What's wrong here?
 

Engine. BME 110
About 8 gallons of gas through
Bel Ray 50:1


Symptoms. 2 weekends ago it began acting funny. At idle the left cylinder was puting out puffs of white smoke. Seems to transition OK. Landing is the worse, by the time the plane is on the ground, the engine will barely run up. It takes probably 10 seconds to run up to full rpm. Once I get it there, it seems to "clear out" and it runs fine .

Took it home and pulled the plugs. The right side was a nice tan color while the left side was dark brown. I figured I had a bad plug. I put a new plug in and the symptoms didn't change. Any thoughts?

To me it almost seems like an ignition problem?

RE: What's wrong here?
 

Hi,
To eliminate ignition, you should able to swap plug cables since both cylinders fire together. Check the entire exhust system for leaks, loose or missing parts that would cause one side to run leaner. If you have a compression tester, comparing the cylinder readings would be helpful. If you have a big difference it could cause problems. Check to see if your baffling is all in place. Maybe there is a cooling issue. Just some thoughts. I'm sure you will get many more suggestions from some top notch troubleshooters. Good luck.

Dave

RE: What's wrong here?
 

Thanks Dave. I guess the first step is, like you said, to switch the cables around and see what happens.

RE: What's wrong here?
 

Crash- Just for the heck of it, pull the mufflers and look thru the exhaust ports and see what the cylinders and piston skirts look like.

There was a bad batch of ignitions a long time ago, C&H will replace it if that is the case.

When you say slow to "run up" can you tell if it is rich or lean? I would try cleaning the carb anyway.

I had a similar problem with my 110 the first time I cowled it. The engine would not want to run up either, it did not sound rich or lean just constipated. I had to cut a hole below the carb and that cured everything. I don't know if that will help yours or not being that this problem just came about.

I would start with the carb/fuel system then the ignition.
Ralph

By the way, when you mentioned one cylinder was puffing , front or back? The smoke was white and not a blueish color?

RE: What's wrong here?
 

Thanks for the replys. It may have been a blueish color I really didnt pay that close attention. I have the 110 in a H9 Sukhoi so it is my belief that it is not the cowling. I will pull the plugs again and see how they look. My biggest concern was that while one plug was light tan, the other was black and oily. If that is the case again then it would almost have to be a problem with either the ignition or an air leak no? I mean, other than that what would cause 1 cylinder to run richer/leaner than the other??

RE: What's wrong here?
 

Hi,
The answer to your question is unequal back pressure.

Dave

RE: What's wrong here?
 

What causes that?

RE: What's wrong here?
 

Hi,
Its all hypetethical, but differentence in header lenght, can size, stinger diameter or lenght. Any leaks or restrictions in exhust. Try this, pull one plug and turn the engine over with ignition off of course. Then replace the plug and pull the other plug and turn it over. This will allow you to get a feel for the compression. If you can't tell the difference between the cylinders they should be within 10% of each other.

Dave

RE: What's wrong here?
 

Thanks Guys. I will check a few of these things and report back.

RE: What's wrong here?
 

All twins have this problem to some extent. It is in the design off these engines, as Dave mentioned about exhaust set-up can cause this too.

RE: What's wrong here?
 

OK. I finally pulled the cowl and checked things out. It seems that although both cylinders have compression, the left one has noticeably more than the right. I pulled the muffler off the right side and looked at the piston. It looked clean behind the rings. The left cylinder was running richer than the right.

So, what's my next step?

RE: What's wrong here?
 

Sounds like you have a compression ring that hasn't seated properly, ot the oil mix is too rich. BTW, it's normal for one side to run a little leaner that the other due to the design of the carb and reed valve. I would consider getting in touch with Gene at BME and checking to see if you could lean out the oil mix. 50-1 may be too rich for the engine, causing loading up of the one plug. Excessive oil would also delay the seating of the rings. You probably don't have a serious problem that requires the return of the engine, but again, a call to Gene would be in order to determine that.

RE: What's wrong here?
 

I would e-mail Keith (He WILL respond in hours) and explain what you are seeing. If you are running stock exhaust I know how you might be able to balance them.


When you say left, do you mean the forward cylinder or the backward cylinder when looking from the front.

RE: What's wrong here?
 

Hi Silversurfer! How about some news.

RE: What's wrong here?
 

Crash,

Which Bel-Ray oil are you using??

RE: What's wrong here?
 

Now that you mention it. I just switched from lawnboy at 50:1 to HR1 at 44:1. This began about 1 gallon into the Belray. Any thoughts?


When I say left I mean viewing the engine from the cockpit. Thanks guys.

RE: What's wrong here?
 

does anybody have the E-Mail addy for BME? It doesn't seem to be listed on the "Contact BME" page. Thanks

RE: What's wrong here?
 

I used to run alot of H1R and MC-1 in the past. And at least for the engine I was running it in, that would have been to lean of an oil mix. I had to run it 25 or 30 to 1 on H1R. However the same engine ran best with a 50:1 ratio of MC-1.

I have seen another 110 suffer problems right after switching from the lawnboy to a full synthetic. He solved his problem by increasing the oil for a couple gallons and slowly backing up to the leaner oil mix.

Dan

RE: What's wrong here?
 

[email protected]

RE: What's wrong here?
 

Thanks guys. I will email BME. I'll keep you updated.

RE: What's wrong here?
 

I emailed Keith and he agreed. Change the plugs and lean her out a bit. I spent some time with it on Sunday along with a friend of mine with more experience than I and we got it running pretty good. He turned the spinner and said that it is still "tight" so I should expect even more improvement over time.

The only overloading I have now is after a down line so my low end may need a little more tweaking. Thanks guys.