Ever feel like you met your match??

[DGXSER]

I will check battery when I get back Friday.

I am going to go through the carbs.....again. Maybe swap out pickup coils, even ignition coils. Of course those will be one at a time.

[BA80]

Pull the rubber cap off of the vacuum nipple on that cylinders carb boot, use a can of spray carb cleaner with a straw on it and stick the straw in the nipple.

Start the engine and let it idle. Squirt some cleaner in the boot with very short bursts and see if that cylinder will fire at idle then. If it does it will save you from swapping a bunch of parts for no reason because then you will realize that it's a carb issue. Which I'm confident it is because I just went through a similar scenario with my 79.

[DGXSER]

In my mind I do feel like it is a fuel issue. Just running out of fuel options. As to spraying carb cleaner in the vac port, isn't carb cleaner more volatile and therefore require less spark to ignite?

Be Friday before I can try anyway, sitting in Charlotte waiting to get to New Orleans for two days.

[BA80]

In my mind I do feel like it is a fuel issue. Just running out of fuel options. As to spraying carb cleaner in the vac port, isn't carb cleaner more volatile and therefore require less spark to ignite?

Be Friday before I can try anyway, sitting in Charlotte waiting to get to New Orleans for two days.

The difference is insignificant. It IS a valid test for lack of fuel. Used that exact method on JWs XJ550 this last weekend. It needs carb work we found out.

[LoHo]

Could number 1 intake valve be too tight to get a flow through to the cylinder?

[GLoweVA]

Could number 1 intake valve be too tight to get a flow through to the cylinder?

I was kind of thinking the same train of thought, but he said the compression numbers were all about the same.
If #1 intake was too tight, then I would think the compression numbers should be off(lower) on that one and not the others.
But then again, he said all his numbers were kinda lower, maybe if he got the compression numbers back up (valve shims, etc) then the problem might clear itself.
In other words, maybe #1 is just a little more off than the others and thus the problem shows up in #1. (kinda like a premature detonation thing, thus the back fire)

Just thinking out loud. Hope this helps.

[Toolmaker Tim]

Valves

With the compression loss and the back fire it sounds like a valve clearance issue. Checking them would rule it out. What George says makes sense.

[DGXSER]

Got the bike two years ago in very poor condition and had sat for years in a barn or field. Compression was worse then. Never really bothered to recheck till now. Improved about 20 and evened out. So the lower than spec compression is not as suspect as it may seem. Originally improved with oil which is indicative of rings, thought they might reseat with use. Not as much as hoped.

[DGXSER]

OK, so, there are no carbs even fresh off the factory line cleaner than mine are now. Between pull them apart, using the USC, carb spray and compressed air, there is no place anything could be hiding. Unfortunately, the only thing accomplished is that I reminded myself what a total PITA that little flippin ball bearing can be to get into place. And it is a good thing they give you the extra one on the no 4 end.

I went through the coils, all caps are right at 5k ohms, coils are right about 12k ohms. And one has a crack in the outer casing. So now I know why the bike is such a PITA to get restarted after a trip to the car wash, but has no issues in the rain.

So, I seem to be down to electrical or a valve issue. Maybe, perhaps the cam chain is THAT worn and a cam skipped a tooth, but then it would seem like it would effect more than one cylinder.

Well, tomorrow is daughters HS graduation, so the bike will wait yet again.

[ddragon63]

I had a similar problem started end of last year on Old Man. Decided to check the valves... all of my intakes were tight, all my exhaust valves were good, #4 was off alot from the rest. it popped a little @ idle and ran like a car with a flat cam till over 3500 and then ran fine... hotter it got, worse it got. JAT

Here the map of what I found when i popped mine open. as you can see the intakes were all a little tight. #3 was the worst... an #4 needed it on both ends. Before doing this my compression was pretty close except #4 and all seemed low #1-3 were 130's and #4 was 110ish (it was too many beers ago to remember, I need to write this stuff down ). I was expecting to do a ring job soon. After valves we are 167 to 173 on all 4... it may just be that simple my friend

[DGXSER]

NExt chance I get to work on it, probably Sunday, I may pop the valve cover and see what is going on. I know I re-shimmed the valves not overly long ago, like within the last 4-5k miles since that is all it has on it since I got the bike. And I know I put the gap to the wider end of spec if not a hair over spec.

When I started it and had to hold the choke open, that is what you get when you reassemble and put the ball in before you check for a spring in there, I could feel the popping backfiring through the carb body a couple times.

[ddragon63]

food for thought... if there was build up (carbon or such) on the valves from PO and sitting and you adjusted valve. You could have easily cleared this build up now and the valves have tightened on the head causing the clearance between the cam and shim too get too tight in a hurry. Like I said food for thought.

[DGXSER]

Stole soem time this morning. I can confirm the valve clearances are all within spec. Most are on the loose side of spec. I do need to check the battery, but I had 14.5 volts at the coils red/white with key on bike not running.

[bikerphil]

I do need to check the battery, but I had 14.5 volts at the coils red/white with key on bike not running.

That seems a little high, maybe battery is shorted.

[BA80]

Try what I suggested with the carb cleaner Don. Just takes a minute.

I still think your chasing a carb problem in the elactrical system.