Oil in Carb

[2strokesurvivor]

I was breaking down my stock carb ('03 CR 250) after having problems with power loss at 1/4 throttle or so..haven't ridden in some time. I noticed that there seemed to excess oil in the carb. Is that normal after sitting for some time? Could this be causing my problems? I am going to put in back together with jet settings stock and see what happens. I was having similar problems but at higher throttle, 3/4 to full. I had cleaned the filter and then decided to change the reed valves. I only found 1 reed with a small piece missing on an outside edge. Replaced with v-force. At least now I now where the jets are and have the owners manual to make necessary adjustments. Got to start somewhere. Sorry for the rant, really just curious about the oil. Could it be from my filter if heavily oiled? Does anyone remove filter and plug air intake if storing bike for a long time? Thanks.

[2strokesurvivor]

Put it all back together and ran the bike...still bogging under load at low rpms. Once I hit higher rpms or keep the bike at high rpms, there are no problems. Ran fresh fuel with 32:1 ratio, checked filter and exhaust. Jetting/air screw are at stock (screw 1 1/2 turns out, slow jet 30, main 420, and clip on second groove. I tried to check my float, but only have a digital caliper that won't actually touch the float, so I was guessing. Could someone point me in the right direction for checking the float, do I need to purchase a special tool? I haven't looked at my power valve yet, but I cleaned when I did my top end and have only rode 5-6 times since. How would I know if it is stuck? I also see that it could be related to the slow jet, air screw, or clip position. I only have one more setting to go leaner on the jet needle. I just don't feel like it is one of those problems, as I never had any issues with riding under the same conditions for 3-4 years. Any advice is greatly appreciated. I did some searches, but can't seem to find exactly what I'm looking for.

[cowboyona426]

You've done everything I can think of man... I'm wondering if the "oil" in the carb was the beginning stages of varnish, try a good thorough cleaning of the carb and tank to remove any nastiness that might be lurking about and see what happens.

[2strokesurvivor]

So..today stopped by a Yamaha shop and a picked up 2 spark plugs and asked the mechanics on duty what they thought about my problem. They seem convinced that it was the slow jet. The stock is #30, so they said to try a 27.5 and a 32.5 and see which one fixed the problem. Well got home and tried both and neither one worked. Leaning it out (27.5) seemed to make it worse. While riding it also seems to rev high after throttle release, and even stuck wide open for a few seconds. I don't think that it is a throttle cable issue, but what else could it be? I checked the v-force web site to double check that part number, it was correct. Could the power valve cause this problem? I read on one post that you should not be able to move the valve by hand when tightened correctly. What about the top end or air leaks? I know I might just have to take this in to a shop, but I would really like to figure it out and do the work myself, not so much for the money saved, but so I can DO the work and understand the bike better. .....FADED where are you??

[DRGSin393]

how about an air filter having too much oil???

[2strokesurvivor]

Yes, I thought about that also. I took out the filter and checked it, seemed to have plenty of airflow. I haven't been on here in awhile, and forgot about the knowledge base. I checked it out and found some good threads on jetting....seems that the 03 CR250 can be a pain in the jetting department.

[dogger315]

Does anyone remove filter and plug air intake if storing bike for a long time?

Yes. Remove the air filter and place it in a zip lock bag and cover the
intake with a wash cover like Twin Air sells.

I'm wondering if the "oil" in the carb was the beginning stages of varnish

That's my guess. If the gas was left in the carb long enough to go bad,
it can take more than new gas to get rid of the damage. You will probably
need to disassemble it and soak it in carb cleaner for a while. Then use
compressed air to blow out the passages. You might even have to replace
some of the jets if you can't get all the varnish out of the tiny orfices.
Concentrate your efforts on the slow jet and coresponding passages,
that's what is causing the problem.

Could someone point me in the right direction for checking the float

The float level can easily be checked with a simple ruler. Hold the carb
sideways and tilt it slightly until the float just contacts the float valve
(not depressing it), then measure from the top of the float to the bowl
mounting flange. Since the bike ran fine before sitting, I'm betting the
level is good just like the reeds and power valve.

If you have had good luck with the Mikuni and are satisfied with the
performance and reliability, just clean it up and go. If not, I would do
the PWK swap like so many others.

dogger

[2strokesurvivor]

Thanks for the reply and insight. I am not able to do much work to my bike on the weekends...or riding for that matter. I work (air conditioning) every other weekend, and my wife works the opposite. We have a 2 yr old daughter, and so I am watching her on my weekend "off". I may just track down a new carb, but I think I am going to see this problem through first to give myself some edumacation (and a few headaches I'm sure). One thing I had forgotten about, the last time I was out at the track, some other rider was trying to help me, and thought that my idle screw was my air screw..air screw was buried under mud. We made adjustments all the way out and back in, and of course it did nothing to help. How can I tell if this screw is set properly? Thanks again.

[Faded]

Originally Posted by 2strokesurvivor

While riding it also seems to rev high after throttle release, and even stuck wide open for a few seconds. I don't think that it is a throttle cable issue, but what else could it be?

I would replace the left side crank seal. It's cheap and easy but you'll need a flywheel puller. I've posted the how-to on here a few times.

If you're looking for air leaks, spray carb cleaner wherever there's a gasket with the bike running and listen for the idle to change. If you have an air leak it should be easy to find.

If the bike has ran fine on that jetting in the past don't try and fix the problem by rejetting. You should only need to clean the jets and the carb and then you need to look somewhere else.

[2strokesurvivor]

Thanks Faded,

I read the post on the seal, I'll give that a go and take some pics (in case I really mess up). I'll give the carb cleaner sprayer a go.