My 1980 XJ650 Project - Not Easy

Hi Gurus,

I am rebuilding the carburetor and ran into an issue that I need you to help shed some light on. I broke the rack and separated the carbs for shaft seal replacement. After removing the valves (look like silver coins) from the butterfly shaft I found that 3 of the 4 butterfly shafts would not come out. After using lots of WD-40 and a large punch and hammer I was able to knock them free of the car body. The shafts would no go back into the carb bodies without some sanding/polishing (1500-2000 wet or dry paper) of the shaft ends and carb body receiving holes. After the carbs were reassembled I found that the valves (silver coins) will not seat properly for bench synching. There is still light around the valves and I cant get them to seat tightly. The valve on carb #1 is rubbing badly against the inside throat of the carb body which is especially strange since there isn't any thing holding in the shaft but some shims and an E-clip. Please help!

 

I'm no guru but the shafts and throttle plates must be oriented and relocated the exact way they were removed.

Gary H.

 

the shafts are sealed with throttle shaft seals. replace them.
did you mark the butterflys as to the carbs they came from?
they do not completly seal the carb throat you will see the light.
disc #1 is probaly in the wrong hole

 

Yes, I replaced the seals and made sure to put the correct valves back into the proper carb. I took apart the rack again and found that Carb #2, 3, & 4 are closing completely. #1 will not close completely no matter what valve/disc I install. Something is wrong and I cannot figure out what. Here is a pic above of what #1 looks like as opposed to the others below when light is on inside the carb body.

 

This is #1 carb fully closed. It's still open at the top and the little holes are visible.
This is how carbs 2-4 look when in closed position. No holes visible.

 

Inspect the spring and linkage orientation. Loosen the screws and see if the plate will shift.

Gary H.

 

Loosen the throttle plate ("valves") screws so the plates can settle into place, then tighten them. Don't forget to use a medium strength thread locker.

If they still don't close completely, mark them (use letters so you don't confuse them with the carb numbers) and move them around until they all fit. It's easy to mix them up if you did not mark them with the number carb they came off of (all I see is orientation arrows).

Your pic for the #1 carb is how they should all look in regards to the idle byass hole (second hole) when they have been bench synched.

 

It's been a couple of years since I replaced my throttle seals so my memory is a bit fuzzy, but I did have trouble with one of my throttle plates not closing properly. After much head scratching and reviewing pictures I had taken before disassembly, I believe I had the throttle shaft turned the wrong way. After turning the shaft and mounting the throttle plate to the other side everything lined up and it snapped shut properly.
Hopefully I am remembering that correctly!

 

The good news: I think I found and solved the issue. When I had to tap out the throttle shaft with a punch and hammer, I believe it slightly deformed the carb body so the valve wouldn't seat properly.

Last night I loosened up the screws and actuated the throttle shaft multiple times to make sure the valve was seating properly. I tightened up the valve screws and actuated the throttle shaft a dozen times quickly to see where the valve was getting hung up. The valve left two pronounced dark marks where it was rubbing too close on both sides of the carb body, right near the shaft holes. I took out the shaft and valve again and lightly sanded with 1500 and WD-40 until the areas were smoothed out. I assembled, checked, marked high spots, disassembled and sanded multiple times until the valve closed all the way over both little holes in the top of the carb body (like 2,3,&4 do). Now the valve opens and closes smoothly and tightly not allowing tons of light through when I shined the flashlight thought the air intake side of the carb.

The bad news: I destroyed one of the new throttle shaft seals with all the dissembling. It got pinched and a little piece tore off. But that's not too bad, i also have to order a new pilot o-ring too since it dropped out during the installation and I can't find it anywhere.

I replaced float needles, and needle seats, pilot o-rings, throttle shaft seals and screws. I also rebuilt the caliper, new pads, got a new master cylinder, brake lines (Although I'm in the process of getting a test fit line made for flatter bars.) I got new manifolds, air boots, air filter, fuel line and 90 degree filter, plus color tune and 4 column synch gauge. Plus tires; I got Bridgestone Trail Master. I love how they look and hopefully will serve me well in the farm land and mtns of Western MD. I also need some shims, but first I had to buy the metric feeler gauges to zero in on the correct sizes. Man this free bike is costing some money. I hope it pays off with some exciting future rides in the hill country!

 

Today was a good day! I got a nice Birthday present in the mail, shims from Hogfiddles have arrived. I installed them and rechecked all clearances - all in spec!!

What is the best way to remove the old valve cover gasket? This thing doesn't wanna come off, it's like it's deep fried crispy!!

