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Carb jet kit question (SOLVED)

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PostAuthor: Xumi » Mon Apr 26, 2010 2:20 am

That's absolutely your prerogative, coalstoves, and I for one won't judge you for it.

But in fairness to the vendor in question:

I have used them before, and had no problems with them. They shipped on time, and the parts came in as they were supposed to, and have worked perfectly.

They charged exactly the correct amount to my credit card, and no issues with over or repeat or unknown charges (plus I have credit monitoring service, and no flags in the 6 months since I bought from them.

Also in their favor, is that their order page is SSL certified with a real cert provider (equifax)- I'm in the web development business, have helped businesses get SSL certified, and it's impossible to forge a verified SSL certificate.

Personally, I'll trade the cheap website for cheaper parts.

I have no favorites for vendors... I will go with any of them that will provide a good part at a good price, and ship it when they say they will.. At least for the order I placed with them, they met all 3 of those criteria.

Just my $.02 - Take it for what it's worth.

EDIT:

Correction - SSL certifications can be forged if someone has enough firepower to create an MD5 attack and some cash to buy some real SSL certs from older providers and attack them for several weeks to determine the CA key....- at least older ones that use MD5 encryption.

Equifax is Not one of the vulnerable, as they use SHA-2 encryption, which to date has not been cracked in the SSL market.

Sorry if I confused anyone.
1981 XV750 - Rescued garage queen, restoration in progress
1979 XS650 (Lady of the Lake) - Barn find, restored, sold
1995 VN1500 - Daily driver

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Re: Carb jet kit question / Update

PostAuthor: ghostdad » Mon Apr 26, 2010 7:34 pm

Ok, I used 3M liquid electrical stuff to seal up the vacuum leaks on the boot. I sprayed carb cleaner all around both boots and have no indication of any leak but it doesn't come down to idle very quickly and it is back firing through the exhaust. What has me confused is that back firing through the exhaust is usually a sign of a rich condition. Right? But the plugs are firing good and if anything may be a bit lean.
Also the way it slowly comes back to idle isn't that usually a sign of a vacuum leak? I will be ordering new boots but trying to get things in tune but these contradicting signs have me at a loss. Anyone have any suggestions?
1983 Virago XV920K - second generation starter system, MCV removed, second ground added.
1982 Virago XV920J - Seized motor parting out.
1997 BMW R1100RT - gone but not forgotten
1992 BMW K75RT - gone
1980 Honda 1100 Interstate - gone
1982 Yamaha Maxim 750 - gone

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PostAuthor: funkamongus » Mon Apr 26, 2010 7:52 pm

Well.. I would do a valve adustment, set my mix and do a sync on the carbs. Then, I would see where I was at. May be so out of sync that it sounds like a vac leak. we talked already about removal of you MCV right? Cap off the front two vac ports on the front carb holder. The rear carb holder has one port to the petcock, leave that.
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PostAuthor: slowpoke » Mon Apr 26, 2010 8:12 pm

Stupid question, but have you checked the routing of your throttle cable? It could be binding and causing the slow return to idle.
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Re: Carb jet kit question

PostAuthor: ghostdad » Mon Apr 26, 2010 8:13 pm

Yes Funk the MCV is removed the valves are adjusted. I was thinking about checking the synch but ran out of motivation tonight, I will try that tomorrow. I had the carbs synched before but maybe with the vacuum leaks i had maybe it is way off now.
1983 Virago XV920K - second generation starter system, MCV removed, second ground added.
1982 Virago XV920J - Seized motor parting out.
1997 BMW R1100RT - gone but not forgotten
1992 BMW K75RT - gone
1980 Honda 1100 Interstate - gone
1982 Yamaha Maxim 750 - gone

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PostAuthor: funkamongus » Mon Apr 26, 2010 8:25 pm

Could be. Could be the cable routing like Pokey says.. how is your breathing situation? The molded air lines going through the frame could be blown out, if you have a compressor, might have bugs in there,, there is a calm air inlet for each carb too, the little plastic elbow, check those for air flow, too.. I understand they can be cut open and the filter material replaced and glued back together. Make sure your mixture is good. Float level right. Air filter clean, make sure your battery is fully up to snuff, adding an additional ground wouldnt hurt, things get weird with a weird ground... Cant think of anything else, off the top of my head, that can act like a vac leak... Could be just like you said, you compensated for a vac leak with your sync settings,, now that you may have fixed the leak, the vac settings have changed..
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1982 Yamaha XV920J
1982 Maico Alpha 1 MC250
1982 Yamaha XZ550RJ Vision
1972 BMW R75/5 W/Toaster tank, I babysit

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If at first you dont succeed,, maybe skydiving isnt for you..
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Re: Carb jet kit question

