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Honda Spada Smells like Petrol

Discussion in 'Technical and Troubleshooting Torque' started by jaguarfanster, Nov 16, 2011.

  1. Really would like some advice here or opinions

    My honda spada tends to burn fuel far too quickly, and smells like petrol on idling and acceleration....i.e. its running rich. Also the insides of the exhaust are black as coal. I took apart the carburetors cleaned them, and now I'm sure the problem does not lie here. Also the air filter is new, and the choke is not stuck.

    However the engine has a rattly, ticking noise from the cam chain. So, will a loose cam chain affect valve timings so much that fuel doesn't burn properly leaving the bike smelling like petrol? I'd really like to be sure of this before I open up the engine.

    Thanks a heap
  2. Doubt it's timing. I'm betting you've got a bit of crap under a float needle.

    Is it still clearing up at higher revs? If so it's pretty much certain.

    check your header pipe temperatures when it is running rough. Put your hand near each of them (not on it).

    You'll probably find one is much colder than the other. Confirms you are drowning one spark plug at low revs. Its only when the revs match the fuel flow that it clears up.

    Need to clean the bottom end of the carbies.

    Your fiddling in the other post suggest you should pull them and give them a good going over as well as a sync when you get them back on.
  3. Make sure that the choke is not sticking on and that the choke mechanism in the carbs is intact.

    I've had a choke stick due to corrosion, which was fairly obvious. However, I've also had one fail because the plunger in the carb lost an o-ring which I didn't know it had, causing me to spend a couple of solid days chasing a fault whose presence was obvious but whose cause was not.
  4. Well I completely cleaned out the carbies a few days ago. I took everything apart, as in the floats, the vacuum chambers, and the jets. Cleaned all of these parts with carb cleaner and checked the float mechanism. By check I mean I sent a bit of air through the fuel lines, whilst filling the carbs with carb cleaner. The air flow was restricted almost completely when the floats rose, and closed off the valve i.e. indicating the float mechanism was fine. Furthermore the carbs almost look brand new or well serviced by the previous owner, with no varnish, and a very distinct shine. The bike is over 20 years old....

    As for the choke, I think the cables must be too old or whatnot, hence it was sticking. So I removed the cable from the handgrip, bringing a bit of slack into the cable, and now it doesn't stick. However if i ever need choke I need to physically pull the cable from its attachment at the carb vacuum chambers. Bit of a hassle, but peace of mind it doesn't stick.

    By clearing up at higher revs do you mean does it burn fuel properly at higher revs? It smells petrolish at all ends of the rev spectrum, and my fuel consumption is dismal for the spada. I'm looking at around 15kms a litre maximum. These bikes were meant to do 50kms a litre at 50kmph.....normally people are talking around 20km/l to 25km/l. :(
  5. I'm referring to throttle response. A float needle not seating will fell like; Nothing, nothing, nothing, EVERTHING, as the revs rise.

    It won't idle properly either, but you fiddled with the idle, so that's not valid any more.

    If you've cleaned the bottom end and set the float height then this will fix this problem, if that is the problem. Next thing to do is sync the carbies.
  6. Yes that used to be case with the needle jet....I had accidentally not put back the spring and the symptoms were exactly as you described....it just doesnt seem like it is giving the fuel average it's meant to, and has way more petrol smell than my mates cbr250rr.....if I sync the carbs will this reduce the smell? And should I tighten the cam chain and re-check set valve timings before I do this? I remember reading somewhere that tuning carbs to a bad engine is not going to be effective
  7. thanks for your insight too btw ibast
  8. This is correct, but a sync is really just making sure the two carbies are responding the same to the throttle.

    It does make a big difference performance.

    I'd be still really suprised if the cam chain was causing any major problems. Once the carbies were right, I'd then be looking at plugs and leads.

    Checking tappet clearance won't hurt but is more of a noise and engine preservation thing than performance.