Getting an old bike back on the road (blog)

Hello everyone. I just got my bike and have been going through it to try getting it back in shape. Posted a hello thread here: http://www.xjbikes.com/Forums/viewtopic/t=36400.html . This will be my gas saver for getting to and from work (only about 20 there and back). Fired up after cranking long enough and took her for a 5 min ride and it sprayed oil all over the rear wheel almost making me wipe out already So I changed the oil and found about an extra quart and a half in there... really thin to. Must have had lots of gas in there, and was soooo black. After changing the oil it would only start cold and wouldn't run or start at all when it warmed up with the choke on or off...

Things finished:
replaced rear wheel and brake shoes (front wheel still looks great although it's date code shows it'f from 2003...)
cleaned and greased rear axle and bearings
adjusted chain
Cleaned grease off whole underside of bike

Things in process:
Shimming valves
Rebuilding carbs (parts received from Len already)

Things to do soon:
rebuild front brake caliper
rebuild/replace MC (Already bought SS lines from Len)
change fork seals (slight leak)
clean inside gas tank

Ok, so where I'm at now. I did a compression test and received the following numbers:
1=140psi 2=110psi 3=125psi 4=130psi
I read on here that I did the test wrong though, I only pulled one spark plug at a time. I'll pull all plugs next time.

So I pulled the valve cover and checked all the clearances and got the current installed pad numbers. I checked all pad numbers with digital calipers to make sure they were correct. I read the following:
Exhaust:__________________Intake:
1=0.004 (0.102mm) (Y270) 1=0.003 (0.076mm) (Y270)
2=0.005 (0.127mm) (Y275) 2=0.006 (0.152mm) (Y260)
3=0.005 (0.127mm) (Y275) 3=0.003 (0.076mm) (Y265)
4=0.003 (0.076mm) (Y275) 4=0.002 (0.051mm) (Y265)

After looking up the spec I found them all to be way out! So I got some shimming to do in this one after all. I figure I can swap 3 and get 4 more for the others. At least one is in spec, woohoo lol!

According to the service manual I need to replace the shims with the following:
Exhaust: Intake:
1=Y265 1=Y265
2=Y270 2=Good as is
3=Y270 3=Y260
4=Y265 4=Y255

Can someone smart please check my numbers? So I'll just be cleaning an finishing the carbs while I wait for the shims in the meantime. I just wanna cruise on this thing already! I just hope the valves and gas in the oil didn't ruin the motor already! I'll post some pics tonight.

 

Exhaust one will still be tight if you only go down one size shim. Better to go down two sizes.

I doubt you hurt anything as long as you didn't run it very long full of gas.

Wait until the valves are in spec and the carbs off and do another compression test. We should see an improvement in those numbers.

 

Did you figure out how the gas was getting in the tank? That's kind of important ...

Given how bad the oil was, you may want to add Some Seafoam to the oil, run it for a bit and then change the oil again in order to remove any built up crude. One of the many uses on the can label. They don't tell you to just run it for a short period and then change the oil again, but I wouldn't feel comfortable leaving it in there for longer in my bike. Run it to warm up the engine, let it sit. Do that two or three times then drain oil/replace filter - the filter will probably be choked with all the stuff that was "shaken" loose.

 

Someone on here told me not to put seafoam in my oil on this bike, one of this wizards if I remember right...

 

I wouldn't leave it in, but for a short period to clean it, I don't see why that would be a problem.

 

It might have been me...

Don't do it.

Just do a couple of "short" oil changes if you're worried about sludge. The best thing to flush the motor out with is hot motor oil.

All SeaFoam will do is dilute the oil which is not a good idea in a 30-year old plain bearing motor. That's already happened when gas got in there anyway; what the motor needs is nice clean oil.

 

See? Many different opinions and as we recall about opinions, they are like arse holes, everybody has (at least) one.

In this case, BigFritz is one-heck-of-a-lot more experienced and knowledgable than I ... but I have done it and would do it again if the bike warranted it. There were no indications of problems and ick that I could see (with a light) before was gone ...

Yes it will thin the oil, but for the length of time I leave it in there, getting the engine up to running temperature and holding it there for about 5 min, it shouldn't be a problem. I let it set for at least an hour to let everything drain to the bottom, then I drained it, changed the filter (again) and was ready to roll. (Of course, at the time I was going by a one time discussion here that said Rotella oil (Shell) was good for these bikes. I recently saw that we should only use 4T motorcycle oil and it should be 20W50.) I have only done it once, but the bike needed it as the oil that had been in there was pretty old.

