Need your help urgent!!!...

[wildweasel_pt]

Sorry to be so hasty guys but tomorrow im attending a bike show (i hope) and i run into a problem with my bike that is driving me mad. So the stories goes like this...
Before i assembled the tank (regular type on top) i started the bike and it run with no issues. Today i assembled everything up and tried to start her and she wasn't cooperating. Lots of farting and flames behind but no start with choke on or off (one or more cylinders were not burning due the pop and bang behind). I removed the rear spark plugs and noticed they were a bit wet, so i cleaned them up and checked for spark, both of them were sparking, the thing is that when i cranked the engine with both rear plugs out (#1 and #3) the engine started and was running on 2 front cylinders, that got me wondering. When i removed the rear plugs i removed the compression on rear cylinders so the 2 front ones were able to run the motor. The thing is if i have spark on rear cylinders and the plugs were wet what am i missing here? May the plugs be wet from previous successful starts? (don't think so). I even tried to switch the rear leads (they could be connected wrongly but with no success as well). Might it be the fuel not arriving properly to the rear cylinders. One thing i can assume, front cylinders are working, they did when i removed the rear plugs. So the exhaust bangs can only be from fuel coming from rear cylinder that was not burn right? Im confused. I need your help guys .Thanks in advance....

 

[donnelly317]

Use a infrared thermometer see if the rear headers are getting hott. If they are u know its running on all 4 then id start checking out carb/fuel delivery

 

[SpecOps13]

Use a infrared thermometer see if the rear headers are getting hott. If they are u know its running on all 4 then id start checking out carb/fuel delivery

I'm at a loss to add anything but I'll help keep the thread active. Someone here may have a fast answer if they've experienced the same thing....

Good Luck,
Dave in Florida

 

[wildweasel_pt]

I removed the tank, replaced the ignition unit and still doesn't start.
This one is a '92 with a single pickup. (the rear plugs have visible spark and the engine was running on front cylinders only when i removed rear plugs for checking)
Tomorrow i'll try to use different plugs. These are 9 grade so cooler than normal. I'll go fetch a grade 8 to see if i can get some result with new plugs. I hear a backdraft on carbs when i release the start and the bike stalls. she only runs while i have starter button pressed.

Thanks guys... I have tomorrow morning to sort this out... Any other comments are highly appreciated as well...

 

[donnelly317]

Try just the rear two see what that does.. also hold a finger over rear spark plug holes make sure u gots your self some compression back there!! Crank the engine with no plugs it it see if a bunch of fuel comes out of your rear holes.. sry I thought u got it tunning before that's why I said to check the temp

 

[ridinnoshiftin]

Sorry to be so hasty guys but tomorrow im attending a bike show (i hope) and i run into a problem with my bike that is driving me mad. So the stories goes like this...
Before i assembled the tank (regular type on top) i started the bike and it run with no issues. Today i assembled everything up and tried to start her and she wasn't cooperating. Lots of farting and flames behind but no start with choke on or off (one or more cylinders were not burning due the pop and bang behind). I removed the rear spark plugs and noticed they were a bit wet, so i cleaned them up and checked for spark, both of them were sparking, the thing is that when i cranked the engine with both rear plugs out (#1 and #3) the engine started and was running on 2 front cylinders, that got me wondering. When i removed the rear plugs i removed the compression on rear cylinders so the 2 front ones were able to run the motor. The thing is if i have spark on rear cylinders and the plugs were wet what am i missing here? May the plugs be wet from previous successful starts? (don't think so). I even tried to switch the rear leads (they could be connected wrongly but with no success as well). Might it be the fuel not arriving properly to the rear cylinders. One thing i can assume, front cylinders are working, they did when i removed the rear plugs. So the exhaust bangs can only be from fuel coming from rear cylinder that was not burn right? Im confused. I need your help guys .Thanks in advance....