PostAuthor: ghostdad » Mon Apr 26, 2010 9:40 pm

Ok, the throttle snaps back emidiatly, so that is not the issue, all the air tubes are clear and air flows freely, float level is set and fuel level is correct about 1 or 2 mm below the top of the bowl, air filter is good, battery is good, original ground is good but also added another ground and fastened it to the frame behind the battery box. So I think I have the basics covered, I will synch the carbs and try and adjust mixture tomorrow and see what I come up with. I'll keep you posted as to the results.
Thanks for all the suggestions and help..
1983 Virago XV920K - second generation starter system, MCV removed, second ground added.
1982 Virago XV920J - Seized motor parting out.
1997 BMW R1100RT - gone but not forgotten
1992 BMW K75RT - gone
1980 Honda 1100 Interstate - gone
1982 Yamaha Maxim 750 - gone

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PostAuthor: funkamongus » Mon Apr 26, 2010 9:48 pm

RIGHT ON!! Cant be too far away then! Let us know!
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Scott Parsons
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1982 Yamaha XV920J
1982 Maico Alpha 1 MC250
1982 Yamaha XZ550RJ Vision
1972 BMW R75/5 W/Toaster tank, I babysit

Pictures -http://picasaweb.google.com/funkamongus20?feat=email-
Videos -http://www.youtube.com/funkamongus20-

for pics and vids from above..
copy between the "-" signs, and paste it in your browser..

If at first you dont succeed,, maybe skydiving isnt for you..
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PostAuthor: Xumi » Mon Apr 26, 2010 11:52 pm

Sounds like you're on the road to getting it fixed, ghost.

And lean running can definitely cause backfires and hunting idle - two of the most common symptoms, in fact. Backfires could be caused by lean (especially on deceleration or through the carbs) or by rich conditions.
1981 XV750 - Rescued garage queen, restoration in progress
1979 XS650 (Lady of the Lake) - Barn find, restored, sold
1995 VN1500 - Daily driver

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Re: Carb jet kit question

PostAuthor: ghostdad » Wed Apr 28, 2010 2:21 pm

Ok here are the current symptoms, while letting the bike sit and idle to warm it up for synching the idle will suddenly start to climb and it won't come back down. It does it on it's own without even touching the throttle, if I shut off it will start right back up and idle good for a few minutes and start to rev on it's own again. I checked for vacuum leaks using carb cleaner and get no idication of said leak. The carb synch is very close at idle and is at dead zero at 3 to 4K rpm's. At idle the the front carb is pulling slightly harder than the rear, the idle stop screw is missing on the rear carb so as soon as get a new screw/bolt for it it will solve that issue.

When the bike is idling it pops through the exhaust but if I unplug the vacuum port on the rear cylinder the popping stops. It will still start to rev on it's own but without popping. I have the mixture screw turned into about 1/2 turn from soft seat with out any difference in how it runs.

Is there something I missed in the carb to allow extra fuel to bypass the idle curcuit and cause what appears to be a rich condition?
1983 Virago XV920K - second generation starter system, MCV removed, second ground added.
1982 Virago XV920J - Seized motor parting out.
1997 BMW R1100RT - gone but not forgotten
1992 BMW K75RT - gone
1980 Honda 1100 Interstate - gone
1982 Yamaha Maxim 750 - gone

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PostAuthor: Xumi » Wed Apr 28, 2010 2:36 pm

Definitely a Lean condition, unless you have a strong fuel smell from the exhaust... not rich. Floating/climbing idle is usually lean, and so is popping.

Most likely when you are pulling the vacuum line, you are killing that cylinder - the popping is most likely the only activity in that cylinder.

Put your idle/mix screws at 3 turns out from soft seat and see what happens.
1981 XV750 - Rescued garage queen, restoration in progress
1979 XS650 (Lady of the Lake) - Barn find, restored, sold
1995 VN1500 - Daily driver

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PostAuthor: grazingazer » Wed Apr 28, 2010 4:14 pm

check the o-rings on the pilot screws
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PostAuthor: funkamongus » Wed Apr 28, 2010 4:55 pm

and THAT is why GG is da man. I bet thats exactly what it is. I hope to know as much, one day, as he's forgotten. Right on, GG.
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1982 Yamaha XV920J
1982 Maico Alpha 1 MC250
1982 Yamaha XZ550RJ Vision
1972 BMW R75/5 W/Toaster tank, I babysit

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Re: Carb jet kit question

PostAuthor: ghostdad » Wed Apr 28, 2010 7:24 pm

Xumi - it is a rich condition and strong smell of gas in exhaust. The popping has got to be because of a rich condition and when I unplug the vacuum line on the rear cylinder it leans it out enough to run decent. If I pull the vacuum cap on the front cylinder it dies probably because it is then too lean.

GG - the o-rings are brand new along with the pilot screw, they came with jet kit I bought. I started out with them set at 2.5 turns from soft seat and have tighten the the pilot screw on the rear cylinder so now it about a half turn out from soft seat. I will check them tomorrow to verify but would be surprised if they are bad already.

