continuing dramas on my dr, have pulled head to find nothing other than 1 exh valve a very light brown colour and the other all soooty and black, could this be just valve adjustment or a bent or fukked valve , or more , cheers W
L-Plate Rider
continuing dramas on my dr, have pulled head to find nothing other than 1 exh valve a very light brown colour and the other all soooty and black, could this be just valve adjustment or a bent or fukked valve , or more , cheers W
Unexpected Spanish inquisition
No, that's normal - in simple terms the black sooty ones are inlet (run cooler due to fuel mixture passing over them) the light brown ones are exhaust (run hotter due to the escaping hot gasses)
See attached pic
Now all you have to worry about is whether they are seating properly and your valve clearances.
Before you judge a man, walk a mile in his shoes. After that, who cares? ...He's a mile away and you've got his shoes
L-Plate Rider
dr 250 has 2 exh valves and 2 inlet valves, ( being a current 19 86 model eh ) its the 2 exh valves im meaning here, cheers again W
will try to get a pic up, but havnt done it before so bear with me al right!!!
Rider Coach
Could be that one has been replaced reciently.....
Can you see hone marks on the bore? (Cross Hatchings).
Does the piston crown look rather silver, or is that a little dark and sooty too??
How were the clearences? Have you checked them yet?
L-Plate Rider
can see cross hatching in bore, piston crown is silver on outer 5mm and sooty as in middle, havnt checked valve clearances, and this is interesting , when i checked the timing marks i had to move cam chain back 2 tooth to get marks in right spot , bought bike thinking it had carb issues, WTF ?!! cheers W
Forum whore
Does it have twin carbs? That was an '80's thing,but don't know if Suzuki did it.If it has,that will be the reason for one exhaust valve being a different colour - and it's normal.
Unexpected Spanish inquisition
Ah...ok, some good pointers from others here, but yes a pic will be a big help. If you have trouble posting a pic let us know and someone will be sure to help you get it sorted.Originally Posted by w arwick
Before you judge a man, walk a mile in his shoes. After that, who cares? ...He's a mile away and you've got his shoes
Rider Coach
Right! As I suspected.
In the recent past, your engine had "Dropped" a valve.
They replaced one. It also damaged the piston, so they replaced that. Might have even put in a 0.5mm over sized one in there, and gave it a re-bore.
Could have replaced it with a standard one if the bore wasn't touched, but gave it a hone to mate with the new piston and rings.....
I also suspect that when they put it all back together, they mucked around with the cam timing to try and get more poke out of the little 250....
Trouble is, this will make it a real bitch to start...... OH, WAIT!
SO, put it all back together, and set your timing marks to nominal, and see how it goes.
At least you are at a starting point.... And in my opinion, have found something that is not helping, if not the total cause.
BTW, the dropped valve is just one possibility, but I can't really think of a reason to just to replace one... In fact, personally, If 1 dropped on me, i would replace both in a single... After all they are the same age.
In a 4, you are talking 8... So I can see why not to replace all, because one went AWOL.
Forum whore
Flow of gases in the head might not be perfect, ie not equal flow through each valve, so one valve gets hotter and burns off the soot more than the other. Maybe.
Early japanese four valve head designs were more of a marketing exercise than flow bench developed optimum (eg single cam CB750 Honda heads flowed better than the first twin cam four valve CBs.) TSCC Suzuki design was said to be one of the better ones.
it's not a bad thing till you throw a KLR into the mix.
those cheap ass bitches can do anything with ductape.
(PostalDave on ADVrider)
Rider Coach
May be... BUT, I thought they got it pretty sorted by 1986.... Or was that just Honda with their RFVC? Radial Four Valve Combustion Chamber, Not slydexic for some Superbike, for those that don't know.
Unexpected Spanish inquisition
I suspect you are right, especially that last sentence. It'll be interesting to hear the outcome.
Before you judge a man, walk a mile in his shoes. After that, who cares? ...He's a mile away and you've got his shoes
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