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jasonmcc

please help, no one can fix my bike?

12 posts in this topic

About a month ago I posted a message about a problem with my bike. I still havent got it sorted out. The problem is that my bike will start up ok and idle good but when you twist the throttle it bogs down. when you let go of the throttle it backfires. The exhaust smells very rich of fuel and the plug is dark. I totally dissambled my carby and cleaned it, put it back on and it still didnt run properly.

I then took it into a bike shop. They traced the fault to the pickup coil. This was sent away to be rewound. 2 weeks later it came back with a note saying it tested out ok. They put it back on and no difference. They then swapped the carb with one from another yz or wr. That still didnt fix it. Does anyone have any ideas, they think it is the CDI but they dont have one to put on.

Anyone got any ideas? I havn't been able to ride my bike for a month. Also anyone interested in me posting some pics of were I ride, Darwin, NT, Australia.

Thanks Jason

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Bummer about not being able to ride Jason, I know how you feel.

If you cant ride the next best thing is to talk about it. Post them pics.

------------------

Darin from Missouri - 1999 WR 400F

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That really sucks..... You need to find a sympathetic person who will let you swap the CDI off his bike.... It should only take a half hour to do it and then ride it for a few minutes.

I would try going to a race somewhere nearby and spend the day walking around looking for somebody with a YZ400F who seems friendly, and talk to him for a while and then ask if him if you could try the swap after his racing is done for the day.

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Jason if it isn't the CDI, (this is a long shot) check that your crank seals arn't leaking.

Lou*

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DeBarker has a good idea, where is the donor bike for the carb swap they tried?

When you swapped the carb did the TPS get swapped with it? I’m not sure exactly how they function but there is another sensor under the shifter (on my US 426 anyway) and the advance is altered according to input from this (indicates what gear the bike is in) and the TPS. What you describe sounds like it might be overly retarded timing (backfires & won’t gain revs).

Never been to Australia but I’d like to go someday, so I’d like to see the pics too. There must be lots of wide open spaces for riding. Do you have “public” lands like we do in western US? Any tree huggers down there? If not I may just want to move down there.

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I dont know excatly what bike the carb came off but they did swap the cdi but would not out any spark at all. I think maybe it was a 98 wr400. Does anyone know what year model wr or yz's CDI will work. Will a 99 yz400 work?

The gear sensor only tells the CDI when the bike is in neutral, so the rev limit s lowered. I tested the TPS on my carby with a multimeter and it reads ok as in my manual?

Jason

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I dont know excatly what bike the carb came off but they did swap the cdi but would not out any spark at all. I think maybe it was a 98 wr400. Does anyone know what year model wr or yz's CDI will work. Will a 99 yz400 work?

The gear sensor only tells the CDI when the bike is in neutral, so the rev limit s lowered. I tested the TPS on my carby with a multimeter and it reads ok as in my manual?

Jason

PS what sort of warranty do you guys get? I only got 3 months.

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Hick, Yes we do have tree hugers here and yes we have the best riding in the world as far as my limited knowledge of the world goes, I met a cousin of mine from New York in Europe last year, and never saw one trail bike, I was only there for 1 month though.

After being there nothing beats this beautiful country called Australia. Come on down sometime you'll love it.

Lou

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Originally posted by jasonmcc:

The exhaust smells very rich of fuel and the plug is dark.

Put in a new plug and DISCONNECT the accelerator pump (just remove the push rod). If the bike runs fine then, you know at least that the problem lies within the carb - going on from there will take some more time. Your symptoms sound a lot like fouling plugs, because of a too rich mixture. This often looks like electrical problems and can cause a lot of confusion.

Another thing might be that the float level is not set right. You can check for that when disassembling the carb to remove the AP push rod. Look in the manual for the right procedure.

Michael

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Originally posted by jasonmcc:

remember the complete carby was replaced with one from another bike and it did the same thing ?

Sometimes the combination of parts causes the problems - not any bike is the same. If the replacement carb had the same jetting, that might just be the problem. When those mysterious problems arise, you have to be creative ;-)

Michael

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The bike has been running perfecely for the last 9 months and just suddenly this happened. There is no way that jetting could be causing this? Today we are going to loosely couple an osiliscope to the spark plug lead so we can see whats happening to the spark.

jason

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