1981 CB650 #1 Cylinder not firing

If it's broken or just needs tweaked

Moderators: Volker_P, tidd650

Kidonaclassicbike
Posts: 16
Joined: Wed Mar 30, 2016 7:51 am

1981 CB650 #1 Cylinder not firing

Postby Kidonaclassicbike » Thu Mar 31, 2016 9:19 am

H
Last edited by Kidonaclassicbike on Sat Aug 05, 2017 8:05 pm, edited 1 time in total.

User avatar
Folsoml
Posts: 1630
Joined: Sat Apr 07, 2012 9:02 pm
Location: North Florida

Re: 1981 CB650 #1 Cylinder not firing

Postby Folsoml » Thu Mar 31, 2016 2:37 pm

Your plan is sound. Did you check to see if the plug is firing (Remove plug, ground against the engine, and turn the engine over a few times)? I would recommend getting a compression tester.
Have a problem with your CB650? Have a technical question? Click here!


My Current Bikes: 2005 HD FLHTCUI Electra Glide Ultra Classic, 2007 Yamaha Vino,

Kidonaclassicbike
Posts: 16
Joined: Wed Mar 30, 2016 7:51 am

Re: 1981 CB650 #1 Cylinder not firing

Postby Kidonaclassicbike » Thu Mar 31, 2016 3:21 pm

Will get a compression tester. I found some really cheap ones in Canadian Tire.
Will test the compression.
Will buy new spark plug DR8EIX because the spec is #8 right ? And I will get the Iridium cause someone on the internet said they are better :D
Will test the spark with the old and new Spark plug.

What about some wires and spark plug caps suggestions ? I have no clue what I need :(

Edit #1 Oh i just found a thread that says 7mm is the one to use and I can buy it from NAPA by the foot.

Edit #2 The same thread mentions Resistorized Caps and I am confused once more. Which type of wire I need Metal or Copper and which Caps should I buy that match the stock caps ?

Edit #3 This is what I need i guess: http://www.ebay.com/itm/NGK-Spark-Plug- ... VR&vxp=mtr

I will just cut the end of the wire a little and put a new Cap and a Spark Plug. If this doesn't fix the cylinder, but it fires against the block, then we have a problem I guess.

This is the thread: http://forums.sohc4.net/index.php?topic=17863.0

User avatar
Volker_P
Posts: 5326
Joined: Mon Mar 06, 2006 1:53 am
Location: southern Germany

Re: 1981 CB650 #1 Cylinder not firing

Postby Volker_P » Fri Apr 01, 2016 1:29 am

Welcome here! :D

My first check would be swapping plugs #1 vs. #4 and see what happens. Then try to plug the #4 cable to #1 (still with the plug from #4 in there) and see what happens.
If #1 fires up now, you have an ignition issue on #1.
Note that the ignition circuit is two cylinder pairs in series, so both plugs of a pair (1+4 and 2+3) have to be connected for testing.

One can do a coarse compression test by turning the engine by hand with a 24mm socket (not at the 10mm nut and not with force!) at the right crankshaft side.
One should feel four equal compressions during two turns. If it feels equal, it should run on all four at least somehow from the compression side. So no immediate need for a compression tester just to decide if it would run at all.

The spark plug caps have resistors (5kOhms) and also the spark plugs are resistive type (again 5kOhm) which means 20kOhms for each pair circuit. Some say this is too much but mine ran fine like that all the years.

Kidonaclassicbike wrote: Will buy new spark plug DR8EIX because the spec is #8 right ?

8 is the correct heat value. Iridium plugs seem to have some capability to compensate minor problems. So if it should run better with iridium plugs, probably already something else is weak at your ignition.

Kidonaclassicbike wrote: And I will get the Iridium cause someone on the internet said they are better :D

Of course I cannot compete with this argumentation. :lol:

If you have doubts on your ignition cables, run it in the dark and move the plug cables with thick(!) and dry(!) leather gloves.
If you see some kind of fireworks it is time to get new cables.
And if you really want to know it for sure, spray with water and repeat.
Cosky's great (free) online manual: http://cosky0.tripod.com

forum links to common technical issues

cb650
Posts: 2945
Joined: Fri Mar 03, 2006 7:20 am
Location: Denver CO USA
Contact:

Re: 1981 CB650 #1 Cylinder not firing

Postby cb650 » Fri Apr 01, 2016 2:28 am

sometimes you need to just unscrew the plug boot and trim it back some.
Did you clean the tank out?!?!?!?!

