PDA

View Full Version : 225dx carb/timing problem



78z2+2
07-07-2014, 07:36 PM
Recently purchased a yamaha 225dx that needed a little work. It has been sitting for a while so there was a lot that had to be done. I got a carb rebuild kit for it and completely went through the entire carb and cleaned and replaced everything I could. I also took off the stock airbox and just put on an aftermarket air cleaner. I got it to start up and idle perfectly. The problem is driving it, when I give it more than half throttle it just bogs down and dies out. It will also backfire from time to time. I have the little screw down by the bowl adjusted to 1 1/2 out, and have the carb slide needle all the way down as that is when it runs best out of the five little lines. I really don't have a good choke set up currently, it had the choke assemble then a piece of the cable hangs down by the carb and has a washer on it and you can pull it up with that. It never needs the choke to start though, and starts right up with the electric start every time. I took off the little rubber cover above the pull start to check the timing, but all I can see down in the little hole is oil. When it is sitting idling I can give it throttle and it will pick up some, but it still stumbles some and when you get to full throttle it just bogs. Anyone have any suggestions. I do have the clymer manual and have been reading up on carb adjustments but I am really baffled with this machine. Oh and the float level is set correctly according to other posts I have looked at saying to flip it upside down and set it level to the carb body. Any and all suggestions are appreciated, thanks!

muthey
07-08-2014, 12:38 AM
I recommend putting the stock air box back on. but if you really don't want to do so then you are going to need to rejet. Running an aftermarket open air filter you are leaning the machine way to much to use the stock jets. you oem air filter is an oil bathed filter as well, so beyond the long draw through the frame for air it also has to go through a coating of oil. the timing mark right beside the pull start is a cap with a allen socket on it, and is threaded in. it would help if you took pictures so we can see where you are looking. there is a good start of things for you to try. I can't help you with what jets to run as I run oem on mine, with oem airbox as well. I am no re jet expert by any means but with everything you have described to run the way you are set you are going to need to richen up your machine. Once we've seen were you are actually checking for timing, you can double check you're valve adjustment as well. You shouldn't have that much oil coating your stator, try a flashlight while you are looking in there, and you should see an f mark and a t mark. T is for top dead center, but when you check make sure your piston is at the top of the cylinder head when it is marked.

78z2+2
07-08-2014, 03:09 PM
I thought the air cleaner may have something to do with it, and was planning on going back to stock. I need to find the rubber hose between the carb and the airbox as mine didn't have it when I bought it. Anyone have one? I'll do some searching on eBay as well. And once I get a chance I'll check out to see if I'm looking in the wrong spot for the timing marks. I removed a little circlip and a rubber plug and though that was the viewer but I guess that isn't the right spot according to the information you just provided me. Thanks for the help, and I will keep you updated.

muthey
07-08-2014, 11:32 PM
I just went and looked and you were looking in on the transmission there bud lol, the timing marks are right behind the pull start, under the allen head bolt there. you won't have to pull the pull start off either it is on the case right behind it. let me check on the air box hoses I have for my ytm 200 air box, I might have one that will work.

dougspcs
07-09-2014, 07:16 AM
In addition to what Muthy said..

Spend a bit and put a proper choke cable on and recheck the plunger operation.

That isn't a choke but a fuel enrichment circuit..

Problems there will just mess with your head as you're trying to set up you jets and needle settings.

The backfiring on accel to me says you're running lean on the mid-circuit, but sound like you're rich on your idle circuit since you can start from cold with zero choke.

Start from ground zero and do it again!!

Lastly a compression test wouldn't be a bad idea..an engine with low compression will be impossible to get your carb set right since your intake pressure will be too high.

78z2+2
07-09-2014, 02:28 PM
Well that explains why all I saw was oil lol. I may be home early enough from work today to go back and take a look at it. Hopefully I can find me a hose pretty soon for the carb to the airbox. @doug I was also planning on fixing up the choke the right way. It is operational and I went in and cleaned it all out when I did the carb and put a new o-ring on. I have to find me a choke assembly next. I will try to get a conpression test done too and compare it to numbers in my manual and let you guys know the numbers as well. Thanks all for the great input