Dead cylinder whoes

[saddlebum]

Go figure spent all last summer rebuilding my bike after it got smashed up. Had two good rides out of it before parking it for the winter. yesterday. I changed the oil and filter fired it up to go for my first long awaited ride for the seaso and wouldn't you know it, an engine miss put my hands on the exhaust pipes and the left front one is stone cold , YUP a dead cylinder I put a spark tester in line with the plug and opened the gap to test spark strength and was over 1 inch and still getting strong spark jump across the gap. pulled the plug and although it was black it was not wet like a misfiring plug would normally be. going to do a compression test todayand see what my compression is. I sure hope it isn't some delayed damage from when the bike went down.

Edited March 29, 2009 by saddlebum

[autopilot]

Good luck with it!! Let us know what you find out.

[Yammer Dan]

These things seem to eat plugs.

[ToRide1]

You say it has spark, it could be a exhaust valve is hung up just a little in the open position from sitting that way all winter. you did not say its popping threw the carb so the intake valve is ok.

[bongobobny]

Change plugs!!! Drain carbs and observe what comes out. Use seafoam. I kinda doubt that it is anything else to just go bad from setting. These engines are darn near bullet proof...

[Marcarl]

Change plugs!!! Drain carbs and observe what comes out. Use seafoam. I kinda doubt that it is anything else to just go bad from setting. These engines are darn near bullet proof...

Agreed!!! if you want, just move 2 plugs around and see if the miss follows the plug. If it does, you've found the culprit. If it stays in the same cylinder, it the carb. Had 2 carbs die on me last year, cleaned them with CTC carb cleaner and air, and now all is well. If you find it's the carbs, let me know and I'll tell you how I cleaned them.

[GeorgeS]

Drain that Carb---

 

Also, how many years since you have done a Complete Tank Drain ??

 

Drain at petcock, drain all 4 carbs, Start over with Fresh Fuel, add a little HEET,

and Sea-Foam.

 

Even if its still missing, take it out for a run, Even if only running on 3 cylinders !!

 

Left Front!! Did you check that vaccume hose, from the Intake Manifold going up to the Barro Sensor??

Is it in place, not leaking?? Also from the " T " Connector on that line, hose runs up to bottom front of

the Air cleaner Box. Is it In place properly ??

[saddlebum]

When ever I park the bike for the season I fill the tank, spike it with a good dose of seafoam and run the engine to run it through the carbs. I thought about stick valves as well and thats why I intend to do a compression test.. and a cylinder leakdown test ( although I would have expected to hear some ticking noise from the top end if the valves were stuck). As far as the plugs since I have to take them out to do the cylinder tests I may as well replace them because even though they look ok I have no Idea how long they have been in the bike. There again if it was spark failure you would expect the plug to come out wet which it did not. Which leads me to believe it may be some sort of carb failure. When I think back though when I left Marcals place last fall I think I started to notice a bit of a miss about 3/4s of the way home. Ya I checked for PEPERETS shoved up the tails pipes but I didn't see any. Carl you may have to fill me in on your ctc and air cleaning technique. I'll check the hoses as well maybe when I put the bike back together last fall I didn't secure something enough.

Edited March 29, 2009 by saddlebum

[rek58]

Last year I had a problem somewhat similar to yours and it ended up being the coil. Bike ran fine at startup but after running it for a while, it started acting up. But you might want to check it out, there is a test for it. It sounds unlikely that this is your problem, but who knows.

[Venturous Randy]

I worked on a friends Venture that had a dead cylinder and it ended up being a corroded resistor in the spark plug cap. It may fire on the tester, but not the plug. Pull it off and take it apart. And, change the plugs.

RandyA

[davecb]

Spark plugs can go bad just sitting over the winter. I never would have believed this, but I have seen it happen....