XR6 Running Issues

[96Skeeter]

Mercury XR6 Serial #OG303865

Compression/ Leakdown Numbers
1- 102psi/7%
2-92psi/3%
3-88psi/10%
4-102psi/5%
5-101psi/7%
6-104psi/3%

Motor starts and idles fine, but in hot, humid weather (90 degrees/ 75% humidity) the motor hesitates and falls flat on its face when throttling up. Cool weather/ low humidity it throttles up just fine. The hesitation/ stall can be overcome by hitting the enricher when throttling up. However, it doesn't always hesitate, and sometimes it will just throttle right up in the hotter weather.

I had some electrical issues and had the stator, trigger, switch boxes, timer base, and regulators replaced. I also had a cracked reed, and those were replaced as well with Boyesen carbon fiber reeds. Carbs were also cleaned/ rebuilt at this time. I've plugged a small gas tank directly to the fuel pump to rule out any external fuel line issues, as well as pumped the bulb while throttling up with no resolve to the issue. The primer bulb does not lose prime between runs.

I realize that the number 3 cylinder is a little low on compression and high on leakdown, and might be suspect. However I'm not getting any other classic symptoms of low compression. Any thoughts?

[96Skeeter]

Forgot to add that I'm leaning toward a coil pack issue. I'm assuming my mechanic checked those out, but know that sometimes they can have an issue that's hard to detect unless all the conditions are right. My mechanic is at a loss as to what is causing the issue, but isn't saying for sure that it's the compression.

[blackboat]

Since all 6 cyl are low compared to factory specs,unless the motor has a million hrs,your mechanic's testing method is suspect IMO. Should be warmed up with throttle wide open and all 6 spark plugs out Leakdown test on a 2 stroke is difficult to do properly and mostly inconclusive...also IMO. Check all the grounds on the coils and maybe buy 1 new and switch out one at a time if you think that's the issue. I don't think compression is the problem.

[JOE54]

hey skeet by hitting the choke to overcome bog tells you that its to lean low speed might look at idle timming [ 4-8 retarded ] and consider checking float levels and or richening low speed on carbs hoe this helps ya JOE

[EuropeanAM]

Definitely low compression numbers (overall- each and every cylinder). Agree that test method is suspect.

Are you placing the engine at LEVEL trim, and pumping the bulb firm before EVERY SINGLE engine start?