Problem with the intake and filtering

[kolo]

  On inspection the other day I was alarmed to find I have ingested a good deal of dirt and gunk, noted carbs were good up and beyond that down into the valve chambers. I hate to do it but I really think I should pull the head and see the extent of the damage. I have wiped out and cleanded what I can reach from the intake but can see the valves have a lot of oily greasy build up on them. The bike is an 86 with 37,000 on it. I have read about tuliping of the valves and that the valves should be upgraded. Checking on Ron Ayers part #'s seem to show an intake valve change around  1990, is this the only up grade and is it just a matter of doing a valve job and dropping in the new valves.  Seats different?   Don't know what happened to cause this but must have a sealing issue with the air cleaner,  Anybody else ever have this problem?
   Do you think I could use and additive to the fuel or direct inject something like Seafoam or Berryman's to get the valves cleaned up without the Teardown?

[T Cro ®]

Before you go through the trouble of pulling the head you perform a compression test and compare the cylinders ideally they should all be within 10 percent of each other with 128 PSI as the lowest allowable and 196 PSI as factory fresh.

If your getting a wide variance between cylinders you than test the ring seal by pouring a teaspoon of motor oil in the cylinder through the spark plug hole and doing the compression test over again, if the compression comes back up your rings may be worn. But of the compression stays low your going to want to check the valve clearances to make sure that they are not too tight and are allowing compression to be lost past the valve seats.

If you have tuliped valves it is much more involved than just "dropping" in a new set of valves and in fact your better off getting another complete head from a newer model bike as they all swap out.

[kolo]

  Familiar with the compression test , whole drill, add oil for sealing. As far as Tuliping and dropping in valves, I meant in the process of doing a whole valve job just to be clear. But if the heads have been changed or updated I can see where getting a used head would be the route to go. As far as cost of redoing my head vs. a used head, I think a used head probably should get the works before putting it in, big job to take it back off if it isn't sealing.    Bike was running very well, just found all this grime in the intake runners when I took the carbs off. This all started when I wanted to change out the fuel line and just couldn't get the clamp on the back of the carbs, so I pulled them and discovered the oil / Grime build up.  Can this have anything to do with the breather and more specific the oil seperator down under the breather cover?
   Bike is also due for a valve adjustment, but with the build up on the valves I'm wondering if I have a problem. How about cleaning them like i stated in earlier post, Seafoam or some other product, any suggestions.  I will run the compression test tonight if I have time.

[SteveJ.]

A couple of things to check:

Look for a split in the air box, depending on where it is, it can introduce unfiltered air into the carbbies. The most common place for a split is on the front, at the bottom. Coincidentally, that spot will allow unfiltered air to carbs.

Is the little 90* hose at the bottom of the air box attached to the airbox AND the crankcase? This is a crankcase vent, and dumps its air into the airstream after the air filter.

Once things are cleaned up, avoid using gasoline that is not Top Tier.

http://www.toptiergas.com/

Good Luck.

[SteveJ.]

There is some sort of carbon remover stuff, about $25 at your Yamaha dealer. Kawi has their own take on it also, for about $10. Dunno which is better, I used the Yammie stuff.

[midnightrider]

My 2004 had that same buildup on the back of the valves. I think its a product of the rich factory jets, big overlap on the cams, and the airbox design. I went to 120 main jets with foam in the intake, and started using only shell gasoline with 2 oz. of TCW3 2 stroke oil in every tank and they are staying clean now. Just my theory. YRMV.