Author Topic: V7 bad hot restart  (Read 4689 times)

Offline rbond

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V7 bad hot restart
« on: March 23, 2015, 02:42:01 PM »
I have a 2012 V7C. Bought new last year (44 miles on it). Not too long after I did the 600 mile service, if I stopped it for about 29 minutes, it would start fine, rev fine, but not idle. Sometimes the high idle lever would speed it up or I would have to hold the throttle up, to keep it going. After almost a full minute, it would idle somewhat and slowly smooth out and pick up a little speed to it's proper idle speed. If I did not wait for it to smooth out, I could still drive away normally, from then on I could stop and it would idle fine. It seems like the oil is thinning out as it sits, then it needs to run a little bit to cool the oil so it will thicken (viscosity rise) in order to improve compression. I have not attempted to do a compression check, as my tester's 'o' ring would probably melt from engine heat.? I did change first service to Red Line 10w60, then next service, to Liqui Moly. Still acts the same. Also, cold start in the 60's, would idle fine, start it in the 70's would need the high idle lever on to keep it running. Colder weather would sometimes require high idle lever, sometimes holding throttle up was needed to keep it going until warmed up. It starts fine, runs fine, gets about 44 to 50 mpg consistently. Both plugs have a good color, valves were not tight when serviced. I am assuming some sensor is acting up, any thoughts?
2012 MG V7C
1976 Suzuki GT500A
1978 Suzuki GS400C (long gone)
1973 Suzuki TS 100K (first new bike)
1969 Honda S90 (very first bike)

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Re: V7 bad hot restart
« Reply #1 on: March 23, 2015, 02:55:52 PM »
It seems like the oil is thinning out as it sits, then it needs to run a little bit to cool the oil so it will thicken (viscosity rise) in order to improve compression.

I know next to nothing about that bike, but I don't think you're on the right track with your oil thinning/compression theory.
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Offline rbond

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Re: V7 bad hot restart
« Reply #2 on: March 23, 2015, 03:05:38 PM »
The oil thing was just a thought, I am leaning towards some sensor going bad. The dealer is about 100 miles from me, may have to ride down for mechanic to play with it...
2012 MG V7C
1976 Suzuki GT500A
1978 Suzuki GS400C (long gone)
1973 Suzuki TS 100K (first new bike)
1969 Honda S90 (very first bike)

Vasco DG

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Re: V7 bad hot restart
« Reply #3 on: March 23, 2015, 03:22:04 PM »
I have a 2012 V7C. Bought new last year (44 miles on it). Not too long after I did the 600 mile service, if I stopped it for about 29 minutes, it would start fine, rev fine, but not idle. Sometimes the high idle lever would speed it up or I would have to hold the throttle up, to keep it going. After almost a full minute, it would idle somewhat and slowly smooth out and pick up a little speed to it's proper idle speed. If I did not wait for it to smooth out, I could still drive away normally, from then on I could stop and it would idle fine. It seems like the oil is thinning out as it sits, then it needs to run a little bit to cool the oil so it will thicken (viscosity rise) in order to improve compression. I have not attempted to do a compression check, as my tester's 'o' ring would probably melt from engine heat.? I did change first service to Red Line 10w60, then next service, to Liqui Moly. Still acts the same. Also, cold start in the 60's, would idle fine, start it in the 70's would need the high idle lever on to keep it running. Colder weather would sometimes require high idle lever, sometimes holding throttle up was needed to keep it going until warmed up. It starts fine, runs fine, gets about 44 to 50 mpg consistently. Both plugs have a good color, valves were not tight when serviced. I am assuming some sensor is acting up, any thoughts?

What did you do at the first service?

Pete

Offline guzzisteve

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Re: V7 bad hot restart
« Reply #4 on: March 23, 2015, 03:29:20 PM »
Sounds like things need a reset w/diagnostics. Set TPS . Pour a can of injector cleaner in the tank also, all doesn't stay the same all the time. Specially w/dual throttle body models.
If you hook the bike up, it may tell you what's wrong. Well worth doing.
« Last Edit: March 23, 2015, 03:32:41 PM by guzzisteve »
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Offline sign216

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Re: V7 bad hot restart
« Reply #5 on: March 23, 2015, 06:44:25 PM »
I like the idea of checking the valves.   
Also, difficulty idling is a sign of an intake air leak, and this model often has a problem at the joint between the head and the metal intake manifold.   Check there w a carb cleaner spray to locate the leak.

Keep us posted,
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Online Kev m

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Re:
« Reply #6 on: March 23, 2015, 07:11:32 PM »
The OP was a little confusing.

But I was left wondering IF there is an actual problem. It almost sounds like the OP is worrying because on COLD starts (30 minutes should be time to cool below operating temps no?) the motor needs the fast idle lever to idle smoothly until it warms up.

Rbond, you also talk about holding the throttle open a little when cold. You do realize that's all the fast idle lever does (I.e. it holds the throttle linkage open slightly for a slightly faster/smoother idle when the motor is not fully at operating temp).
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Doppelgaenger

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Re: V7 bad hot restart
« Reply #7 on: March 24, 2015, 12:38:44 AM »
Could you be having a problem with the fast idle lever sticking or not working at all?

I spent years chasing a throttle that would stick open on my SV650, but only when hot. It turned out to be the radiator hose would get slightly longer when hot and hold the throttle open. Sometimes the weirdest problems have the simplest causes.

Otherwise, the intake leak sounds like a plausible cause and heat swells it shut.

Vasco DG

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Re:
« Reply #8 on: March 24, 2015, 06:26:27 AM »
The OP was a little confusing.

