An unhappy cylinder?

[Corndog]

Hi all,

I have a bit of a franken-bike that is not running quite as well as I would expect. I got the bike a few months back from my dad, as he had two. This bike had a hydrolock on the #6 cylinder which bent the con-rod, so a new engine was bought out of Florida.

Ever since the new (to me) engine was put in, it was a little lopey sounding, and didn't seem to have quite the same jam as I was expecting. It wasn't until I rode my dads valk when I really noticed it. Smoother from the start and a overall smoother idle (the idle jumps around a bit as it sits now, sometimes you get some burbling)

As the bike sits now:
- K&N (no prefilter)
- Cobra 6to6 w/ baffles
- 38 pilots/107.5 mains/ 1.5 turn on the mixture
- ECT mod
- Compression @ 165-175 on all 6
- New plugs (gap checked)
- Spark on all 6 (not as strong as I'd expect to see, but all 6 seem to have the same intensity)
- Carbs sync'd

I have pulled and cleaned the carbs 3 times (the last time soaking the orifices with carb cleaner and blowing them out numerous times). Cleaned everywhere where I could. It seems the problem cylinder is the #4. When the bike is at operating temp, I sprayed the headers with some water. All but #4 fizzed off immediately, while #4 had a slower evaporation rate. Also, when riding, I pulled the left side plug leads one by one. #2 and #6 let out a bang when I reconnected the leads, but #4 did not. At idle, it is variable when sometimes the rpm will drop when you pull #4.

I'm getting a bit frustrated with this, anything else I can try to narrow this down?

Attached is a pic of the plugs in order (top left is #2).

[Michvalk]

Looks to me like you need to balance the carbs. A good sync will do wonders

[Corndog]

Looks to me like you need to balance the carbs. A good sync will do wonders

Sync was done on Saturday. No noticeable change 

[longrider]

Throw a new plug into 4.  A few years back I changed out a set and had similar symptoms.  One of the new ones was bad   Would fire a bit here and there but was no good

[Pete]

#4 sure looks rich or fouled.

[longrider]

I agree. Looks to me like it's not firing correctly.  I'll bet a new plug solves your problem. Cheap easy fix

[indybobm]

Could #4 plug wire be bad?

[Blackduck]

How were the float levels? Particularly #4.
Would have thought any plug wire/resistance problem would also show up on #3
Could try closing the mixture screw on that cylinder.

[Corndog]

Plugs are new. Less than a week old. i never noticed the float levels. I didn't think they were adjustable on these. All the float valves looked in good shape and the little springs were all good. Could you compare the volume of fuel drained from each float bowl?

[john]

ANY CRAP IN THE TANK ... RUST ECT.                    ???

[pancho]

Notice the electrode tips on all the plugs in the left bank compared to the ones from the right. I would check the float valves  (AGAIN) to see if the springs are shot. Possibly too much fuel in the bowls on the left from years of being on the side stand and float valve spring degradation? You can check the float height (although not adjustable) and the springs when the carbs are on the bench.

[h13man]

Definitely a issue on #4. Trade the plug with another next to it and see what happens. Also you can check the OHM's of that plug. Should be 5000k new. 10,000 mi. plug 3500k.

[Corndog]

Definitely a issue on #4. Trade the plug with another next to it and see what happens. Also you can check the OHM's of that plug. Should be 5000k new. 10,000 mi. plug 3500k.

I'll check when I get home. However, the old plug from #4 looked the same. A quick test is good peace of mind though!

Notice the electrode tips on all the plugs in the left bank compared to the ones from the right. I would check the float valves  (AGAIN) to see if the springs are shot. Possibly too much fuel in the bowls on the left from years of being on the side stand and float valve spring degradation? You can check the float height (although not adjustable) and the springs when the carbs are on the bench.

Sounds fair. I just ordered a new set of float valves just in case. Even if its not the issue, I like to collect spares.

ANY CRAP IN THE TANK ... RUST ECT.                    ???

Nice and clean.

[pancho]

Notice the electrode tips on all the plugs in the left bank compared to the ones from the right. I would check the float valves  (AGAIN) to see if the springs are shot. Possibly too much fuel in the bowls on the left from years of being on the side stand and float valve spring degradation? You can check the float height (although not adjustable) and the springs when the carbs are on the bench.

Sounds fair. I just ordered a new set of float valves just in case. Even if its not the issue, I like to collect spares.


WHile waiting on them, you could close off the pilot screw some on #4 like Blackduck suggested, just to see if that clears up the plug a bit.

[Corndog]

WHile waiting on them, you could close off the pilot screw some on #4 like Blackduck suggested, just to see if that clears up the plug a bit.

I'm going to be a pro at pulling these carbs in no time!  I'm a little cautious about backing out the mixture any more. Judging by what others have their carbs set at with similar setups to mine, 1.5 turns out is already pretty lean.

