SOHC.co.uk Forums > CB500/550

running on unleaded !!

(1/5) > >>

Johnwebley:

 I have recently been forgetting to add "lead substitute" to the fuel,

 and have got what appears to be sticky valve !!!

 as the motor get warm/hot,after cruising around 6K rpm for several miles ,the engine runs rough,noisy tappets,and feels like its on 3 only,

spitting in the carb,and spitting in exhaust.I still have 4 - 4 pipes,

after checking,setting tappets at 3th inlet/4th exhaust,and re-using Morris lead substitute again,the bike runs well again,

is it common?
if so,I hope you take notice,and use an additive as well,


John Webley

PS,I should say I have a '74 CB500/4. and the handbook does say it needs "some" lead in fuel

matthewmosse:
I got 180,000 miles from my 500/4 on it's original engine for the vast majority of it - the issue that got that motor pulled was jumping out of second and definitvely Not fuel related. The vast bulk was done on unleaded - simply because I have done all my biking in the unleaded era and Honda built the 500 and 550's top cope with unleaded and at the milages I was doing the cost of additive was going to add up. I will admitt I felt it ran a tiny bit better when visiting a garage that ran a 4star pump in Hereford where my mates lived ditto on the 'special' or super unleaded that you can buy and with my current commuter (Honda rebel 125) it runs better or so it seems on fuel from the independant / Texaco garage then when I fill up at Tesco - maybe Tesco run a higher ratio of bio fuel which is more likely to be an issue then unleaded. Maybe the tesco fuel is too horsey ;D ) I must say at this point my conclusions regarding Tesco fuel may be coincedence induced, but on a couple of occasions the bike has run underpowered after about 200 yards riding from filling up at Tesco, then run like a dog until 200 yards after filling up at my regular fuel stop.
I do like to run a bit of redex occasionally to clean the system out a bit - on my 500 I would do so if the floats started sticking causing overflow - roughly every 6 months - it would get a shot in the fuel tank and a bit neat into the petrol pipe after riding the last 200 yars or so with the tap off, then leave it to stand overnight. Far easyer then remving the carbs, and genrally always sorted a overflowing carb - other fix being to tap the offending carb bowl with a screwdriver I went many years without removing those carbs.

Bryanj:
No Honda since the late 60's needs leaded fuel, if you have a sticking valve without you have the start of a mechanical problem mate

Johnwebley:

--- Quote from: Bryanj on May 26, 2013, 04:50:14 PM ---No Honda since the late 60's needs leaded fuel, if you have a sticking valve without you have the start of a mechanical problem mate

--- End quote ---

OK,its runs well,got just over 52K miles,great starter,etc,

 what could be the issue ?

matthewmosse:
I'm wondering if a worn valve / stem / bent valve, might be masked by added lube from an additive? I had an engine built from used parts that had a suspected sticky valve - symptoms were a rattly noise once hot and ran rough, once hot and on checking the clearances it emerged that one valve was discoulored from excess heat. I pulled the engine out and intend to get the valve and guide fitted by someone competent and who has required kit.

Navigation

[0] Message Index

[#] Next page