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Crf50 High Revs Start

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RootDown

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Discussion starter · #1 ·
Been lurking for a couple months while i researched and bought a bike. Bought a 2007 CRF50. I've done a coupel garage mods like adding a UNI filter, BBR handlebar kit, BBR rev box, HD Spring front and rear, and a Tall seat. I do not claim to be mechanically inclined, but i figured this would be a great project to sink my teeth into. In adding the UNI filter, i've run into a couple snags. First i had read that i needed to adjust the needle in the carb, and more than likely wouldn't have to jet by only adding a air filter. Guy at the local honda shop told me to move the clip down on the needle to the bottom position, and I'd be good to go. Tore into the bike, and found out that the 2007 doesn't come with an adjustable needle. Ended up buying a needle kit for a 2005 that is adjustable. I put the new needle in at the specified notch, and put the thing back together. When i fire it up now, it revs super high. When i have it choked down to the first detnet, it seems to idle at a decent rpm, but it doesn't sound like it's running all that smoothly.



I've warmed it up with the choke on, turned the choke off, and attempted to adjust the idle screw on the carb to no avail. It still revs super high. I'm at a loss, haven't tried to adjust the needle too far, as the stock 2007 needle seemed to be at the 3rd position on this new adjustable needle.



Any ideas?
 
#2 ·
make sure you installed the slide correctly. theres a long slit and a short slit on either side with corresponding "pins" sticking out in the carb body. if you put it in reversed then the slide wouldnt drop all the way down. this would cause incontrolable high revs. also if you pulled on the throttle cable and its either sticking or the end of the cable is popped out of the carb cap it'll cause the same problem. bottom line, make sure the slide goes all the way down.
 
Discussion starter · #4 ·
Yea, funny thing about that carb slide.... First time i put the slide and cap back on it wouldn't rev down. After reviewing the BBR instructions for throttle assembly, i noticed i had the slide in backwards. Haha. Turned that puppy around, and viola, i actually had tension on my throttle cable (when it was in backwards, there was nothing but slop on the throttle). Unfortunately, this didn't solve the problem.



I took a trip down to my local honda shop and spoke with one of the knowledgeable parts guys, and he said it was more than likely 1 of 2 things. First he said "check for an air leak. Take the look at the filter, make sure it's sealed up good n tight. Look at the manifold/carb fitting and make sure that is all snugged up." And the last thing he said was, "With your adjustable needle set to the bottom position, you're running it rich. That may not be enough. Sounds like maybe you're running lean. You need to get in there and back out the air/fuel mixture screw 1/4 a turn at a time."



So i came home, tore the carb apart. Verified the slide was seated properly in the carb. Looked at seals on airfilter, manifold et al. No fixey. Then i take a look at the fuel/air mixture screw and say "Hmm, that's an odd screw...". Turns out, i got that stupid D shaped screw, and no proprietary driver to adjust it. Gonna take the bike down to the local shop and seeing if adjusting mixture screw will fix the problem. If that's not the case, i'm guessing i'm going to have to bump up the main jet to a 60 or 62.



I've read mixed things saying with a pod filter and a stock pipe, i shouldn't have to re-jet, and that the needle adjustment should be enough. I'm at maybe 500' above sea level so given that the needle is in the lowest position, i may end up having to bring it up one notch. Who knows.



Thanks for the tips. And if anyone has anything else to add, i'm all ears. I will post another update when i get her all up and running for posterity's sake. Maybe this thread will give some future 'non-mechanically inclined' soul a helping hand.
 
#5 ·
if you can get your hands on a "older" crf/xr 50 carb (i believe before 03) you can adjust the air mixture screw. ive also heard of people drilling out the cap and tapping it for a screw but thats an extreme. im pretty sure older bike carbs are readily available with all the guys running bore kits out there. good luck.
 
Discussion starter · #7 ·
squidwell said:
Yo Root I see your in WA where? I'm in Seattle, if I can help let me know.
Click to expand...


I live over on the eastside, Issaquah to be exact. After takin her down to RMC the tech said she has a lean hang. Try as we might, just not enough adjustment to be had. Ordered a 60 and 62 main jet, and hopefully that'll fix up the issue.
 
