Walneck's Classic Cycle Trader - November 2007 - (Page 56)

MONTHLY FEATURE STORIES BENCH RACING BENCH RACING #92 NOVEMBER 2007 OPINION OPTIONS Dear Mark, I have a 1984 Honda CB650, I had a hard time trying to start it, and I took the carbs off to see if they needed cleaning, so far they look clean. I put the carbs back on. Then I took the gas tank and petcock off to see if there was dirt or rust obstructing the starting procedure. Next I ran gas thru a funnel straight to the carbs, the bike would run as long as you kept revving the engine, I drove it to a bike shop for repair, I got a couple of miles and it died on me. I could not get it started, I got a truck and threw it in back and took it to the bike shop. A couple of weeks went by, so I thought I would stop by to see if it was done, the mechanic thought it may be the CDI system. I was thinking if was the CDI system it may not have fired at all the last time I rode it. I think that it could be a simple carb adjustment. Do you have any opinion of what it could be? L. Smith I always have an opinion and in this case it’s to find a mechanic that’ll run some diagnostic tests instead of guessing. First disabuse yourself of the notion that itís a simple carburetor adjustment. It isn’t. Engines need three things to run properly, good clean fuel, Presents By: Mark Zimmerman compression and a spark occurring at the right time. If an engine won’t start your first job is to figure out which of the three is missing. If it runs poorly you have to figure out which of the three things is there but isn’t up to snuff. The fact that the bike ran, but wouldn’t idle indicates a carburetor problem, the shutting off maybe carburetor related, or it maybe a CDI or compression problem but without more information to go on I’m simply guessing instead of diagnosing, which in my opinion is always a bad thing. I think What you have is a detonation problem. What caused it I can’t say without examining everything, but yes, ignition may have caused it. The first thing to do is eliminate all other causes. I’ve never seen a lubrication problem hole a piston so we can pretty much discount that one out of hand. Lean mixtures can cause both seizures and holed pistons, so go through the carburetor with a fine tooth comb. Assuming nothing obvious is found you’ll have to go through the ignition, paying very careful attention to the timing. If nothing leaps out at you, have the crankcases pressure tested, it’s possible there’s a small air leak somewhere that’s making the bike just lean enough to detonate. Bench Racing about 4000 miles of trouble free riding on this bike. I ride it daily to work. A couple weeks ago she seized up on me. Upon inspecting the problem, I found the center cylinder seized and a hole burned through the top of the piston big enough for a pencil to slide through. I instantly assumed it to be related to the carburetor, fuel(leaning out) or oil pump line debris. I went on an internet web site for answers and was surprised at the number of replies I got saying, in their opinion, I had an ignition problem, not carburetor. What do you think? Thanks, Gordon H1 HORRORS- OPINION #2 Hi Mark, Just wondering if you could give me your opinion on my 74 H1 Triple Two Stroke seizure. I have I WALNECKS.COM STICKY SLIDE I have a 1979 Yamaha XS 750 SE Triple. On one of the carburetors 56 NOVEMBER 2007 I WALNECK’S CLASSIC CYCLE TRADER® http://WALNECKS.COM

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Walneck's Classic Cycle Trader - November 2007 Contents American Tip of the Month by Mike Brown The Buzz by Buzz Walneck Harley-Davidson XLX-61 Sportster True Motorcycle Related Conversations Antique/Classic Motorcycle Club Need for Speed-Quiz by Dave Hull Newspaper Headlines You’ll Never See Bench Racing by Mark Zimmerman Barber Vintage Festival Preview Calendar of Events British Triumph T100 - 498 c.c. o.h.v Loved to Pieces European BMW R65 Japanese Honda CL-450 Biker of the Month by Mike Brown VMD Auction Result w/Ratings Competition Motorbikes & Scooters How to Place a Word Ad How to Place a Photo Ad Area Code Directory How to Subscribe Let Us Help With Your Event

Walneck's Classic Cycle Trader - November 2007

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