Question about Motorcycles

1 Answer

OK so I have a 98 xc 600 and all carbs ,needles, jets are all new n were set at dealer so my problem is its only backfires when choke is all the way down or off and it bogs on take off to and wet plugs ... But if I leave the choke on half way it doesn't backfire or bogs but I can flip choke off once I'm going and no problems at all ... Where do I start????

Posted by on

1 Answer

  • Level 1:

    An expert who has achieved level 1.


    An expert whose answer got voted for 2 times.

  • Contributor
  • 4 Answers

Sounds like the idle jets are making it too lean. Replace or adjust them. If it has EFI, it can be fixed by changing the calibration map.

Posted on Dec 12, 2014

  • tony christenson
    tony christenson Dec 12, 2014

    how do u adjust the idle jets

  • digitalmoore Dec 12, 2014

    check that the clamp attaching the carby to the motor is tight and isnt allowing an air leak first. the mixture screw is on the lhs near where the bowl attaches, screw it out a half turn and see what happens. if it neither of those it might have the wrong needle shape installed, the dealer needs to fix it.


1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

New carb idles good but will not throttle up with out choke misses and backfire 07 grizzly 450

either the float height is wrong, the main jet needle needs lifted or there's an air leak somewhere.

Mar 26, 2017 | Yamaha 2007 Grizzly 450 Auto 4x4

1 Answer

When I ease into gas, it dies/or stalls. if I hit the gas no problem.

1 = Check between carb and head for vacuum leaks
2 = Float height could be set to low
3 = Needle height low

Give the carb a good clean with carb cleaner making sure all passages and jets are clear. Reset float height and make sure all flanges seal properly.

May 09, 2015 | GAS Motorcycles

1 Answer

We are having a problem with the Polaris 500 - it runs backfires and then have to crank it again. On a cold start we have to choke it, small amount on the throttle and do it several times. It will...

The number 1 problem with ATVs is the carburetor. This could be a mixture problem... too rich will cause backfiring and difficulty starting as the carb needs more air. Try leaning it down a 1/8 turn. The choke is always intended to be used when starting; if you don't need to use the choke, the card is definitely running too rich. If you can't adjust to make it behave properly, then rebuild the carb, It's not difficult.. get a new throttle spring and float too. Ensure you place the keeper clip on the correct groove of the needle valve... where the throttle cable connects. Replace all the jets and gaskets... don;t get them mixed up. One larger jet is the primary jet and the smaller one, is the secondary. Get new screws, if the screws are a bit dog eared. Write down your previous mixture settings and start from there to adjust the mixture for starting and assure a slightly skipped idle. (Don't worry as you add throttle it will run smoothly.)

Mar 01, 2015 | ATVs

1 Answer

My 1996 yamaha yzf600r will attempt to run if i hold my hand over carbs i have took the bowls off and the pilot jets and needles and cleaned them really good and if i dont hold my hand over them and turn...

Hi, Anonymous and the usual suspects are:
1. Fuel cap or fuel tank is not venting properly.
2. Fuel filter clogged.
3. Fuel line pinched or kinked.
4. Float needle and seat sticking.
5. Float level too low.
6. Carburetor bowl vent line clogged/blocked/pinched.
7. Idle adjusting screw set too low.
8. Air/fuel mixture screw set too lean.
9. Idle port, transfer ports, slow air jet clogged.
10. Slow fuel jet clogged.
11. Faulty fuel pump.
For more information about your issue and valuable "Free" downloads that you will need please Click on the links below. Good luck and have a nice day.
YZF600R Forums View topic Starting Choke Issues
YZF600R Forums View topic choke not working
Yamaha YZF600 YZF600R 1994 2007 Service Repair Manual PDF Download Manuals...
OEM parts for Yamaha
Yamaha YZF600RP Owner Manual

Oct 30, 2013 | 1996 Yamaha YZF 600 R thunder cat

1 Answer

94 yamaha fzr 1000 was running fine, went to start it an it would start run on choke but cut out as soon as the choke was closed, definetly getting petrol as far as the carbs an getting spark, wud the...

