Oil in cylinder

millertm937 · Posted: Fri Jan 29, 2010 12:57 pm Post subject: Oil in cylinder

I believe my cb175 has oil dripping into the right cylinder from the valve. I have good compression, spark, and fuel but the plug keeps fouling out. After I let it idle for 10 mins I will pull the plug and a little smoke will come out of the cylinder and the plug is black. Does this mean I have to rebuild the top end? If so what in particular, guides, valves, seats, seals? Or is there a fix where I don't have to disassemble the engine? Any help would be great.

05c50 · Posted: Fri Jan 29, 2010 4:45 pm Post subject:

Welcome to vjmog millertm. Is the spark plug black and oily or black and sooty? Are you sure it's oil fouled and not gas fouled? It's more common to be gas fouled from an over rich carb, but you could have a valve guide problem allowing oil to pass into the cylinder.

..............Paul

Russell · Posted: Fri Jan 29, 2010 5:42 pm Post subject:

Following on from the above response.Have you checked carb float level for the offending cylinder?I've acquired a CB175 a few months back and it has a fresh top end.It wasn't running well though with tired float valves and seats and it has taken quite some time to get it running sweetly.I don't have to be much 'out' on carb adjustments to have a black and dampish looking plug.

millertm937 · Posted: Fri Jan 29, 2010 6:13 pm Post subject:

I checked the plug and it was black and oily, not sooty. I also set the float level with a caliper to exactly 21mm, which is what the book said. At first the cylinder wasn't firing at all and I then checked the plug and it was wet. So I adjusted the float level like I mentioned and then the cylinder fired. The pilot jet was set at the required setting of 1.25 as well. thanks for your replies

05c50 · Posted: Fri Jan 29, 2010 6:57 pm Post subject:

If I remember right, that bike has brass floats. I had one that kept fouling the plug even though I set the float right. Finally figured out that the float had a tiny hole and was filling up with gas. I've had 50/50 luck fixing brass floats. got one soldered up with no problem, another one blew up in my face........guess I didn't get all the gas out Shocked

.

...........Paul

Goss · Posted: Sat Jan 30, 2010 5:41 am Post subject:

The quickest and easiest way to check what is actually happening in the combustion chamber is by using the Gunson Colour tune http://www.gunsons.co.uk/product.asp?lot=21&pnid=254&deptid=10&xdid=3 this product is incredible for adjusting tickover mixture and comes with a great guide.

I purchased one many years ago for a similar fault and it worked, I have also used it on other vehicles and it helps identify the slightest of faults.

Goss

Bikegeezer · Posted: Mon Feb 01, 2010 11:03 am Post subject: Re: Oil in cylinder

Steve Searles · Posted: Mon Feb 01, 2010 1:53 pm Post subject:

Pin hole in float is a good theory. Take brass float out and shake it to see if there is gas inside. Have you replaced the needle and seat??

millertm937 · Posted: Thu Feb 11, 2010 1:03 pm Post subject:

I don't remember gas being in the float at all but I really wasn't looking for that when I had it apart so I can't confirm. I have not replaced he needle and seat either. Could that contribute to oil leaking in the cylinder?

Steve Searles · Posted: Thu Feb 11, 2010 1:46 pm Post subject:

Definetly replace the needle and seat if possible.

Bikegeezer · Posted: Thu Feb 11, 2010 2:54 pm Post subject:

millertm937 · Posted: Sat Feb 20, 2010 10:08 am Post subject:

great suggestions, thanks guys. I will eventually get to looking at the float and needle and seat to see if that was the problem. I started thinking about putting a hotter spark plug in to see if that would burn the oil with out fouling the plug. Is this a mistake or is it something to look into? The standard plug uses the D8HA I believe? I tried looking for a plug that was one range hotter but could not find anything. Does NGK make a plug that is one range hotter or do I need to go to another brand? Or should I just forget about this idea all together and look at the carb like you guys said.

ol55 · Commuter Joined: Feb 09, 2009 Posts: 391 Location: VA

When the geezer speaks, I listen. Smile

Carbs.

Larry

Bikegeezer · Posted: Sat Feb 20, 2010 2:39 pm Post subject:

millertm937 · Posted: Sat Feb 20, 2010 3:08 pm Post subject:

thanks guys. Ya I understand that I need to fix the actual problem and not cover it up. Just was curious. Thanks again for the repiles