[camshaft]

Ok here's the short story, bought a basket case 2004 250R with a broken crank and broken cases. Replace bottom end with an eBay special, bought a new head with Kibblewhites from CRFSOnly, assembled the engine, new plug....wait for it.....no start.

Now I don't know if this bike ran well prior to previous owner grenading it or not. With that in mind, I checked and rechecked timing and disassembled carb to clean it out only to find absolutely nothing clogged, dirty, or other wise. Reassembled and installed on bike. After kicking for so long that the bottom of my foot is bruised it finally started and ran for about 15 seconds until I clicked the choke off and it hasn't started since.

Again, tried a couple of plugs, checked spark(with the plug, NOT a tester, this is next), plug is sometimes wet and sometimes not when after kicking it over many times. More often than not it is either wet or at least has a slight sheen like fuel is reaching it. I took the valve cover back off again this morning to again verify timing and it is still dead on, rechecked valve clearance and those are all dead on the spec except for the right intake which was .006".

It is about 50° in my garage this morning. Main jet is a 160. Fuel screw is at two turns from seated. Fuel is fresh.

I don't have the right adapter for my compression tester but it feels like it has compression and it did run so until I go into town to get an adapter I can only assume the compression is good.

With a background in automotive mechanics (GM Master Technician when I left the biz in 1997) and have and have had many dirtbikes and quads, raced karts, etc. so I'm embarrassed to be asking these questions on a forum but I'm at the point where if I hadn't just dropped $700 on a new head, I'd cut my losses and sell this damn thing.

My main question is; Do I have the wrong jet in this thing for the temperature mentioned above? It does backfire out the exhaust every once in a while which leads me to believe it is a lean condition.

Any ideas I haven't covered?

Thanks a ton in advance!

Cam

[crfsonly]

welcome to CRF's Only message boards! there are so many things that could be preventing it from starting. i won't list them all in one post. so, my first thought was the cam. is the cam the same cam that was in the bike when it imploded? if so, it's possible when everything locked up the cam gear moved on the cam. this would give the impression it's timed correctly when it is actually off. if it is the same cam do you have another known good cam you can swap in to test?

also, it's very difficult to tell if a jet is slightly obstructed. i would replace with new just to eliminate this as a potential issue. also, did you check the fuel screw? often debris from a damaged or broken o-ring gets lodged in the circuit.

lastly, check your kill switch. unplug it at the harness just to eliminate a bad switch or harness connector. also, check all electrical connections are solid.

ken

[camshaft]

Thanks Ken! You mentioned something that just might be the issue. When disassembling and cleaning the carb, I did remove the fuel screw and there was no o-ring on it at all. I'll order one from you today and see what that does.

I had considered the cam being a problem, but didn't go much further with that as there was no damage to the old head from the engine implosion, but it is definitely not ruled out. I don't suppose there is a way to tell if the gear has moved is there?

[dirtae]

I'm just going to throw this out there, I doubt it's whats causing you're problems but worth a double check.

After re-assembling everything (this was after a valve job too) The bike was ready to be started. took it out and kicked like an dork for 20 minutes. Bike started briefly for maybe 5-10 sec then died at one point during the kicking marathon.

Anyway, I eventually remembered that I had turned the idle down when the bike wasn't running (I ended up turning it WAY down). I was (and still pretty much am) a newbie with the bike. So it was a bonehead move on my part lol. I turned the idle up and the bike fired right away.

Just something to double check.

Here is a chart for jetting for the '04 250R stock fuel screw setting is 2 1/4 turns out, and stock main is 160.

[camshaft]

I'm just going to throw this out there, I doubt it's whats causing you're problems but worth a double check.

After re-assembling everything (this was after a valve job too) The bike was ready to be started. took it out and kicked like an dork for 20 minutes. Bike started briefly for maybe 5-10 sec then died at one point during the kicking marathon.

Anyway, I eventually remembered that I had turned the idle down when the bike wasn't running (I ended up turning it WAY down). I was (and still pretty much am) a newbie with the bike. So it was a bonehead move on my part lol. I turned the idle up and the bike fired right away.

Just something to double check.

Here is a chart for jetting for the '04 250R stock fuel screw setting is 2 1/4 turns out, and stock main is 160.

