Compression?? Check!!!

[greg78gs750]

well, fellas and ladies, we are getting there.

i checked my compression with my shiny new compression checker this afternoon: 135-140 psi across the board, dry, with wot. can you say, YES!!??

here is the issue:

work i have done so far:

valve adjustment.
new plugs
carb clean and rebuild, with all new orings, including boots, courtesy of mr. barr.
airbox sealing.
new exhaust gaskets.

i have a new (well, a few years old, but newer) petcock. a por 15'ed tank. a well grounded (but, honestly, still suspect) reg rec.

the problem is this: my #3 pipe was cold, as in slow to warm up, before all this work, and is still cold after it. so, i am looking for the cause. i was awake all last night DREADING the compression test, sure i was going to have some bad news. but, 135 psi seems like pretty good news.

so, where do i go from here? i havent adjusted the carbs yet, just a manual synch, and set the screws (pilot fuel and air) to where they were before the rebuild. the fuel screws are 1 1/2 turns out. the air screws...well, i cant remember right this second, i havent set them with "highest idle" yet. maybe i should do that....i havnet run it much because i was scared that the 3 pipe was still cold.

any ideas, guys? i am just going to keep bothering you until you give me the solution, so lets just do this the easy way and get this fixed!!:-D:-D

thanks for all the help i have gotten so far, and for this great forum!!!

greg

[Dave8338]

Have you dropped a new plug in the #3 yet...this would be the first thing i'de do. If so, then as much as it may hurt to hear, your #3 carb may still be in need of "cleaning". :shock: Also...have you varified spark to the #3?

[BassCliff]

Soooooo close!

Mr. greg78gs750,

I could also be a bad plug cap or plug wire. Like Mr. Dave8338 says, check for spark. Caps, wires and plugs are pretty cheap.

You're doing some great work. It won't be long now. \\/


Thank you for your indulgence,

BassCliff

[49er]

Have you dropped a new plug in the #3 yet...this would be the first thing i'de do. If so, then as much as it may hurt to hear, your #3 carb may still be in need of "cleaning". :shock: Also...have you varified spark to the #3?

I presume that #3 pipe is cold at idle. If so, you may need to re-clean the pilot circuit passages on that carb, including the idle mixture and idle air screw ones. They are quite small and often get partially/fully blocked after a bike has sat for long periods without running. If you did your bench sync accurately, minor carb imbalance won't cause this symptom.

[greg78gs750]

i have spark. it isnt "fat and blue", at least not in daylight, but it is present. stock coils, and i have not done the planned relay mod yet.

the carbs were pretty clean when i took them off, and pretty near spotless when put back on, but i GUESS i will take them (or at least #3) apart again. meanwhile....any other ideas i should check?

thanks for the quick replies, guys, i will be outrunning those harleys any day now, i can TASTE the wind already.....

greg

oh, and, yes, 4 shiny new b8es plugs

[Dave8338]

This sounds like it may be spark related. Under compression, if your spark is poor, it may fail altogether.

[greg78gs750]

oh, and i did snip the ends of the wires for a fresh connection. the plug caps are newer, maybe 4 years old. i should probably get new ones. i want to get new wires, but they are "glued" into the stock coils and i havent had the sack to dig them out. i could splice new ones on, but, really, a splice? that option never really seemed like a good solution. new coils will happen before that.

my wife is gonna be UPSET with me for re-dis-assembling those carbs.....maybe a trip to the jewelry store.....

well, better than bad compression, right?

maybe if i ran a hot load of seafoam?

oh, i should quit whining and break # 3 down again....its not like i dont know how...

ok. to the garage.....honey?!?!?!....im, uh, going outside for a while.........

hehe
greg

[greg78gs750]

maybe i will do that relay mod now and see if that helps....i wanted to make sure it would start before i "fixed" something else, and it for sure starts.....cold with no choke!!! which has NEVER happenned before....

[seuadr]

i think a cheap possibility for a fix would be replace that plug wire. i've had weak spark issues with cars before where the wire was arching, but only intermidetatly, so it was not obviously the problem. another way to check is clear the path around that wire, and then take the time to start it in as deep a dark condition as you can, and watch to see if there is any arching anywhere.

[greg78gs750]

well, the plug seems to be firing, at least as well as the #4. the insulation on the wire IS a bit cracked, though, and wire replacement was on the list anyway, so that will be next. easy enough as long as the tank is off anyway. tomorrow i will replace the wires (pretty sure i can pick up some wire at the local auto parts? 8mm copper core?) and do that relay mod, too, while i am at it. we will see where that leaves us.......

greg