Water injection decoking a VF500. Before and after pictures.

I have a very nice VF500 that looks great but is a pretty poor performer on power and mpg. (Search for my old posts if you are interested).
I like riding it but I really like messing with the bike. Main reason I bought it.

I bought the bike a couple of years ago and the seller, who had only had it a short while himself, told me it had been part of a collection. So I assume it had sat around a lot. Probably not unlike many 27 year old bikes that have only done small (20K) miles. I knew the internals weren't pristine cos when I put a screwdriver down a piston hole and scaped around a bit, it came out with oily ash like deposits.

Anyway after lowish compression tests I assumed the most likely culprit was the rings being a bit gummed up. I have no evidence this is true, just a guess. I don't have a leakdown tester (yet).

I tried a few snakeoil remedies like Redex, BG44K, STP, but these did very little as far as I can tell. Marvel Mystery Oil and Seafoam are unobtainable over here but I guess these fall into the same category. I have also given the bike plenty of Italian Tune ups albeit sticking to a 9K rev limit to save my valves and springs.

I bought a cheap endoscope/borescope off Ebay but being an idiot I got one too large to go down the VF sparkplug hole. In the end I don't think this matters as the focal length of these cheap items is about 6 cm so you can focus on the piston crown anyway.

I knew about water injection being used in aviation and other areas to increase short term power but I have also heard about it being used to clean engine internals. So after a spirited ride, I connected a hose to the cylinder 3 intake vacuum takeoff and allowed it to suck up about 500ml of water. This cylinder had given a compression reading of 135psi.

I revved the engine a bit and plumes of water vapour emerged from the exhaust but the bike took it in its stride (only one cylinder remember). It sucked the water down pretty damn fast and it was possible to completey submerge the hose. There was no chance of it hydraulically locking IMO. The hose was from my Morgan Carbtune btw. To make sure I didn't leave my exhaust wet, I then went for another spitirted ride. Bike felt the same but then I had only done one cylinder.

Pictures show before and after. The before clean patch is from where I scraped around with the screwdriver. the water injection has cleaned it a bit but not a lot. It has confirmed my piston crowns are covered in a tenacious layer of crap though.

It is very easy to do but I don't think I'll do it again. If I do I think I would probably do all four cylinders at the same time to even out the loads on the crank. I didn't do it for very long, a minute at the most. Maybe if I had revved the ring out of it it might have had more of an effect.

I think for now I'll just stick to high detergent fuels and buy a leakdown tester.

Before

After

 

I've heard of mechanics spray water vapor/mist down the intake to clean carbon build up. Appearantly Honda cars are worst at carbon buildup than most. Not sure if this holds true for the bikes. But basicly the cool water on the hot carbon deposits breaks them loose of the engine parts.

 

try Marvel mystery oil in your fuel for a few tanks, I've had amazing results. It's not as traumatic to engine internals. The inside of all my bikes looked as bad as that to begin with. After a few tanks everything inside was either bright and shiny or that yellow color that aluminum gets inside an engine.

MMO doesn't actually burn, it vaporizes under the pressure before combustion and absorbs into the carbon eventually softening it and causing it to turn loose and be blown out the exhaust. Two ways this it better for your engine than water. 1. it's such a small amount and it's in the fuel it doesn't cause any thermal shock to the internals. 2. The carbon is soft when it leaves, not fractured crystals as it is with water.

MMO was created in the 20's as a fuel additive for supercharged aircraft engines. It was a top end lubricant/ super charger lubricant. Remember they didn't have Teflon strips for super chargers back then or these converted turbos that are gear driven we have now. It was metal to metal supercharger rotor contact and it had to lubed or planes crashed.

The main draw back to MMO in your fuel is the smell. My wife likes it, it is sickening to me.

BTW why can't you get MMO over there? no one sell it or is it illegal? If it's just not sold there and it's legal I could send you a bottle or two or you could go to the MMO website and see if they will ship you some.

It has tons of uses, one of my favorites is dried out rubber bits. Let them soak in it for a while and they will swell and soften like they were suppose to be in the first place. It also works great in cars if you have a rubber seal leaking, put a bottle in about 500-1000 miles before your oil change, it'll soften the seals and most of the time stop an oil drip. I use it in everything I own except two strokes, including my diesel truck. I know a guy that even put a little in his forks when the seals started leaking a little, he ran it till the leak stopped then changed the oil in his forks. Personally I'd just change the seals but to each his own.

 

I think you can get it in the UK but there are very few distributors. I should be able to get hold of some. Thanks for the offer though. I suspect sending it in the mail would be fraught with difficulties in this health and safety obsessed world we live in. I have a few cans of BG44K left to run through so I'll see if they do anything first.