Valk not running right: Another ECT sensor question

[YoungValkFan]

Hello everyone,

Ive read incessantly about what kind of ignition timing problems are possible due to issues with the ECT sensor. I haven't found what im looking for so I'll ask here. Essentially, Im trying to figure out why my Valk runs like crap under 3k rpm and then beautifully above that.

Symptoms:
- Low on power below 3k, sounds like maybe its missing or something like that - generally sloppy and unrewarding and doesn't sound very healthy. But the moment it gets past 3k, everything gets much better.
- I get the intermittent temp light flashes all the time - it even comes on riding down the highway in 60 degree weather. However, teltru oil temp gauge never reads above 210-215.
- I get about 28 mpgs (not so gentle with the throttle, cruising between 70 and 90 doing pulls etc.)

Possible relevant info:
- Cobra 6 into 6 (Stock air filter, 38 slows and 100 mains w a couple of shims under the needles).
- Carbs are clean as a whistle! I've dismantled them allllll the way down - replaced jets, floats, float valves, the works. All passages clean, all clamps are tight. Carbs are synced with digisync and pilots were set using a gunson color-tune.
- Going to rebuild the petcock next. It does not hold a vacuum and maybe its causing a lean condition in the cylinder its hooked up to under lower vacuum conditions? Idk.
- Compression is good across the board.
- I once hooked the battery up backwards (yes, im that dumb  ). The main fuse blew but the bike seemed to be fine other than that.

However, I would like to start doing tests on the ignition system. The bike runs, so I doubt that it would be something like a completely faulty ICM. I may get a timing light to see what's going on.

Anyone have any other ideas as to what to investigate next?
I am somewhere between an intermediate and idiot mechanic. Any ideas appreciated! TIA

[Challenger]

Has this machine been "desmogged", are all rubber parts in good order and no vac leaks, are all air box to carb boots on correctly, has anybody modified the air box in any way?

[YoungValkFan]

Yes, I desmogged it. I believe those modifications are fine but I could check them. No modifications to the airbox. Everything is air tight - I even sealed between the airbox and runners.

[sandy]

With 38 low jets and a couple of shims under the needles, your bike is running WAY too rich. Return this to stock and set the pilot screws to 2 turns out. Make pilot adjustments from there.

[SCain]

It sounds like your pilot jets are clogged, I know you mentioned your carbs are clean and sync'd.
When you cleaned the carbs did you throw out the gas that was in the tank and start fresh?

Several years ago, this happened to me, I had just filled up and the bike ran like crap at low RPM's, I made the mistake of leaving the same gas in the tank after I went through the carbs.

Good luck.

[gordonv]

It does sound like classic slow jets clogged. Go read some longer posts, that people are sure they are clean, and re did it 3 times, in an ultrasonic bath, and then it worked fine.

How well does it idle? Did you do the carb cleaning yourself, and tested the passages with air to insure they are cleared?

I would start my classical easy way, buy some Berryman B12 from wally world, 1/2 a can in half a tank of fresh fuel, and drive it in town in high gear and low speeds (5th/30mph). Also I would choose the Chevron Techron fuel. After the one can, if no improvement, then it might need another cleaning in an ultrasonic bath.

I wonder if there is a way to figure out which carb(s) are the problem? Pull the plug wire, ground and run, and see if no improvement or worse????

[Bagger John - #3785]

How do the plugs look?

[dizzy]

Petcock problem would more likely show at higher rpm when you're using more fuel.  There's an off chance it's leaking fuel through the vacuum line that runs the petcock.  If that's the case, the left, most rear spark plug would look especially rich (source cylinder for the petcock).  Try allowing idle if possible and slowly apply fuel enrichener.  If it runs better, rpm picks up, it's lean and you likely have a slow circuit issue.  If it gets worse, either you're rich or have an ignition problem.  Don't overlook the spark plug resistor caps.  Check for evidence of arcing to the head.  A 'quick and dirty' way to identify which cylinder is dead is check head pipe temperature while warming up.  A good way to do this is with one of those laser temp readers...please don't use your fingers if you value your fingerprints.  Of course the dead cylinder will be alot colder.     

[Jims99]

Following. Any updates on your bikes condition? Is she breathing better? Did you figure out what she had? 

[YoungValkFan]

Hello again everyone - just an update.

I put the KnN filter back in and its running much, much, better. It has regained a lot of the missing power - especially down low. I also replaced the rubbers in the petcock and put new clips on all rubber parts related to carbs.

It is still very sloppy below 3k once the bike is warmed up. So it must be running rich still? Either that, or there is still something going on with my ignition timing as I previously thought. I tested the ignition system with a spark gap tool - per the climbers manual and everything checked out.

I still get a temp light on for no apparent reason. it comes on when the oil temps are still around 160-180. Then it will turn off again as they climb to their usual temperatures - I know the bike is not overheating.

This is why im thinking there may be something going on with the ignition timing. I suppose the last thing to do is rent a timing light and investigate timing with the bike warmed up.

Does anyone know a good way to test the ECT sensor/system? The clymers manual suggestion is too cumbersome.

TIA

[Jims99]

Temperature light is most likely the sensor. A lot of the early models were set up different and have the same issues. There’s an upgrade you can do to use the newer style sensor that’s fairly easy. I believe it’s in the shop talk section.  Lack of lower rpm power still sounds like carb adjustment.

[YoungValkFan]

Just an update for everyone.

I replaced the ECT sensor and it got rid of my problem. I learned a lot trying literally every single other avenue that it could possibly me. And in the end, it was the long shot that was the solution.

I'll test the old one and post the results.

The temp light still comes on when oil temps are ~180 - but I figured that's the faulty module between the sensor and the light.

A happy ending.