Topic: Something suddenly isn't running right at all...

[80650C_Dude]

Hello all!  I have discovered this forum and hope to make infinite use of it in the future, but for the time being I have a question that has gotten me nothing but different answers from every bike shop I've taken it to.  I have a 1980 Honda CB650 Custom with 10,000 miles on it.  I just got it last year from a guy who had garaged it for roughly 6 years and dealt with the cost of getting it back to road worthy status, rebuilt carbs, new battery, fluids, pretty much anything and everything.  Everything was great until a few weeks ago when I decided to wash it.  I used bike wash and the less forceful nozzle choice on the hose and ever since it's been nothing but trouble.  It developed a backfire/missing problem on either the 3rd or 4th cylinder.  When I pull the plugs 3 is usually wet and 4 is covered in carbon... I replaced all the plugs and gapped them as it said to and nothing changed.  It also won't hold a steady rpm when I rev it, if I twist the throttle and try to hold it at 3,000 rpm I get anywhere from 2,500 up to 3,500 rpm without even moving my wrist.  All of this has created a surging motion as I travel down the street so there is no such thing as a smooth ride at the moment.  I take it one place and they say it's too lean, another says it needs new wires, everyone has their own answer and it usually is expensive.  With the knowledge that is found here I hope that some of you can shed light on my problem so I can get back to enjoying my motorcycle, it's killed me these past few weeks not to be able to ride it without getting all angry.

[TwoTired]

Is your bike still in showroom stock configuration?
Bear in mind I'm not familiar with your particular bike.  But, here are some basic things check out.

Check your fuel for water contamination. And, perhaps drain your carb bowls into a catch pan to look for water or other contamination.
Check your fuel tank vent to verify it is clear and that air can easily replace the volume of fuel used while operating.

Cheers,

[mcpuffett]

sounds like you got water where you should'nt have  poss plug caps ,carbs,? you will have to check everything  but do 1 at a time and retry your bike  good luck mick.

[TwoTired]

Have you tried swaping plugs 1&2 with 3&4 to see if the problem follows the plug?

[80650C_Dude]

Thanks for the posts guys!  Anyway, I've drained all the bowls with no evidence of water contamination.  I've also tried moving the plugs, and have checked all the caps, wires, boots and just about everything else with the spark plugs and wires but the issue is always on the 3 and 4 side.  The bike itself is as stock as they come except for things like tires and other replaceable items.  When it first started I thought it might be water somewhere but now that it continues and gets worse as the weeks go by I have less and less of an idea of the problem.

[TwoTired]

Might be time for a compression test.

[Wes]

Youve probably craked your head gasket or head. Better the first than the last the last will get into your wallet.

[057 adnoh]

you may have filled the air box with water

[80650C_Dude]

Thanks again people.  I think I'll try to eliminate possibles as they come in to get this as specific as possible because I really want to find and fix this problem.   The airbox is clear, nothing in it but the airfilter.  I washed the bike when it was cold, I hadn't ridden it in days and didn't ride it until the next day, and I don't see any evidence that I cracked anything.  The compression test is now on my list of things to look into.  Please keep sending in suggestions so that I can narrow this down as much as possible!   Thanks!

[Bob Wessner]

Everything was great until a few weeks ago when I decided to wash it.  I used bike wash and the less forceful nozzle choice on the hose and ever since it's been nothing but trouble.

This theory may be all wet  , but have to go back to where/when/what may have caused this and it clearly seems to be related to the washing.

How about if some water has gotten into the sheathing wrapping the wiring harness? If some of the wiring insulation is questionable and damp, you could have intermitant elec. problems. A long shot, but you might try removing the tank, raising the seat and using a blow drier on warm setting, go back and forth trying to warm and dry things thurougly. Might we worth while to part it in the sun with tank off and seat raised. If water has gotten into the harness wrap, it could take some time to dry it all out.

OK, I admit, it may be nuts, but thought I would toss this into the mix. Also, did you check up inside the plug caps for any moisture?

[80650C_Dude]

Ok, after some serious listening and plug pulling it is in my opinion that the problem is only occuring on the 3rd cylinder.  The 4th plug is cleaner and doesn't seem to be the real problem but 3 is always wet(with gas) everytime I pull it out of the block.  I've tried moving the pilot screw(s) as was the suggestion of one of the shop guys but the plug is still wet.  Am I really going to have to pay out to have the carb fixed (cleaned or whatnot) and still that doesn't seem to have anything to do with what seemingly started this whole mess.  I just don't want to be doing any internal damage to the engine by riding around with it backfiring all the time.  I still have to take it to see if it needs syncronized...being as how I have yet to find a manometer that is in my price range.

[80650C_Dude]

Alright, sorry to be back and a bother but now there's new problems afoot.  So I broke over and took it in to the shop and after a few days got it back.  They did find some dirt in one of the carbs but not a lot, the compression was low on one of the cylinders and said one of my valves was sticking.  So I pay up and ride it home, funny thing though because it stalls out once.  I just thought that it might be low on gas so I filled it up with premium like I always do.  When I get it home I notice that the 3rd wire isn't on all the way so I push it into place.  The bike had started to backfire a little on the ride before but now it was loud and frequent... It won't stay running, they put a fuel filter on it but it acts like it isn't getting enough gas, it will run but it won't idle at all because it drops below 1,000 rpms and dies.  At least before it would run, it was bad but it ran, now it won't stay running at all.  I plan on taking it back here this week because I don't want to waste my money...   I was just wondering if maybe new plug wires would fix the backfiring.  I haven't seen any arching or anything between the wires but maybe??   This problem just got worse so any advice would be great.

[marzubus]

I had similar issues. check for broken or damages needle in carbs. also check coils and check that they arnt cracked physically. I put GSX 750 coils on my 81 650C and its all worked great.