A seemingly unusual issue with Zong Storm 250GS

[AustinConnell]

Thank you weld and grind. You're proving your name!

I do have everything besides the valve spring compressor which I could probably makeshift something in place of that particular tool.
I have heard that I might need to soak the head as it sits, the cylinder, and piston in a vat of gasoline in order to soften the carbon. Using a stiff nylon brush I could scrub the deposit off. Does this sound legitimate?

[Weldangrind]

Sure, I just like power tools. Nylox brushes for your drill are cheap and effective. I'd probably use a little aerosol carb cleaner instead of gas.

[AustinConnell]

So I worked on this project a bit more tonight. I got a lot accomplished in my opinion considering it is now 2am and I'm exhausted. ha. Anyways, I chose to soak the parts (head and valves, piston, and cylinder) in the gasoline. This did help immensely when trying to scrub off all of the excess carbon deposit. I soaked them for about 45 minutes, then I repeatedly scrubbed with a nylon brush and a blunt tip flat head screwdriver and kept dipping the part that I was working on into the bucket of fuel that I had. This method was very effective. The grime was not easy to remove by any means, but it came off after quite a few cycles. The piston was the easiest part to clean, while the cylinder was slightly more difficult due to the tedious motion I had to go with in order to avoid damaging the edges and the walls. The valves were the most difficult things to clean. I had to continually dip the entire head into the fuel and turn the sprocket in order to open and close the valves so I could clean the rear areas. I got it all to my satisfaction and reinstalled the top end using brand new gaskets to seal everything up. Here are some photos of my progress. Again, sorry for the poor quality since these were shot with my phone camera..

The piston before


The piston and cylinder after


Valves and head after


Reassembled

[Weldangrind]

That looks much better! If you choose to take the head off again, you could turn it upside down and fill the combustion chamber with water. If the water doesn't leak out, you have valves that seal well enough.

[AustinConnell]

Originally Posted by Weldangrind

That looks much better! If you choose to take the head off again, you could turn it upside down and fill it with water. If the water doesn't leak out, you have valves that seal well enough.

I didn't include that in my description, but while I was cleaning the head, I did that with the fuel. I dried the underside and poured fuel in from the intake and exhaust side. They were sealing just fine after I cleaned around them. Before, they weren't sealing at all. I could shine a flashlight through the valve and it would shine right through!

[Weldangrind]

Excellent! So, you managed to clean the valves while they were still installed in the head?

[AustinConnell]

yep, I was avoiding having to remove them and reinstalling them. I didn't want to have to make any adjustments as that is a bit out of my knowledge area. I was able to use a small screw driver wrapped in the course side of a velcro strip to scrub away the build up on the back side of the valve. The valve itself was not bent or gouged from the deposit surprisingly. I just slowly but surely got behind everything and cleaned it all up. I also degreased the spring since it seemed to be slightly sticky. After I did that it was moving smoothly again.

[Weldangrind]

Sounds good. Had you removed the valve, there would be no adjustment necessary. The only adjustment to worry about is the timing marks (which you already established) and the valve clearance (which you should do).

[AustinConnell]

I definitely need to get my hands on some feeler gauges... I would have checked that if I had some readily available. I know they're somewhere in the garage. I will probably just pick some up tomorrow from the parts store when I pick up some oil to refill the engine with. (1.1L 10W30).
I'm really hoping that this was the main issue with the bike loosing power at higher RPM. This bike is a blast to ride and is really comfortable as I have lower back problems. It handles great and doesn't look to bad either! Although, all of these are useless if it can't get down the road without dying on me...

Am I right in thinking that the valves and head gaskets being damaged would cause the oil in my airbox issue?

[Weldangrind]

Please don't use 10W30; find either a four stroke motorcycle oil or a non-energy conserving oil (like Rotella). The weight is up to you, but I would choose 10W40 in colder weather.

I would have thought that oil in the airbox would be due to excess pressure that is being released, but you couldn't build excess pressure because of the poorly sealing valves. That stumps me a bit. Maybe there is reversion that occurs, which is blowing oil back through the carb on the compression stroke. Did you find any evidence of oil in the carb?

[AustinConnell]

Oil type noted. Thank you.

As for oil being in the carb, there is none. It was definitely coming out of the breather hose attached to the top of the engine. I removed it and ran the bike for a few minutes and it began to ooze out of the top. There has to be some way for the valves to be lubricated, I'm thinking that maybe while the valve was open, the fuel was combusting and the pressure from that was feeding back through the oil routes in the head causing over all pressure in the cooling system. The only place for the pressure to be relieved would in turn be the cooling hose right? This hose being connected to my airbox would explain the oil being there. Then when the oil is sucked through the head again, it would be exponentially causing the carbon build up and fowl out my plug causing the motor to die like it was..

This is a theory of mine, I have no idea if this is a legitimate one though!

[FastDoc]

Good job .

Something important I want to point out though :idea: .

Working with gasoline as a solvent is very dangerous. The fumes are bad for you, it gets in through your skin and is carcinogenic, and most importantly it is flamable and explosive 8O .

Mineral spirits, kerosine, diesel, heating oil, and Jet A are all basically the same and much safer to use as a solvent, and they work just as well.

In my shop I use diesel and mineral spirits. At the airport I use Jet A just because it's available.

[Weldangrind]

Excellent point Doc. I cringed at the gasoline, but I forgot to mention it.

AustinConnell, that's a terrific theory. I hadn't considered that combustion gases were travelling through the oil passages to get to the crankcase. Hmm. You ought to have a good runner now.

[AustinConnell]

I was out in the driveway when working with the fuel, I had some old gas sitting around that I needed to get rid of anyways. I didn't have any of the other chemicals around.

Today I rebuilt the bike and it is running. I will detail the process in a bit!

[FastDoc]

I'm really glad to hear about your success and I'm looking forward to many ride reports of good times on your bike.