I pulled and checked the plugs - front is fine, the rear plug is black but not wet. (it is firing consistently)
1983 Virago XV920K - second generation starter system, MCV removed, second ground added.
1982 Virago XV920J - Seized motor parting out.
1997 BMW R1100RT - gone but not forgotten
1992 BMW K75RT - gone
1980 Honda 1100 Interstate - gone
1982 Yamaha Maxim 750 - gone

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PostAuthor: funkamongus » Wed Apr 28, 2010 7:40 pm

Hmmmmm..... an enigma.....
lack of Air in??? air filter? calm air inlet?? intake manifolds?? hmm has anyone drilled the pilot jets? Air jets nice and clean inside the carbs?? Carb Diaphragm ok?
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Scott Parsons
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1982 Yamaha XV920J
1982 Maico Alpha 1 MC250
1982 Yamaha XZ550RJ Vision
1972 BMW R75/5 W/Toaster tank, I babysit

Pictures -http://picasaweb.google.com/funkamongus20?feat=email-
Videos -http://www.youtube.com/funkamongus20-

for pics and vids from above..
copy between the "-" signs, and paste it in your browser..

If at first you dont succeed,, maybe skydiving isnt for you..
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Re: Carb jet kit question

PostAuthor: ghostdad » Wed Apr 28, 2010 7:55 pm

air filter is good, air inlets are clean, all passenges in the carb are clean - sparayed out with carb cleaner and compressed air, the intake manifold would only lean out the mixture if they were bad not cause a rich condition.. Right?
As far as the pilot jets being drilled - I don't know. Is there anyway to tell?
1983 Virago XV920K - second generation starter system, MCV removed, second ground added.
1982 Virago XV920J - Seized motor parting out.
1997 BMW R1100RT - gone but not forgotten
1992 BMW K75RT - gone
1980 Honda 1100 Interstate - gone
1982 Yamaha Maxim 750 - gone

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PostAuthor: funkamongus » Wed Apr 28, 2010 8:14 pm

"Manifold..." unless something is plugging it up!!! HAHAHA Maybe a small cat or something stuck in your manifold!! Hmm. Did you check that it has the right jets and needles in the correct carb? (they are probably side specific) you installed your carb kits right?!?!
We'll get down to it,, it can only be so many things, right?!?!?!?
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1982 Yamaha XV920J
1982 Maico Alpha 1 MC250
1982 Yamaha XZ550RJ Vision
1972 BMW R75/5 W/Toaster tank, I babysit

Pictures -http://picasaweb.google.com/funkamongus20?feat=email-
Videos -http://www.youtube.com/funkamongus20-

for pics and vids from above..
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PostAuthor: funkamongus » Wed Apr 28, 2010 8:14 pm

checked your float level?
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Scott Parsons
South Lake Tahoe

1982 Yamaha XV920J
1982 Maico Alpha 1 MC250
1982 Yamaha XZ550RJ Vision
1972 BMW R75/5 W/Toaster tank, I babysit

Pictures -http://picasaweb.google.com/funkamongus20?feat=email-
Videos -http://www.youtube.com/funkamongus20-

for pics and vids from above..
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If at first you dont succeed,, maybe skydiving isnt for you..
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PostAuthor: grazingazer » Wed Apr 28, 2010 8:24 pm

i'm assuming that you're working with hitachi carbs and have set your float levels correctly and did not leave out the washer that goes around the main metering jet and checked the petcock vacuum line for the presence of gasoline...that might suggest that your trouble lies in having developed a weak spark [which can be caused by something as simple as a loose battery connection] why not stop pulling your hair and check for a hot blue or blue/white spark...lots of times spark issues immitate carburetor problems...so it's worth a look and it'll save you from becoming fixated...goes without saying make sure there's no fuel around when you test the spark
if you're asking for help please include the year and model of the bike in your signature
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PostAuthor: Xumi » Thu Apr 29, 2010 12:31 am

Ah - rich it is - sorry about that ... and if I'm covering things you've already tried - sorry there too, just want to make sure you've looked at all angles.

Four possibilities:

Too much fuel?
Too little air?
Not enough spark?
Fuel going through wrong path?

Too much fuel:
Check for drilled jets - look for drill scratches with magnifying glass, or with a set of hobby drill bits, finding the largest one that will fit down the hole, and the size of that bit.

Float height checked with clear tube = 1-2mm below carb/bowl flange.

Too Little air:
Have you tried with the air intake boots disconnected?

Fuel down wrong path:
Disconnect petcock vacuum lines, plug them (a screw will do), and put the petcock on prime. If problem is gone, then issue is with petcocks leaking fuel into vacuum line.

Choke circuit? If fuel is getting through there with choke off, will cause rich running.

Spark:
As GG said, visually inspect for bright blue or white spark when grounded against engine, make sure carbs are dry.
1981 XV750 - Rescued garage queen, restoration in progress
1979 XS650 (Lady of the Lake) - Barn find, restored, sold
1995 VN1500 - Daily driver

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