off sometimes you would have to let it set before it would fire again. I got the tank cleaned and took it for a little spin ran great. Had a float sticking so took carbs off cleaned then replaced. Got it to start ran just long enough to heat up the pipes and it acted like someone shut the key off. Now I can't get it to fire. No spark! Every once in awhile you will see a faint spark jump the plug gap when you let off the starter button but other than that nothing. I know pretty much nothing about the electronic side of motorcycles. I would appreciate any help/advice you all can come up with. Thanks alot.

 

Welcome, Randy. I have an 85 Maxim, also. Runs like a champ, thanks to this forum. First, you say that you "took carbs off cleaned then replaced." How far did you tear them down? Did you clean the carbs completely or just the bowl areas? The rubber components are 30 years old and need to be changed.
Second, valve clearances. With our "airheads", 1st check is due at 3000 miles and every 5000 after that. At 7800 miles, it's due provided that the initial check was done. (don't hold your breath about that)
Definitely, get the valves in spec. Tight valves cause a lot of problems that you wouldn't think were related. After that, we'll talk about getting your bike safe.

Ahh, Young Grasshopper, you are about to embark on a wonderful journey into the world of XJs. Heed the advice of Masters Bigfitz52 and Rickcomatic for they are wise. Have fun and stay safe.

 

Here's a case where I can't say this strongly enough: CHECK THE VALVE CLEARANCES RIGHT AWAY.

Yes, you probably have carb issues. The brakes will need work. There's a lot more to this than you ever could have expected or imagined---

But "starts fine cold, won't start warm" is a classic sign of some too-tight valve clearances. When it starts happening you have crossed into the danger zone and are about to burn a valve.

 

Thanks guys for the heads up on the valve clearance issue I'll definitely check that out. I did a complete carb clean while I had them apart. I did it step by step from the forum that is posted on here. This site is a awesome place. I haven't found any other place even close. My issue has to do with not getting spark the one little ride I went on was to my buddies house I went to fire it up when I was gonna leave and it would start. He took a car key pulled a plug wire had me fire it and grounded the wire to the head bolt. It cranked for a second then fired. He said it had weak spark and the resistance he caused with the key got it to fire. I am definitely looking forward to learning all I can about this bike and getting it safe and enjoying the open road. Well heading to the garage now to check out the valves. Let you all know what I find.

 

Can anyone tell me the valve clearance for my bike? I researched it and came up with a few different answers. Thanks guys

 

AIR cooled, right?

Intake .11mmm ~ .15mm; exhaust .16mm ~ .20mm.

How to: http://xjbikes.com/Forums/viewtopic/t=14827.html

Part Deux: http://xjbikes.com/Forums/viewtopic/t=29209.html

 

Yes sir air cooled. I ran the check on these yesterday afternoon and the intakes were all between .12 and .14 and exhaust is from .18 to .20. I'm assuming this would be considered spot on?

 

If those are metric measurements then the answer is a resounding yes. For them to be that nicely in spec, somebody's adjusted them already.

Cross that off the list and proceed.

 

Yes they are metric measurements. As far as someone adjusting them before I would say that is probably true. I am the 3rd owner of this bike. I would say just by the overall appearance of it that owner number one took really good care of it oil was clean when I changed it. I ran it just in the garage on several occasions getting it up to temp every time changed it again and it looked just as clean as when I put it in. Hell even the sight glass looks like it never had oil in it. Owner number 2 never got it licensed. He however stored it in a way that got the inside of the tank rusty and put some scratches in the paint by having crap piled all over it. I bought it dirt cheap guy was needing the space to pile more crap. Lol. So now to my firing problem did a little checking. The voltage at the ignition fuse is 10.7 a buddy of mine thinks the key switch needs taken apart and cleaned. Does this sound like it might be the problem?

 

I can only speak from '78 ~ '83 Yamaha experience when it comes to things electrical. Does that bike have the original fusebox with glass fuses? If so it needs to be rebuilt or replaced with a modern blade-type box. The clips in the original crystallize and break all on their own.

But I don't think that's the whole problem. These bikes DO have a rather "watery" spark even when everything's right.

Honestly, if the bike sat for 8 years it needs actual carb service, not just a casual cleaning. Some rubber bits may need to be replaced; and you'll need to wet-verify the float levels. The cool thing is, you've eliminated valve clearances (#1 in the maintenance procedures in the manual and a prerequisite for synchronizing the carbs.)

-Fusebox
-Carbs
-be sure you use brand new plugs

I'm betting it's not going to be "one thing" but rather a combination of little things. Slow down; be thorough. Despite being well-maintained, go through everything maintenance-related step by step. (You can start with step #2. The air filter and then the carbs themselves.)

 

The fuse panel on an 85 700 Maxim is behind the idiot lights between the speedo and tach. It uses blade style fuses and 4 screws hold the cover on.

 

Yes the fuses are the blade type behind the idiot light panel below the key switch. I checked all the fuses they all check good. I checked the voltage on my battery it's putting out 13.2 but only getting 10.1 or 10.2 at the ignition fuse and the headlight fuse. I don't know if this would give the coils enough juice to fire or not. As far as the carbs are concerned I did a complete cleaning on them they didn't seem too terrible considering. The rubber parts are still plyable but I definitely will go in deeper if it needs. Kinda want to get it running before I tear them apart again just to see if the cleaning helped any. I was thinking about getting new needle valves for the floats or is that needed? The neoprene tips looked good no grooves or anything like that. I really am getting into learning how this thing ticks! Any other ideas of what I need to do to make her safe and trustworthy would be greatly appreciated.

 

That is an excessive amount of voltage drop. Check and clean every electrical connection, paying extra attention to the chassis and engine grounds.

 

Thanks k-moe. I'll check those things next. A friend of mine said something about the key switch possibly having build up and not making good contact does this sound like it might have something to do with it also?