How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask Doug E. Your Own Question

Doug E.
Doug E., Kawasaki Master Technician
Category: Motorcycle
Satisfied Customers: 2865
Experience:  Professional motorcycle mechanic since 1978. Vintage motorcycle restorer.
Type Your Motorcycle Question Here...
Doug E. is online now
A new question is answered every 9 seconds

intermittently..one of the cylinders had low compression..lean

Customer Question

I have a 2000 Arctic Cat ZR600 that would bog down intermittently whether under hard throttle or moderate throttle. It would seem to run out of gas as if the floats bowls were not filling up fast enough but again this was not a regular occurrence. Since then I discovered one of the cylinders had low compression only to learn it was running extremely lean and burned up the one of the pistons. I replaced the piston and rings and have throughly cleaned out both carbs. One of which was really gummed up which would explain why the camber was starved for fuel. I now have plenty of power but it still bogs down during moderate throttle. Spark plugs show correct color, not to lean or rich, and both cylinders show 95lbs of compression. I'm told the throttle/ignition monitor switch could be the problem. If true, what is the adjustment for this switch under the thumb throttle or is it best to replace?
Submitted: 4 years ago.
Category: Motorcycle
Expert:  Doug E. replied 4 years ago.
Hello,

The throttle switches are a real bother, but will save you should your throttle cable freeze and the throttle stick wide open. When these fail or are out of adjustment, the engine will cut out or miss as you open the throttle. If the engine is just doggy, there are other issues.

There are a few things to check. First off, your compression numbers are low. Check them again with the motor cold, throttle wide open and pull till the gauge stops. Repeat the test when the engine is warm. Let me know what the readings are. A new motor should be about 145 and 125 is ok, but there should be no drop when the motor is warm. A motor running at 125 that drops to 110 when warm has problems.

Did you soak both carbs with the jets removed to make sure all of the varnish is gone? You may want to do this to make sure there isn't going to be a continuing problem. You might want to replace the jets and float valves to be sure. I use Yamaha carb cleaner. You mix it with water, heat it and it boils out the varnish.

There are magnets inside of the carb slides on the VM carbs. Did you take a look to see if they have come off? If so, epoxy them back into place. On the side of each carb is a wiring plug. Take your jumper plug from the tool box (or make one) and unplug the carb. Plug the jumper into the harness side and test the sled. Repeat for the other side. If this solves the problem, the magnet is loose or the wiring sensor needs to be adjusted.

If that doesn't solve the problem, pull up the handlebar pad and plug your bypass plug into the kill switch junction on the harness side. That bypasses the kill switch and safety switch. Does that solve the problem?

Let me know what you find. If you run those tests that should narrow things down so I can get you fixed up.

Doug
Arctic Cat CatMaster
Doug E., Kawasaki Master Technician
Category: Motorcycle
Satisfied Customers: 2865
Experience: Professional motorcycle mechanic since 1978. Vintage motorcycle restorer.
Doug E. and other Motorcycle Specialists are ready to help you
Customer: replied 4 years ago.
Thanks Doug! Great direction...to answer a few of your questions. Carbs were not soaked but were thoroughly cleaned by hand three times. I wanted to soak but did not have tank or solvent. Floats/Jets were not replaced. I did not notice any "magnets" as you described...my Carbs according to the manual are TM38? Also, is there an adjustment for the throttle/ignition monitor switch under the thumb throttle? Or do I need to bypass it to simply check if the switch is the problem? Also what is the factory setting for the fuel/air mixture screws? I turned them down until gently seated then backed them out to where they were at approximately 2 turns. This sled has 2000 miles on it and runs strong but with the occasional bog in performance which is corrected by cracking the throttle a little more. The replaced piston camber after three pulls reads 110lbs but did come down to approximately 95-100 after warm up. I did not sleeve the head or replace it...
Expert:  Doug E. replied 4 years ago.
That was the year they went to a TPS type sensor instead of the magnets. The TM has the sensor and the VM has the magnets. My mistake.

The throttle cable play is the only adjustment in the system. The TM carbs have no freeplay between the throttle lever and housing. The washers above and below the lever wear out and need to be replaced every year or so. The housing itself can wear out if the rider twists the throttle instead of pushing straight on it.

On the engine block by the recoil, unplug the main 4 pin connector. Does the sled run fine? That bypasses all the switches and safety switch.

