Suzuki VZ800

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millerdog
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Suzuki VZ800

#1

Post by millerdog »

Hey y’all! I got a problem with a Suzuki VZ800. It recently holed a slide diaphragm, so I decided to do a complete rebuild. Turns out all the rubber was rotted on both carbs. I completely rebuilt both carbs, with OEM Suzuki parts. The problem I’m having now is, it will idle fine, and take throttle great while it’s standing still. If I run it down the road, it busts out bad at WOT. I suspected it might be coils, so considering they’re pretty cheap, I got new coils. The battery was 5 years old, so I got one of them too. Lol. Im still having the same issue. System is charging from 12.9 volts at idle, to 13.8 at around 2k rpm’s. I can’t figure this out to save my life! Hahaha. Bike ran fine till it holed the diaphragm. Carbs are synced. Any brains I could pick, would be much obliged.
1976 sorta stock GL 1000. 1997 VZ800 definitely not stock Suzuki Marauder. Ride em like you stole em!
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Re: Suzuki VZ800

#2

Post by millerdog »

I forgot to mention that after a run with it busting out and all, the front plug is fouled. A rich problem. I can’t figure out how the front carb could be getting too much fuel at WOT. Float levels are spot on on both carbs. Fuel runs to rear carb, and a fuel line runs from rear carb to front carb. It has a fuel pump.
1976 sorta stock GL 1000. 1997 VZ800 definitely not stock Suzuki Marauder. Ride em like you stole em!
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flyin900
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Re: Suzuki VZ800

#3

Post by flyin900 »

I would check the new replacement rubber slide diaphragm(s) to be sure they are both well seated in their respective grooves if they have that in their carb tops.

I had a similar issue with my GL1200 after a carb rebuild and the original diaphragms had shrunk slightly with age, they are not available for replacement from Honda. I found two diaphragms weren't seating well at the top carb area and leaking vacuum, so I used Hylomar sealant to seal the area.

The initial leak prior to discovery caused a real running issue once underway. No top end at all was the biggest issue with the diaphragm leak. The bike started and idled fine and was Ok on start off, yet down on power and it's usual pulling power once underway.

That's all I have. :-D
Current Bikes:

1966 CL77 - Honda 305cc - Dual purpose - "Gentleman's Scrambler" was a period moniker.
1967 CL175K0 - Low production number with #802 engine serial- winter 2019/2020 full restoration.
1972 CB350F - Baby Four with low mileage - Cosmetic refresh to the next level 2021/2022.
1978 CB550K - Very original bike with only 7499 Km. from new - light cleanup and refresh done.
1981 GL1100 - Standard model - Sept 2018 cosmetic refresh, nice original condition.
2 X 1983 CB1000 Custom - Both low mileage with full cosmetic restoration back to factory new.
1984 GL1200 - Standard model in showroom condition - two owner bike from new.
1984 CX650E - Restored summer 2017 - a rare Eurosport model - excellent one owner bike.
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millerdog
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Re: Suzuki VZ800

#4

Post by millerdog »

Thanks for the input 🙂👍🏼 It’s an issue only with the front carb. I’ve been in it twice now. Lol. I’m gonna do a stator test today. I’ve been reading everything I can on the subject, and it seems that my symptoms are spot on for a bad stator. I’m hoping not, but at this point, I’ve pretty much ruled out any gas flow issues. I’ll update after the test. Fingers crossed. Thanks again for the reply!
1976 sorta stock GL 1000. 1997 VZ800 definitely not stock Suzuki Marauder. Ride em like you stole em!
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Re: Suzuki VZ800

#5

Post by 05c50 »

I'm pretty familiar with the Suzuki 800 Vtwins and I'd be very surprised if your problem was related to the stator. I've had bikes with bad stators that ran fine, but the battery would go dead. Although the pickup is part of the stator, both cylinders should be affected if it was bad. Can you give a better discription of the problem? "it busts out bad at WOT."

......Paul
I prefer to ride my wing naked,thank you
My wife asked me "How many bikes does one man need?" My answer "Uhhh.just one more"
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millerdog
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Re: Suzuki VZ800

#6

Post by millerdog »

05c50 wrote: Sat May 07, 2022 8:44 am I'm pretty familiar with the Suzuki 800 Vtwins and I'd be very surprised if your problem was related to the stator. I've had bikes with bad stators that ran fine, but the battery would go dead. Although the pickup is part of the stator, both cylinders should be affected if it was bad. Can you give a better discription of the problem? "it busts out bad at WOT."

......Paul
It ran fine until one day I cranked it up preparing for a ride, and it started running bad. Bad enough to cancel the ride. Lol. I figured carb problems, and sure enough, the vacuum slides and coaster valves all had holes, or spots that were almost rotted through. Did a complete rebuild with all new factory parts, and now it will idle fine, and take gas great while just idling. When I take it out, it will run up through great at low throttle, but when I get on the throttle hard, it busts out and backfires real bad. Get back and check plugs, and the front is fouling. I checked everything twice. Lol. All the usual suspects. The rear is running perfectly. I checked spark at cranking speed, and both plugs seem a little weak to me. Like they have multiple little sparks, instead of one fat spark. It will run good at lower throttle. Just not wide open.
1976 sorta stock GL 1000. 1997 VZ800 definitely not stock Suzuki Marauder. Ride em like you stole em!
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05c50
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Re: Suzuki VZ800

#7

Post by 05c50 »

It's possible that the ignition is breaking down at high rpm, but if the battery is fully charged, I think you can eliminate the charging system. The amount of spark is controlled by the coils, The ignition pickup and ignition module signal the coils when to fire, not how much. You said that one plug is fouled, have you replaced the plugs? I've been burned (pun) more than once by a spark plug that was "good." I would concentrate on things related to the one cylinder that is fouling, carb, coil (replaced), wire, spark plug. I know that it can be very aggravating, I've been down that road before.