 

Plastic putty knife or a bit of hardwood cut into a wedge. Scrape, scrape, scrape, but don't gouge the cover.
This stuff helps a lot.

 

If its still on the cover try dipping in a tray of brake fluid to soften it up. might also take teh paint off though so make it shallow..

 

Thanks guys! I ended up using Permatex Foaming Gasket Remover. It worked ok, but it was the best I could find. Next time I will either soak the gasket for a day or two or get something stronger.

The good news I got the new gasket installed and Valve cover is back in place and looking very clean. Underneath that cover are 8 very happy clearances! I gapped and installed new spark plugs too.

Next step: install new carb boots and carb rack which is zestfully clean with all new o-rings, float seats, needles, & bowl gaskets thanks to Xj4ever! Carbs are bench synched, wet float heights set, and ready to fire up.

 

Brakes. Rebuild them if you haven't already done so. Stopping > going.

 

Thanks K-moe! I took you's guys advise and am currently waiting for my custom fit brake line - Xj4ever sent me a test fit which I mailed back for crimping. I swapped bars for straighter bars and needed to shorten brake line for the flatter replacement MC to the union joint. Brake caliper rebuild complete and the rear pads don't show any signs of delamination.

 

I installed new carb boots and gaskets last night and am ready to hook up carb rack and new air box boots. Before I get into synching and color tune I have a few questions.

1. I set my pilot air mixture screws to 2 1/2 turns out. Do they need to be different for a non-YICS 1980 xj650?

2. Do I Colortune or do a running synch at the first start up? Fingers crossed it starts right up without any high or hanging idle!

 

Did you find that in a store or did you have to purchase online?

 

No. between 2 and 2.5 turns out from soft bottom is the starting point for all xj's.

Synch first.

Gary H.

 

Actually, according to Len's information (which I've been reading through a lot cause I've got carbs to go through soon) the 1980-81 XJ650's used coarse thread screws for the idle mixture screws and should be set to 1.5 to 2 turns out to start. The 1982 and up XJ650's switched to fine thread screws and should be set at 2.5 to 3 turns out to start. That's assuming the bike has the original carbs and the correct thread screws on it.

 

My local NAPA carries it.

 

Non YICS engines 1 1/2 is baseline.

 

Thanks guys! I will set the mixture screws to 1 1/2 turns out to start. I'm going to synch and Colortune anyway. Excited to try out my Morgan Carbtune Gauges and Colortune plug!

I got the carb boots, carb rack, and air box boots installed today.

 

@waldreps and k-moe...
Thanks for the correction.

Gary H.

 

Gary,

I only caught it cause I happened to be reading through Len's wealth of information at the time. I'm surprised that my head wasn't spinning too much to even comment...lol...lots of information to soak in.

Stacy

 

Lol. I'm glad you caught it.

Gary H.

 

First Startup! I tried starting the bike but the battery would drop to 11 volts when I hit the button. Got a new battery installed and the bike fires up on the first blip of the button and ran without stalling.

I'm going to synch it now since it's hiccuping every 10 seconds. Then Colortune!!

 

Well... I went to start up the bike with the freshly charged battery and all I got was a "click". I checked voltage and its reading over 12v when starter button is depressed. I took apart the starter and two of the commutator plates were badly scorched and deformed, brushes are worn down to nubs, and one of the brush springs was melted and broken. I have another starter from my 1982 XJ650 and tried to swap the armature and brush assembly plate over to the starter on my 1980 XJ650. I can't seem to get the gears to line up right though during reassembly. Does anyone know if swapping starter parts is doable from a '82 to an '80? I noticed there are some notches in the housing on the '82 that aren't on the '80. Please help!

 

Ok, so thanks to Len I learned that I can swap starter parts from the '82 xj650 parts bike to the starter in this bike. The parts bike's armature and commutator were in great shape as well as the brushes and plate so I swapped them over. Once I had it all cleaned up and put back together the bike started right up. I used wet or dry sandpaper on the commutator and polished the copper with some brass/copper cleaner I had. I'm going to try to synch the cabbs tomorrow w the Carbtune gauges. Hopefully I can keep it running long enough to tune it.

 

The bike stayed running and I was able to do an initial synch with the Carbtune gauges. However it hesitates when you blip the throttle, then revs a second afterwards. What would cause this lack of throttle response? It's like it bogs then catches fuel. Would a Colortune smooth it out? I haven't performed one yet as I just got it running again.

