Running advice

[mickymidas]

Spec 1st,
P200 with HB s/4 barrel , head , piston & HB fettled orig vespa crank , & drilled filter over a dell , Si 24/24.Timing on I.T mark 18*
HB recommended 122-125 main jet & 4% oil mix

Up until a few weeks ago I was running the above with a 60/160(HB drilled) pilot & 125 main jet, all seemed ok on the flat but a tad boggy uphill, but no big deal .
Dropped the main to 124 to try out.
After that became a bugger to start .
Put the 125 back in today & still a pain to kick over , also when eventually running & on the road seems to be a flat spot in between 1st , 2nd & 3rd , but ok when going up to 4th. Could that be down to fine tuning the air/tickover screws ? Or is there somewhere I am going wrong with the jetting ?

TBH the starting is more of a worry than anything, but looking for any advice.
Had starting probs last year , but rectified with new float & needle

Recent new flywheel side bearing , and no petrol in oil when changed to do this.


Anyone ?

[pxguru]

I think a lot of this had been said several times on here but here goes anyway It does sound like its running not so well so have a go with the following and report back

Main jet - I would have a 125+ main jet in this set up and even bigger if it has an expansion exhaust.
Pilot jet is too big - 55/160 max. The one you have is so big it is affecting the main jet and causing the bogging.
Mixture screw is badly set - With a pilot jet that big, it would only need to be 1/2 a turn out.
If its a well assembled engine it should take 21 degrees timing and like it.
Track bikes don't need 4% oil. Any road scooter however much it is tuned, does not need anymore than 2% oil, ever!

The mixture screw is your starting issue if......now I am assuming here.....it starts not so bad when cold but is terrible to start when warmed up.

[mickymidas]

Cheers pal

Just to clarify a few things , I have been running the above set up for a couple of years with no probs, but only recently have had starting issues ( cold & hot).
All the spec is as written down for me when I picked up the barrel kit from HB.
I get what you are saying about the oil mix , but , I have dropped the mixture in the past , the engine ran so hot , the f/wheel side bearing race expanded and slipped out off the crank& through the seal, sending the bearing on the p88s and seizing the crank.
I will definitely try the pilot jet & main jet tho.


I have got a SIP road exhaust on as well

Many thanks, Mick

[henri]

weird,i'd of thought dropping the mix to 2% would of richened ya mix ,but from your saying it leaned it out enough for the lump to "spit the dummy" an blow a bearing,
as that set up has run ok for years an only recently given starting probs ,i'd suspect something has changed/worn out , poor startings often down to poor spark , before jetting i'd reccomend going thru ya lectrics makin sure of good connections ,ht lead n cap , an a new plug , jettings the last thing to set after ya sure everything else is tip top, H

[pxguru]

Running ok generally translates to "doesn't blow up and is still ride-able". Seems like as H said you are having many problems and looking for just one solution to them all. Seems like your bogging is one issue, bearing another and starting something else.

The flywheel bearing does not need 4% oil not to seize. This is the same for all of us, 2% is plenty. On some engines the flywheel oil seal covers the oil feed hole to the outside of the bearing. On these engines it is necessary to file a little gap in the oil seal and push it in carefully. I guess yours is one of these engines.

If its bad starting hot and cold, then the float needle is leaking, poor compression/oil seals or the spark is no good.

If its bogging and has flat spots the jetting HB gave you is no good for yours. An HB barrel and an SI24 should jet in perfectly and run as good as a factory standard.

[mickymidas]

Cheers for the input boys , will spend some time in the garage this week & work some stuff out

[mickymidas]

FAO Henri & PX Guru

New Cdi , HT lead , plug cap & plug .....also dropped pilot jet back to 55/160, started 1st kick & a couple of laps around town before the rain started , ran as sweet as a nut & a nice tick over.

Cheers both , just shows you CAN teach an old dog new tricks

[henri]

my spidey senses say "a trip to halfords ,new plug an a choppin session" are in your future , just to be sure n safe eh, cant have this "old dog" losing his bone ,eh , H