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New bike with some small minor issues

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Hi all, i got this a few weeks ago. Its a 05 CR250. Extremely happy with it and it has alot of power, its my first two stroke. It seems to have a few extras on it, vforce3 reeds, hydraulic clutch system and a jdjetting kit.

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I noticed a small leak yesterday after a ride, is this serious? how do i go about fixing it?

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I think I may have a small jetting issue aswell. I'm on my second spark plug in about 6 hours. I'm pretty sure the first one was buggered by my poor 2 stroke riding technique - just not enough revs, however the latest plug (NGK BR9EIX) lasted 3 rides, and these rides had alot of revs. I'm wondering if they are fouling from the idling when warming up and putting the bike on the trailer, so im thinking the jetting might be a bit off? If it helps the previous owner did a season of racing before he sold it so it could be set up for that. I plan to do trails and harescrambles with it.

Im running a mix of 32:1 which the previous owner also did and by some searching on the forums - premix doesn't foul the plugs, incorrect jetting does. Any tips or suggestions on fixing it myself?

Apart from that its a really tidy bike and will serve me well. Will do a top end rebuild in about 20 hours after I manage to track down a service manual.

Thanks for the help in advance, this looks like a very informative forum and I plan on contributing as much as I can.

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So after talking on the TT chat its a gasket that isnt on right. Ill grab a new one and put it on. I guess with the gasket not being on right its taking a bit of oil from the bottom end causing it to run too rich and fouling plugs.

Hopefully that should fix it.

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There could be a couple things going on there. How hard is it to start the bike? Normally with a bad head gasket it will cause a lean causing a hard start plus in my past experience there is normally signs of coolant loss. Are you sure its not just coming from the pipe and working its way around? I have never really seen oil like that leak in that specific spot. Maybe an overly gummed up PV as well could be the culprit. Check your jetting and post it here. Just to be clear your bike should not have any oil in the bottom end. The mixture should only be entering the cylinder, firing and burning off and out the exhaust. Try a BR8ES plug, I have always had good luck with them as well and they are cheap. I also run a 40:1 mix using a higher end 2T oil. What oil are you using to mix as well?

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Bike with a new plug starts first kick without choke every time. Will double check the oil leak.

Sorry what is a PV?

How do i check the jetting?

Im using castrol tts pre mix oil.

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Looks like your Vforce may be leaking also, they are very prone to do this. your best friend is the Leak Tester in the sticky section.

Make sure you wash the bike very well to keep the dirt out while you work on it.

Get a Service manual, never assume the previous owner took proper care of it, look for problems short of splitting the case.

also - Your chain looks tight

I love my 05 and it looks like you got a great bike, just needs a good going over as mine did when I got it.

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PV= power Valve but in your case its the RC Valve. In the pic you can see the oil built up on the bottom of it and then it transfers down to where the jug meets the bottom end. I bet if you pull that side cover that says RC valve you will have a really nasty gummed up section. To check the jetting you need to pull the carb and disassemble. Fouling plugs like you are could be anything from wrong jetting to the floats just being off. Either case can also cause excessive spooging as well.

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Yeap, took the rc cover off and there was alot of black oil in there. I was a bit nervous about taking covers off - this is all new to me.

Where does the oil come from? is a seal broken or does it just happen occasionally?, im looking up how to clean it out now. Got any tips?

Will adjust my chain when i put back wheel back on - went to replace bearings but noticed I need a retainer tool, ordered it off ebay so will be here soon I hope.

Will check out the leak section about my reeds.

Thanks for the help :smirk:

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All that goop can be signs of improper jetting, possible float height issues or a worn top end.

Grab a manual and get familiar with tearing everything down, you should be able to find a downloadable PDF here somewhere. Its pretty easy if you follow along. I chased a fouling plug issue along with massive spooge leaking out the pipe for a while. We rebuilt the top end, changed jetting, etc and it still had issues. Ended up being the floats were off by a couple mm's. Once the floats got situated it was like a whole new bike and ran great. I heard everything from a right hand crank seal to warped head when it was a 10min fix inside the carb.

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Ill try hunting down a manual, seem to only see 02-04 ones, are they similar?

The top end is about 20 hours old according to the previous owner.

Will check out the jetting settings tonight after milking.

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Ill try hunting down a manual, seem to only see 02-04 ones, are they similar?

05 - 07 is the range for the service manual

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I may be wrong , but I believe you are running the wrong heat range plug. My CR125 takes a B9 range plug and I believe your 250 takes a B8 range plug stock. I believe most 250's take a b8 plug.

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I may be wrong , but I believe you are running the wrong heat range plug. My CR125 takes a B9 range plug and I believe your 250 takes a B8 range plug stock. I believe most 250's take a b8 plug.

BR9 is correct

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Ok so have taken out the jet needle, its the blue one and the clip on the third indent, just trying to take the bottom off the carb now to give you the pilot and main, but the screws are on insanely tight. ok these screws arent coming out, they are just getting rounded if i carry on.

damn

edit:

Ok got em.

So my jetting is blue jetting needle with clip on 3rd, main jet 400, slow jet 32.5

my problem is im running too rich. how do i fix it?

thanks

Edited by speights

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What elevation and temps are you at right now?

That jetting sounds pretty good. Flip the carb upside down and look at your floats. A good rule of thumb is they should be parallel to the bowl. Make sure they aren't sitting to low or to high. The Blue needle is the richer needle in the series, you could try to raise the C clip up one notch away from the tip or even try the other way if that doesn't help, moving the clip up will lean it out a little and may help clear it up. How many turns in your air screw out? Should be somewhere between 2-3 turns I believe.

Oh yeah and BR9 is the correct plug but you can run a BR8 series with no problems. The 8 is just a hotter plug so unless you are wide open at the track an 8 series plug will be fine as well.

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Im at around 100m above sea level and 20degrees celesius.

Will check out the float now.

Is there any harm in moving the clip up to lean it out a little?

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jetting is like a game, sometimes you may find the right mid range power but not the proper top end power. You change the main jet a size or two and you will have your top end power back but lose mid range. You just need to find the happy medium.

The needle is meant to be adjusted, if you adjust it and notice poor improvement right away go back to where you were at and start over. This is the joys of tuning a two stroke.

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Yeah defently just got to play around with it. I put the airscrew out to 2 1/4 turns and i think its running a bit nicer. This is all new to me so I just got to play with it and test it out. Ill need to find a new source of plugs, the last one cost me $20USD. Where can I buy them online? Most of your guys shops have international shipping so it could work out.

Is it better to play with the airscrew a bit or change the clip? Is the clip for more dramatic changes in lean/rich? and the airscrew a bit more minor changes?

Thanks for the help :smirk:

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