Mokwepa

Member
Jan 27, 2008
47
0
Hi guys

A mate has a 97 yz250wr. When the bike is cold it starts fine but after that it really battles. Im tired of push starting the thing. I am not sure what the jets are but i do know that the air skrew is all the way in.

What i think is that the pilot jet is too small. If i start the bike and turn the A/skrew one turn out, it dies. The bike also doesnt want to idle at the moment.

Any ideas???

Dylan
 

mox69

Member
Mar 26, 2007
236
0
Did these problems just show up or have they always been there?

1. Clean the carburator fully. Take it off the bike, take it apart and clean all of the holes in the jets. Make sure the float is working, etc.

2. Clean the air filter.

If those things don't help, refer to the links at the top of this forum on how to jet your bike. If you can give the numbers of your main and pilot jet , people can probably give you more information. Get this info when you clean the carb.
 

rmc_olderthandirt

~SPONSOR~
Apr 18, 2006
1,533
8
Mokwepa said:
Hi guys

A mate has a 97 yz250wr.


There is a YZ-250 or WR-250 but not a YZ250WR

The YZ and WR look a lot alike, but the WR would have a kickstand, an 18 inch rear tire and a few other minor observable differences. The big difference is in the transmission.

Let's make sure we are talking about the right thing. I am assuming it is a WR-250, which would have the air screw on the right side of the carburetor and the idle speed adjustment on the left. It also has a lever for operating the cold start enrichment (choke) that is operated on the left.



Mokwepa said:
I am not sure what the jets are but i do know that the air skrew is all the way in.

What i think is that the pilot jet is too small. If i start the bike and turn the A/skrew one turn out, it dies. The bike also doesnt want to idle at the moment.

Dylan


I don't understand what you mean when you say the bike doesn't idle, and when you turn the air screw out it dies. Will it die even if you are reving the engine up? I would not expect the bike to idle with air screw all the way in.

Like Mox69 said, I would start by properly cleaning the carburetor. This involves a soak in a really nasty solvent. I highly recommend a new set of gaskets and possibly a new float valve. You will need the manual so that you can set the float level properly. Making any mixture adjustments without the float level being proper will be a waste of time.

If the carburetor is clean and the float level is proper the next step would be to get it to idle. Turn the idle speed up to whatever you have to in order to keep it running. Now adjust the air screw for best (fastest) idle. Now turn the idle speed down a little, as low as you can take it and keep it running. Adjust the air screw again for best idle. Keep doing this until you obtain an acceptable idle speed.

IF you are able to get the idle acceptable, don't mess with the air screw! It is only for idle. If there are problems with bogging, sluggish or top end then you need to work on jetting, don't try to compensate with the idle circuit.

Rod
 
May 1, 2007
85
0
rmc_olderthandirt said:
There is a YZ-250 or WR-250 but not a YZ250WR

The YZ and WR look a lot alike, but the WR would have a kickstand, an 18 inch rear tire and a few other minor observable differences. The big difference is in the transmission.

Let's make sure we are talking about the right thing. I am assuming it is a WR-250, which would have the air screw on the right side of the carburetor and the idle speed adjustment on the left. It also has a lever for operating the cold start enrichment (choke) that is operated on the left.

Rod
I have heard several people tell me the same thing but there is in fact a YZ250wr. My title, bike bandit, and Clymer manual say so. The only difference between a 1989 YZ 250 and a 1989 YZ250wr to my knowledge is the wide ratio gearbox. The wr in the name might not even have anything at all to do with a WR250 but might just stand for YZ250 wide ratio. I can't tell you that for sure but I can tell you they exist.
 

Mokwepa

Member
Jan 27, 2008
47
0
robbieisurfriend said:
The wr in the name might not even have anything at all to do with a WR250 but might just stand for YZ250 wide ratio. I can't tell you that for sure but I can tell you they exist.

You are spot on!
 

yamarider88

Member
Jun 24, 2007
153
0
yea on a lot of these old 2stroke wrs and yzs the heads would hook right up to either or so you could put a wide ration in a yz and a higher compression head on a wr i thought about doing it once but decided it wasn't worth it for me. i also think the newer wrf and yzf are the same way.
 
May 1, 2007
85
0
I also want to add that the stators, and maybe all electronics are not interchangable with a YZ. The YZ250wr might not have lights but it still has the lighting stator of the WR. (atleast in my year.)
 

zoommx

~SPONSOR~
Apr 23, 2001
282
0
In 97, the WR model was that a WR250, and the YZ was a YZ250. in 89, there was a yz250wr. Now on to the problem, sounds like the pilot (also known as slow) jet is probably plugged or at least partially so.

Roger
 
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