Frustrated with MX5-troubleshooting

[challenger]

hi anyone,
just aquired challenger mx5,starts ok but burbles badly unless revs are kept high,stalls when try to pull away(not clutch drag),did get going and ran well,have ceaned carb and replaced jet etc . am no mechanic just understand basics,would like to here anyones thoughts,am new member just joined,thanks:

[Andy Z]

hi anyone,
just aquired challenger mx5,starts ok but burbles badly unless revs are kept high,stalls when try to pull away(not clutch drag),did get going and ran well,have ceaned carb and replaced jet etc . am no mechanic just understand basics,would like to here anyones thoughts,am new member just joined,thanks:

If the carb is all OK, then I would check the crank seals.

[challenger]

thanks for reply,not a job i can do on my own may have to find someone who can help,was hopeing it would be more straight farward.

[greeves246]

Challenger rough running weak

no could well be side seals ! you can drill a hole can use a self tapper screw and cairfully and pull out the side seal with plyers and clean and press a new supple one in replacement.

BUT!.

Check for air leaks on the carb to barrel and check carbrettor flange for
flatness using a ruler across the flange if its bowed use sand paper on a surface plate TO GET IT FLAT.

ALSO CHECK CARB NUMBER 389/
OR 932 R

CHECK INLET ON THE CARB HAS A CHOPPED BRASS SPILL (TWO STROKE CARB)
IF ITS FOUR STROKE CARB IT WILL HAVE A PLAIN SPILL

IF THE ENGINE CUTS OUT AT MID THROTTLE CHECK THE PLUG IF ITS WET ITS IGNITION PROBLEM.

IF ITS DRY THERES NO FUEL (STARVATION).

OR WORN THROTTLE SLIDE WILL ALS CAUSE WEAKNESS IN THE MIDDLE OR WRONG CUT AWAY (NUMBER SLIDE).

[challenger]

Thanks greeves 246 for your reply,i have plenty to think about now,just need time to get in shed.I have ridden bike but needed push to get momentum then it ran ok.Was trying to get bottle for a classic scramble but seems long way off at the moment !!!!!!!

[stormer254]

It is unlikely to be the seals, their most prominent symptom is the engine ticking over too fast and will not throttle back, I assume it has a fibreglass tank, this is a major problem with the ethanol now in petrol, this can cause all sorts of carburation problems with the smaller jets, i.e. pilot jet being effected most. I would check the inside of the petrol tank and see if it is starting to go sticky and soft. Never leave petrol in a fibreglass tank if you are not riding the bike.

[challenger]

Hi Stormer 254,
Thanks for your reply,interesting to hearabout the seals,as for tank it is alloy which is just as well by the sound of it.
Found problems with carb this afternoon,float bowl not tight,threads damadged,also pilot jet snapped off.
Learnt a lot today,not sure next step yet !!!!!!
Did ride bike ,engine felt ok and handled well,but wouldn't pull away without push,deep burbling sound from standstill and when revs low when cornering.
Thanks again for your help
Actually i had stormer before challenger

[greeves246]

Challenger rough running weak

BEST WAY IS TO BE METHODICAL AND GO THOUGH EACH THING TILL YOU COME TO THE PROBLEM SOUNDS LIKE CARBURATION YOUR PLUG SHOULD BE N3 CHAMPION AS WELL ? OR N3C (COPPER CORE) NO PANIC

YOU CAN AJUST FLOAT HEIGHT WITH TAPPING THE BRASS INSERT IN THE FLOAT BOWL BY REMOVING THE BANJO BOLT BUT THATS COMPLICATING
THINGS :-)

MY 24MCS 1961 2ND KICK FROM COLD

http://www.youtube.com/watch?v=KkKOIhwh2Es

GARY AKA GREEVES246

[challenger]

Hi Greeves 246,
Thanks for reply,trying to be patient but thought i was getting ridable bike.
Swapped my stormer with dealer in old bike mart on trust !!!!! was told it was race ready (i know ,it's just my nature i suppose )
i let someone borrow stormer parts catalogue and someone else tools never got them back.
Anyway i like the greeves,handles well,thanks again

[greeves246]

i know where theres a stormer !!!! needs tlc though !

[challenger]

Hi Greeves 246,
will keep trying with challenger,still burbling badly atlow revs,difficult to pull away then still burbling slow corners etc,have new spark plug and air filter on order,swopped all carb internals but pilot jet is snapped off and threads are not good to tighten float bowl,thinking about new carb !!
if its anything like crank seals (i cant do that) i would have to take it to someone,i've done more on this bike than i've ever done !
But out of interest what cc is stormer you mentioned,wiill get another one day,but would also like to keep greeves(mus'nt let wife read that bit!!!!!!
thanks
'

[stormer254]

Have you tried screwing the air screw out a bit, they are normally 1 to 1.5 turns open , try following the Amal tuning guide you can get from their website

[challenger]

Yes,tried addjusting airscrew bit better,biggest improvement to date was tightening cylinder head.think have to sort carb (pilot jet snapped off)thought it might be blocked slightly ? Ihave new pilot jet but can;t get broken one out.When i first took carb apart last week(first hour i had bike),also found main jet holder was unscrewed agood quarter inch.At worst it might be new carb!!!!!!!
Learnt a lot this week,as i said i only know basics.Ankle getting better still very black bruseing,will be kicking again soon.
I have no manual.trying to find out which oils suit,can.t find level screw for chaincase,and is that gearbox filler on top,directly under carb ?
Thanks for all help

[greeves246]

better ?

yes the filler is under the carb alloy bolt wit worth thread

sounds like your sorting the old girl out !

head lose ? 22lb ft torque should be if you pull a thread on the head bolts get a
heli coil kit and heli coil the bolt

oils are contreversial
gearbox is availible easly monograde but the clutch oil is hard to get in right viscosity some use ATF

i use castrol scooter racing oil seems most stable octain
fuel might be worth trying av-gas 110 LL (110 OCTAIN IDEAL FOR 11-1 UPWARDS COMPRESSION RATIO

[challenger]

Thats some usefull information,will see what i can sort out.
Bit short of time,be on case soon as pos!!
Oh yes would you know how much oil per fork l
I think that will do me for a while,thanks again .