2cyc "Loading up" ?

[Jim Thirlwell UK]

Re: 2cyc "Loading up" ?

I dont know your engine, but if you have knocking it is a timing problem or the wrong grade of fuel.<br /><br />Do you have electronic ignition? If not it could well be the points need adjusting. Put a stobe on and check that it is firing at the right position.

 

[jerrypark1]

Re: 2cyc "Loading up" ?

Thanks for the info. I have tried new plugs, and played with gaps between 30 and 40. They are l77jc4s. and not the QL77JC4s as recommended, but I've been running that type for quite a while. <br />My next guess was timing....maybe it got bumped off somehow. It is electronic ignition, so no points. The knocking started me down the timing path, but now I'm thinking it may just be an exhaust leak that makes the engine louder....vs an actual ignition knock. I'm going to check the exhaust first, then timing is next on the list if it's still having problems. I'm procrastinating the timing work as much as I can....don't have the tools to check it, so it'd be a trip to the store....as well as blocking a heavily used boat ramp to perform the testing....How do you check the timing when you've got a line of boats waiting on you to get off the ramp? I'd do it on the water, but it's a bit bumpy and would be a bear.

 

[Seasport]

Re: 2cyc "Loading up" ?

I'd check the timing. Rule out basics first. Can you borrow a timing light? You can use Joe Reeves timing method to get it approximately right without running in the water.

 

[jerrypark1]

Re: 2cyc "Loading up" ?

Kevin H, I just noticed your post, sorry I missed that the first time. All the plugs were very similar....light brown, all physically identical. No blistering, not super clean, no excessive carbon. I've also suspected a possibe water leak, but since compression is the same across the 3, and all plugs look identical, I'm ruling that out for now. I did see Joe's timing FAQ, so I will go through that as a baseline to rule it out for now as well. The knocking does seem like it's tied to the firing of each cylinder, but it's a bit hard to tell. Anyone worked on the exhaust system before? Is this a full teardown to get at it, or can I inspect/work from below? Again, I am greatly appreciative of all of the help.

 

[jerrypark1]

Re: 2cyc "Loading up" ?

Well, here is where it all sits:<br />Pulled the powerhead and replaced the gasket between PwrHead and exhaust housing, carb rebuild, fuel pump rebuild, and new plugs. Still having the same problem of rough idle, occasional stall, it runs a bit louder now with some knocking, and lowered WOT by 200RPM...and generally just running poorly. I ended up taking it into a mechanic, and even he is now stumped. He did mention that the motor is running cool (which I noticed also), and I did replace the thermostat, but it is quite cold running. (my guess is that it never gets over 100 degrees since I can keep my hand on the head indefinately). He also suggested that I simply cut up the cover to let in more fresh air since it still seems like there's an exhaust leak, but neither he nor I could find it. (I'm not a big fan of that idea). I (and now my mechanic) are stumped.....this motor did run very well this spring. I have absolutely no idea of what to do now.....HELP!!! Why would it run cold? If there were restrictor plates in the head somewhere that were removed....it did run well this way this spring. I'm totally stuck.

 

[jerrypark1]

Re: 2cyc "Loading up" ?

Thought I'd add a few more details. This maintenance has been done within the past 18 months.<br />Running QL77JC4 plugs (gapped at 30). Plug wires, carb kits (twice), fuel pump kit, fuel hose (w/new primer), thermostat, water pump, pwr head to exhaust housing gasket, decarb, compression check good (didn't do leak down test), reeds visually look okay, power pack, L/U service, and re-jetted for proper altitude (from 61 to 54 jets). Timing looks fine as well per mechanic. Could running cold cause rough idle? When it finally gets above 3000 RPM, it does run pretty well, just loosing 200RPM there.

 

[jerrypark1]

Re: 2cyc "Loading up" ?

Letting everyone out there that helped out know....found it!!! I pulled the head for a second time, and took a closer look at a hole in the plate between the exhaust and p-head. The first time I saw it, I did look pretty closely at it, and it was so perfectly round, it looked machined and that it was supposed to be there. It turns out that below that plate is a small hole (this one is supposed to be there) in the inner exhaust housing that is only 2 inches from the hole in the plate. A few globs of JB-weld on the plate and it runs great. Just need to get my over-cooling figured out and I'm set. Thanks to all.

 

[Solittle]

Re: 2cyc "Loading up" ?

Fallen Rock - Thanks for the "after action" report. All too often we get an interesting thread with no end to the story - so we don't know what solved the problem. I wish more guys would do this.<br /><br />Hint! - - Hint!!