I don't know the inside of these engines, but I know with cars there are some really tiny passages for the oil that can easily be stopped up and then cause major damage (small enough that the PTFE additives once touted are said to be able to clog them which is why they were pulled from the market for the most part). I wanted to make sure anything like that was cleared and removed.

 

"Seafoam is kind of a "miracle in a bottle". It can be used as a carb cleaner and fuel stabilizer. But it's not really all it's cracked up to be. If your carbs are gunked up this stuff won't do anything to clean them. If you are storing it for the winter, Sta-Bil is a much better product for treating the petrol. DO NOT USE IN OIL on a motorcycle. See clutch problems above [referring to my iffy frictino plates]." --tskaz, another wizard, responded to my questions about seafoam prior. Went and foud it. Not good for wet cluch, I guess.

As far as oil, after reading a great deal on these forums and checking haynes, the word on oil is: No synthetic (except one brand was 'different'--Mobil 1?--and acceptable), Most people should usde 20w40, 20w-50 is a lot easier to find and works, if you use it in pretty darn cold weather conditions (not relevant to most people) 10w30.

If you had old oil, change it a second time after 300-500 miles to flush the extra gunk it picked up. Change filter every other time normally according to haynes/Yamaha, but changing the oil filter with every oil change certainly won't hurt your engine.

 

SeaFoam is camp stove fuel; more "snake oil" than "miracle." Marketing miracle, maybe. Dump it in your gas tank all you want; leave it out of the sump.

"Short" oil changes are still the best way to clean out the motor; that way you can get it really hot and not hurt it.

And replace the filter with EVERY oil change; at $5 a pop it's cheap insurance.

 

Fitz is right here!
New filter every time! (NOT Fram)
No Seafoam in the oil.

One thing I DONT agree with is Seafoam being stove gas. I
t's not white gas!

While Seafoam won't fix neglect, I believe it is an ounce of prevention in the fall.
(just DON'T use it on dope!!!)

 

Fitz is right here!
New filter every time! (NOT Fram)
No Seafoam in the oil.

One thing I DONT agree with is Seafoam being stove gas. I
t's not white gas!

While Seafoam won't fix neglect, I believe it is an ounce of prevention in the fall.
(just DON'T use it on dope!!!)

 

Fitz is right here!
New filter every time! (NOT Fram)
No Seafoam in the oil.

One thing I DONT agree with is Seafoam being stove gas. I
t's not white gas!

While Seafoam won't fix neglect, I believe it is an ounce of prevention in the fall.
(just DON'T use it on dope!!!)

 

Sorry about the posts Snow.... Not sure how I did this but I'll be more careful.

 

Seafoam is a high percentage of Naptha - primary ingredient. To see exactly what is in there (and how much by percent) search for the MSDS on Seafoam. It was the only way I found any information. It would seem that one could easily reproduce it for a whole lot less using that information ... Of the different types of Naptha, I would guess that the one used by the makers of SeaFoam would be from the type(s) used as cleaning solvents, the light naptha which boils between 30 and 90 degrees C as opposed to the heavy naptha which boils between 90 and 200 degrees C.

Unfortunately, "naptha" in and of itself is not an exact item. There are many variants made out of different things:
From Wikipedia:

Naphtha is used primarily as feedstock for producing high octane gasoline (via the catalytic reforming process). It is also used in the bitumen mining industry as a diluent, the petrochemical industry for producing olefins in steam crackers, and the chemical industry for solvent (cleaning) applications. Common products made with it include lighter fluid, fuel for camp stoves, and some cleaning solvents.

Naphtha (play /ˈnæfθə/ or /ˈnæpθə/) normally refers to a number of flammable liquid mixtures of hydrocarbons, i.e., a component of natural gas condensate or a distillation product from petroleum, coal tar or peat boiling in a certain range and containing certain hydrocarbons. It is a broad term covering among the lightest and most volatile fractions of the liquid hydrocarbons in petroleum. Naphtha is a colorless to reddish-brown volatile aromatic liquid, very similar to gasoline.

In petroleum engineering, full range naphtha is defined as the fraction of hydrocarbons in petroleum boiling between 30 °C and 200 °C.[1] It consists of a complex mixture of hydrocarbon molecules generally having between 5 and 12 carbon atoms. It typically constitutes 15–30% of crude oil, by weight. Light naphtha is the fraction boiling between 30 °C and 90 °C and consists of molecules with 5–6 carbon atoms. Heavy naphtha boils between 90 °C and 200 °C and consists of molecules with 6–12 carbons.

 

Anywho... I tried to post some pics last night but I guess the forums weren't havin' it. I'll try again tonight. I got ahold of a shim pool on here and my shims are on the way. I have actually started assembly on the Carbs but I'm still waiting on some o-rings from Len. I ordered a brass fuel T and the o-rings on it were a little cracked up, possibly sitting (prebuilt) for to long? No hesitation Len shipped me some replacements so I'm waiting on those before I put the rack back together. Coming along quite nicely! Something I keep forgetting to do though, is look at my MC to see what type of sight glass it has. Once I do, I'll put another order into len for that and a MC rebuild.

 

I may have ran into a snag... I got the valves adjusted, all in spec except one exhaust valve is still .001 to tight. I'll get another shim for that soon but I wanted to do a compression test. I got only 20-30 psi across all 4 cylinders! What the crap happened? All I did was bring the valve shims into spec!

I have the carbs currently off the bike, this shouldn't have any effect on a compression test, correct? I'm really searching here. I got decent compression readings with the valve shims tight as hell like I listed in my first post... WTH?!

 

You may have changed your valve timing by accident, put 1&4 at TDC and check your marks, I bet you'll find you are 1 tooth off one way or the other. Make sure that the throttle is wide open when you do your test.

 

Ok, I'm headin home to check that now. I don't know how that could have possibly happened but it can't hurt to check... Just more wrenching. And how would holding the throttle open affect anything when the carbs are off the bike. Did you read my post?

 

I'd be more inclined to think your gauge has developed a problem.

Just bringing the valves into spec shouldn't have caused all 4 to suddenly lose compression. Especially all nice and evenly like that. Borrow a different gauge, and re-charge the battery.

 

Fitz has a good point that I had not even considered, but if a different gauge shows the same thing...

 

If that's the case then we need to know what else besides adjusting the valves happened since the first compression test.

 

I checked the valve timing and it's still spot on. I thought it was waay off at first but then after looking at the picture in the manual I noticed I was looking at the wrong dots! After finding the correct dots (on the cams themselves, not on the cam chain gears) it's spot on. (I pulled the cam chain adjuster in preparation for moving the timing, so at least that's cleaned up and adjusted now)

The only thing I did was remove the carbs, and adjusted the valve shims. Literally, that's it. Now it's turning over really slow even with the charger set to start 55A. I don't know if the battery is dead or not but I just pulled it off and put it on the charger and I'm trying to take out the battery box to clean up connections that are a bit corroded...

My friend is loaning me another compression tester tonight and I'll report back...

 

After going through wiring, getting the grounds spotless and clean and putting dielectric grease on them I figured I'd pull the battery off the charger and put it together again. I just compression tested them again and I got:
1=30 psi 2=0 psi 3=30 psi 4=60 psi

This sucks so bad! Any ideas on this? With timing on point I really have no other ideas

 

The only thing I can come up with is you may have weak springs or the guides or the shim buckets are causing the valves stick. I would also advise you to pull the cams so there is nothing obstructing access to the shims; pull the buckets out and inspect the bores for scuffing or scratching don't apply any lube until you have tested the valves this way you'll know if the valves were sticking in the guides, then try some penetrating oil or WD-40. The wrong type of oil may leave a residue inside the valve guides that might increase drag. One other thing comes to mind and that is the valve seals, if they have been exposed to harsh solvents or gasoline they may become gummy, this would be a bummer because you have to pull the springs to change them.

 

NO WD40 or anything else to attempt to lubricate the valves with. Bad idea. If the valves were "sticking in the guides" the shim clearances would be HUGE.

Do NOT take the cams and buckets out then reassemble without lubricating. Bad idea.

Bad valve stem seals won't produce low compression readings.

And these numbers are with the second compression gauge? Both gauges giving you the SAME readings?

Let's revisit the valve shims.

Are you using a metric feeler or an American feeler with "metric equivalents" on it?

Check your clearances again and post your findings. A zero reading means valves aren't closed or the piston has a hole in it, which I kinda doubt.

 

FITZ! did you even comprehend what I wrote? I did not tell the guy to re-assemble without lube. I did not say bad valve seals would give a low reading, what I said was if the seals were affected by gas or solvents that they could get gummy. Maybe I should space things out so you don't get confused. You also didn't even mention weak springs as a possible, all be it an improbable factor.

 

No I didn't get a second compression gauge yet, I ended up staying home. I just used my compression gauge on a car I had checked last month and got only 50 psi on the cylinder... So I'm guessing my gauge suddenly went bad?!

I remember doing something now... I accidentally put to much oil in cylinder 3 after I finished the first compression test before starting the valve shims. It was the lowest reading of the 4. My gauge went up to like 160 and oil was dripping out after I pulled it off... Will that ruin a gauge? Just a little oil?

 

Ok, I just went and got a new compression gauge and apparently that was the problem! I didn't want to admit to myself that the gauge was bad but I'm glad I tried a new one before I went on a ghost hunt. Thanks guys.

Well said sir, well said...

I am using a standard set of feeler gauges with metric equivalents. I tried to find real metric ones at a few places but no one has them. I looked on amazon to but all the metric ones didn't have the correct sizes. Like they went from size 0.10mm directly to 0.15mm... How are you supposed to get in spec with those?!

New compression numbers:
1=150psi 2=113psi 3=142psi 4=158psi

So, although that's a healthy jump up from what my compression numbers were with the valves running tight as I received the bike, cylinder number 2 still worries me a bit. Is that going to mess with my tuning efforts or can I run it like this this summer and tackle this winter or is it just to far off to even bother getting it to run correctly?

 

Well now you know how many things can affect compression. I think you should re-check #2, that is a big discrepancy and it will have a bad effect on the tuning of your engine.

 

Yeah, it's not changing. It's just low...

 

Have you wet tested cylinder 2 with this new gauge yet? What was the outcome?

You may think about doing a leak down test. It should at least tell you if it is a valve issue, ring issue or both. I wish I had done one (to be thorough).

 

No, I haven't done a wet test yet. I tried it once and oil got inside my gauge and broke it... Also, all the compression numbers obtained this far are with the engine cold. I know your supposed to warm it up first but the bike wasn't running yet. After I get my last shim in to pull one exhaust valve fully in spec I'll warm it up and check them all again...

A few pics, just finished the carbs. I took tons of pics, way to many to post lol

 

More. Just to give you an idea of how the spare rack of carbs I got off eBay looked...

 

Finished Job, awaiting the yics tool. Started up and ran but needs to be tuned... Is it weird that all of the float levels were spot on after assembly? What are the odds of that?!

I was buying a compressor from an older gentlemen last month and mentioned that I was going to be rebuilding the carbs on my new bike. He used to restore bikes and decided to give me the carb sync tool in the last pics. Score! At least he knows it'll be used. Just had to replace the super old hoses on it... When it did start they were all pretty close to each other already but I don't think that means anything since the yics isn't blocked (shrugs?).

Ohh, and the comments about old rubber on here... absolutely true! Most of the o-rings crumbled and the throttle shaft seals were literally like rocks! Thanks for hooking me up len!

 

Finally got my YICS tool from len and I was ready to start. I then had a starting issue, no matter how long I let the battery charge on "55A start" it still wouldn't turn over So I tested the battery and it was fine, I tested the amperage to. So I pulled the starter and saw the brushes were worn all the way to the end lol! So I ordered a rebuild kit of eBay. Well... that kit came tonight! After rebuilding and reinstalling the starter it turns over just fine, woo! So now I'm trying to tune it!

I have a 4 manometer (mercury), a YICS tool installed and temp gun. I fiddled with it tonight in the dark, and after syncing and messing with the idle screw it would finally idle down. For a long while it would't idle down after bliping the throttle, like it was staying at about 4k for about 8 minutes or so. It's seeming to behave better after a bit of adjustment though. I couldn't get it to read exactly the same on each cylinder on my gauge although I got it pretty close, how close should I be able to get them? Am I being to much of a perfectionist?

After running for a while I noticed that the temps were getting really hot. I measured 265 deg F on the head a few times. What temperature can these handle or run at? I noticed that the #4 cylinder was way cooler on the header than the rest so I pulled the spark plug and there was almost no gap! I must have dropped it or something, sooo careless! So I went through them all again. Now they are a lot closer to the same temperature, at least within 20 deg F of each other.

Well I'm going to try to get this done tomorrow after work, sunlight would really be helpful. Once I get the sync done how do I adjust the idle mixture correctly without a colortune plug? I really don't want to buy one. I also don't want to be running lean either though... I remember reading how to do it on plug chops but I can't find it now...

 

When syncing/tuning you need to put a good strong fan on the engine. Remember, it is an air cooled engine and running over idle without air movement is a bad thing. Heck, I wouldn't let it sit long in idle without a fan.

 

Ok, roger dodger! It was a cooler night with a slight breeze so I thought I might be alright but I'll try an dig up a fan today...

Anyone else able to answer any of my questions?

 

Tuning without a colortune:
http://xjbikes.com/Forums/viewtopic/t=3 ... uning.html
See Rick Massey's write up - 4th entry in the thread.

Please be more clear regarding the idle speeds:
What does it do when you first start it?
Choke on or off?
Is it still going to 4K and then coming down after several minutes? Sitting at 4K for 8 min without any cooling ... you are getting pretty close to cooking something ...

Does your manometer have any dampening features? Good ones will have some sort of restricter which makes the readings fluctuate a lot less. Sorry, I don't know numbers or what it should read.

 

Yeah, that's what I was looking for! Thanks!!

Well I did a lot of fiddling and got it running really well. I got a fan, and it was windier today so the temps stayed a lot more reasonable. After syncing the carbs once it was all warmed up and set the idle speed I gave Ricks procedure a try. It made perfect sense after reading it, and everything worked exactly as he said for the first carb only. When I moved onto the 2nd carb nothing happened no matter how far I adjusted the screw. So I started over a few times and it was the same every time. So I set them all to 3 1/4 turns until I get a color tune plug.

I took it around the block tonight and it purrs! Idles smoothly and is very behaved. But the battery still needs a jump to start it. I finally checked the voltage while running and it's barely charging at all... I'm going to order a new set of brushes for the alternator and hopefully that solves that...

But better than everything else, the oil isn't overfull and my rear tire didn't get covered in oil causing me to slide all over the road! Woo! I'm going to order a color tune tonight and make sure everything is set correctly before doing any major riding though.

Last week, in the middle of everything else, I re-did the front brakes. SS lines, caliper rebuild and new pads. So I finally got to seat the new pads in and they grip a whole lot better now, thankfully. I will bleed them again though as I suspect a bubble or two left...

Sorry if this is hard to read, I'm just kinda putting my thoughts down in a random order...

 

No, my sticks are old mercury vacuum sticks. They are kind of difficult to use, it seems that they are taking on water somehow so there's a slight bit of water riding ontop the mercury... No dampener or anything.

 

Ok, now that I got the engine seemingly running well enough I am tackling the dead battery issue. I bought a new battery yesterday and put it on a trickle charge overnight. Installed it and it started up a few times just fine. Checked the voltage, 12v idle and 13.8v at 3000 rpm. A little low yeah. I checked the alternator brushes and they are well within limits, the PO must have replaced them already. I took about a 10 mile ride and shut her down in the driveway all proud. Went to leave about 30 min later and it wouldn't start, argh! Battery is dead again, turns over really really slowly then just clicks. It push starts pretty easily actually but what gives? That's not actually a solution for me though...

What else could be bad? I was reading a lot of threads here about this and there are so many different problems I'm not sure which thread to follow. I'm going to go start looking at all the connections and cleaning them. Anything specific I should be looking for? It was a brand new battery this morning, fresh off the trickle charge and it's dead after a 10 mile ride?!

 

I dunno what's going on but I went out and it started right up, battery came back?! Ugh, anyhow, I rode it for about 30 miles today and the battery is failing to start the bike... I had to push start it a few more times... I'll just have to keep working on these electrical demons

On the bright side, I ordered a sweet helmet today! People keep looking at me weird because my only helmet is a dirt bike helmet lol!

 

Silly question, but have you replaced the fuse box? If you still have the original glass fuse box, ditch it ASAP for one that uses contemporary blade fuses. If you have the original, odds are good you have dirty/intermittent connections there which are part of your problems. A second good possibility is a short somewhere.

I started a post yesterday or the day before, about sych gauges. You can find a 4 bank set on eBay for about $75. Last year, I got the same set for $50, but I couldn't find them that low now. I believe the brand is EMCO, but I am not certain.

 

Some PO must have changed them to individual blade style fuses already. I'd like to re-do them anyway because the way they were put in takes up all the room under the seat...

Anyhow, the more miles I put on it the better it is starting to behave. I'm sure there are still dirty connectors somewhere but in the meantime, It's running pretty well. I let my younger brother try it and he weighs about 70 pounds less than me. He hates the way the whole bike looks, feels, and says it's low on power. When I ride it though, it feels lke the riding position is comfortable and has plenty of zip for me. I said it was quick not fast and if it was any faster I'd probabally hurt myself lol.