Hi, Anonymous and the usual suspects are:
1. Fuel cap or fuel tank is not venting properly.
2. Fuel filter clogged.
3. Fuel line pinched or kinked.
4. Float needle and seat sticking.
5. Float level too low.
6. Carburetor bowl vent line clogged/blocked/pinched.
7. Idle adjusting ***** set too low.
8. Air/fuel mixture ***** set too lean.
9. Idle port, transfer ports, slow air jet clogged.
10. Slow fuel jet clogged.
For more information about your issue and valuable free downloads that you will need please visit the websites below. Good luck and have a nice day.
FZR 600 post storage idle stall issue The FZR Forum
View topic FZR 600 carbs only runs with choke on Help
Exup1000 co uk Tech FZR1000R
OEM parts for Yamaha

Feb 26, 2013 | 1991 Yamaha FZR 600

1 Answer

I have a coleman powermate premium plus 6250 generator,put in new plug ,new filter ,changed oil,cleaned the carb,put in new gas. runs ok at half choke but when go full choke it starts backfiring and runs...

if you are running the engine at full CHOKE, then it is flooding the engine, but if you meant off full choke, then the carb is still stopped up. Try soaking in carb cleaner overnight after removing jet & all rubber goods. HOPE THIS HELPS.

Dec 17, 2010 | Coleman Powermate Premium Plus 6250W...

1 Answer

04 yz 450 backfires and is hard to start when is cold runs better with choke on

Runs better with choke means the mixture is lean,
Has the exhaust been changed.?
Did this problem just begin.?
Check for air leaks on intake manifold.
Clean carb.
Check valve clearances
raise the needle jet one notch
one size up in the main jet.

check one item at a time, and write notes about jetting changes.and improvements
I also run Moreys upper cylnder lube, helps starting hot or cold, and helps stop "cough stopping" with heavy rear brake use

May 20, 2010 | 2004 Yamaha YZ 450 F

1 Answer

Bike only starts with choke on and wont idle .by the way its a ktm 250 xc 2006.air filter is clean and has new plug . wondering about needle adjustments?

If your bike ran good previously - and nothing has been changed that would require rejetting or a needle adjustment, I would look for problems elsewhere. Such as:
Has the bike been stored for more than a few months at a time? If so, the carburetor jets could be plugged with fuel varnish. Only being able to start with the choke applied - and an inability to idle are both classic symptoms of this. Remove and disassemble the carburetor. Clean it and the jets out with carb cleaner and compressed air, then reassemble. Also make sure the fuel in the tank is fresh and that the fuel strainer (usually with the fuel petcock) is clean.
There are three ingredients required for combustion: fuel, compression, and a spark (at the right time). So long as you've got each of these - it has got to run.

Feb 21, 2010 | 2008 KTM 250 XC

1 Answer

I have a 2007 Midnight Venture. It idles extremely rough (seems to be on 2 cylinders)spits and backfires even when warm except when the choke is on. Low end torgue seems to be missing. It also backfires...

Your primary jets in the carbs are clogged. (FYI- each carb has three metering jets, a primary, the needle or butterfly and the main jet. Each jet has an RPM area where it controls.) Simply blowing them out will not fix this problem. The carbs need removed and properly cleaned, the jets need to be probed and cleared then a new fuel filter installed to prevent it all from happening again. best wishes.

Aug 20, 2009 | Yamaha Royal Star Tour Deluxe Motorcycles

1 Answer

Idle problem

An air leak somewhere between the carb and the cylinder can cause the RPM problem. Tighten the mounting bolts. The carb may be clean but there is still a problem on the inside. Possibilities include plugged main jet, and/or needle jet. Also an incorrect needle jet setting. You have a very sophisticated carburetor. If you have already cleaned the inside of the carb I would let the dealer check it out.

Please rate this answer. Thanks kschomig!

Apr 06, 2009 | 1999 kawasaki VN 800 A Vulcan

Not finding what you are looking for?
Motorcycles Logo

Related Topics:

98 people viewed this question

Ask a Question

Usually answered in minutes!

Top Motorcycles Experts

Arnie Burke
Arnie Burke

Level 3 Expert

4514 Answers


Level 3 Expert

74896 Answers


Level 3 Expert

102366 Answers

Are you a Motorcycle Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides