Sonic's Workshop

HONDA CB400F

Have you ever had one of those days? If you have, then you'd know what kind of a month it's been. My flame adorned purple VW Fox, (the eyesore of Ajax) dumped all its rad fluid whilst on the way to the fix-it shop to check why I couldn't get the temperature gauge to function. Needless to say without coolant or any way to monitor the engines temperature I didn't realize there was a problem until #3 piston parted company with its connecting rod. The resulting noise and smoke told me, this is a bad thing. To make matters worse, in an unrelated incident I broke the first rule of motorcycles and lent my dirt bike to a friend to try in the back yard. Seemed safe enough he has his own bike and is also a mechanic...Start it up no warm up rev the piss out of it tear up the lawn bog it out at the bottom of the garden and push it back. Mums the word. Unsuspecting me takes it out the following weekend for a well deserved blast in the woods with friends and finds it won‚t start. That's funny! Me thinks ran fine the last time we were out, but after 45 minutes of trying and a couple of shin busting raspberries from the kick starter I retired to the back of the truck to contemplate rule #2 always carry tools and a spare spark plug. As it turns out everyone had a great time I got a nice tan and fed the mosquitoes and upon arriving back home the spark plug was removed to reveal fuel fouling as the reason for not starting. Hang my head in shame.

For all those who've been following along these many issues you may remember my dealings with a possessed Honda CX 500 some time last year. Here's an update...

Executive Editor Rob and I and a surgical team, the likes never seen before at the old Sonics Garage, had gathered in one last ditch attempt to save the patient and a few bucks. The third motor was removed from the bike and painstakingly disassembled to reveal a snapped cam chain tensioner blade. Was this it? Could this be the reason for the knocking? The surgeons conferred and a definite maybe‚ was guessed at. A good tensioner blade was removed from one of the three CX 500 motor tubs I just happen to have on hand (can't imagine why I'd have those.) The new blade was installed along with new gaskets and huffed back into the bike. Fresh oil and filter and new antifreeze and we were ready to revive the patient. Va-room! Ta Dah! Wasn't the problem, the motor knocked along just as loud as before. Were we beat? No!! We lowered the hoist to better evaluate the patients condition and crushed the CX gas tank that some how had wondered under the steel 'I' beam hoist with a 500 lb bike on it (still don't know how that happened). Were we beat? No!!! Now for some reason, in addition to the knocking, the rad fan was hitting its protective shroud. I figured it would be necessary to stick my hand onto the stinking hot head pipe. I do mean stick I had to leave half my palms skin on the pipe in order to pull my hand away. Sore? Oh yeah! Pissed off? Oh yeah!! Beat? Damn straight!!! The official time of death was recorded at September 14, '97 at 2:27 AM. That's right ... in the morning! Now with that monster laid to rest, my hand healing nicely and another failure notched into Sonics ratchet it was time to take on something older and simpler, a bit more reliable. A $100 Honda CB400F with good cosmetics and low km's parked out behind a dumpster, was just what the doctor ordered. Believe it or not it even ran, a bit rough though, only 1,2 and 4 were getting gas. A quick carb strip should sort things out.

With the carbs out and apart it was apparent that all four could use a good scouring. Once cleaned, inspected and reinstalled in the bike, fresh fuel was fed via the IV bottle. With the carbs filled and the choke on the bike fired up right away, and on all four I might add. Victory, I foolishly thought. The engine warmed up quickly and didn't need the choke for long. Mmmh, seems to be running a bit rich, black smoke from the exhaust. I checked the air filter... Ah ha! Filthy, have to get one of those. $48.96 from Honda, doh. Not in stock, doh!

All things considered a two day wait wasn't bad for a 1976 air filter, besides it gave me time to check a few other things that may be contributing to the problem. The black and sooty spark plugs were whipped out and replaced with new NGK's. While the plugs were out I checked the compression which measured all in the 140 P.S.I. range. The new plugs were put in and the H.T leads were trimmed back 6 mm and new spark plug caps were installed to ensure that Mr. Sparky was getting all the way to the cylinder unhindered.

The new filter arrived and was popped into its new home and it looked like all systems go for the second attempt. Fired it up... Mmmh, seems to be running a bit rich, black smoke from the exhaust. Damn, what could this be then? I remember about a year ago having a similar problem with a Yamaha XS400 and, as it turned out, it had gas in the oil and the breather pipe from the crankcase was venting the gas fumes back to the air box giving a fuel contaminated air mixture entering the carburetors before it mixed with the fuel. Result - rich mixture. I traced the crankcase ventilation pipe back from the engine on the Honda to under the air box where it hung there disconnected, leaving a hole into the air box. Was this someone‚s quick attempt to fix a rich running bike? I did not like how this was beginning to shape up.

