Bike 'bogging down' when throttling on

**onearmedbandit** · 17th September 2010, 13:42

Originally Posted by imdying

Sounds like you might have originally had a kinked fuel line which you fixed when you refitted the tank.

No, all fuel lines were fine as I had checked them previously.

**imdying** · 18th September 2010, 11:27

Well taking nothing out of the tap can't have fixed it!

**onearmedbandit** · 18th September 2010, 11:34

Originally Posted by imdying

Well taking nothing out of the tap can't have fixed it!

Who said I took nothing out of it? All I said was I didn't sight anything. That does not mean there wasn't something, just maybe it was that small that it was easy to miss. All I know is that after weeks of checking everything, reassembling, test riding and with no result, it was finally resolved when I removed the petcock assembly, 'cleaned' it out and reassembled it. It never suffered from that problem again.

**imdying** · 18th September 2010, 11:42

I bloody hate it when that happens. Well more so now, back when I was a teenager I would've just been stoked it went at all

**onearmedbandit** · 18th September 2010, 11:45

Originally Posted by imdying

I bloody hate it when that happens. Well more so now, back when I was a teenager I would've just been stoked it went at all

I'm quite confident that was where the problem was, as others have experienced issues with the tap on this particular model being blocked easily. I replaced no parts, and checked everything else with no success.

**ducatilover** · 18th September 2010, 11:51

I've see problems with the diaphragm returning to the closed position before and I've heard of one or two "sticking" and blocking fuel flow. Mine was returning, it would start and run for a few minutes then die, would drain the carbs/fuel line and take years to start

**rustyrobot** · 18th September 2010, 21:08

Originally Posted by onearmedbandit

Have you reassembled it and test ridden it?

Well, tried that and no luck. Will take it all apart again tomorrow (was working this weekend) and have another look at everything as suggested by ducatilover, shadows and Jonno.

It's actually pretty inspiring to see that people get/got so much more out of their Spadas. If my bike was running like that it would be like having a new bike. Let's just hope it doesn't cost me as much as a new bike to get to that point.

Problem is that the Spada Service manual I have has hand-drawn black and white pictures so it's hard to tell from the pics what I am looking at sometimes. Also have to convert all of your jargon into total idiot-speak so I can understand what to work on

Had good motivation to get working on it this weekend, cycling to work and back 3 times in the windiest storm the Waikato has seen for a fair while certainly got me ready to get into it.

**ducatilover** · 18th September 2010, 22:50

Send me a PM if you need any further help mate, more than happy to try talk bikes =D

**ducatilover** · 18th September 2010, 22:56

Another quick thought, the airbox is made of three parts, top, middle and a steel base that screws to the carbs. The middle cracks where it screws to the steel as I mentioned before, but, there is two "trumpets" in the airbox, these can leak every now and then at the base.

**rustyrobot** · 21st September 2010, 17:18

Well, I tried everything suggested by all of you, plus two suggestions from Warr... 1) disconnecting the fuel line from the carbs and the vacuum line from the (whatever its called) and sucking on the vacuum line to test the vacuum action (on both 'res' and 'on') and 2) unscrewing the screw on the base of the carb float bowl and draining the gunk out of the carbs.

I found nothing at all conspicuously wrong, put all back together and... voila! It runs! Thanks everyone for your suggestions, one of them helped, and I know a whole lot more about the fuel system of my bike.

Now to tweak it so I get the same performance as other people's Spadas. Suggestions?

**barno** · 8th June 2011, 23:47

I'm having a similar problem with my 87 impulse. 95% of the time it's fine. Then sometimes when it's warm, at the lights, it just wants to die. If you accelerate off at low revs, it splutters like hell until you get up to about 4000 rpm then it roars off like a rocket. Bloody annoying as it doesn't do it all the time. So far the suggestions I've accumulated (Not sure if I can discount any at this stage because it happens sporadically as opposed to always):

Vacuum leak somewhere
Bike running a bit lean
Crap in carbs, fuel line
Fouled plugs?
Cooked coils?
A dodgy plug lead?

It's probably going to cost a bit to get the carbs and fuel line cleaned, with a new filter, as well as new plugs and lead / coil checking, wondering if folks have any suggestions which to get done first?

Apparently the coils were done a few thousand km ago, and it apparently has iridium plugs. No guarantee of course they're set to the right gap, but you might think if one was seriously off, the bike would always be spluttering....

**ducatilover** · 9th June 2011, 08:22

Set your fuel screws to the factory settings.
If it's below 4000rpm needle height and main jet shouldn't have to much effect.
Check for air leaks/blockages.

If it's spluttering it's too rich.
Lean is flat hollow sounding power.

Good luck mate.