Try some of the Yamaha carb cleaner next time you have to soak carbs. You can mix up what you need and put it on a hot plate. In 15 minutes the carbs are clean as new. The cleaner can be saved and used again and you can wash the carbs in water to finish the job. Although not good stuff to breath, this is a far safer product that what's sold at auto parts stores. That crap will kill you 10 different ways.

If there was some scoring on your cylinder walls, that would explain the compression drop when warm. The rings are loosing some of their seal. I still think the problem is in the safety switch.

Doug


Customer: replied 4 years ago.
Thanks for the great guidance!
Expert:  Doug E. replied 4 years ago.
Anytime. Let me know what you find.

Doug

JustAnswer in the News:

 
 
 
Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.
 
 
 

What Customers are Saying:

 
 
 
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P Elm City, NC
< Last | Next >
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P Elm City, NC
  • used your service this weekend with "Trecers" help. thank you ,thank you, thank you. replaced an A/C fan motor. Local Auto Zone had part. $15.00 "tracer" fee and $40.00 for parts, I saved several hundreds of dollers at a shop. i will recommend you and use you in the future. David L. Richmond, TX
  • 9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much. Phil Marysville, CA
  • Lurch. Thank you very much. I had real doubts about this website but your promptness of response, quick followup and to the point answer with picture was incredible. Charles Walnut Creek, CA
  • As a single woman, I really appreciate an excellent and affordable opinion.
    Thank you Geordie, I will not hesitate to contact justanswer in the future!
    Sue Charleston, WV
  • Another great insight to what may be the problem. I will have my mechanic take a look at it tomorrow. Thanks again, Frank...you do indeed know your stuff. Jim Castleberry, FL
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
 
 
 

Meet The Experts:

 
 
 
  • Harley Tech

    Motorcycle Mechanic

    Satisfied Customers:

    1297
    35+ Years Experience on Harley/Honda Specialising in HD Tuning Super Tuner etc
< Last | Next >
  • http://ww2.justanswer.com/uploads/harleytech/2008-09-21_185638_phpts91u2_c2pm.jpg Harley Tech's Avatar

    Harley Tech

    Motorcycle Mechanic

    Satisfied Customers:

    1297
    35+ Years Experience on Harley/Honda Specialising in HD Tuning Super Tuner etc
  • http://ww2.justanswer.com/uploads/EX/extremeccs/2012-6-10_19914_steve11024x768.64x64.jpg Steve's Avatar

    Steve

    Motorcycle Mechanic

    Satisfied Customers:

    6027
    30+ yrs. experience, MMI, HD technician, HD early, engine rebuild/performance, bike builder, kit bike program manager, CCI 2001-2004
  • http://ww2.justanswer.com/uploads/jpolicky/2009-4-3_43150_200009a.jpeg.jpg Jeff Policky's Avatar

    Jeff Policky

    Motorcycle Mechanic

    Satisfied Customers:

    2381
    Yamaha Gold, Suzuki Gold, Honda Bronze, Polaris Bronze, BRP
  • http://ww2.justanswer.com/uploads/Guest/2008-01-28_125643_phpbZSI1u_c2AM.jpg TIMOTO's Avatar

    TIMOTO

    Motorcycle Mechanic

    Satisfied Customers:

    1101
    Honda registered technician, silver level award, former Kawasaki/Suzuki tech, 40+ years exp.
  • http://ww2.justanswer.com/uploads/LoriExpertsMod/2010-04-15_002245_192503.jpg Andre Pilon's Avatar

    Andre Pilon

    Motorcycle Mechanic

    Satisfied Customers:

    1027
    Over 25 years experience, ICS, MMI, Owned shop for 12 years, worked tech-support for Harley Davidson
  • http://ww2.justanswer.com/uploads/GlennAII/2008-5-26_12926_YUMMY_2.jpg Glenn Adams II's Avatar

    Glenn Adams II

    Motorcycle/ATV Technician

    Satisfied Customers:

    393
    6 years Motorcycle/ATV/Water Craft; 4 years auto; 18 years carpenter
  • http://ww2.justanswer.com/uploads/AS/asphaltcycles/2012-7-31_151258_311842101502880177646218277720n.64x64.jpg asphaltcycles's Avatar

    asphaltcycles

    Motorcycle Mechanic

    Satisfied Customers:

    383
    I operate a motorcycle dealership and CCS Ducati Race team.