 

It's a bit lean on the idle mix screws

 

That would explain the popping I'm hearing too! It's not constant but every 10-15secs

 

I set the float Heights on my bench with a level on the carburetors. I hooked the carbs up to the gas tank and put gasoline in them while they were on the bench, and made sure the fuel levels were each 3 mm below the carb body. However when I checked the float height with the carbs on the bike with the bike on the center stand, The fuel level is right at the screw heads which holds the bowl on. So the fuel levels are lower when installed on the bike, is this normal?

 

Yes it would.

 

Yes. The bike is not perfectly level, but the fuel levels are specd' with the carbs level on the bench. If you remeasure closer to where the pilot and main jets are, you will find the fuel level to be correct.

 

Update: I installed the custom 16" brake line (compliments to Xj4ever) from the MC to the union joint and bled the brakes. Changed the oil because it smelled like gas due to sticking float needles which since have been replaced. I actually found the middle gear oil drain plug this time and drained it as well.

Next I took the bike to my friends garage out in the country and away from neighbors so we could color tune it and not worry about revving the engine for an hour fiddling w the idle. After a frustrating time of adjusting the pilot screws and being confused by the lack of color and excessive popping in the combustion chambers (carb spray produced no vaccuum leaks), I finally ditched the Colortune plug and just turned each screw out to 1 3/4 turns. Wow, the bike sounds amazing and stopped popping/back firing, and the idle stopped "hanging". It's slightly on the rich side but I prefer that to lean and popping. I hooked up the Carbtune gauges and synched it to perfection. Oh man it's butter smooth now!!

Next I installed the correct length clutch cable (Xj4ever) from the 550 model to fit with my flatter bars. I took it out for a ride and my goodness does it have loads more power now that the valves are adjusted and carbs are zestfully clean with all new o-rings and vaccuum leak free! It revs so smoothly to 8k and everything feels right with the world. This has been over a year of hard work and money spent to get this bike purring again. Thanks to all you gurus!!

The bad news: the headlight just quit and I don't know what to do. any help is most appreciated. Love you guys!

 

Are there any links to instructions on how to trouble shoot the headlight not working? All other electric seems to be functioning perfectly - blinkers, brake lights, neutral light comes on, and bike fires up at the blip of the starter and runs smooth through all Rpms.

 

Here is my XJ currently. With non working headlight.

 

I like those tires!

 

Nice bike. I like the crash bars or case protectors, whatever they're called.

 

Per the headlight, it was working the other night but then it turned off somewhere in the process of having it up on the lift tuning the carbs. I took it for a ride and the light came on after hitting a pothole. Then it turned off again after hitting another bump. I tried simulating another bump and even checked fuses to see if it had blown. The original fuses and fuse block seems fine and the old connectors are not fractured or damaged. But I haven't broken out the multimeter as I don't have much experience using one, other than battery voltage readings. I checked again to see if the light would turn on after everything cooled down but still nothing. All other electrical components working aside from headlight and guages display light. Neutral light comes on too. Please help!

 

For the headlight, there is a relay for it under the left side cover below the TCI and regulator. I would check those connections and the relay itself.

 

If your headlight still isn't working just scrap it and put in dual headlight relays. You'll have brighter lights and you'd be done by now.

 

So pretend I'm a child and don't know anything about relays and how to "check the connections" or test the relay or even what it looks like, how would you explain the procedure... to myself the pretend know-nothing child?

 

It's this guy circled below. Try unplugging and cleaning the contacts with some contact cleaner. It comes in spray form at the auto parts store.

You should do the same with the actual headlight connection in the bucket too.

I'll have to look at the wiring diagram later to give you the details on testing it etc.

 

There's really only a couple things in play. You said the gauge lights go off too? That would indicate something wrong with the fuse or relay/relay connection then. Since it appears to happen when you hit a bump and you have the original fuse block, I would suspect that first.

See below, power goes from the fuse to the relay, and then to the dimmerswitch and gauge lights. Since the gauge lights go off at the same time, I would think that the switch and light is fine.

 

Your relay *may* be under the tank. The manual for a 1980 G bike says that it's under the tank, but the cabling picture shows it where my picture does.

 

Thanks guys, the rain has finally stopped so I can look into these solutions today. I'll check the relay and headlight connections and test the headlight to see if power is getting to it. How do you test the relay?

Is it true that due to the headlight relay the light shouldn't come on until the bike is started? I'm pretty sure the light was coming on once key was turned to the "on" position. But I've been wrong before... 1997 I think it was.

 

On yours, the headlight will be on until you hit the starter button, then it will turn off until the engine starts, then it will come on again.

 

You sure? Looking at the diagram, the relay would be open until voltage from the charging circuit energizes the relay. After it closes, there is power fed from the NO terminal on the relay through a diode back to the coil on the relay to "latch" it on until the key is turned off.