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Post by bryno on Jul 8, 2014 10:49:30 GMT
Had an intermittant issue for a long time now on my '85 PX200E
Get to about 60 and sometimes it sails on to 70, sometimes it just stutters at 60, won't rev any higher, like it is suffering fuel starvation (never misfires, just feels like running out of fuel).
Some days it can stutter at 60 on the way to work then be good as gold on the way home same day, sometimes I can have the problem for a week, then it goes away for weeks, seems no pattern of when it happens though I think more likely when past half way mark on the fuel gauge.
So far i've done this;
Cleaned tank (zero rust)
Swapped carb body, float, needle valve, air corrector (not tried main jet)
New fuel line, exact same length as OE
New fuel tap - fast flow
Tried different brands of fuel
Drilled air hole in filler cap
Drilled air filter & 2 point upjet, filter is clean
Changed cylinder head, stator plate, CDI, Plug, lead, cap, wiring
Run out of ideas now, all suggestions welcome!
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Post by sbwnik on Jul 8, 2014 11:22:33 GMT
It's not weather related, is it?
A bit of moisture in the air and mine is noticeably faster.
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Post by pxguru on Jul 8, 2014 12:25:34 GMT
Bryno, just a few more questions first.
Is it completely standard PX200 engine? What exhaust and how old? ignition timing on the A mark (23 degs)? What number main jet 118 or 120? and atomiser BE3?
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Post by bryno on Jul 8, 2014 13:28:41 GMT
Hm, i've not thought about weather, I do tend to notice it more early morning (I ride pre 7am) not so much on my evening return..
Standard P200 just drilled filter and I changed from a 116 (it wasn't marked at all so I presumed a 116) to a 118.
For some reason I had fitted a BE5, now back on a BE3, stutters on both.
Timing is to the factory setting, maybe I should check, I've had the scoot from 6k and nothing had been messed with when I got it, but maybe timing never has been spot on.
Standard exhaust, it's the original so near 30 years old although only 13k of use, i've also tried a standard repro (not new though).
I have ordered a 119 main and guess I should do a proper strobe on the timing....
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Post by henri on Jul 8, 2014 17:47:32 GMT
definetly strobe it ,but maybe degree disc an your own known good timing marks ,unless where you live is up a mountain an work at sea level weather whilst noticeable in effect shouldnt add up to 10mph i think. which fast flow tap is it , bgm=good rep ,sip=not so , an does it have a breather tube ,some blame them for cavitation but my understanding is to prevent that is why they are there. most have there fuel lines at oe or longer ,so tank can be pulled still attached at banjo ,as prob is more present at half tank an less,when theres less head of petrol to force down the pipe,as youve done everything else i'd trim the line shorter ,means when next you pull the tank pipe has to come of banjo first ,extra 10mins to job max, but a more direct ,less looped petrol pipe is less likely to air-lock or slow the flow .
a choked exhaust ,binding brake , out of ideas . H
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Post by pxguru on Jul 9, 2014 4:38:07 GMT
The BE5 is the second richest atomiser and the BE3 is the second weakest. Which would be ok if there was only 4 of them but there are 6. If it was running rich in the mid range for a long time, that old exhaust could be choked up. Put that other exhaust on for a few weeks to eliminate it.
The other thing might be compression. Does it feel ok?
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Post by henri on Jul 9, 2014 7:18:15 GMT
the exhaust was also my second idea,but ya said you'd tried a repro 1 an it made no difference ,but ya also said it wasnt new,an exhausts dont choke n unchoke so dont explain the problem coming an going ,i'd still give 1 exhaust a caustic soda soak an a going over with a blow torch til it flushes clean ,it will need a barby paint job afterwards ,but if its 30 years old probably could do with it anyway . takes 1 thing out of the equation ,
is this the p2 with a stuck rear hub youve mentioned before ,if so maybe its time to try ya diy hub puller ,as my 3rd guess was a binding brake ,easy to tell,next time it happens stop on the front brake an feel rear hub ,warms ok ,ouchy =binding ,adjustment or clogged with dust can cause it ,aswell as ovalled hub. could be caused by whats seizing it on the splines ,havent found this on vesps myself but earlyier brettas did have weak shafts with the splines as the weak point ,twisted splines trapping hubs on there cones ,or in bad cases in ld's n earlyier a mis-gearchange or emergency brake mess up leading to rear hub breakaway an overtake ,
a stab in the dark maybe ,but you seem to of covered all the "usual suspects",maybe its back to nics idea an keep a diary with air pressure n humidity marked an see if theres a correlation to performance ,but wouldnt expect such a marked effect on a standard engine .there set to run from sea level to about 5000 feet an on all sorts of petrol .Henri
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Post by vespasco on Jul 10, 2014 9:24:31 GMT
My first thoughts are:
Blocked exhaust
Different fuel. Recently, my scoot will run like crap if i fill up with Shell. F@£kin ethanol.
Also the weather as mentioned. Especially if it goes well when colder, not so well when warm.
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Post by bryno on Jul 10, 2014 12:55:42 GMT
thanks for the suggestions all.. plan is
- Clean out the OE exhaust and refit
- Check timing accuracy (currently on factory setting, whatebver that is)
- Check fuel line not kinked somewhere, may shorten
Fuel - I switched from my usual Shell to Texaco last week, no better really
Hub - I don't think the brakes are binding, but will check, Henri - yeh I tried my DIY hub puller, it bent! that hub is stuck fast, I need to make something more substantial!
Fuel tap - it's the crappy SIP one, but I had same problem with the OE tap, so dont think tap is a problem, not sure SIP has that breather tube
Timing wise, is common practice to retard the timing from the OE setting these days?
on lammies people use 19 BTDC rather than 23 BTDC, given my PX was pre unleaded does same logic apply to retard by a few degrees off the book setting?
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Post by henri on Jul 11, 2014 20:33:50 GMT
the offer off a loan of my "franken-puller" still stands.an most advice ive heard both with scoots an in the classic car lot is retard about 2 degrees ,but run my 66 triumph right on the factory setting an dont have pinking, more than is standard anyway ,tho it is a tired engine an prob down on compression.following advice with my new re-built lump have retarded 2 degrees but not got round to fitting ,squeezing the last hundreds of miles from old lump coz i'm tight an i got recovery.
an the timing doesnt explain it coming an going ,unlees its running at edge of comfort zone an weather tips it over 1 way or tother, but might be overthinking this an reckon its a simples ,an doh moment coming up. Henri
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