But I was left wondering IF there is an actual problem. It almost sounds like the OP is worrying because on COLD starts (30 minutes should be time to cool below operating temps no?) the motor needs the fast idle lever to idle smoothly until it warms up.

Rbond, you also talk about holding the throttle open a little when cold. You do realize that's all the fast idle lever does (I.e. it holds the throttle linkage open slightly for a slightly faster/smoother idle when the motor is not fully at operating temp).

Fairy-nuff, but there seemed to be an implication that there wasn't a problem prior to the self-administered 'First Service'. Hence the request to know what was actually done.

Pete

Online Kev m

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Re: Re:
« Reply #9 on: March 24, 2015, 07:54:05 AM »
Fairy-nuff, but there seemed to be an implication that there wasn't a problem prior to the self-administered 'First Service'. Hence the request to know what was actually done.

Pete
Yeah, I noted that too, that's why I'm wondering if.

Then again, 600 miles, that can go in a blink of an eye...
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Offline kevdog3019

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Re: V7 bad hot restart
« Reply #10 on: March 24, 2015, 09:05:50 AM »
Sounds pretty normal to have to use the fast idle lever at startup. If warmed up it shouldn't need it. Where does your idle sit when warm?  Should be about 1200rpm. If you are below 1100 you are too low. Won't take much to make it feel lousy, hence having to rev it at warm startups.
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Offline rbond

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Re: V7 bad hot restart
« Reply #11 on: March 24, 2015, 11:24:17 AM »
Have done two services so far. Changed engine oil, trans oil, and rear end oil. Both times valves were not tight, second time, only two actually had to be adjusted. As stated before, cold start when ambient temps are in the 60's, don't need high idle lever. Normal idle speed when warm is approx. 1200 rpm. When ambient temps are in the 70's,  need the high idle lever until it warms up, then turn it off. All that is not a problem, just seems backward. Problem is, go for a ride, somewhere, etc. and turn it off for about 20 minutes. Re-start engine and will not idle, wants to die unless either hold throttle up or sometimes the high idle lever. Not every time will the lever raise the idle. Run it for almost a minute then bike will idle normally. Engine will accelerate properly all the time and will otherwise run properly. When riding, stopping at lights, etc. engine idles at 1200 smoothly, kill engine for about 10 -15 minutes, bike will restart either normally or sometimes stumble a little then speeds up and smooths out in a very short time. Engine other wise runs normally, accelerates normally, runs smooth and gets consistently good mpg.
2012 MG V7C
1976 Suzuki GT500A
1978 Suzuki GS400C (long gone)
1973 Suzuki TS 100K (first new bike)
1969 Honda S90 (very first bike)

Online Triple Jim

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Re: V7 bad hot restart
« Reply #12 on: March 24, 2015, 11:38:51 AM »
Too rich on warm start maybe?  See if there's black smoke when the problem happens.
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Re: Re: V7 bad hot restart
« Reply #13 on: March 24, 2015, 11:58:25 AM »
Too rich on warm start maybe?  See if there's black smoke when the problem happens.
This could be it. Wonder what the tps is set to? Have the linkages been touched at all?
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Vasco DG

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Re: V7 bad hot restart
« Reply #14 on: March 24, 2015, 12:26:12 PM »
Have done two services so far. Changed engine oil, trans oil, and rear end oil. Both times valves were not tight, second time, only two actually had to be adjusted. As stated before, cold start when ambient temps are in the 60's, don't need high idle lever. Normal idle speed when warm is approx. 1200 rpm. When ambient temps are in the 70's,  need the high idle lever until it warms up, then turn it off. All that is not a problem, just seems backward. Problem is, go for a ride, somewhere, etc. and turn it off for about 20 minutes. Re-start engine and will not idle, wants to die unless either hold throttle up or sometimes the high idle lever. Not every time will the lever raise the idle. Run it for almost a minute then bike will idle normally. Engine will accelerate properly all the time and will otherwise run properly. When riding, stopping at lights, etc. engine idles at 1200 smoothly, kill engine for about 10 -15 minutes, bike will restart either normally or sometimes stumble a little then speeds up and smooths out in a very short time. Engine other wise runs normally, accelerates normally, runs smooth and gets consistently good mpg.

Not likely to be relevant to the issue at hand but did you re-torque the heads? It's just that if you missed that I wonder if you missed something else as well or perhaps altered something that shouldn't of been altered.

Pete

jennygirl

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Re:
« Reply #15 on: March 24, 2015, 12:45:06 PM »
I have the same exact issue on my '87 22re Toyota 4runner. Chasing that gremlin for 6 months now!

Best of luck figuring it out. Any aftermarket stuff to the intake/exhaust?

Offline flangeman_70

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Re: V7 bad hot restart
« Reply #16 on: March 24, 2015, 12:50:51 PM »
Has this model got a lambda/O2 sensor? If yes then it sounds like a heater issue. But I would expect a code/warning light.
Check you haven't pinched the loom or pulled a wire out the back of it when changing oils etc.

Good luck!
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Offline rbond

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Re: V7 bad hot restart
« Reply #17 on: March 24, 2015, 04:59:56 PM »
I have re-torqued the head bolts. Did it before and after. Will check wiring harness anywhere near the oil drain bolts. Bike is otherwise stock. It is a leftover 2012 model that was never sold until I came along.....
2012 MG V7C
1976 Suzuki GT500A
1978 Suzuki GS400C (long gone)
1973 Suzuki TS 100K (first new bike)
1969 Honda S90 (very first bike)

 


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