Saving Old Seagulls

Unable to start and I suspect a lack of crankcase suction and consequently lack of fuel.
Should I be able to detect crancase suction at the carburettor spigot when trying to start the engine. Any suggestion most welcome.

Add a little 30 grade oil into the crankcase and turn crank shaft, then turn engine upside down and turn crankshaft again. This should allow the oil to create a seal in your crankcase. I have had to do do this on a couple of very worn engines to get them going after they have been sitting for a few years.

Agree with Tinker, often have to do this with motors that have been laid up for years. See also tip about 'superflooding' on FAQ page
Regards
John
SOS

John@sos wrote:Agree with Tinker, often have to do this with motors that have been laid up for years. See also tip about 'superflooding' on FAQ page
Regards
John
SOS

Tried adding oil to crankcase but still little or no suction at carb spigot. Also tried "superflooding" but the spark plug does not get "wet" and no signs of fuel. I'm now considering a complete strip down and obviously need to know if all parts are available before I go ahead.
Regards,
Peter H.

Hello Peter, think you are going to have to do some further investigating. All the bits available here on the shelf.

Suppose you have poked a pencil in to see if there is a piston in there! Would not be the first to be sold with out one!

Last week an owner came to me after buying a 'good runner' on Sharkbay, no spark, when he took the top off the flywheel, no coil!

Manual a good start, £11.50 plus £1.50 P&P UK, contact me by e-mail

Regards,
John
SOS

Hi John, do you have a manual for the EFNR?

I'm assuming there is no manual for the SD's?

Cheers, Hugo.

Hi Hugz,

the standard workshop manual covers all the square block models, including the EFNR and it also covers the model 102, the SD, bargain then at £11.50!

contact me direct by e-mail and I can arrange for a PayPal invoice link to you for payment and include P&P, believe you are down under?!

Regards,
John
SOS

Hi John,

Yes I've done the usual checks like checking for sparks etc and find one aspect confusing. Compression seems to be quite good which would suggest piston and rings are OK so if this is the case, why no crankcase suction, there are no obvious leaks and no sign of cracks etc.

Regards,

Peter H.

Helo Peter,

compression new on the 102cc was 55psi, they can run with as low as 35psi. when you realise a car can be in excess of 150 psi you can see compression is not something Seagulls worry about.

Wonder of someone has striped and rebuilt this and blocked the transfer port, or the main bearings are so worn all the vacumn s being lost there... Think you are going to have to strip this one to find out........

Unless anyone has a better idea...

Regards,
John
SOS

Peter

I've seen crankcase compression lost thru the upper main bearing. The lower main doesn't seem to wear as much.

Simple test;
* remove the flywheel,
* rattle the crankshaft fore & aft.
* if you can observe any flog between the crank & bush, then it's worn out
* maybe put a drop of thin oil into the bearing, this helps act as an indicator, as it squeezes out when you rattle the crank

Rex

The maximum crankcase compression found in a Seagull is no more than 1.35 : 1, which is less than 5lbs pressure.

As most adults can blow around 7lbs, try blowing hard into the inlet stub, you will hear any leaks, even is it leaks a little it only has a maximum 5lbs for less than a quarter of a revolution, at peak revs of 4000, that equates to 0.00375 of a second to leak, I don't think you'll loose a lot of gas in that time & at that pressure.

If you still have doubts pour a cup full of fuel mix into the inlet stub, then turn the flywheel so that the inlet port closes, then turn the flywheel as hard as you can, if there's a leak you will see the drips.