Breaking-up/sputtering revisited

Wayne Beaver wayne at
Wed Sep 3 10:42:20 PDT 2008

Hi all,

I have a very slight update to the below. Still grateful to hear an ideas...

Here's what I've done so far: 

Cleaned carbs, replaced air filter, replaced plugs (the color on the old ones
was fine, maybe a bit on the gray side of tan, but looked normal to me...),
visually inspecting wiring, checked fuel filter, verified fuel line
routing/venting, visually inspected sure coil wires and spark plug leads,
verified that foam under tank was well glued, verified plug leads were well 
attached to plugs with drain hole poining correct way, verified against obvious,
exhaust leaks, verified ground wire firmly attached to rear of engine, verified
negative battery lead OK. 

Here are results of my latest test ride:

The first maybe mile was OK - accelerating
powerfully through three or four gears with no sputters, no probs. Then,
suddenly, the tach stuck at 8K and the engine started sputtering again - in
seemingly all gears, all rpm ranges. I  *hobbled* home with severe lack of power
and inability to make the bike move forward. The Tach stayed stuck unil I turned
bike off.

IIRC, the tach drives off a one coil, correct? So seems like problem is either
coil or upstream of coil? I had similar problem many years back with an early
80's Honda Interceptor, - where an ignitor only shorted when bike was hot, etc.,
at which time tach danced, pulses to fuel pump stopped and I was left stranded.
Wondering if this could be similar?

Unfortunately I don't have a peak voltage adapter for my voltmeter, and not sure
it would help anyway unless I could keep it attached while riding, after bike is
warmed up :-) Yes, I can start simple replacing all of the bits one-by-one, as
well, but just aksing again if anyone here has had similar experiences.


> Quoting Wayne Beaver <wayne at>:
> Did a track day at NJMP/Thunderbolt yesterday, which was great fun until the
> bike started acting up (which, unfortuantely, was mid-way through second
> session).
> The bike feels like it's missing in various parts of the RPM range, which
> changes slightly depending on which gear the bike is in. It often misses
> between 5 and 6k, then again between 8 and 9k. Won't climb above 7k in top 
> gear. Seems to run fine at idle and through rev range when parked. 
> Only slight blip between 5-6k in first gear.
> Has something similar happened before to anyone here? Any ideas where I
> should start?

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