Kidonaclassicbike
Posts: 16
Joined: Wed Mar 30, 2016 7:51 am

Re: 1981 CB650 #1 Cylinder not firing

Postby Kidonaclassicbike » Fri Apr 01, 2016 7:41 am

Thanks for all the suggestions and guidance.
I was going through the advises one by one.

Changed the oil.

Cleaned the electrical contacts (Under the left and right covers and under the seat) Now this is where I don't know if i am doing a good job. I just sprayed them with contact cleaner and scraped them a few times with a really small flat screwdriver. Suggestions on how to do it better ? I have a Dremmel kit in my neighbor, but he is coming back in a few days so I dont have it right now. I think there are some tiny wire brushes in their that can do the job.

Changed the spark plug.

Tried starting.... Same thing: Really hard to start and after it started doesn't want to idle and #1 not firing.

Changed the cap from #4 to #1, same thing...

I sat on the ground and just started staring at it. I was thinking its a Carb issue and I have to spend hundreds to get it to run, and I already blew my budged on the bike because it was in such a good shape and I was hoping with just a little TLC and its gonna be perfect. Then I saw some glue residue on a an unfamiliar plastic part, which turned out to be the Breather Boot between the Air Filter box and the Air box, this thing:

http://www.ebay.com/itm/Honda-650-CB-CU ... iI&vxp=mtr

The glue was dry and there was a gaping whole, which was letting unfiltered and unobstructed air straight in the carbs.... Pushed it from the inside to close it temporeraly.

The bike started like brand new. Half a second after I touched the start button. Idled at 1100.

I turned it off cause it was already late and left it there.

Will do some more testing tomorrow. Will buy sealant and glue it tight.

Edit #1 I just got VERY PARANOID. I tightened the Spark plugs quite a bit after reinstalling them, and now I am reading you only need half a turn :( :(

How hard it is to strip the threads on those CB650 heads ? I didn't feel anything giving up when I was tightening and I had surgery on my elbow last years so I am quite weak in the arms, but I am so worried right now I cant think about anything else :(

What should I do when I get home ? Unscrew them and try screwing them back in by hand and see how easy it is ? If they go in by hand rather easy that means that the threads are fine ?

Arghhhh rookie mistakes :oops: I should have known better.

User avatar
Folsoml
Posts: 1630
Joined: Sat Apr 07, 2012 9:02 pm
Location: North Florida

Re: 1981 CB650 #1 Cylinder not firing

Postby Folsoml » Fri Apr 01, 2016 2:23 pm

First: Relax :wink: Your plugs are probably fine.

When cleaning your electrical contacts, what you are doing is probably sufficient. I think trying to use a dremel tool on anything is more likely to tear something up. You may want to add some pipe cleaners to your process. When you plug things back in, make sure that the connection is good and tight--not just the plastic plug, but the metal contacts inside. Inspect the plug and the wires around it for evidence of previous overheating incidents (melted insulation). Do not just clean the contacts under the side covers, take out the headlight and you will find many more connections inside the bucket. Take the cover off the fuse box and make sure the fuses are intact and their connections are clean. I never heard if you did a spark test on the #1 plug.

I think you may be on to something with that hole in your air box. Correct this, and address any other air leaks, and see if that improves your problem.

If it comes to cleaning the carbs, do not fret. It is not hard, it is just a little time consuming. There is a document here on the site that will walk you through the process.
Have a problem with your CB650? Have a technical question? Click here!


My Current Bikes: 2005 HD FLHTCUI Electra Glide Ultra Classic, 2007 Yamaha Vino,

Kidonaclassicbike
Posts: 16
Joined: Wed Mar 30, 2016 7:51 am

Re: 1981 CB650 #1 Cylinder not firing

Postby Kidonaclassicbike » Fri Apr 01, 2016 2:45 pm

I am trying to relax, but it ain't easy :D

There is spark on #1 I tested it against the block.

#1 fired up right away after I pushed that rubber boot in the direction it needed to go and the bike Idled and ran good.
I am about 95% sure now that everything will be resolved after I patch up that boot. What type of sealant should I use ? I am thinking ALL PURPOSE 100% SILICONE for outdoor use.

Is that the correct sealant to use or is there something better ?

Right now I am just praying I have not damaged the thread of those Spark Plug holes.

