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Looked easy on YouTube! Carb cleaning gone wrong...

6K views 18 replies 6 participants last post by  Habitat3 
#1 · (Edited)
Edit May 10:
I've corrected the issue but feel free to read the thread as I made some mistakes along the way and learned a few things. I removed and dismantled my carbs four times and only needed to do it once. While I became very efficient, each time increased the odds of mistakes or damage (i.e. tank) and luckily nothing happened.

First, this isn't difficult. You don't need specialized tools or knowledge, although a repair manual helps, and I would suggest finding an instructional video walk through - I'll link the ones I used below. You'll need a set of metric sockets (8,10,12,14mm), wrenches (wrenches in bike kit will work - needed for throttle cables and speedometer cable), Phillips screwdrivers, needle nose pliers, carb cleaner (not fuel injection cleaner), small container to capture fuel, lights, and small vice grips as the screws attaching the float bowls are often seized if they've been on for a while. I also replaced the screws attaching the float bowls and I believe they were metric 4mm x 12mm and 12 were about $2.

Second, I would suggest a carb rebuild kit. My primary issue was caused by attempting to re-use the o rings that were in the carbs and as they no longer sealed properly (probably caused by my unseating them) they allowed fuel to leak. Kits range from $12 to $75 - I purchased from a carb re-builder on eBay for $12 and it worked great - your experience may vary with non-OEM parts.

Third - take your time if you're in-experienced. I had a secondary issue caused by an error with re-assembly. And if you have questions - this site and Google will help you through.

Video walk-through I used (I only cleaned/dismantled what I could access from inside the bowl - he goes much further):




Original post:
I’ve ridden my new to me bike around 30 miles and it needed a good cleanse - had great midrange power but was very cold blooded and stumbled from idle. This is a 2008 I just purchased with 1,500 miles on it so carb varnish/gum/clogging seemed reasonable.

Watched several YouTube videos where the tank was pulled, float cover removed and inlets cleaned to solve the issue. When I started today I couldn’t get the Phillips screws loose and instead of trying chemical cleaning decided to pull the carbs. Once I got in I went ahead and disassembled and gave it a good cleaning.

When reassembled it fired right up and idled great. Took it for a short ride and immediately noticed lack of power past slight throttle (fuel starvation?) and when I got it back home it died and wouldn’t start. Noticed it would leak fuel and found it leaking from the vent tube so my assumption is something is wrong with a float.

Guess I got to pull it all apart again. I did take my time and did one carb at a time so I don’t know what went wrong?

-Eric

93803
 
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#2 · (Edited)
Went in deep but I didn't get too crazy. I've watched 2 in-depth videos on YouTube since the issue and I re-assembled correctly. I'm going to dismantle again to ensure the float valve moves freely and attempt to blow into the fuel inlet with the valves seated.

I can only imagine one of the valves is sticking or I need to replace the O-Ring and it's leaking around it - I didn't use a rebuild kit and re-installed the original parts.

93804


93805
 
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#3 ·
Pulled the carbs, removed the float bowl and ensured I can blow into the fuel inlet with either float opened and can’t with them closed.

Took some pics of the O ring on the rear carb as it might cause an issue. Both float valves look good.

Reassembled and got the bike to start and run using a small funnel with fuel into the fuel filter - ran fine but needed to have the choke at least halfway on to keep running. Is this due to lack of resonator and air filter box (too much air)? Didn’t have any fuel leaks.

Initially stumbled from idle.

First cleaning - idled great but seemed starved then would push fuel out the overflow tube which would indicate the float valve wasn't seating allowing the bowl to overflow. It would overflow as soon as I turned on the ignition to engage the fuel pump before it was running.

Second cleaning (now) runs but not correctly (no resonator or intake). Doesn’t push fuel from the overflow.

Pics below and it appears the needle valve on the rear carb sits differently than the front - can anyone confirm this is correct?

-Eric
 
#5 ·
Found my error with fuel starvation - the seat for the needle jet has a flat side for proper orientation - I didn't realize this and installed incorrectly yesterday.

Corrected this morning and the bike runs great - full power and smooth from idle. However, once ridden for a few minutes I'm still getting fuel from the overflow/breather tube - even with the engine off as the fuel pump engages before starting. I'm (nearly 100%) positive I didn't damage/bend/drop either of the floats when I had them out so they shouldn't be out of adjustment. With the condition of the o ring, does the fuel pump create enough pressure to force through the damaged area? Could I find a suitable replacement o ring at an auto parts store or should I give in an purchase a rebuild kit? Other than the needle valve and float - is there anything else that could cause the carb to overflow? Needle valve and seat appear fine but I don't want to keeping removing the carbs.

-Eric

Installed incorrectly - flat spot is on the left.
93852


Flush
93853


93854
 
#19 ·
Hey man, I'm having the same problem. Same situation. I have it narrowed down to the carb closest to the front of the bike. The bolt circled in my picture broke off so I hallowed out a screw to replace it. The screw might have been too long blocking fuel from coming in. What did you do to help your fuel starvation?
Auto part Carburetor Engine Automotive engine part
 
#6 ·
A bad float valve has been an issue in the past. That's where I would start. Here's a thread addressing the situation.

 
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#7 ·
A bad float valve has been an issue in the past. That's where I would start. Here's a thread addressing the situation.

Thanks!
Should probably order an overhaul kit with new valves. Interesting that my floats don’t bounce like in the video and are more of a flop. This didn’t leak before I dismantled it so my assumption is the o ring has failed and when I removed it I made it worse.

-Eric
 
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#10 ·
If you were not getting a good bounce from valve, no. The spring in valve is weak. If you want to try the oring, sure. If you have a Harbor Freight or Northern Tool close by, get a large assortment of orings, they both carry the one below, they are cheaper and work well, I've used for years.

93856
 
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#11 ·
If the pin in the float needle gets bound up or the spring thst holds it out becomes weak the needle is trash. Don't try to get away with using if it is questionable. I have replaced a lot of float valve o-rings with good results...but...if the needles arent in perfect working order you run the risk of contaminating the engine oil with gasoline and that will destroy the big end rod bearings in an engine = $$$
A fresh set of needles and seats costs alot less than an engine.
 
#12 ·
if you dont have the air box and air filter connected to the carbs the engine will get way too much air, for the amount of fuel from the jets, and it will run terribly lean

this is why people put bigger air intakes and air filters on their bikes, but you have to put bigger jets and adjust the PMscrews to match

Short version: the engine will not run right without airbox and filter
 
#15 · (Edited)
Received my rebuild kit and installed this morning. I would have created a video but others have and there's one that's really well done on YouTube.

After I finished bike it started on first try and runs well - good idle, throttle response and acceleration. I drove for several minutes and then stopped and checked the breather - no overflow! I'm going to take a longer ride tonight and again tomorrow before I declare success with 100% certainty - but it's looking good.

Couple of things I noticed:
  • New needle valve has significantly more "spring". Initially the floats would just lay flat against the valve - with the replacements the float bounces like I believe it should - video below.
  • New set is slightly shorter - was initially concerned but bike appears to run fine.
Thanks again for everyone's input!
-Eric

Original on left, new on right:
94062


Original on left - new on right. New is slightly shorter:
94063


Float bounce after new valve:

 
#16 ·
Good job. As you found with the float valves, the little things make a big difference.
 
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