Continually seizing with panels on

[Mark 1]

Finally got my DL150 back on the road after too many years, sorted my problem with no rear and tail lights - I had put an old 6v bulb in the headlight instead of 12v

I am running an AF175 with PWK 30 and a scootrs expansion, have had this set up for years but think I now have the jetting spot on.

Been running around locally with panels off and no problems. Took it up the dual carriageway today (panels on) and after about 8 miles it nipped up doing about 50, I was almost home and coming down hill so coasted 150 metres dropped the clutch and it purred home absolutely fine. Got home and it was that hot you could not even touch the engine mounts. This was happening before I took the scooter of the road and I think the problem is the heat effecting fuel delivery (is that possible?). The siezure isn't a full on lock up, just like a whining sound and no sparking

It has done this with the panels off but only after about 70 miles with two up and luggage.

If it is heat, what's the problem and cure?

I am using a NGK B7ES is that ok?
I have changed the gearbox oil and using Castrol.
The cowls are correctly fitted.
I am runing a 3% mix with the fuel.

This is the spark plug looks like a chocolate colour to me, in the centre anyway and I've always presumed that's where you look, am I wrong??

Any help appreciated as I need to be confident it's going to get me home when I go further afield. :fb:
Thanks
Mark

[col68]

Did you take plug when it nipped up and have a look ? what petrol do you use not supermarket crap ? I use super unleaded all the time now . plug looks ok when you got home. I normaly run an 8 plug in my gp200. col

[Dryballs]

I'd be using a B8 or B9 for anything except central London riding

I'd be looking for problems in all the usual places - timing, jetting, air leaks, fuel starvation etc

[Mark 1]

Thanks Col, I was looking at all my discarded bits from when I brought this scooter (ten years ago ) and it looks like I used to use 9 spark plugs, can't remember when or why I changed

I didn't take the plug out for about an hour as it was stupidly hot. I get my petrol from an independant with a green sign, think it may be called 'Harvest' or similiar.

Thinking that I may cut 4 inches of the bottom of the panels to help heat escape.

Mark

[WINTERMODEL150]

I'd be using a B8 or B9 for anything except central London riding

I'd be looking for problems in all the usual places - timing, jetting, air leaks, fuel starvation etc

As dryballs said get your engine pressure tested for air leaks first,if its got that hot then I'd strip it down for a top end inspection as I would expect the heads distorted and needs checking for straightness and maybe the barrel and piston has suffered some scoring around the exhaust port.

I'd advise 17 degrees timing by strobe light and check the flow rate from the tank to carb, it should be 1 pint per minute approx.

Not sure on jetting for the pwk but a dyno set up wouldn't go a miss.

Dean

[Mark 1]

OK, thanks for comments chaps. There is scoring in the barrel (didn't think too bad though) and I bought the af kit after I had similiar issues with the original head that had been bored out to 175.

Sorry had to take a break and watch the scooters at the Olympic closing ceremony

The original engine rebuild was by Readspeed so I'm pretty sure it's bullet proof, maybe I never ran top end in enough

I'll change plug to a 9 but can't see it'll reduce heat that much.

If the head is distorted do I have to start again? i.e. buy a new barrel/piston/head

Already spent my money this year and nothing left in the piggy bank thoough was hoping to buy a Mugello next year.

Cheers
Mark

[WINTERMODEL150]

If the heads distorted then just get it skimmed but check the squish again as this will alter depending how much is machined off the head,you may need to get a thicker head gasket to obtain the correct squish .

Dean

[Mark 1]

OK, thanks Dean. It may be getting a bit beyond my capabilities (check the squish ) to correct the problems so I think it best I spend a little money with an expert rather than potentially keep putting pressure on the bottom end and end up paying more.

I have seen a mechanic in my area http://www.ashburtonscootertech.co.uk/ (anyone got any feedback for this site?) so will start there.

Thanks
Mark

[rosscla]

Buy Sticky's book....Lambretta 101

£20 that will save you hundreds ...

[Mark 1]

I do have stickys first edition. It's already saved me £'s :fb: I took my whole scooter apart for first time, stripped it, painted it, re-assembled and it started second kick

I'll read up on the squish bit, I do have a rough idea. How much is a head skim? Is it almost worth buying a new head from Rayspeed? Think i bought the cyliner without one and used the original, so many years ago I don't remember

Thanks folks