 

Dont put your battery on a 55 amp charger no more! Thats way too much for a small motorcycle battery. You'll blow/burn something up-just my .02 cents.

 

Also, 13.8V at 3k RPM is not good. You may have checked your brushes, but you need to troubleshoot your entire charging circuit. At 2k RPM, your charging system should be able to regulate to 14.5 +/-0.3 V.

"A little low" isn't cutting it, and that's why you can't start the bike 10 miles out (I've done the EXACT same thing). You'll end up cooking a new battery if you keep running it down like that, your whole bike is basically running off the battery. When you go to start, you zap what little juice is left, and you'll start sulfating the cells, and you'll end up needing a new one soon.

I've posted up a link in the past to charging system testing that goes step by step. Search for it.

 

Do yourself a favor: go to your local autoparts store and get a little extension cable they have for trailers. It is two wire and has a male/female connection on both ends. Cut it, wire one part to your battery and position it so that it sticks out from behind the side cover and then attach it to your frame (I used a zip tie). Then get a float charger with auto shutoff, wire the other end to the charger, and you now have a quick connection to trickle charge your battery on a routine basis, keeping it fully charged all the time.

Next, when you do have to replace this current battery, make certain you replace it with and AGM or GEL battery. They are maintenance free, and won't spill if you go down on your bike. The also hold a charge much longer (months) than a lead acid battery and do not suffer (as much) from off-season shelving. They cost about 50% more than a lead acid battery, however, it will out last more than 2 lead acid batteries, quite likely 3. (Even more if you spring for a gel ...) Higher up front cost, but significant long term savings.

Finally,. buy a can of the spray electrical contact cleaner and a tube of dielectric grease. Pull your connections apart, spray them, then apply the dielectric grease. I found the best way to do this was to push the tip of the tube against the female connector and squeeze some in. Easy to wipe off any over flow and not have to worry about cross connecting something by accident. You don't have to do them all at once ... start with all the ones that deal with starting and battery. Go from there as you can.

 

FYI: The alternators on these bikes is barely enough when the idle is up. That is one of the reasons so many want to convert lights to LEDs - to reduce the power load. You might also consider cleaning as many of the connections as you can access ...

To restrict the flow of air to the manometer, you can rig up your own by taking a thin tube of some sort, like one of the ones that comes with a can of brake cleaner or such, and secure it (glue?) within a piece of the tubing for the manometer. It is not adjustable, but should work. I have a cheap set of gauges that came with valves in the hoses with which you can adjust the air flow.

I got this off of eBay last year for $50, now they are all running like $77.
http://www.powersportparts.net/ProductD ... de=57-8006

 

True, but I just wanted to work on the bike and it wasn't turning over! So I turned up the POWAH! I should not be doing that though, correct... I wan't really thinking at the time...

 

I noticed the bike is running lean as all the plugs have pearly white insulators. The bike ran perfectly fine however. I didn't understand why though because I checked all the jets when I rebuilt the carbs and all were stock size. And then I found the air filter was an aftermarket UNI type. That must be it I thought.

So I got a stock filter on yesterday and rode around the remainder of the day. Today I checked the plugs and one and four show a little color but two and three are still clean and lean. I finally got all my stuff to colortune tonight so I began. Since my last carb sync, I changed 2 shims and the air filter, so it was a little off. I did a sync first with the yiks blocked off. Then inserted the color tune into the first cylinder to check color. I was nice and blue. Turning the screw all the way in and all the way out had only a slight color variation, what gives? Then I started noticing a few other oddities. The idle adjust screw isn't having much effect. And just to see the color on the color tune plug change I thought, what the hey, throw some choke on. The more I choked it the more the plug showed it getting yellow. That means when I'm applying the choke it's getting leaner?! WTF?

It was at about this point I noticed a noise coming from the intake. It would idle nice for a few seconds, then the intake would make a noise like a puff for a second while at the same time the color tune plug would flash yellow showing a lean condition, the it turned blue again and idled well for a second. This would repeat. I thought maybe it was an air leak somewhere but starting fluid sprayed or propane all around had no affect. It almost looks and sounds like it's backfiring up into the intake somehow? I was able to see some flames come up into the tube for the vacuum sync now that I think about it.

Ideas? are the valves possibly not sealing all the way letting the fuel coming in ignite?!

Anyhow, I gave up for the night... this was getting weird. Looks like I have to drive the truck to work tomorrow...