The timing was next, maybe it's simply retarded or the point gap‚s all wrong. Grabbing the feeler gauge and the book I set about adjusting the gap which wasn't far out to begin with. Then, using a light tester, made sure the points were opening when that little F came a spinning on by. What do you know, the timing is retarded. Ye ha! Lets get the timing light on it just to be sure, yep it's right on now. Timing light off, points cover back on, bike idling along nicely... Mmmh, seems to be running a bit rich, black smoke from the exhaust. What to do? What to do? On the advise of a fellow bike guru I was told to change the rubber O rings on the main jet as gas might be getting pulled past the 22 year old rubber. I ordered the carb rebuild kit and two days later like magic my wallet was lighter and the parts were in my hands. The following day with much preparation and demons begone chants from the local witch doctor I was ready to have another go. If you ever get a chance to work on carbs like this, don't. They're full of an assortment of tiny bits just looking for an opportunity to bounce into oblivion. With the new rubbers happily seat around the main jets, which incidentally happen to be the right size, I removed the main jet needles hoping to see the tampering of some adrenaline pumped youth trying to get a perceived more horse power by raising the needle height like it said to do in some 70's Hot Bike Magazine. But to my dismay the needle height was two notches lower than standard height, probably done by some dying mechanic in an attempt to fix a rich running condition. I've got the Devils bike, the entity that had possessed the CX500 has fled the remains and entered the 400 Four. Time to call in the big guns. "Hey Rob, how's it going?... How's about tea and bagel?... Oh yeah they're fresh ! Just picked em up ... Great, see you in a half." He he he.

In the next five hours the only thing we came up with that hadn't been checked was the cam timing. Perhaps the engine had undergone a top end rebuild at some time and the cam chain was a

tooth out on the cam. This would cause the low intake vacuum and incorrect burning of the fuel. It was worth a try. The valve cover was removed and the timing checked against the marks on the crank. Spot on, nothing a miss. The Poltergeist now living in the 400 obviously didn't like the attempts to exorcise it, for now in addition to the bikes rich running problem the idle would fluctuate wildly without human interference. Now what? Let‚s get Marj out here. Ya she's got an old 75 Honda she may have an idea. Now trying to pry someone away from studying for her electronic engineers papers to come outside at 10:00 PM to have a look at a 20 year old bike takes some finesse. Okay, begging and pleading. But three hours later all three of us were stumped. "Maybe there was a reason it was parked behind a garbage dumpster" she said and we called it a night.

Now seriously what do you do when you've exhausted every known option? You take it to someone else (I told you, at this point there is no such thing as pride I just want to know, and the truth is out there, you simply have to believe Scully). Oh sorry, it's late. I spoke to Willie at Yamaha Sports Pickering where I bought my sons PW80. Both Willie and Ron are top notch bike guys and are experienced with antique Honda‚s, and Willie's a great guy ... What? ... Oh yes ... A super great guy. How's that Willie? What? Oh, yes sir Mr. Shim Ping.

The two greatest minds in history ...

Seriously though we talked about the problem and Willie didn't feel as bad as I was making it out to be so I dropped the bike off the following evening. The carbs were taken out again and the float needles and needle seats were replaced at a cost of $116.00 and another $82.12 for the slide needles. The carbs were given a wash in the custom carb washing bath, reassembled with all the new expensive parts and it ran great - no fluctuation in the idle at all. Mmmh ... seems to run a bit rich, black smoke from the exhaust. Time for the conference call to go over everything we had done and everything he was checking. "Only thing I can think to try is to alter the standard settings and see what happens." Willie suggested. I pictured an old mechanic rolling in his grave as we follow his ill fated footsteps. Mmm... seems to be running a bit rich, oh hell you know the rest by now.

Well at this point I honestly don't know how it will turn out, guess I'll take Virago out to the O.M.G. Fall Ride. Damn she's blown a fork seal and she's leakin' bad. What a month! Hope to have an answer to the 400 Four thing by next article. Sonic.

Tips:

1) Don't follow my tips.

2) Use combustion chamber cleaner when cleaning carburetors, it's stronger and makes short work on gummy gas and varnish. No rubber of any kind allowed.

One of the great ...

3) To remove stubborn cross head screws use a Philips screw driver (in socket form), placed on a medium extension. Tap this firmly into the screw to be removed with a hammer - this will seat the bit into the head of the screw helping to prevent stripping the head and also shocking the threads loose. Works well even on most damaged screw heads.

4) When a fork seal blows on you out on a ride on a Sunday and you don't wish your brake pads to absorb all the oil, a temporary fix to get you home is to lift up the dust cover and soak up the excess with a Kleenex. Then role up another snoogy rag and place it on top of the seal and press the dust cover back over it. The snoogy will absorb the leaking oil until you get home. Unless you're me and have a gusher.

5) One final note I received a letter last week on the use of WD40 to remove grips. The reader was concerned that WD40 will destroy the rubber material of the grip. WD40 does have an adverse affect on some rubber items. In my case however any grip that I'm taking off has seen better days and is on the way to the bin. Once off, the handle bar is thoroughly cleaned and the new grips put on with Grip Lock˙ glue. Bel Ray˙ makes a product called 6 INTO 1 lubricant that is supposed to be rubber friendly.

Sonic

© 1997 Canadian Motorcycle Guide