Well here is what I would try. Try hooking up your test tank and see if it runs again with no issues. If it does, there is something with the Vmax gas tank that may be causing issues. I would even maybe first try taking off the fuel cap and see if it runs that way. If it does, you probably have a vent issue. Did you paint the outside of the tank? Your original set up allowed for gravity flow from the top mounted tank. It could be a bad fuel pump, but with the tank up high, enough fuel was passing to make it run well without a load. Go back to square one and isolate the issue. Also, drain your carbs and see if there is any crap in the bowls, especially the rear ones. Also take note on how much fuel comes out of each bowl. Does your fuel pump cycle properly when turning on your key? If it was running before with those plugs, I would leave them alone until you find the problem. Doing ten things at once you never know what the problem was or if it was fixed. Slower process doing one thing at a time, but you isolate the problem and are confident when you do the repair.

Todd

Todd

 

[donnelly317]

Good call ^

 

[wildweasel_pt]

Try just the rear two see what that does.. also hold a finger over rear spark plug holes make sure u gots your self some compression back there!! Crank the engine with no plugs it it see if a bunch of fuel comes out of your rear holes.. sry I thought u got it tunning before that's why I said to check the temp

I have fuel in all 4 carb bowls. I'll try to start it with rear cylinders only to see what comes up.

 

[wildweasel_pt]

Well here is what I would try. Try hooking up your test tank and see if it runs again with no issues. If it does, there is something with the Vmax gas tank that may be causing issues. I would even maybe first try taking off the fuel cap and see if it runs that way. If it does, you probably have a vent issue. Did you paint the outside of the tank? Your original set up allowed for gravity flow from the top mounted tank. It could be a bad fuel pump, but with the tank up high, enough fuel was passing to make it run well without a load. Go back to square one and isolate the issue. Also, drain your carbs and see if there is any crap in the bowls, especially the rear ones. Also take note on how much fuel comes out of each bowl. Does your fuel pump cycle properly when turning on your key? If it was running before with those plugs, I would leave them alone until you find the problem. Doing ten things at once you never know what the problem was or if it was fixed. Slower process doing one thing at a time, but you isolate the problem and are confident when you do the repair.

Todd

I have main tank removed since problem appeared. Im using a funnel hang up high connected straight to the carbs.
Fuel pump is clacking ok eventhough is not pumping fuel right now due not being connected to the carbs.
I think the fuel is getting to the carbs because i get rear pop and fire on exhaust, its just not being burn and im suspecting of the rear cylinders because the bike started well on only the front ones with rear plugs removed. The fact that the plugs were wet may have prevented the spark from being strong enough eventhough its there on both plugs (i've checked them against the frame and they do were sparking). I don't know why but when im cranking and i quit by releasing the starter button i get a back draft up through slider on carb 1, it kinda spits back just like its releasing pressure or similar. I've looked around the intakes and i checked everything is properly bolted so an air leak is improbable i guess... And again the bike already ran without me touching those parts...

 

[naughtyG]

Just a few things...

Are you using COPs or OEM coils/HT leads/plug caps?

If the latter maybe try unscrewing the rear plugs covers, cut 1/4" off the HT leads and rescrew - that gets rid of any HT lead oxydation

Have you checked your battery/cranking/charging voltage? Maybe try jump starting from the car battery, if it works you have a tension problem

Also try putting a little fuel straight into the plug holes and see if it helps starting, if it does maybe the fuel isn't coming properly from the carbs

 

[donnelly317]

Maybe a stuck intake valves? I don't know much about these bikes in particular but if u can get it going still might not be a bad idea to take of the rear valve cover to check out valves. (If u can do it on the bike) but that would be the last ditch effort. U shouldn't get any air backdrafting up threw carbs. Wish kyle or Sean would chimp in the seem to know this engine inside and out.

