Scooterotica

Evening all!
I have had my 1982 Spanish P200e since April. Starts 3rd or 4th kick, every time, ticks over nicely, with minimum use of chome. It can be a slight bit hesitant revving at low throttle when riding, but generally runs and pulls well, until, I have done 5 or 6 miles or so, when I assume it is getting nicely warmed up.Then it starts misbehaving! First time it happned, it felt exactly like a soft size. I managed to pull in clutch, and coasted to a stop. It kicked straight back up, but I had to 'nurse' it the couple of miles home. Thought it may have been carb related, so stripped it down, cleaned all jets etc, and rebuilt. Started straight up, and was fine just riding a mile or two here and there. Went a little further again last week, and similar symptoms, but more like fuel shortage. Put it on reserve, got nearly home, stopped at traffic light, and bike was starting to rev higher than normal. Got it home, checked carb again, plenty of petrol, plug good colour, no apparent issues! Out this morning, 7 miles round trip, and half mile from home, cut out at traffic lights. Kicked straight up, but had to rev hard to set off ( ended up pulling an embarrassing wheelie in the middle of town). When I got home, tick over was much faster than it should be.
Previous owner had fitted a new plug, ht lead, low tension coil, carb hose and gasket.
I have read loads of threads from other owners with similar problem, but none gave a definitive solution to the problem.
Anyone on here had a similar problem, and managed to sort?
Any and all suggestions, gratefully accepted.
Sorry for length of post, hope it makes sense!
Cheers
Martin.

Initial thought would be that you have an air leak somewhere, however check that the throttle cable, slide is returning fully first as this would also cause your increase in revs. If all well, if start with the easy checks, carb and box gaskets, cylinder head and flywheel side seal. Don't panic yet check out these first.

Thanks for reply Shaun. Air leak is on my 'suspect' list, but not sure why symptoms would only manifest themselves when engine is hot! Guess I am going to have to just check each possible component to eliminate! Read on various threads that CDI may be a culprit, so may buy a cheapo replacement just to check!

Hi
My p200 was doing the exact same thing. Turned to be the fly wheel side bearing seal was leaking letting air in.

Lambretta67 wrote: ↑Sat Jul 14, 2018 8:54 pm Hi
My p200 was doing the exact same thing. Turned to be the fly wheel side bearing seal was leaking letting air in.

Wow! How did you manage to suss that out? Would probably be one of the last places I'd consider checking!

Was the last thing I checked but also found that the crank bearings were shot causing the seal to fail

Martin20 wrote: ↑Sat Jul 14, 2018 8:35 pm Thanks for reply Shaun. Air leak is on my 'suspect' list, but not sure why symptoms would only manifest themselves when engine is hot! Guess I am going to have to just check each possible component to eliminate! Read on various threads that CDI may be a culprit, so may buy a cheapo replacement just to check!

Doubt it's electrical TBH.
Lambretta67 is on the right track. I had exactly the same issues with an old LML years ago. It showed no signs of leaking from the flywheel seal but after checking and replacing things as per my suggestions, turned out that once warm the slight expansion from the casing was just too much for the hardened seal to manage. Simple fix but took a fair bit of tracking down.

Martin20 wrote: ↑Sat Jul 14, 2018 9:01 pm

Lambretta67 wrote: ↑Sat Jul 14, 2018 8:54 pm Hi
My p200 was doing the exact same thing. Turned to be the fly wheel side bearing seal was leaking letting air in.

Wow! How did you manage to suss that out? Would probably be one of the last places I'd consider checking!

It was the last place I checked

In light of both of your experiences, think I will change flywheel seal first, then take it from there! Never had much to do with Vespa mechanics, but have read that it is possible to change flywheel seal with engine in situ. Is this so, and if so , much of a job?

Easy job. Just prize out old seal with a screw driver GENTLY and push new seal in. Check your flywheel for up & down & side to side movement. To much & your bearings might be worn