Author Topic: Throttle balance question  (Read 325 times)

Offline nwguy

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Throttle balance question
« on: February 15, 2026, 04:30:22 PM »
I'm on step 11 of Jeff B's "Late model Cal/EV FI Tuneup Procedure" with my 99' Bassa:

https://archive.guzzitech.com/EVTuneup-Jeff_B.html

It'll only run for about 30 seconds when I start the bike,  then sputters and dies and won't start again. The repeated start attempts have run my battery down so I'm having to recharge it between new attempts.

The bike was not warmed up before starting this at step 3. I adjusted the valves a few days ago. My TPS base and idle settings seem spot on even after briefly starting my bike. The high idle (choke) cable is adjusted so there's freeplay with the lever off, but it'll move the right side TB linkage when the lever is pulled. I've pulled the choke lever when trying to start it.

I've done this procedure a couple of times before, but only with the bike warmed up. I'm thinking this is probably the difference. Any suggestions?
« Last Edit: February 15, 2026, 04:46:38 PM by nwguy »
1999 Moto Guzzi Bassa, 06 Yamaha Morphous

Past: 2020 Husky Svartpilen, 08 Norge, 07 Burgman, 3 Buell Lightnings, 02 BMW R1150RS, 05 Ducati Multistrada, Kawasaki Concours, Kawasaki Vulcan 1500 Classic, 02 Honda ST110, Aprilia Falco, Suzuki VX800, Yamaha Radian, Suzuki TS185, Yamaha RD400

Offline Guzzidad

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Re: Throttle balance question
« Reply #1 on: February 15, 2026, 06:35:34 PM »
   Sounds to me like a failed electric petcock.

Offline guzzisteve

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Re: Throttle balance question
« Reply #2 on: February 15, 2026, 06:41:26 PM »
It is designed to give a bit of throttle (choke lever) when stone cold, that sends signal of richness to ecu. I didn't look at the steps or video, just saying how it works. For batteries I use a 12V35AH AGM U-1 Group They last 12 years, You can crank forever w/o fail My storage space has no lectrics, I let them sit 4-6mo at a time, they go all the time.

OK, now I looked-------- With the screws closed it won't want to idle SO you have to give it the gas to keep running till you get the airscrews open 1/2 to 3/4 open

**** Hope this works
« Last Edit: February 15, 2026, 06:47:21 PM by guzzisteve »
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Offline nwguy

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Re: Throttle balance question
« Reply #3 on: February 15, 2026, 06:56:14 PM »
Thanks Guzzi Steve. I'll try that after I replace my battery. Now with the charger light green, not orange, it won't turn the engine over.

I have a new manual, not electric petcock.
1999 Moto Guzzi Bassa, 06 Yamaha Morphous

Past: 2020 Husky Svartpilen, 08 Norge, 07 Burgman, 3 Buell Lightnings, 02 BMW R1150RS, 05 Ducati Multistrada, Kawasaki Concours, Kawasaki Vulcan 1500 Classic, 02 Honda ST110, Aprilia Falco, Suzuki VX800, Yamaha Radian, Suzuki TS185, Yamaha RD400

Offline guzzisteve

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Re: Throttle balance question
« Reply #4 on: February 15, 2026, 07:26:31 PM »
« Last Edit: February 15, 2026, 08:16:07 PM by guzzisteve »
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Offline Wayne Orwig

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Re: Throttle balance question
« Reply #5 on: February 16, 2026, 08:20:27 AM »
Do you smell fuel? (too rich) Maybe pull a plug and check.
Sounds like the TPS is set wrong. What are you setting it to? You do have a 15M ECU under the left side cover, right?
Are you hearing the fuel pump run as the motor cranks?
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Offline n3303j

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Re: Throttle balance question
« Reply #6 on: February 16, 2026, 09:01:19 AM »
That batt I use is for scooter in  the grocery store. $100 at Batteries+ Crank all day.

https://www.batteriesplus.com/productdetails/SLADC12=35J?storecode=652&source=google&medium=search&campaign=ecommppc&gad_source=1&gad_campaignid=23501381673
I'm surprised a deep cycle battery designed for electric vehicles is providing service in a Cold Cranking Amps application. I couldn't even find a CCA specification on that battery. Certainly is cheaper than Odyssey. What service life are you getting from this battery?
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Offline elrealistico

