Valve adjustment for the GZ250

Chris · 02-21-2009, 05:51 PM

I've mentioned that I have a friend who used to be a motorcycle shop mechanic and has had several promotions since then so he is a national motorcycle maintenance expert. This guy is a real resource for motorcycle information and a lot of other things. And a good friend.
Today he came over to adjust my valves and I said in this forum that I would report back on what he said and did. He said that most people had no idea if their valves needed adjusting or not. If they are too tight that is bad and too loose is bad. If they get out of adjustment it could toast your engine and most people simply would never know it was coming.
So how do you know if they need adjusting? You never would. He said to make the first adjustment at about 5000 miles (mine has 5400 right now) and about 5000 miles after that. Best is to get it done about 5000 and then every 5000 miles. Sometimes you go in there and they don't need any adjustment, but then you are sure it is right.
He says this has a very small effect on performance and even on valve noise. Too quiet is bad as the valves are probably too tight (mine were).
I offered to ride the bike to his house, but he said that it takes the engine so long (2 hrs.) to really cool down that it was easier for him to just come to my house. I won't tell everything he did, but it started with taking the gas tank off. Then the chrome cover on the left side where the spark plug is. My spark plug was loose, but no damage had occured. My plug looked great. Then he tried to take off the small plate on the left side of the engine to be able to move the piston to TDC. But the plate would not budge so rather than bung up the plate we put the bike in 4th gear and by moving the bike that moved the piston (without the plug there was no compression so it was easy) back and forth until the piston was at TDC. It comes to TDC twice and you want it at TDC on the compression stoke. Hard to know when this is, but when the valves are loose that is it (valve caps are off. Labeled #1 and #2, put them back the same way).
Loosing the nuts and adjusting the "valve adjustment screws" and tighting the nuts was tough. There are two valves: exhaust in the front and intake in the rear. He adjusted both and put everything back together. I videoed all of this so I can do it the next time.
Honestly, this was pretty hard to do and I don't think the average rider should attempt it.
Probably $100 at a shop. With my video I think I will do it, but just starting from scratch I don't think anyone should try this. Unless you have done this on other engines.
So it went well and I owe him a big favor. Just thought you would want to know.

Chris, retired, Atlanta

02-21-2009, 05:51 PM	#1
Chris Senior Member Join Date: Sep 2008 Location: Atlanta, Georgia Posts: 109	Valve adjustment for the GZ250 I've mentioned that I have a friend who used to be a motorcycle shop mechanic and has had several promotions since then so he is a national motorcycle maintenance expert. This guy is a real resource for motorcycle information and a lot of other things. And a good friend. Today he came over to adjust my valves and I said in this forum that I would report back on what he said and did. He said that most people had no idea if their valves needed adjusting or not. If they are too tight that is bad and too loose is bad. If they get out of adjustment it could toast your engine and most people simply would never know it was coming. So how do you know if they need adjusting? You never would. He said to make the first adjustment at about 5000 miles (mine has 5400 right now) and about 5000 miles after that. Best is to get it done about 5000 and then every 5000 miles. Sometimes you go in there and they don't need any adjustment, but then you are sure it is right. He says this has a very small effect on performance and even on valve noise. Too quiet is bad as the valves are probably too tight (mine were). I offered to ride the bike to his house, but he said that it takes the engine so long (2 hrs.) to really cool down that it was easier for him to just come to my house. I won't tell everything he did, but it started with taking the gas tank off. Then the chrome cover on the left side where the spark plug is. My spark plug was loose, but no damage had occured. My plug looked great. Then he tried to take off the small plate on the left side of the engine to be able to move the piston to TDC. But the plate would not budge so rather than bung up the plate we put the bike in 4th gear and by moving the bike that moved the piston (without the plug there was no compression so it was easy) back and forth until the piston was at TDC. It comes to TDC twice and you want it at TDC on the compression stoke. Hard to know when this is, but when the valves are loose that is it (valve caps are off. Labeled #1 and #2, put them back the same way). Loosing the nuts and adjusting the "valve adjustment screws" and tighting the nuts was tough. There are two valves: exhaust in the front and intake in the rear. He adjusted both and put everything back together. I videoed all of this so I can do it the next time. Honestly, this was pretty hard to do and I don't think the average rider should attempt it. Probably $100 at a shop. With my video I think I will do it, but just starting from scratch I don't think anyone should try this. Unless you have done this on other engines. So it went well and I owe him a big favor. Just thought you would want to know. Chris, retired, Atlanta Login or Register to Remove Ads
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