User avatar
Folsoml
Posts: 1630
Joined: Sat Apr 07, 2012 9:02 pm
Location: North Florida

Re: 1981 CB650 #1 Cylinder not firing

Postby Folsoml » Fri Apr 01, 2016 3:25 pm

I'm not sure if there is a "correct" sealant for fixing holes in air box insulators. If it works, go for it! I would find some kind of high(er) temp silicone, but please note this--do not ever try to substitute any kind of RTV or silicone sealant for an engine gasket. Little pieces of it will break off inside your engine and travel places where they should not be--clogging oil passages in the process.
Have a problem with your CB650? Have a technical question? Click here!


My Current Bikes: 2005 HD FLHTCUI Electra Glide Ultra Classic, 2007 Yamaha Vino,

cb650
Posts: 2945
Joined: Fri Mar 03, 2006 7:20 am
Location: Denver CO USA
Contact:

Re: 1981 CB650 #1 Cylinder not firing

Postby cb650 » Fri Apr 01, 2016 6:22 pm

I always use some hi temp rtv sealant on my boots to keep water out. And on the electrical connections use dielectric grease.
There are a few connections not under the covers you need to hit too. Both sides just in front of the covers. Especially trace the wires to the ALT.
Did you clean the tank out?!?!?!?!

Kidonaclassicbike
Posts: 16
Joined: Wed Mar 30, 2016 7:51 am

Re: 1981 CB650 #1 Cylinder not firing

Postby Kidonaclassicbike » Fri Apr 01, 2016 6:40 pm

Phew... Unscrew, screw back the Spark plugs. They went out and back in easily. I am gonna have a few beers to celebrate for sure.

The weather is bad again, so I cant really do a lot of work on the bike today and maybe even in the next week.

As soon as the weather gets better I will seal the airbox and update this thread. I have my hopes up. I think the sealing of the airbox will be the end of this thread.

I still have to wash the bike real good, put some elbow grease and Aluminum foil to all the metal parts and measure all the different voltages to decide if I want to open the headlight and start cleaning stuff. I will clean the Fuse box, but I am a little reluctant to go in the headlight. Maybe when my Clymer manual gets here I will get some courage :D :D

Can you guys give me a little info on how / when the Charging system seems to fail on those bikes. I have seen dozens of threads about the problems of the system, but no clues to how many miles on the bike when the problems start. My contacts seem in pretty good condition for 35 years. The bike hasn't seen much daylight and has been stored inside all its life, so not much corrosion going on. The contacts and the wires are a little dried up, but I think they will last a year or two more. Does the Rotor and R/R fail when you rack up some miles, or they can fail at any time, which will mean I better not leave the city and put a Voltmeter on my handlebars if I don't want to end up on the side of the road waiting for a tow truck.

Should I do this: (That is a suggestion by Pinhead in one of the charging system failure threads)

"I'd bypass the aged wiring harness by running two additional wires to the battery terminals.

Attach one directly to the positive terminal of the battery and the positive output of the rectifier. Attach the other directly to the negative terminal of the battery to the negative side of the rectifier.

I believe the charging current flows from the rectifier all the way through the wiring harness up through the headlight bucket and back down to the battery. All of this extra wire adds resistance to the charging circuit. Any connectors between the rectifier and the battery will further limit the charging ability.

The two extra wires will make the entire charging system much more efficient."


Sorry for the long posts and the ton of questions. I just want to do as much work to the bike before I get to ride it this spring.

User avatar
Folsoml
Posts: 1630
Joined: Sat Apr 07, 2012 9:02 pm
Location: North Florida

Re: 1981 CB650 #1 Cylinder not firing

Postby Folsoml » Sat Apr 02, 2016 5:51 am

Kidonaclassicbike wrote:
Sorry for the long posts and the ton of questions. I just want to do as much work to the bike before I get to ride it this spring.


Long posts and a ton of questions are the whole point of this forum! :D

I've never tried Pinhead's method. I would be inclined to leave as is until there is a problem. You may wish to install a voltmeter if you are concerned about it.
Have a problem with your CB650? Have a technical question? Click here!


My Current Bikes: 2005 HD FLHTCUI Electra Glide Ultra Classic, 2007 Yamaha Vino,

Kidonaclassicbike
Posts: 16
Joined: Wed Mar 30, 2016 7:51 am

Re: 1981 CB650 #1 Cylinder not firing

Postby Kidonaclassicbike » Thu Apr 21, 2016 3:41 pm

I am back after a couple of week of bad weather.

