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TZR50 splutters after 7000rpm. Help!!!


tzr50 Mike
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hmm..

is the bike standard?

try checking your carburettor for blockages, if you were on reserve before filling up, it's likely you will have taken some crap through the carb, partly blocking the main jet, simple enough to remove and clean out.

Alex

I took the whole carb out yesterday and gave a thorough cleaning , however to no avail ! :(

However the bike seems to sound like its being strangled in some way or another , the choke doesn't seem to be sticking at all , so I wonder if it could be a problem with the exhaust ?

thanks for the comments guys , I will get to the bottom of this ..... Eventually !

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Not exactly a bike but I found this thread the other day whilst searching similar symptoms in a 2 stroke Yamaha outboard engine. Everything looked ok but it wouldn't rev, despite cleaning the carb with carb cleaner etc.

I finally managed to get it sorted today by opening up the carb and giving it a good bath in an ultrasonic cleaner. I also had to make a new gasket out of gasket paper with a scalpel using the old gasket as a pattern. I guess there must have been a tiny blockage somewhere.

2 stroke exhaust ports can coke up, but it's usually something that gets gradually worse over a long period of time and doesn't come on suddenly. There are lots of possibilities but the usual culprit is fuel related in 2 strokes. What condition is the spark plug in? It can give a clue to over/under fuelling...

Alex

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I dont actually own an ultrasonic bath , would you have any idea where i could find this facilty ?

The fuel i had in the tank before had been sitting around for ages before i filled up , I wonder if a mixture of new fuel and a tight corning could have fulled a load of crap though somewhere ?

The spark plug itself is brandnew ( about a week old ! ) and but does show signs of over fueling ( black fluid on the pulg ?!?! )

I hope this is the bottom of it , I dont intend on forking out for a mechanics bill again !

Cheers for the pointer :)

Many thanks again ,

Jordan

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I took the whole carb out yesterday and gave a thorough cleaning , however to no avail ! :(

However the bike seems to sound like its being strangled in some way or another , the choke doesn't seem to be sticking at all , so I wonder if it could be a problem with the exhaust ?

thanks for the comments guys , I will get to the bottom of this ..... Eventually !

how strange, no blockages in the main jet?

have you checked the air box for anything that could be dramatically restricting air flow?

there could be a problem with the exhaust, but the effects from an exhaust problem will not come on over night, so i'd say it wasn't the exhaust.

what colour is your spark plug tip?

Alex

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how strange, no blockages in the main jet?

have you checked the air box for anything that could be dramatically restricting air flow?

there could be a problem with the exhaust, but the effects from an exhaust problem will not come on over night, so i'd say it wasn't the exhaust.

what colour is your spark plug tip?

Alex

Ive tried running her without an air box , which made no difference :( the spark plug is black in the end and there is a black fluid on the thread too , im guessing she's running too rich , but I don't think this would have made such a sudden and dramatic affect :\

Thanks again

Jordan

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I dont actually own an ultrasonic bath , would you have any idea where i could find this facilty ?

The fuel i had in the tank before had been sitting around for ages before i filled up , I wonder if a mixture of new fuel and a tight corning could have fulled a load of crap though somewhere ?

The spark plug itself is brandnew ( about a week old ! ) and but does show signs of over fueling ( black fluid on the pulg ?!?! )

I hope this is the bottom of it , I dont intend on forking out for a mechanics bill again !

Cheers for the pointer :)

Many thanks again ,

Jordan

Jordan,

I'm not sure where you'd find an ultrasonic bath to be honest, do you have any carb/engineering places near you? They can be had quite cheaply off fleabay but the cheap ones aren't as effective. Failing that you could use mine if you're anywhere near the Bristol area?

Wet plug does tend to suggest over fuelling though as you say. I'd recommend an ultrasonic clean, reassemble and then re-tune, unless anyone else has any better ideas! I am basing my advice on outboard motors and not bikes after all!

Alex

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I live in Frome , just south of bath , so about 45 mins from Bristol, however being bike less I may have to post it !

I suppose 2 stroke engines are all the same really :P

Ill let a mechanic have a look and if he can sort it for a fair price ill let them sort it , if not ill have to look into an ultrasonic bath !

Cheers guys , ill keep you updated !

Jordan

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I know Frome, I'm down that way a fair bit. Will probably be down there in a couple of weeks in fact, if you get nowhere in the meantime give us a shout.

best of luck!

Alex

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Ive tried running her without an air box , which made no difference :( the spark plug is black in the end and there is a black fluid on the thread too , im guessing she's running too rich , but I don't think this would have made such a sudden and dramatic affect :\

Thanks again

Jordan

yep definitely running too rich, and believe it or not, running that rich can have a sudden, dramatic effect like this.

though you need to find what has caused the mixture to turn so rich, have you checked the exhaust for any problems? seeing as it's running rich, i'd suggest checking the operation of the choke, making sure it isn't sticking.

if all else fails, try down jetting?

Alex

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  • 3 weeks later...

Hey guys , I told you that I'd tell you when i got to the bottom of this !

I was told to take a look at the exhaust pipe by a neighbour , turns out it was blocked ( as in nothing would pass through )

So iv taken this opportunity to buy a sports exhaust , Thanks for all the help guys really appreciated it :)

Thanks again

Jordan

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