CBR150 won't rev past 5,000rpm

[CanInBKK]

Hey, got a problem that just started and luckily it happened as I was pulling into my driveway. I've gota CBR150 (carb'ed version) that seems to start fine (easy turnover on button press) but sputters and dies when rev'ed up to 5,000rpm in neutral. Being in first gear doesn't help either as the engine still dies just as the wheels start rolling.

What could be up with the engine (about 15,000km) and how can I fix it?

[desmondspencer]

Have you cleaned the carb and air filter yet?

Don't contribute/troll the problem unless you've got a solution!!

[NomadJoe]

^ Yep. Characteristic of a dirty carb.

[guzzi850m2]

+1 to above and check the fuel filter (if any).

[KRS1]

in this order until it goes away: clean carb, clear vacuum lines, change vacuum operated fuel valve, change cdi

the fuel filter is a straw connected to the fuel valve within the tank, highly unlikely that alone would cause it, the entire straw filter would have to be clogged and its about 3 inches high.

[luis888]

Not familiar with the bike but if carb model, it should have vacum carb, check if slide not stuck/sticking or if rubber diaphram on slide not damadged. The slide goes up with vacum created by rpm, if there is damage to the rubber on the slde or interferance with slide the motor won't rev properly. I hope this helps

[CanInBKK]

Thanks for the input guys, looks like I'm going to need to take out and at least clean the carb. Question though, how difficult is this task? Does it require the removal of the fuel tank and seat or can the carb be removed just by taking off the fairings?

What kind of tools/chemicals would I need to purchase in advance to get this carb cleaned up?

[paz]

Thanks for the input guys, looks like I'm going to need to take out and at least clean the carb. Question though, how difficult is this task? Does it require the removal of the fuel tank and seat or can the carb be removed just by taking off the fairings?

What kind of tools/chemicals would I need to purchase in advance to get this carb cleaned up?

Hi, to be honest with you, if you're asking that, it mean DIY not the best approach. Also, since there is not 100% guaranteed that the problem is dirty carb, you could face wasted time and frustration. Bring it to the shop or have the guy come over with the tools.

[KRS1]

Thanks for the input guys, looks like I'm going to need to take out and at least clean the carb. Question though, how difficult is this task? Does it require the removal of the fuel tank and seat or can the carb be removed just by taking off the fairings?

What kind of tools/chemicals would I need to purchase in advance to get this carb cleaned up?

not terribly hard, i use to be able to pull the carb in 10 minutes.

Remove seats

Disconnect hoses and indicator plug from tank, make sure you dont scratch the side panels with the tank.

Disconnect carb cable, unscrew choke cable and remove.

unscrew carb sleeves from airbox/intake

remove

carb bowl screws are made of cheese, find the biggest philips you can find that will fit in the screws (you have to do this) put philips screwdriver into screws and give quick whacks with hammer to unset the screws, then unscrew them. Its crucial that you find the biggest philips that will fit.

Can of carb cleaner , i saw some at either Lotus or Big C, expensive stuff 200-300 baht. A local shop will use old gas and compressed air to clean the carb - not the cleanest.

Take a picture of all the vacuum lines, the older CBR 150 didnt have all the vacuum crap (grey frames)...the late models with black frame were a vacuum nightmare.

Or you can take it to a shop and theyll do it for 200-300 baht - just bring them a can of carb cleaner.

[CanInBKK]

The certified mechanic route is probably the most sound choice, problem is that I live in the city and motorcycle shops are scarce, pushing the bike to the shop (about 3km) away is technically feasible but realistically it would be hell. I'll give the DIY route a go first to see if I can at least get the bike moving under power so I can ride it to the shop and have them take a thorough look at the engine.

Thanks again for the help, hope it all works out.

[sate ayam]

and while you are at it you might as well want to clean the gas tank. remove the petcock and fuel strainer (don't lose that small o-ring !!) shake, rinse, refuel a couple of times

my result was a lot of black grid and even drops of water

best is to install a fuel filter

[B1ade]

before stripping the carbs, the tank needs to breathe and if the line is clogged it can create a vacuum so fuel can't be drawn through as mentioned above, i cleaned the carbs once with the same problem on an old simpson 50, took a while and was a waste of time, the vacuum line was clogged and was only a 30 second fix in the end, start with the easiest fix!.

Edited March 30, 2014 by B1ade

[papa al]

Fire, fuel, rotation: 1,2,3.

1. Got spark? Fouled plug? Loose lead?

2. Carb issues and dirty fuel and venting as the guys suggest. A dirty air filter can present as you have indicated.

I had same problem once...easily rectified. I was out of gas. 5 5

3. n/a

A good reliable mechanic is like gold...hard to find but very valuable.

Good luck. Never give up.