crf150r throttle (carb) issues

[nsxxtreme]

I purchased my girlfriend a used 2007 crf150r. The only thing aftermarket on it is a whitebros xcr exhaust everything else is stock.

My problem is the thing dies if it idles and then you crack the throttle wide open. If you roll the throttle it does fine. The original owner changed the pilot jet to a 45 instead of the stock 40. I changed it back thinking this might fix it but no I was wrong.

Next I'll be changing the spark plug just for good measure but the way it runs it seems to me a carb issue.

Any ideas?

 

[jackflack44]

Where are you? What altitude are you at?

 

[Rich Rohrich]

The stock pilot jet is too lean with the stock pipe, with an after market pipe and depending on your fuel you may need to go even richer than the 45. The 45 might work if change the leak jet as well, but that depends a lot on your local fuel , and the air temp.

 

[nsxxtreme]

I'm in Oregon and we usualy go riding at Brown camp. I'm not sure on elevation? It usually in the 60's here. I run 91 octane chevron gas.

This problem is only off idle if your riding the bike and crack the throttle it does fine. But if you idle then crack it, it dies. The original owner said it was this way since new. If you say its lean with the 40 maybe I'll put the 45 back in. How much larger then a 45 do you think I should try? leak jet :whoa:? that's new to me time to break out the owners manual.

I was reading the paper work from whitebros exhaust and they recommended the stock jets which is what made me change it back.

I'm really impressed with the 150r its a powerful little bike.

Thanks for the replies.

 

[Rich Rohrich]

Keep in mind, no matter what you do to the jetting you can't just whack the throttle wide open on a four-stroke from idle.

 

[nsxxtreme]

Keep in mind, no matter what you do to the jetting you can't just whack the throttle wide open on a four-stroke from idle.

ok that's news to me. I'm a 2-stroke guy. This is the first newer 4 stroke we have owned. So I shouldn't expect to be able to crack the throttle open from idle? How should I expect it to run?

 

[Rich Rohrich]

How should I expect it to run?

Expect it to run like a four-stroke. In other words learn how to ride by rolling the throttle open and rolling it closed.

 

[_JOE_]

The needle and ap circuit have a huge impact on the throttle response. Mine always hesitated if I cracked it more than 3/4 turn until I timed the squirt and did the o-ring/leak jet deal. I also shaved the rivet down on the diaphram. Now I can whack it pretty hard and it rips. My wifes ttr won't take more than half throttle off idle. I've not had any luck finding pilot jets local so I just let it be. She's never had it happen to her.

 

[nsxxtreme]

The needle and ap circuit have a huge impact on the throttle response. Mine always hesitated if I cracked it more than 3/4 turn until I timed the squirt and did the o-ring/leak jet deal. I also shaved the rivet down on the diaphram. Now I can whack it pretty hard and it rips. My wifes ttr won't take more than half throttle off idle. I've not had any luck finding pilot jets local so I just let it be. She's never had it happen to her.

I put the 45 pilot jet back in and rode it around knowing I can't wack the throttle. It seems to run good has tons of bottom end and virtually no top end,seems like I was always grabbing for more gears. The Cr80 smokes it up top but the bottom end is sweet. And its why I bought it anyway the girlfriend loves it.

I have no experiece with 4-stroke dirtbikes so I didn't know what to expect. Thanks for all the replies!!

 

[_JOE_]

Try getting a few bigger main jets. You should be able to wake the top end up. It may be getting close to time for top end service too. Performance will drop off as compression/valve seal does.

 

[whenfoxforks-ruled]

I know the 250f and 450f can get the engine/carb to respond, whack off bottom for killer response. Valves, top end and carb are all crucial. I will bet wear and tear suffer, trailbike, do you really what to try this? Ap and pilot, then its the fuel. Ever since the 150 came out, I go listen to the riders, bouncing off the rev limiter, it sounds like money to me? Rollon with a newer rider, that engine will last a lot longer! If the book claims 15 hours on the rings for the 250f, how short can the 150f be?

 

[Rich Rohrich]

Try getting a few bigger main jets. You should be able to wake the top end up.

Joe - The main jet is pretty rich from the factory on the 2007 carb and most people have to go the other way to get them to run on top. The White Bros can is a POS which just complicates things further. It will likely run better on top with the stock exhaust can.

 

[_JOE_]

Wow. That's surprising.

 

[Rich Rohrich]

Wow. That's surprising.

I think they leave it rich as a safety measure, just in case there is an extended period of high load WOT running.

This isn't an uncommon practice. EFI cars are pretty much the same way. I've hooked up my DAQ system and ran a second wideband O2 sensor on my smallblock Dodge V8 and watched the A/F ratio under lots of conditions. The system stays in the 14.0:1 - 14.8:1 range till you go to WOT 100% on the TPS , then it shifts in to an open-loop mode and runs the A/F ratio at an insanely rich 10.3:1. It's so rich at WOT that I can run a nitrous shot straight into the intake without any extra fuel added, if I trigger it to just run at the 100% throttle voltage from the TPS.

I guess they are trying to save us from ourselves. :whoa:

 

[nsxxtreme]

I have the stock exhaust. It came with the bike. I could try it out. The bike seems to run fine to me other then not being able to wack the throttle from idle. And I bounce of the rev limiter pretty easily. Tons of bottom end just not much up top. The little cr80 screams past it once it hits the power band.

Were talking about the 150r not the 150f if that makes a difference. I might try leaning out the main jet and see how that goes.

Thanks again guys for all the useful suggestions.

 

[whenfoxforks-ruled]

STAY OFF THE REV LIMITER! Please?

 

[nsxxtreme]

STAY OFF THE REV LIMITER! Please?

Easier said then done when your used to a 2-stroke. It should not be an issue for the girlfriend though. She really likes the near instant throttle response of this bike. She always shifted the cr80 right before she hit the powerband. Her riding style is what made me buy this bike for her and so far she loves it. I would have bought it for her sooner but couldn't bring myself to spend $4k on one of these bikes. I picked this one up for $2200. It was owned by a 10 year old that didn't ride it much.

I'm only riding it to get used to it so I know what to expect out of it and know when its time to tear it apart. And its actually a blast to ride. It will lift the front wheel in second just by rolling the throttle and I'm 180lbs. I think the top end could be improved a little and think I'll try Rich's suggestion of leaning the main a little.