My new to me 04 200 has the knock everyone talks about. I'm thinking i'll give it a good de carbon. Is this as simple as pulling the head and cleaning the piston top and i would assume underside of the head. Or do you have to pull the jug too? And how and what do you use to clean/scrape the carbon off with. The owners manual is pretty minimalist. Is there a service manual for this bike? I'm in the states btw.

Previous owner did all the carb mods and i realize there may be some jetting i can play with plus mixing race gas etc etc. but I'm wondering whats involved with going the de-carbon/coke route

Hi from down under.

I don't know how severe your knock is, but a new plug is always good value. Factory recommend the champion ny7cc, which = NGK BP7ES (both off the top of my head).

Regardless of how you fix it, be sure to post your solution!

Cheers,

Chris.

Here in the UK, they reccomend using a BPR5ES which is a slightly hotter plug. I've never been sure whether having a higher resistance plug (BPR5ES) has any effect either.

Not too sure about your top end clean up, but I think the carbon should just wipe off.

Bob

Skid...with the work it takes to get the head off your a 1/3rd of the way there to doing a complete top end. Yeah it will cost you some money but having a nice fresh bike sounds nice too doesnt it.

As far as removing carbon...the only way I know how to do it is using a O/A gas torch, and the only time I did this was on a pipe. I dont know if the high heat would warp the head, something tells me it might.

I've always just put the head in some cold water to help make the carbon deposit a little more brittle and then scraped it off with somthing a lot softer than the alloy but which is still sufficiently hard to remove the carbon (e.g. a plastic spoon). This has always doen the trick for me.

remove the head, piston and barrel, so you can get right into all the ports and clean out the ring groove . start by scraping with a plastic tool, anything really as long as it does'nt mark the metal. finish off with brake cleaner and a scouring pad (the ones you get from the supermarket are fine, and cheap!), remember to wear rubber gloves ! the result will be ............PING!

I normally use petrol and a rag,if the rag does'nt work get some smooth wet and dry cloth,but but make sure you soak the wet and dry into the petrol first.

getting the head off and de carboning the top of the piston is 'relatively easy' although it is damned fiddly and may not cure your 'knock'

ihave similar symptons on mine on overun and it comes and goes depending how accurately i mixed the oil and petrol and how 'old ' the petrol is (bikes only ridden two or three times a year) use premium fuel and err on the 80.1 oil mix and the 'knock' might just go away for a lot less hasele than a top end strip..

Thanks for the replies. Guess I'll do a little head scratching before i pull any engine parts off!! Definitely don't like the way it runs right now.

One of the best & easiest ways to remove carbon from your motor is to use a product called Ring Free from Yamaha. It was developed to keep outboard motors clean. I have bought it from Yamaha outboard dealers and most Yamaha motorcycle shops can order it for you.