I might through the carb bank from my dad's valk in mine and see if that solves it. His is set up very similar (he has the same setup with cobra's and k&n).

[Lyle Laun]

Have you considered that you may have a poor coil pack or plug wire ?

Lyle

[Ricky-D]

I don't see where you mention that you did a compression test.

You don't even have any prior knowledge of the engine condition, and still don't.

Seems silly to me to sink all that effort into the engine blindly without know if it is  good engine, or not.

***

[The emperor has no clothes]

I don't see where you mention that you did a compression test.

You don't even have any prior knowledge of the engine condition, and still don't.

Seems silly to me to sink all that effort into the engine blindly without know if it is  good engine, or not.

***

He said all six were 165-175.

[indybobm]

Like i said earlier, it could be a bad #4 plug wire. Very easy to swap between cylinders. A lot easier than pulling the carbs.

[Corndog]

I'll try swapping plug wires tonight. I doubted the coil because #3 looks and runs fine.

Last night laying in bed I was thinking about the bike (not in that way) and what about valve clearances? So when the new engine went in (it's a '97 49 state engine, judging by the codes), we put on the heads from the original engine ('00 Cali). This was simply a decision based on mileage (50K on the 'new' mill and 18K on the cali). I've since learned about the R1 vs R2 cams. I'd like to swap the cams (or heads, whichever is easier) as some point, but I don't know if now is the best time 

[Corndog]

I've been dark for a while, but I finally got around to working on the bike.

This past weekend I pulled the carbs and went in with a plan. I stripped all components off and separated them by carb#. I ultrasonic cleaned the carbs (1 bank at a time) in a 80C mixture of water and simple green. A LOT of crap came off these carbs that looked pretty good going in.

In addition to the ultrasonic cleaning, I swapped some components with carb #4 as such:
Coil 1&2 <-> Coil 3&4
HT Lead #6 <-> HT Lead #4
Float #1 <-> Float #4
Pilot Jet #2 <-> Pilot Jet #4
Main Jet #3 <-> Main Jet #4
Diaphram #5 <-> Diaphram #4 (with needles)

I also replaced the plugs on the left bank.

After a 30 minute ride this morning (which didn't seem any better than before), I pulled the plugs. All of the right bank looked as they did before. The left bank looked brand new, except for the problem cylinder that appeared black and sooty (not wet though). Evidently the carb clean or the component swapping affected the issue.

http://imgur.com/a/lMPnL

I'm running out of ideas.

Again, the carbs were sync'd and each cylinder has good comp.

[Ricky-D]

Ok, since everything checks out and you have good compression I think (since #4 shows so much richness) the problem could lie with the slide not raising properly resulting in extra gasoline being sucked in the cylinder through the low speed circuit. You should insure the slide raises easily enough (do it by hand) and even trade out the slides with another cylinder. Insure the sealing with the slide tower is good and the diaphragm is completely seated and has no holes.

***

[Corndog]

Good thought. The diaphragm was swapped with the slide, so I don't suspect it is that component, but maybe it could be the track it slides in the carb. Fortunately that does not require another carb pull! All the seating structures look in good shape too.

[John Schmidt]

To me, the right bank appears too lean, especially #1 & 3. The rest are also a bit lean but not as bad, and if #4 is sooty but not wet, then it's rich. Use the suggestion re. the slide, but might also look for air/vacuum leaks. The plug tips need to be a nice tan color.

[Firefighter]

Is the exhaust open, will not run if exhaust is stopped up.

[DK]

WHile waiting on them, you could close off the pilot screw some on #4 like Blackduck suggested, just to see if that clears up the plug a bit.

I'm going to be a pro at pulling these carbs in no time!  I'm a little cautious about backing out the mixture any more. Judging by what others have their carbs set at with similar setups to mine, 1.5 turns out is already pretty lean.

I might through the carb bank from my dad's valk in mmixture?

ine and see if that solves it. His is set up very similar (he has the same setup with cobra's and k&n).

Am I properly reading this post to be saying backing out (opening) the pilot screws leans the mixture?

[BonS]

I would take a very close look at your fuel enrichener linkage (choke). I have fixed a case where the linkage had been slightly bent and the linkage was not free to completely release an enrichener (or two). Also, the choke linkage return spring could be installed incorrectly and not providing enough spring return force to fully release an enrichener.

Simply remove the chrome rail covers, apply and release the choke and then gently press in each fuel enrichener brass tip to see if it moves in at all. If you feel any movement you've found the problem.

On the bike where I ran into this the owner had removed the carbs and I'm sure he had hit the corner of the linkage just above cylinder #2. The slight bend put a hitch in the linkage and the return spring couldn't overcome the friction. A slight adjustment with needle nose pliers straightened out the linkage and his fouling stopped.