Man thanks for the help. I went out just now to try turning the idle up, but still no go. Just a couple of pops from the exhaust.

Thank you for the chart. Looks like for my elevation I should have a 162 in there. Although I think it should still start.

Are these things normally just a bitch to start?

[crfsonly]

the pilot jet, not the main jet, is what influences start, idle and off-idle performance. if everything is functioning as designed and is dialed in they should start in 1-3 kicks using the correct starting procedure.

ken

[dirtae]

I would run through Kens trouble shoot list. My bikes fairly easy to start. I give the throttle 2-3 full twists to prime, then in 1-3 kicks it fires right up.

[Keith72]

I cant believe that they dont suggest a larger pilot jet for colder temps. My pilots range from a 68 when its blazing hot in the summer to a 45 when its between 40-50 degrees. Get yourself NEW pilot jets, dont bother trying to clean them its a waste of time. A new pilot costs about the same as a can of carb cleaner.

For your temps right now try the 42 pilot first.

For starting it helps to give the throttle 4 or 5 full twists to prime the engine with fuel. Turn the choke on and give the bike a solid kick. Doesnt have to be a fast kick and dont fan kick it. May take 2 or 3 kicks. Let the bike run on choke for a minute or so before turning it off.

[Ryan Obert]

when i start mine i hop on, rub my number plates, pray to baby jesus, sing her a song and then start kicking. no? just me??? just kidding but i turn the throttle wide open 3 times, slowly kick it thru the stroke a few times, get the piston at TDC and kick it thru nice and strong and she fires first time everytime. make my friends (even with fuel infection) extremely jealous!

[dirtae]

I cant believe that they dont suggest a larger pilot jet for colder temps. My pilots range from a 68 when its blazing hot in the summer to a 45 when its between 40-50 degrees. Get yourself NEW pilot jets, dont bother trying to clean them its a waste of time. A new pilot costs about the same as a can of carb cleaner.

For your temps right now try the 42 pilot first.

For starting it helps to give the throttle 4 or 5 full twists to prime the engine with fuel. Turn the choke on and give the bike a solid kick. Doesnt have to be a fast kick and dont fan kick it. May take 2 or 3 kicks. Let the bike run on choke for a minute or so before turning it off.

I'm running my bike this winter with stock pilots and don't have a problem with starting or idling. maybe an extra kick or 2 sometimes when the bikes been sitting outside for a couple hrs at -5 ish C (23 deg F).

[dirtae]

when i start mine i hop on, rub my number plates, pray to baby jesus, sing her a song and then start kicking. no? just me??? just kidding but i turn the throttle wide open 3 times, slowly kick it thru the stroke a few times, get the piston at TDC and kick it thru nice and strong and she fires first time everytime. make my friends (even with fuel infection) extremely jealous!

I usually do something like that after I've been into the engine lol but really.

[Ryan Obert]

well it usually works for me. did you try fondling the exhaust??? in all seriousness hopefully you get it running soon!

[camshaft]

when i start mine i hop on, rub my number plates, pray to baby jesus, sing her a song and then start kicking. no? just me??? just kidding but i turn the throttle wide open 3 times, slowly kick it thru the stroke a few times, get the piston at TDC and kick it thru nice and strong and she fires first time everytime. make my friends (even with fuel infection) extremely jealous!

Well, my number plates are still not back on the bike. Will that make a difference? I did fondle the exhaust, but the bike acted like it wasn't really comfortable with that so I stopped.

What I just a few minutes found out, however, is that if I follow the recommended starting procedure of choke on, 5 or 6 blips of throttle, putting engine at TDC and then kicking it starts. I think I still have a carb issue as it doesn't want to idle. But it is alive. Turns out it was likely just starting procedure.

Thanks everyone for your help!

[camshaft]

For starting it helps to give the throttle 4 or 5 full twists to prime the engine with fuel. Turn the choke on and give the bike a solid kick. Doesnt have to be a fast kick and dont fan kick it. May take 2 or 3 kicks. Let the bike run on choke for a minute or so before turning it off.

Thanks! This helped!! I feel like an idiot, but I'm ok with that.

[Ryan Obert]

oh dude! put the plates back on and she'll fire right up, no problems!