How my CB500 was nearly declared dead…

Unfortunately my CB500 respray project has been on hold for the past couple of weeks. I’ve had nothing but trouble with the bike on the daily (modest) run to work. 

Symptoms: Perfect running until for no apparent reason the bike gets jerky, loses power, revs fall, and just acts as if it’s run out of petrol. Upon pulling over it would stall, and refuse to start for the next 3-4 minutes or so. After it does start again, upon revving it will backfire once or twice and continue to run perfectly until everything starts all over again….

So what does a girl do? Getting sick and tired of having the bike die on me in the midst of rush hour traffic up to three times in a 1.5 mile trip to work, I decided to drop the bike with a mechanic. Picking a “proper shop” nearby, I explained the problem and hoped for the best. Then I remembered that sometimes (every few months or so) the bike tends to overheat and spit out coolant. That little bit of extra information pretty much distracted the mechanic from then on – insisting that both problems MUST be related.

A phonecall a few hours later spelled trouble. The mechanic said he had a look around the cooling system of the bike and found that the coolant level was extremely low. He then tested the fan (which worked) and ran the bike a little. To his horror coolant gushed out of the bike as soon as the engine ran for a minute or so, not enough to make it hot!

His diagnosis: blown head gasket or cylinder ring. He told me he’d do a compression test.

Result: left cylinder: 175psi, right cylinder: 125psi. He was even more sure now that it was a major engine problem causing all my trouble… Quoting me a grand for all the work to put it right, I was totally horrified obviously (especially since the bike had cost me less than that in the first place!) so I decided to take it back as it was.

Mechanic #2. Luckily, there’s this other mechanic close to where I work who helped me out on previous occasions (see: Replacement Spark Plugs) I gave the bike to him, explaining what the other mechanic had said (blown headgasket – repair: 1000 bucks) and although the repair cost gave him a good laugh (and he quoted me about 350 for the same thing) he promised to have a good look around the bike to see what was up.

A few hours and phone calls later: he claimed the bike ran beautifully, and after having it on for a while, coolant stopped leaking out, making him suspect that it had been overfilled. It couldn’t possibly be anything as serious as the headgasket then… 

As my husband and I had suspected from the beginning of this whole ordeal, I told him maybe the tank and carbs are dirty. I asked him to strip the carbs and clean out the tank and see what he finds inside. He was happy to oblige. Indeed I get a cheerful phonecall that evening detailing how he’d found “a load of shit inside the carbs and tank” and the bike was still running beautifully. 

Yay! I got it back last night, drove it around til it overheated and spat coolant out again.. but it didn’t stop even once! Sure I know I should have the radiator fan looked at (It doesn’t cut in even when you could use the engine for a stove), but hey, from home to work it won’t even get luke warm. At the moment (having spent what I have just now on two separate mechanics’ fees) I think I’ve bought myself some time.

Morale of the story: 

1. Before paying a mechanic a grand to work on your old vehicle, take a second opinion!

2. If the bike feels like it’s not getting any fuel, it might just be as simple as it literally not getting any fuel.

3. Older bikes might have rust in the tank which might eventually cause running problems. 

For more information on headgasket problems, see my next post “Headgasket Woes”.