.....Paul
I prefer to ride my wing naked,thank you
My wife asked me "How many bikes does one man need?" My answer "Uhhh.just one more"
75 Goldwing
78 Goldwing
77 CB750a
77 CB550f
80 CB650c
05 Boule C50
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millerdog
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Re: Suzuki VZ800

#8

Post by millerdog »

05c50 wrote: Sat May 07, 2022 10:22 am It's possible that the ignition is breaking down at high rpm, but if the battery is fully charged, I think you can eliminate the charging system. The amount of spark is controlled by the coils, The ignition pickup and ignition module signal the coils when to fire, not how much. You said that one plug is fouled, have you replaced the plugs? I've been burned (pun) more than once by a spark plug that was "good." I would concentrate on things related to the one cylinder that is fouling, carb, coil (replaced), wire, spark plug. I know that it can be very aggravating, I've been down that road before.

.....Paul
Aggravating is putting it mildly. I replaced the coils. Popped two new plugs in. That was my last attempt. New plug wires too. I put an ohm meter on the caps, and they check out good. I could try swapping them I guess. I’m gonna test more today. Clean connectors and such. At this point in the fix, I’m running out of options.
1976 sorta stock GL 1000. 1997 VZ800 definitely not stock Suzuki Marauder. Ride em like you stole em!
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robin1731
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Re: Suzuki VZ800

#9

Post by robin1731 »

Are you sure you got all the vacumm lines back in place when you put when you put the carbs back on. I had one here one time that acted similar. They guy ended up not hooking one of the many lines up when he put the gas tank back on.
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millerdog
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Re: Suzuki VZ800

#10

Post by millerdog »

robin1731 wrote: Sat May 07, 2022 3:45 pm Are you sure you got all the vacumm lines back in place when you put when you put the carbs back on. I had one here one time that acted similar. They guy ended up not hooking one of the many lines up when he put the gas tank back on.

I’ve removed the PAIR valve. Vacuum ports have been blocked off. This bike has a stage 3 mod. I feel like it’s something simple. Something I’m missing. It ran very good. Until it didn’t. Lol. It’s been off the road for a couple years, but kept up. All of a sudden, it went bad. I took it out on the road every now and then. No issues. To be sure the carbs needed to be done, but now I’m thinking that wasn’t my main problem.
1976 sorta stock GL 1000. 1997 VZ800 definitely not stock Suzuki Marauder. Ride em like you stole em!
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Re: Suzuki VZ800

#11

Post by flyin900 »

anim-cheers1 So did you solve it or has that dog had to many Millers
Current Bikes:

1966 CL77 - Honda 305cc - Dual purpose - "Gentleman's Scrambler" was a period moniker.
1967 CL175K0 - Low production number with #802 engine serial- winter 2019/2020 full restoration.
1972 CB350F - Baby Four with low mileage - Cosmetic refresh to the next level 2021/2022.
1978 CB550K - Very original bike with only 7499 Km. from new - light cleanup and refresh done.
1981 GL1100 - Standard model - Sept 2018 cosmetic refresh, nice original condition.
2 X 1983 CB1000 Custom - Both low mileage with full cosmetic restoration back to factory new.
1984 GL1200 - Standard model in showroom condition - two owner bike from new.
1984 CX650E - Restored summer 2017 - a rare Eurosport model - excellent one owner bike.
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millerdog
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Re: Suzuki VZ800

#12

Post by millerdog »

flyin900 wrote: Fri May 13, 2022 8:11 am anim-cheers1 So did you solve it or has that dog had to many Millers
LOL. Not yet. The stator checks out good, as does the pulse coil. Cleaned all connections, although they weren’t even a little bit dirty. Put it all back together, and cranked it up. Put a voltmeter across the battery, and now I’m not charging. Shows battery voltage at idle, and drops down to around 8 volts at rpm’s. Back to the drawing board. 🙄
1976 sorta stock GL 1000. 1997 VZ800 definitely not stock Suzuki Marauder. Ride em like you stole em!
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millerdog
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Re: Suzuki VZ800

#13

Post by millerdog »

Seems like I read somewhere that these ignitions had to have at least 9 volts to operate properly. My thinking is that, if my battery isn’t charging, and running up the rpm’s draws the battery down to 8 volts, then that is probably my problem. I’ve also since downloaded a manual, and it says at least 75 volts across the stator leads. I can’t get any more than 60 now. At any rpm. I’m gonna try and investigate further next week. Have a new reg/rec on the way.
1976 sorta stock GL 1000. 1997 VZ800 definitely not stock Suzuki Marauder. Ride em like you stole em!
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