Spark plug cap resistance very high?

Christianncg

Christianncg

Joined
Jun 16, 2018
Messages
168
Location
Coolidge, Arizona
Bike
1991 Honda ST1100
Hello again.

My my this bike is strange. Every day I'm wrenching. Anyways, I've been trying to find out why my mileage has been so low (35mpg us) despite driving light like a grandma. Turns out I had a spark plug cap on cylinder numero 3 that was 145k to open ohms. That spark plug has been blacker then the rest. Go figure. Anywho I cleaned the inner cap and used a soldered covered screw between the cap and spring to negotiate a better connection. It works well, now with a slight tug of the throttle the bike holds speeds much much better.

My question is, should I resync? Any thing I should do now that it's been fixed. ? My idle sounds lumpier with the occational burble now that all 4 cylinders are firing. All pilots are 2.5 turns out. Runs pretty good, wot not really affected but slower pulls are more clean, less high rpm resistance. I was thinking that the pilots need individual adjusting but not too sure. Thanks. One of these days I'll pass down all of this info I'm getting.
 
What's your mileage and when were the carbs last rebuilt?
Everything does wear over time, synchronizing worn out carbs will do little lasting good.
 
just ride it, nothing to adjust.

However, given that you had fouling on cylinder #3, that also happens when the vacuum fuel shutoff valve develops a vacuum leak, as the #3 cylinder provides the vacuum to actuate the valve diaphragm. Raw fuel can leak past the vacuum diaphragm and into the #3 cylinder, which fouls the plug and decreases fuel economy. You generally have a strong fuel smell upon shutting the bike off though, especially if parked in a garage. Just one last thing to consider checking.
 
The carbs were rebuilt about 1k ago. Mileage 77k on bike, roughly 50k on motor. Vacuum valve removed by PO. Sync is about a week old. Just seems strange idle tone would fluctuate with a firing cylinder. Odd.
 
Welp another thread solved in an hour of riding. Synced anyways because I'm ocd. Idle is perfect now. Cruise is perfect too both low speed and high-speed cruising.

With all cylinders firing the idle went up. I had to turn it down a bit, probably pickling up the sync in the process, very slightly but just enough to bother me.

On the flip side I'm taking the misses to dinner tonight on the ST for my birthday. Should be peaches now.
 
ah, so you had previously synched it with the bad firing cylinder issue undetected, correct? In that case I change my answer to re-synch it like you did. My original answer assumed it had been synched last when all cylinders were firing properly.
 
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