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Re: Throttle balance question
« Reply #7 on: February 16, 2026, 09:04:58 AM »
This is what I used to set mine---lotsa pictures---


https://www.bikeboy.org/tpssetting.html
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Offline nwguy

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Re: Throttle balance question
« Reply #8 on: February 16, 2026, 09:33:03 AM »
At this point I've pretty much memorized both Jeff B's and Brad the Bike Boy's guides on tune ups including valve adjustment, TPS setting and TB balancing.

I have the 15M ECU.

My baseline TPS setting is around 148-149 mV. For idling, with the left side TB stop screw in it's about 510 mV.

The fuel pump does come on when I turn the key. Hard to hear it going with the starter engaged and spinning the engine. I'll pay more attention to that next time.

guzzisteve: When you say "you have to give it the gas to keep running till you get the airscrews open". How would you do that with the TB linkage arm disconnected on the left side and the choke cable's stop screw backed out?

Mobility scooter battery, hmmm...
1999 Moto Guzzi Bassa, 06 Yamaha Morphous

Past: 2020 Husky Svartpilen, 08 Norge, 07 Burgman, 3 Buell Lightnings, 02 BMW R1150RS, 05 Ducati Multistrada, Kawasaki Concours, Kawasaki Vulcan 1500 Classic, 02 Honda ST110, Aprilia Falco, Suzuki VX800, Yamaha Radian, Suzuki TS185, Yamaha RD400

Offline guzzisteve

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Re: Throttle balance question
« Reply #9 on: February 16, 2026, 09:45:30 AM »
quite simple, you leave it put together till it's running, you do not need circlips. I have no circlips on mine for over 10yrs. I can tune anytime in 5min.
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Offline Tom H

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Re: Throttle balance question
« Reply #10 on: February 16, 2026, 10:13:06 AM »
I see the problem your having. When you go to start the bike, use your finger to manually open the non tps side TB just a bit, that should get it to start. Once it's running for a moment, use should be able to let go of it.

To be clear on the instructions. Once running you will be using the non tps throttle stop screw to balance. Then open the bleed screws for best idle and balance again using only the air bleeds only.

And with respect, the engine will idle with the air bleed screws screwed all the way in. Some bikes like one side closed and one maybe 1/4 turn open. Most seem to be about 1/2 turn out.

Tom
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Offline guzzisteve

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Re: Throttle balance question
« Reply #11 on: February 17, 2026, 03:36:44 PM »
Did you get this resolved?
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Offline nwguy

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Re: Throttle balance question
« Reply #12 on: February 19, 2026, 08:29:33 PM »
No. I bought and installed a new Odyssey battery. I re-baselined the TPS and the idle setting. Got it idling by slipping the left side TB linkage arm on the left TB and rolling on a bit of throttle. I thought I got the rest right, went for a test ride and it ran poorly. Came back and reinstalled the old TPS. Maybe my cleaning the new one with deoxit hurt it. Seemed to run better but I can't get it idling between 1000 and 1200 rpm and balanced. Still rides poorly. Turning the air bleeder screws in or out seems to have no effect. I tried them 1/2 turned out per instructions, and cleaned them last year with q-tips and denatured alcohol. Should they be blown out with compressed air?

I've done this procedure semi-successfully at least 3 times in the past, but had a high idle. That's why I thought I'd do a whole tune up over again, to fix that. Not sure if I'll be able to fix this, and am reaching my limit on how much time I want to spend on this. Somewhat devastating after everything I put into this bike since I bought it last April. Am pondering alternatives now for my XC trip in May.
1999 Moto Guzzi Bassa, 06 Yamaha Morphous

Past: 2020 Husky Svartpilen, 08 Norge, 07 Burgman, 3 Buell Lightnings, 02 BMW R1150RS, 05 Ducati Multistrada, Kawasaki Concours, Kawasaki Vulcan 1500 Classic, 02 Honda ST110, Aprilia Falco, Suzuki VX800, Yamaha Radian, Suzuki TS185, Yamaha RD400


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