TZR 50 starts and runs but ?????

[Raphy]

Hello, am new here and to bikes and 2 strokes..so I have a second hand bike.
It will now start ok, ticks over ,revs slightly but will not pull or rev high.
it just faulters like no fuel and dies..
Have cleaned the carb and jets 3 times, changed the flaps, changed fuel to be sure of the correct ratio, oiled cables...
any clues please.
thanks

[monkeyman]

does the bike have an in tank fuel filter or summit?

You could pull the hose off the carb with the fuel tap in the on position, a good flow of fuel would indicate its ok.

pull the plug and give it a clean.

when you say it wont rev, does it bog down? or just stay the same?

This is proberbly going to be controversial like it was last time i said it but, i have used it loads of times as a fault finding tool. Buy some bradox easy start from halfrauds, start the bike up with the air box cover off, spray it into the carb inlet and open the throttle. If the the bike revs up ok then the problem is the fueling if it doesnt its going to be with the ignition. It costs like £5 and will save you so much time messing about.
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[Beamexican]

Have you changed the spark plug there only about 3 quid and sometimes break down under heavy load, may be worth unscrewing the plug cap and snipping 5 mil off the ht lead too.

Check the air filter is clean and not blocked as well.

[Raphy]

hi, thank you for your ideas,
fuel flows ok- the float chamber is always full..Have changed the plug for a spare-but not new, but will try snipping a chunk from the lead...
A worry was that if the piston/rings are worn, it may not be sealed enough for pumping a decent charge round the crankcase to get it moving..but just ok when idling along...
but don't want to strip it on the offchance !!! and have to reseal it all....

[jimmyRS]

as above have asked, does it feel like its lacking fuel? or does it feel like its bogging down due to too much fuel? Does holding it at 1/4-1/2-3/4 throttle make any difference to how the revs climb or does it still die?

if you bought it like this and it hasn't run right since the get go, id suggest that you may have to small/big a main jet.

correct pilot but incorrect main jet size would explain how it idles nicely but revs poorly.

if it used to run fine and all of a sudden now has just decided to play up, i'd hazard a guess at compression buddy. test the compression if you can

gluck

p.s. no hard feelings monkeyman

[Beamexican]

Probably worth getting a compression tester and checking it anyway, always worth having for the future, got a gunson one from halfrauds myself, try and get one that screws in to the spark plug hole as opposed to just pushes in as they're not as reliable imo.

[bikenut]

:karma: hi dude,

nobody has mentioned a blocked exhaust ( and/or port ) as being possible yet?

does exhaust sort of make a fizzing noise with a jet type feeling from the outlet when revved?

its a 2 stroke which need clear exhaust to allow engine to breath.

Have you placed a rag under the saddle which may block the air intake when you sit on the bike?

dont laugh as i've come across this twice in only 35 years, it does happen from time to time.

feedback and some pics for the site would be good.

[Raphy]

The exhaust sounds ok and blows out well.-even the drain hole in the silencer has smoke ..The side panels are off for access and have used a cloth in the intake to choke it...
It feels like it is just run out of fuel..as it drops revs and stops..could be needs a larger main jet...[or suitable needle file..]
I have ordered a standard barrel and piston set plus top roller..-and a new plug..just in case..
my pal has a pression tester and colortune but he's away right now...and we are snowed in so it can wait a while...
its good hearing your advice guys...
thanks..

[Speed]

May be a stupid suggestion so bear with me...

CDI unit?

[st3v3]

Hows the choke on it?

I'd spray easy-start into the airbox/filter rather than taking it off..
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[Raphy]

CDI..would it start at all ? there is a spark ok and it runs, warms up but just won't rev
I know nothing of electronic stuff...
Is there anyway to test if it is or not working ?
Is it a 4.5cm resin filled block with black/yellow/green wires...[centre yellow looks as though it got hot as the terminal cover is browned]
bolted on the tank locating tube.
It is not the coil as that's on the left,,
choke opens and closes ok, cable reoiled, it starts better if it is really open full...

[bikenut]

:karma: hi dude

some pics would be good.

so a second hand bike from a dealer ( warranty )?

been standing for a while?

you've cleaned carb and fuel system so no blocked jets etc?

exhaust clear ish.

cdi ign. a pic of flywheel would be good, cdi auto ignition advance?

does sound like fuel or ign advance.

pics of flywheel for the site.

[Raphy]

Thanks for all the helpful advice, I have swopped CDI unit [borrowed !] and will try that, then order a new one !!!
and let you know how it goes...

[Raphy]

ok lets try adding fotos...

[mysterious_rider]

Sounds like blocked jets in the carb to me.

Remove, and hold up to the light. If you can see through them it's all good. If not you need something to clean them out with.

Air gun, wire dog brush, tiny needle?

[Raphy]

I have removed both jets and blown them clear-see through.. 3 times
and removed the tank switch to check filter- its clean ,and I emptied the tank and refilled with new 2 stroke mix from a dispenser...it flows well on both main and reserve...
have also run it on a pipe and funnel..[no tank]
but not tried riding like that !!!!!
so will try a different CDI unit.

[bikenut]

:karma: wwwwwwwww looks tasty.......

electric start whizzes over engine ok, so good earth ( toppish rhs bolt with thickish wire ).

carb looks very clean but whats the blue stuff on the reed block ( hylomar.......)

make sure that the flywheel ring gear ( the toothed ring welded to the flywheel ) isnt chewing its way through the geny wires ( at about 7 o clock position ), its possible?........

ps chain looks dry and exhaust looks wet.

if reed block upsidedown eng wouldnt run ( may be only possible to fit one way )

[bikenut]

:karma: cant see timing marks but the largish flywheel hole about 1 o clockish, can i see a line on the stator?

any more lines show through this window in anticlockwise direction say noonish?

[dungbug]

run it for a bit & pull the plug out, if it's a white(ish) colour it's lean on fuel, if it's black, too much fuel or wet......Poor/no spark. Have you checked the spark? Should be a big fat blue spark.

[jimmyRS]

[Raphy]

Hi all, I put in a new reed block and it sucks the right way...the dellorto says 12 on it..
The engine is an AM6 -new standard exchange in nov 2010 and its not really run since..so timing should be as factory set..previous youngster didn't use it much since dropping it in snow.
I will try the swopped CDI unit and get back to you all..I have ordered a new one anyway.
good to get all the feedback, am normally playing with other types of propulsions...but this is for junior.
Hopefully a CDI will sort it

[nightshaddow]

no one has asked you to check the inlet manafold

you have stipulated the fuel is good and jets and carb is clean
it has been advised you check spark and replace plug and check lead i presume you have
you have checked the reeds
once you have tried the cdi check there is no holes,splits or cracks in your inlet manafold that would cause it to die instantly when reved had one split on me before it would idle perfect then die with anything above 1500 rpm
[/quote]
____________________
"WHAT DO YOU MEAN 100 MPH THATS IMPOSSIBLE Its chinese OFFICER."
Current rides CB 125 TDE(the next project) NS125RK ( now on the road ) CB125TDC (soon to be project 17) melody ( the nephews )

[Mikey CB500]

[Raphy]

it is a pre oil mix model, so it runs as tank mix...so the carb should be pre set to run on that ?
its 2002 and has a cable rev counter not electronic..although it needs a new inner...
I will have a look at jet size and also try running on the other CDI unit...
let you know results..

[Mikey CB500]