Saito FA100 running problems

Glow expertise required please. My FA100 has been working well since originally installed in my Acrowot but it was running with an onboard glow driver which, I was told, wasn’t really necessary. So, after a bit of accident repair, I decided I’d remove the onboard glow driver. Since then it is not running right. I get it ticking over ok 2.5k then rev it to max revs 9.3k but when I shut the throttle back to tick over then open the throttle again, it cuts.

As far as the settings, the manual says the base setting is with the end of the jet flush with the end of the throttle lever but it was actually a couple of turns in. Running it flush caused an excessive amount of oil from the exhaust so really rich.

What ever I seem to do it’s not happy and it cuts. I’m sure it should be ok without the Onboard glow driver but it would appear that the glow driver was actually overcoming a poor setup perhaps. When I fitted it originally I pretty much fitted it and it worked without any low end adjustments albeit with the onboard glow driver. I don’t have a great deal of experience with four strokes and when I follow what it says in the manual it doesn’t really seem to make sense, or work.

Any advice would be much appreciated

Hobby1964 wrote: it was running with an onboard glow driver which, I was told, wasn’t really necessary

There are lots of things in life that are not really necessary, but if they help then why not...

I would guess that you need a new or hotter glow plug.Other than that, check that the pressure feed pipe between your exhaust and the fuel tank hasn't become defective.

I'm using an OS F

Glow plugs rely partly on the catalytic reaction between the platinum glow element and methanol as well as heat. If you were originally relying on electricity to keep the glow alight, it might be that the element is contaminated and no longer reacts catalytically. Try a new plug if you have one.

Sorry I meant to say, I fitted a brand new one

Re-visiting your original statement, 20% of most glow fuel mixes is oil, and practically none of this oil is expected to burn so you should expect to see a heap of clean oil coming out of the exhaust - if it is dirty it usually indicates a loose exhaust joint or something else aluminium in the engine is rubbing. It does sound like you are running too weak at the bottom end if the motor doesn't spool up quickly and cleanly.

The oil residue is clean with a redish colour. I have, since the original post, checked the valve clearances and the inlet did need some adjustment. Also I am using the last of a can of fuel which has got me wondering if it is has lost some of its properties, maybe worth checking the next time I run with a fresh can.

I have had similar isues with just one of my four strokes. Did did everything mechanically and got a new can of Contest 10 and solved the idling issue

Just managed to fire the saito up on the bench using new fuel and it ran sweet without any problems at all. The last of the fuel I’d been using before must have deteriorated and I can only assume that the onboard glow system I’d used previously had been giving it a great deal of assistance running. So at least I’ve learnt something, if an engine seems to be running rough, try new fuel first. Would have saved a lot of messing about. And, hopefully sharing this might help someone else in the future if they suffer similar.

Thanks for all of your input. Fingers crossed at the field hopefully tomorrow