I've been running the KLXster magic recipe for a while now, and the gains are a hooot.

Something odd has developed on start up, that wasn't present after initially jetting the carb with the k158/1N combo. It feels as if the bike needs to warm up before accepting throttle, something that wasn't happening before. I've had the bike since January, and in the colder temps when one would expect the bike to need a warm up period, there was no issue.

I bought the bike stock, and in the process of owning it have slowly added more fuel as the air flow was increased (buying q4+powerbomb, removing lid etc.) Each step of the way saw no bog or hesitation on a cold engine. I would pull choke, let it idle for about 30 seconds, push in choke and ride away. Now that the weather is warmer, and I'm running the k158/1N, it seems like the bike needs to warm up or it will try and stall when I drop the clutch at lower rpm. I'm not saying it's the fueling set up causing it, but it has to be mentioned. If I rev it up past 5k and slip the clutch, it will pull. Anything less and the bike will lose rpms if I don't pull the clutch in.

Kouba link screw is set to 3 turns out. No visible leaks in the system, AIS is blocked off. Usually a bike that runs better when warm means it is lean... but I can't find it

The engine also seems to be running way hotter than in the winter (I know, it's hotter out) but all the same it seems worth it to mention.

Anyone else experience strange warm up times with known rich fuel settings?

 

Last year I ran

#152 kehin main
N1-tc on 2nd notch
#40 pilot

Instant warm up but the midrange felt a little soft once it was at operating temp.
Just switched to the first notch on the N1-tc and I now do get a lean bog like you describe if its stone cold. Midrange feels snappier when up to temp tho.

 

Thanks for the feedback, Rage. My bike runs great when warmed up too. It's just the first few minutes of riding that has a bog, and like you said only when stone cold- first thing in the morning. Just went for a ride after work, bike started without choke and had no hesitation to mention.

 

Cold engine ops is not on my radar - I just naturally ride "casual" on a cold engine. I've never tried large throttle manipulations on a cold engine - and no one else (using a 1N Lidless setup) has mentioned such an issue..

However, lets think about it.. I assume you are running a #35 @ 3 out and have been since winter. And lets assume nothing has actually "degraded" or is "failing" within the carb..

I could imagine temp changes would affect warmup if your throttle stop is set "wrongly" - (Idle speed set too high, 1500rpm or more..) ???

 

Klxster, to clarify I never mentioned anything beyond "casual" while operating the throttle on a cold engine. The bike bogs on regular clutch release and throttle roll on, from a stop in first gear. I'm not talking about wacking the throttle 30 seconds after starting the bike. This bog happens as I try to calmly leave my driveway at 630a.m. on the way to work, and again when I get to the bottom of the hill and release the clutch and roll the throttle on in a calm fashion. The idle is set to 1500 exactly, sits just under 4k with clutch in.

 

Ok, got it..

To me, there are too many variables involved - I can't get any ONE possible cause to stand out amongst the others.. So perhaps throwing out the list I've come up with..

On cold startup and initial cold running, (choke on), fuel demand from the bowl is quite high and pilot system operation is critical.

A). Since last winter, the fuel level/delivery has changed - faulty "needle/seat" - perhaps slightly clogged filter.

B). Since last winter, the pilot jet has slight clogging/restriction - affecting a small portion of its' functioning..

If the Kouba and pilot jet are functioning correctly, you should be able to lower your idle speed to 1250 -1300 with no issues.. This is the proper idle speed. If it will not idle at this speed, something is wrong - air leaks, pilot system, valve clearances, etc etc..

C). During the last 6 months, the slide has developed a stiction that only manifests during cold ops.. Never heard of this, but I can imagine stranger things...

"If I rev it up past 5k and slip the clutch, it will pull. Anything less and the bike will lose rpms if I don't pull the clutch in."
To me, this is a malfunction - plain and simple.. The fact that it has "come on" slowly over the last 6 months is the "head scratcher"..

 

Before posting this thread I cleamed the carb. I should have clarified that the bog happens with the enricher inactive, after letting it sit for a while with the **** pulled out to warm up. If I ride away with the enricher pulled, Idle just under 4k, there is no bog. The fuel filter did not appear to be plugged either. The bog only happens first thing in the morning, or after sitting for 8 hours after work. If I let it warm up for over a minute, say 3.. no issues.

It's not ruining my day or causing me grief it's just odd... bike still runs fine after that first couple oddities. The k158/1N is fun but I do I wish I had more bottom end, but thats for another day/ bore/ bike

My buddy just bought a wr250r bone stock and it will loft the front wheel easier than my klx... My wr250r (sold) was modded with GYTR exhaust and PCV, didnt loft as easy as with a stock pipe...sometimes the engineers get it right with that pesky backpressure..

351cc kit is getting real attractive these days :O

 

I believe I have. At any rate, if i hadnt... I too have what I would call "cold natured" performance within the 1-2 minutes or riding before the bike warms up, it will feel like lean stumbling if given any throttle. But, considering every carb'd vehicle ive ever owned has acted like this when not fully warmed up it seems normal to me.... Even my leaf blower does the same. And since it clears up after a min or two and runs great at operating temp, it doesnt bother me much

I should add my KLX in particular has had this issue when stock, DJ Stg2, 140/2N, 140/1N, 144/1N.

 

Got a pic of your bike?

 

Here ya go...