Won't Start

[senrak]

Okay, I have searched the site for an answer. Found many, but none have solved my problem. So I guess it's time for new post.
I am restoring my 82 XJ. Had the heads gone through, and cylinders honed at the machine shop, installed new rings. Compression is 130 lbs. on all 4 cylinders, good for not having been run in yet. New coils from Dennis Kirk. Nice hot spark. Checked that all wires are hooked up correctly according to posts here. Went through the carbs. I believe them to be squeaky clean. Had the bowls off again today re-checking the float height. Bowls all fill with gas, new lines, clean tank, no leaks. Engine ran before I took it apart a year ago. Can't get it to start. Sometimes it will fire for a second or two and quit. New battery. Turns over briskly. Cranking with throttle closed and cold start valves open. Seems like there is not enough gas being sucked in. Don't know were to go from here. Any ideas are more than welcome.
DW

[fredintoon]

Hi Dale,
you got good sparks but are they in the right place?
Quick check, swap the outer and inner plug wires onto the other plugs.
Or swap the coil feeds over.
See if it fires up.
If it don't make any difference it wasn't that so swap them back.
Now take the carb rack off, squirt a good dose of ether-based cold start fluid down each intake and hit the starter button.
If the sparks are good it should go VROOOM and quit and you have a fuel problem.

[BA80]

Like Fred says be certain it is sparking the correct cylinders at the correct time.

Did it run before you did the other repairs? If so and the carbs have been sitting without attention for a year it's a good possibility that the passages in the carbs have gummed up and clogged over time.

[SFerinTEXAS]

Since you had the head off Might recheck cam chain. One tooth can shut you down.

[TopCatGr58]

Good points so far. You cleaned the carbs, but did you ensure that the Enrichener/choke jet in the float BOWL is clear and flowing....see the Carb101 tech tip. Oh, and when you cleaned carbs, hopefully you didn't soak them in a caustic carb dip....that can destroy the butterfly shaft seals=vac. leak!!

Next, had jugs/head off, reinstalled, how did the intake boots look? Rubber on mating surface can dry/crack, etc, folks have had to use sealant to get good seal to head. Intake boot synch port caps...old or new..old also can crack/harden and leak even though they look like they are ON!

Others have already pointed out checking valve timing...can have decent compression and still be a tooth off. Can use a timing light to check to see if you are getting spark on the #1 plug at the right time vs. 180 out.

Keep at it, you're close!

T.C.

[ViperRon]

As Fred suggested if the timming is good and spark is good it should fire with starting fluid but I have always just removed the caps from intake ports and sprayed into them. One more thing that I have had as a problem before is plugs. I hate champion plugs due to having intermittant issues with them. If you can find a shady or darkened area take all pugs out hook wires to them and crank bike with plugs laying on engine. You should get a good blue spark from them when cranking. If you so not get a good spark find a clean piece of metal lay each plug on it in turn and with wire groung the metal back to battery post and try again. This will eliminate a possible bad ground with engine issue.

You have 130 cold compression and that is good. I have seen bikes run on 90 so if you have good spark and it will not fire up with starting fluid you have a timming issue. Check with timming light fast crank all plugs out 1st plug laying on good ground so it can fire.

Once you get good spark if it will not start make sure first that gas is good if its been sitting in can or tank for a month with ethanol get some fresh and drain the bowls from underneath the carbs with gas supply off.

[senrak]

Okay, Tried spraying gas in the intakes with the carbs off. Did not fire. Pulled the valve cover to check cam timing. Intake was right on, but the exhaust looked like it was one tooth late. Could swear they were perfect when I did it the first time. Anyway I pulled it and went through it again. This time it looks better. The marks are like an inexact science, they never look perfectly lined up to me. How far off can you be before you bend valves?

While I had my perfectly clean carbs off, I pulled the bowls to re-check the float level and spent some time studying that cold start circuit. Believing that I wasn't getting fuel in that circuit, I looked closer at the passage in the bottom of the bowl. When I looked at them last week I thought that they weren't drilled through, because none of the four were open. My thinking was that, well maybe that's on only certain models. After digging around in there, I found a tiny hole in the bottom of the passage. Had to grind a needle down to .012" to unplug those holes. What a stupid place to put a tiny orifice.

Now I see your tip on these holes, TC. I should have read the 101 closer. The intake boots are new. I wasn't going to take a chance on those, I went through that with my Virago. Vacuum port caps were junk. All new now. The coils and plug wires are as they should be, left/right, orange/green

I'll check in after I get the carbs back on and can try it. I still don't like the lack of an accurate cam timing check.
Always great to get the advise here.

[senrak]

Success! Changed that exhaust cam one tooth. Cleaned those 4 tiny little holes out in the float bowls. Engine fired up immediately. Now it will be syncing and tweaking.
By the way, I got that engine running, turned and looked out the window to see snow falling.
DW