#8 ·
The most reliable way to check for an air leak is to start the bike and let it run, then spray some contact cleaner on the manifold at the head, and on the manifold at the carb. If the RPMs go up or down and then return to where they were, you have an air leak. A very light coating of grease on the manifold o-ring and the carb and spacer o-rings never hurts.
 
#9 ·
Not sure, but I'm a little confused when you say the 07 dosen't come with an adjustable needle becuase the clip position makes this adjustable no? Anyways, if your clip is on the bottom position and idles high, that makes sense cause the needle now sits higher letting in more fuel. I would try moving the clip to the highest postion (top furthest away from the needle point).
 
Discussion starter · #10 ·
2006+ CRF50's do not have an adjustable needle. if you actually look at the needle, it has only 1 groove in it. Only way to "adjust it" would be to shim it with small washers. I didn't want to hassle with finding washers the correct size and have some jenk parts on my bike. 2005 CRF50 had a 5 position adjustable needle, so i just ordered one from the local Honda shop and got it all straightened out.



Thanks for all the replys.
 
#11 ·
RootDown said:
2006+ CRF50's do not have an adjustable needle. if you actually look at the needle, it has only 1 groove in it. Only way to "adjust it" would be to shim it with small washers. I didn't want to hassle with finding washers the correct size and have some jenk parts on my bike. 2005 CRF50 had a 5 position adjustable needle, so i just ordered one from the local Honda shop and got it all straightened out.



Thanks for all the replys.
Click to expand...


Sorry, forgot about this post. I didn't know Honda removed this feature in the newer 50s. Glad you got it worked out.
 
#12 ·
dirtbkr188 said:
The most reliable way to check for an air leak is to start the bike and let it run, then spray some contact cleaner on the manifold at the head, and on the manifold at the carb. If the RPMs go up or down and then return to where they were, you have an air leak. A very light coating of grease on the manifold o-ring and the carb and spacer o-rings never hurts.
Click to expand...




Some leaks are so tiny you cant even see them but they will effect the running of your 50 majorly!!, the only way to test for an air leak is thru this process or a leak down tester. I would try this also just to make sure there is no air leak issues.
 
#13 ·
RootDown said:
Been lurking for a couple months while i researched and bought a bike. Bought a 2007 CRF50. I've done a coupel garage mods like adding a UNI filter, BBR handlebar kit, BBR rev box, HD Spring front and rear, and a Tall seat. I do not claim to be mechanically inclined, but i figured this would be a great project to sink my teeth into. In adding the UNI filter, i've run into a couple snags. First i had read that i needed to adjust the needle in the carb, and more than likely wouldn't have to jet by only adding a air filter. Guy at the local honda shop told me to move the clip down on the needle to the bottom position, and I'd be good to go. Tore into the bike, and found out that the 2007 doesn't come with an adjustable needle. Ended up buying a needle kit for a 2005 that is adjustable. I put the new needle in at the specified notch, and put the thing back together. When i fire it up now, it revs super high. When i have it choked down to the first detnet, it seems to idle at a decent rpm, but it doesn't sound like it's running all that smoothly.



I've warmed it up with the choke on, turned the choke off, and attempted to adjust the idle screw on the carb to no avail. It still revs super high. I'm at a loss, haven't tried to adjust the needle too far, as the stock 2007 needle seemed to be at the 3rd position on this new adjustable needle.



Any ideas?
Click to expand...
Sounds like an air leak, Has it always did that
 
Discussion starter · #15 ·
Slo_R1 said:
Post up Root...



What was the issue?
Click to expand...




Ended up being user error, the carb slide was in backwards and wasn't seated correctly in the carb. After getting that all squared away, it was bogging horribly when i grabbed a handful of throttle. Ended up getting a 2005 CRF50F needle kit from my local shop hoping that needle adjustment would cure the lean hang. Tried every position on the needle and mixture adjustments to no avail. Ended up rej-etting to a 62 main, and adjusting the mixture. Got her running like a top again. Sorry for the late response, after i got it all back up and running i was too busy hooliganing around to revisit the thread.
 
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RootDown
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