Series 2 problems

[HxPaul]

Maybe someone on this forum can help.I have a series 2 with a GP200 engine with a Casa 210 top end and for the most part it runs ok.When I go out for a ride the scooter runs good,but into a headwind or up a slight gradiant if I open the throttle in third it will go really well but when I put it into top it looses power and seems to miss,there is also a noise like a popping sound from the exhaust side which seems to coincide with the missing of the engine.I've changed just about everything-cdi,H.T.lead,plug cap,spark plug and stator plate(twice)I've disconected the green wire in the loom to eliminate problems with the ignition switch.The only 2 things I havn't changed are the flywheel and the carb.The carb is a Jetex and ran perfectly well on another scooter.I dont know which way to go now,my only hope is that someone may be able to shine some light on the problem.

Paul.

[coaster]

The loss of power could be a gearing issue (not the popping), what gearing does it have? Could also be fuel starvation possibly, have you tried timing the fuel flow fro the tank into a measuring jug? something like a pint per minute is deemed good.

[CHRIS in MARGATE]

On the details you give aside from the popping sound, to me it would appear to be over - geared with the exhaust.
What exhaust are you running. If it's an expansion exhaust it may well be coming out of the power band. Clubman type exhausts cope better with headwind and uphill conditions.

[HxPaul]

I'm running a GP150 gearbox and I dont think that is the reason for the loss of power,it actually feels like its miss-firing and each time it misses you can actually hear the sound through the exhaust.I have an OMG fast flow tap and the I've checked the fuel flow and it is over a pint per minute.The exhaust is a 42mm clubman.

Paul

[CHRIS in MARGATE]

Definitely not gearbox/exhaust then.
Worth stripping the Jetex and checking that the float is not sticking on the pin (a common problem with Jetex). Easily rectified. Not saying that's it but another component to eliminate.
After all this it may be blown head gasket or something.

[HxPaul]

Just been out for a long ride and it seems that the miss-firing is in every gear when the engine is under load and the throttle is about 3/4 open. ie.up hills.I've had the carb in bits and cleaned it out with carb cleaner and the float is free and moving ok.The Casa kit is run without a head gasket.The only thing I havn't changed is the flywheel,I've checked it for loose magnets and the centre boss is ok.Could the flywheel be the problem ? By the way its is a 12v electronic system.

Paul

[fiveo]

This might be worth a look , I run a gp 200 on a jetex had the same problem as you describe. I found that the pin that shuts the fuel off to be slightly to long causing fuel starvation at high revs (well I think thats what happend ) I swapped with a black tip dellorto pin this cured my problem so as I said might be worth a look.
Fiveo

[MK Monty]

I was a big fan of Jetex carbs thinking that all the hype was bollox about to get a good one you will have a box full of crap ones. I was converted to a Delorto 26 and its transformed my bike. I can drive out of corners using the throttle and is so smooth not on or off as the jetex seemed to be. I would also check your timing if it's static does it stay static if it's auto advance retard what's it doing under load.

[HxPaul]

Well I've found the problem.The nicasil plating was slightly raised on the lip at the top of the cylinder and caused the cylinder head to sit proud and not seal properly,as a consequence it was blowing.That wasn't the only thing that I found.I used an Indian case for the build,when I fit the Casa 210 kit I didn't do a squish test ( big slap on the back of my hand for that )It turns out that the squish band is almost 3mm I have an Li 125 case that I am having converted to 200 and I will fit the 210 kit on it,but it looks like a long job because Oilteck are mowed out with cases and aren't taking any more until September
Paul

[HxPaul]

Does anybody know who else does the 125/150 to 200 case conversion.I'm in Halifax,West Yorks,but if there isn't anybody in the area that does conversions I'll gladly go elswhere.

Paul

[Wack]

Mike Phoenix does an exchange or buy outright

[Rich Oswald]

Mine was done at Chiselspeed,

Rich'

[Toddy]

Oiltek do them as well

[Rich Oswald]

Oiltek do them as well

Read the thread Mr T

[Toddy]

Oiltek do them as well

Read the thread Mr T

I do apologise most sincerely Richard

[Rich Oswald]

Oiltek do them as well

Read the thread Mr T

I do apologise most sincerely Richard