1987 Honda Hornet iffy

[Tick]

My hornet has recently been acting up, the idle is below 2k rpm. When pulling away, her engine sounds kinda rough (like 1 of the pistons not going/firing) and there's no power. It starts delivering and sounds normal around 6k rpm and up.

This doesn't happen all the time either, sometimes she starts nice and chipper, everything running fine for the day, then decides to get grouchy the next.

Have checked the sparks, they look alright. The air filter was replaced earlier this year and checked just in case, also looks alright (had to check with all this silt in the air).

Any suggestions?

[F5 Dave]

sparks outside the engine won't tell you if they spark in the engine, odd but true.

Start the bike from cold & check each pipe for heat back & forward & see if one or a pair just doesn't get hot noticably as quick. From there you may or may not progress that train of thought depending on the results. Plugs correct & replaced? All same colour? Plug caps measure for resistance?

Other areas may include crud blocking pilot jets esp if rusty tank.

[jasonu]

sparks outside the engine won't tell you if they spark in the engine, odd but true.

Start the bike from cold & check each pipe for heat back & forward & see if one or a pair just doesn't get hot noticably as quick. From there you may or may not progress that train of thought depending on the results. Plugs correct & replaced? All same colour? Plug caps measure for resistance?

Other areas may include crud blocking pilot jets esp if rusty tank.

Hey thanks Dave. My 599 intermittantly does similar things but not as severe as the OP's bike and only to 3k rpm.
I've done the eaisy stuff and now am dreading removing the carbs as it is going to be a prick I know it!
Wish it was a rotary induction motor...

[gijoe1313]

Do a spark plug change - my lil'ol'hornet had the same symptoms, bunged in some new iridiums and away laughing!

[jasonu]

Do a spark plug change - my lil'ol'hornet had the same symptoms, bunged in some new iridiums and away laughing!

Old plugs looked OK and were properly gapped. I followed your advice and hey presto no more missing and seams to run more smoothly. Thanks for the tip mate.

[gijoe1313]

Good to hear, I always prefer the easy fixes!

[Tick]

sparks outside the engine won't tell you if they spark in the engine, odd but true.

Start the bike from cold & check each pipe for heat back & forward & see if one or a pair just doesn't get hot noticably as quick. From there you may or may not progress that train of thought depending on the results. Plugs correct & replaced? All same colour? Plug caps measure for resistance?

Other areas may include crud blocking pilot jets esp if rusty tank.

Sparks = spark plugs
They were replaced quite recently, but yes, my first suspect was spark plugs fouling up.

There was a hole in my airbox tube. Cut the knackered end off and popped it back. Runs sweet as now, just a little stretched.. Is the tube meant to get greasy (with I think carbon grit buildup)

[F5 Dave]

Air box tube? Do you mean a vent from the cam bos or cases to the airbox? That will get some residue in it. Esp with any by-product condensation which will turn it clay colour, my old CBX550 used to produce quite a bit of that.