 

[wildweasel_pt]

Well its like they say if its simple why make it complicated?
I tried to start the bike with only the rear cylinders and removed front plugs. No luck and more important no exhaust pop and fire... So the problem were the rear plugs. I removed all four and the rear ones were greasy and the front ones were matt black. Im running rich. I replaced these touchy Iridium plugs by regular DPR8EA-9 and she fired on first attempt... Its like i said usually the simplest thing is causing the issue. What got me confused was the fact that the rear plugs were sparking outside but most likely were not sparking ENOUGH inside the cylinder with all the accumulated moisture... problem solved... Thanks for your help guys...

 

[06VMAXIMUS]

Glad to hear you got it sorted out!

 

[donnelly317]

Simple just plugs!!! Dam nice. Don't know what time it is over there but hope u make it to your show!!

 

[SpecOps13]

It's always the simplest thing that's the fix but the last thing we check.....:bang head::bang head::bang head: Big Congrats...:clapping:

 

[broook]

What got me confused was the fact that the rear plugs were sparking outside but most likely were not sparking ENOUGH inside the cylinder with all the accumulated moisture.

Just seen this thread and as I was reading down through it I was going to suggest that you take the front plugs that were working and try them in the rear. Many times when you can get a spark at the plug outside the cylinder you will not get a good enough spark under compression. :ummm:I had a CBX six that burned a drop of oil and I found that out on numerous occasions. Well you know now for next time. Good luck.

 

[wildweasel_pt]

Big shit!... LOL
I got this sorted. Got on the bike headed on my way. Did 10 miles and stopped on the shoulder because i got the temp a bit hotter than normal. Saw no leaks so decided to get on my way. Started the bike and 2 seconds after it she dies. Strange... tried again and it didn't even turn. WTF? Are you kidding me? Checked main fuse and that was fine. so went to check the other ones and had one burnt. If i remember well thats the one that feeds the coils. Called the tow truck and went to a friends house to get some help and keep me from kicking the shit out of her... We came to the conclusion that the RR was faulty. Had a reading of about one volt prior to main fuse, so something is fishy either with the RR or the stator. We disconnected the RR and started the bike running just on the battery and ran fine. Now i know i have a phishy problem. Why is that having lower output voltage on the RR will fry one of my fuses? did the RR short to the frame or something? Thats the only reason i find for blowing the fuse, the low volts reading may be a cause of that but in that case shouldn't the reading be zero due being grounded? I need to check stator and RR and the worst thing i might need to look for a short somewhere. I came back home using just the battery. One thing is strange though. When i was arriving home the very same fuse blew again and the RR was disconnected. Any idea guys? LOL... Im about to cry... I've been working on this bike since December aiming to go to this bike show but she gave me a big nay nay... All i got left is go there by car and drink some beers to forget about it. I need to start fiddling with the other bike to keep my mind away from this one... !sigh!...

 

[bazwell]

Oh, that sucks Fred.

I was thinking at first maybe the rear cylinders were rich and blowing out the spark. Spark plugs was easier than that!

With the R/R problem... just thinking out loud... maybe the rectifier is out and it's allowing AC through? The multimeter will give a false reading because it is set for DC. Doesn't explain the fuse, unless it fried a coil a little bit?

Smells like fish to me. :-(
You'll get it sorted easy now that you aren't going somewhere good. Bikes are women...

 

[wildweasel_pt]

I read it in AC as well and it showed the same value give or take. I need to go check the RR and stator trouble shoot threads and worse than that i need to go check for a short somewhere, what i find to be strange because i've insulated the wires pretty well with tape... The thing that is getting me off track is why is that the fuse is blowing? Thats the fuse that feeds the coils, so if i have a short in the coils how can the bike run when i disconnected the RR from the battery? Lots of fish here...

 

[naughtyG]

It really mostly sounds like an intermittent short, and those are bastards to find. Something could be wrong anywhere from the TCI feed to the coils.. Do you have spare coils or COPs to try? If that fuse keeps blowing refer to the electrical diagram in the service manual. You *should* be able to identify wires by their colors, and then test for shorts by using an ohmmeter connected to the frame on one end, and to the possible culprit wires on the other, and then wiggle whatever bit of harness you can get to and see if you get lucky..