Ordered new tires, new clutch and throttle cables and might make an appointment with a technician to do the Valve and Timing adjustments (I am not confident enough to touch those two yet)

Tires and cables will be installed in a shop 3 weeks from now.

Now to the point:

Got the bike to start and idle without the choke.

Glued the Air box boot in place with some weather proof silicone.

That by itself did not help at all as it turns out I have moved the Big Black idle screw too much clockwise which in turn did not give enough gas to the engine I guess, so my bike did not want to idle. After half an hour of fiddling with it i got it to Idle at 15-1600 RPM with choke Closed and 11-1200 with the choke fully opened in a few minutes.

So far so good, but Cylinder number UNO is still giving me grief. Seems to be firing fine in idle, I put my hand on the back of the exhausts and it seems it fires as much as #2 in idle, Ofcourse thats not the cutting edge of misfire diagnosing, so i might be wrong. The header on it gets WARM... Thats it warm... I dont know if it just gets warm from the engine block or the firing of the cylinder but something is not right.

I have spark
I have gas (I think, but every time I pull the plug its wet in gas)
And I think it fires while Idling

I have a few newbie assumptions which are probably wrong, so please correct me and point me at a better diagnosis:

1. Main jet on #1 clogged which results in Misses at throttle so cylinder stays colder than the others

2. Something wrong with Valves on #1 so it doesn't fire at higher RPM

3. Something in Carb #1 is stuck so it doesn't let Air in which results in flooded #1 = No fire

4. Bad timing


As I said I will be taking the bike to a PRO for Valve / Timing adjustment and possibly correction of this issue anyway, but I want to be as prepared as possible. I have already been lied to / overcharged a lot in my short lifespan.

P.S. Checked the charging system with the meter.

Batt ign off : 12.5
Batt idle : 13
Batt 3-5k RPM : 14:25

That looks pretty good to me. All of my connectors / cables (havent checked the Headlight ones yet) look pretty good even before cleaning them. I ordered a 25/35 Watt bulb because I red somewhere its very forgiving to the charging system, so when I am installing that i will check all the connectors in the Headlight.

User avatar
tario
Posts: 166
Joined: Sat Mar 07, 2015 2:26 pm

Re: 1981 CB650 #1 Cylinder not firing

Postby tario » Thu Apr 21, 2016 8:17 pm

You can buy feeler gauges for $10 and do the valves yourself. If you search something like cb650 valve adjustment there is at least one good blog post that explains the process. Might take an hour if you're pretty good with wrenches. Timing would affect every cylinder I would think. Maybe I'm wrong though.
1979 cb650
1980 cb650

jcasey007
Posts: 225
Joined: Sun Jan 13, 2013 3:38 pm
Location: Stratford Upon Avon - UK

Re: 1981 CB650 #1 Cylinder not firing

Postby jcasey007 » Fri Apr 22, 2016 1:34 am

1 - Unlikely to be ignition timing as the ignition for cylinders 1 and 4 are on the same circuit (pickup, coil wiring etc.) the only unique ignition components to cylinder 1 are the plug and HT (thick) lead and cap. So to discount the ignition as the issue just replace the Plug, HT lead and HT cap.
2 - Valve clearances don't change with speed. they can change with heat (i.e. if they are too tight (and I mean really tight!) then the difference between running when cold and hot could cause the clearance to close fully and keep one of the valves in Cylinder 1 open all the time --- I find this unlikely, especially if you have not done any adjustment yourself. Instead of paying a shop to check - why not buy a cylinder compression gauge ( this screws into the spark plug whole) and check each cylinders pressure when cranking. This will tell you more about the condition of your engine, and you can do it yourself (the compression gauge will cost about $20 or less

3 - My money is on an issue with number 1 carb - you say that you can start it without choke, and that the plug is wet after running indicates a very rich mixture- so start with float chamber and drop that off and check the float, needle and main jet. It would be better to do this on a bench but if your not confident in taking the carb rack off then you can drop the float bowl with it on the bike.

My tip of the day :-) get a hand held water sprayer (you know with a little handle you squeeze to mist plants) when you want to see the relative temp of the exhaust headers just spray the water on each you can still see the difference in temp easier than burning your hand

cheers

Jim


Return to “Technical Discussion”

Who is online

Users browsing this forum: No registered users and 19 guests