Honda Firestorm problem

[KMD]

A friend of mine dropped his Honda Firestorm round for a service and just as he's leaving says something about a flat spot in the acceleration, probably carb balancing, would I look at it?

I'm no time served mechanic, just a reasonably competent home spanner-man, and I suspect those who do this kind of thing for a living will have picked up on the throw away comment as the potential for a can of worms So I start the service and notice on tickover the bike has palpitations. It fires for a while then misses a beat. This can be so bad it stalls.

Taking the plugs out, the rear cylinder shows a nice light brown tip, the front is black and heavily sooted up. My first thoughts are the choke plunger on the front card not returning, followed by diaphragm, then a blockage, with some 'expert' adjustments to the mixture an also ran.

I'd like to invite comments please, your thoughts would be welcome on what issues could be the cause of this.

Many thanks guys

 

[Cestria]

On a Firestorm the front cylinder plug lead etc etc gets covered in water and crap off the road. Eventually breaks down sufficiently to give the symptoms you describe. Try watching it in the dark to see if you can spot any arcing. It happend to a mates bike-quick fix was a good spray off with water repellant silicone type spray. Eventually had to replace the leads etc. Hope this helps. Good luck.

 

[KMD]

Thanks Cestria, I have a feeling there may be one or two problems with this bike that could take a bit of finding

 

[JH]

Hi

Not on a Firestorm, but I once had a devil of a job to trace a fault on a Suzuki, with fueling problems on one cylinder causing very eratic running as you describe.

In fact I had bought the bike cheap becuase of this apparent untraceable fault. Eventually, I found that the spring for the diaphragm on the vacum fuel tap had cracked, only slightly. But this was enough to allow fuel past the seal and therefore along the vacum pipe and directly into the cyclinder inlet where the vacum pipe was attached.

This caused the rich fueling on that one plug that had plagued the bike. It cost pence to fix but many hours to trace. Once done it ran like a dream and made me a healthy profit.

Might be worth checking.

JH