Good luck.  

[Corndog]

To me, the right bank appears too lean, especially #1 & 3. The rest are also a bit lean but not as bad, and if #4 is sooty but not wet, then it's rich. Use the suggestion re. the slide, but might also look for air/vacuum leaks. The plug tips need to be a nice tan color.

Yeah it seemed to me the insulators were a little whiter than I'd expect. I chalked it up to newer plugs.

Am I properly reading this post to be saying backing out (opening) the pilot screws leans the mixture?

I was under the impression these are fuel mixture, so backing them out = richer. I may have this totally backwards though!

Is the exhaust open, will not run if exhaust is stopped up.

I hope no mouse has died and plugged it up  .  cobra 6-6 with baffles installed. Looking up the pipes show no blockage.

I would take a very close look at your fuel enrichener linkage (choke). I have fixed a case where the linkage had been slightly bent and the linkage was not free to completely release an enrichener (or two). Also, the choke linkage return spring could be installed incorrectly and not providing enough spring return force to fully release an enrichener.

Simply remove the chrome rail covers, apply and release the choke and then gently press in each fuel enrichener brass tip to see if it moves in at all. If you feel any movement you've found the problem.

On the bike where I ran into this the owner had removed the carbs and I'm sure he had hit the corner of the linkage just above cylinder #2. The slight bend put a hitch in the linkage and the return spring couldn't overcome the friction. A slight adjustment with needle nose pliers straightened out the linkage and his fouling stopped.

Good thought. I have always noticed the enricher on this bike is a bit stiff. I always just chalked it up to needing to lube the cable. On the bench the plungers all move freely and close completely, but maybe its hanging up.

[BonS]

The enrichener always feels stiff at the handlebar control. But it should slide closed with authority when the enrichener slide bar is actuated directly by hand.

[Corndog]

There is no hanging up at all when adjusting at the enricher bar. They all open and close fully.

Back to the mixture, do these bikes have a fuel or air mixture? I.e., does backing the screw out enrichen or lean the mixture? I guess I am used to fuel screws, where back out = rich, but maybe that's not the case here?

[DK]

WHile waiting on them, you could close off the pilot screw some on #4 like Blackduck suggested, just to see if that clears up the plug a bit.

I'm going to be a pro at pulling these carbs in no time!  I'm a little cautious about backing out the mixture any more. Judging by what others have their carbs set at with similar setups to mine, 1.5 turns out is already pretty lean.

I might through the carb bank from my dad's valk in mmixture?

ine and see if that solves it. His is set up very similar (he has the same setup with cobra's and k&n).

Am I properly reading this post to be saying backing out (opening) the pilot screws leans the mixture?

Also my question.

[Roidfingers]

Backing out, enriches the mix. ie more fuel. Turning in makes it leaner. Less fuel.

[BonS]

As others have said. Out = more fuel. There are two kinds of carburetor mixture screw designs. Some are air bleed others are fuel. Ours is fuel. Air bleed are the opposite as they bleed in more air as they are backed out.

[Ramie]

Sounds like you could use a manual.

http://www.valkyrieriders.com/ShopTalk/ValkMaintManAcrobatPDF.pdf

[Ricky-D]

The low speed idle mixture screw to which you refer has very little influence when considering your problem. The size of the idle jet would have much more influence when discussing richness problems. If the jet is stock the screw setting is inconsequential to your problem.

***

[Corndog]

Thanks for the info.

Jets are 38/105 with stock needles.

[Blackduck]

Ricky do you really have any idea on how carbs work?
If you have the mixtures screws too far out it can be too rich to even idle and just what colour do you think the plugs will be?
Those screws have more influence than you think

[Ricky-D]

Naw, you're still existing in the extinct and old automotive frame of reference. He says the screws are 1-1/2 turns out and so any turning, more or less will have no affect. For your edification, the Valkyrie carburetor has four (low speed) apertures to which the screw only impinges one aperture, that being the furthermost downstream aperture. Which means, so you understand, the availability of adjustment is with only 25% of the total low speed circuit. Having 38 low speed jets and 105 main jets have a much greater influence since they are larger than OEM.

***

[Blackduck]

MMMM so turning the screws out to the 2 1/2 point as per roughly standard setting for primary jets will have no effect?
Why do you think they are in at 1 1/2?
Simple, with 38's it will be too rich to leave the screws at 2 1/2.
Sorry you can use all the fancy wording but it does not change the fact the you can over fuel at idle by winding the screws out.
The same as too far in will be too lean and both settings will give poor idle and have an effect up to low/mid range cruise.
I really don't care what you think but will not let you give out misleading information.

[Ricky-D]

You can say anything you want, but the fact remains that he (Corndog) has a problem with his number 4 carburetor, and turning the idle mixture screw will not solve his problem, regardless of what you say to the contrary.

***