cutting out

[Windmill John]

Hi All,
I've just got a 1988 Dominator; always wanted one
The thing is, when you slow down and come to a junction, the engine cuts out instantaneously.
Now, if I'm still moving a bit, it will bump easily; it also starts immediately on the button.
It's not all the time, this morning, it happened just twice on my 28 mile commute.
I can't narrow it down to carb or electric. I feel more carb but???
Now, I used to have a Vigor and that did it occasionally too, but that had Secondary air gubbins and a TPS on the carb. the Dommie is a normal carb.
As this has happened to two bikes which both use the RFVC 650 engine, I wondered if anyone could shed any light?
I suppose it could be electric as it cuts out instantly, but it starts again very easily.
As it's not often, that still doesn't narrow it down to fuel or electrics.
Help please
John

[Simon WS]

I doubt that it is electrical John, as I think the Domie is rather prone to carburation issues which can cause problems like this - my well-behaved Domie has just started doing it too! My first port of call is to check the pilot screw setting on the carb - nominally 2 1/2 turns out. You may be lucky and can do that with the carb in situ, if not remove carb and do it (and clean carb at same time). If it still does it I would back it out another 1/2 turn and keep experimenting until it stops.
Also check that the choke is completely closing.

Simon

[Windmill John]

Cheers Simon,
Always happier when it's carb than electrics.
I'll follow your advice. I planned to do a carb rebuild in the near future, I might just move the timescale.
First commute today, found it mildly hunting when cruising, so a clean and adjust probably suits the bill.
You know it's the right bike when, even with foibles you love it.
I have a very short list of bikes that I'm passionate about.
BMW GS, Dommie, XT500, Vespa,
Got the first two, dreamt of an XT500, regret selling my T5 Vespa years ago.
No need and no space for more than the two bikes; Vespa ,maybe when I retire, or work within 5 miles.
Thanks again.
John

[richie]

Good list John

Fancied a lambreta myself, 20 years ago...

Had a GS now got a dommie, broken down more than on the road. Just niggles really but where I live its hard to get sorted.

[Confucious]

Remembering posts from about 2-3 years ago, engine cut-out is a cute characteristic of the Dommie - I love it ! . There's always the option to increase the idle a tad, but I just fine tune my coordination skills with throttle, clutch and brake exercises on the run up to junctions. BTW - a little reminder that the rubber insulator (piece between carb and cyl) has a tendency to split on the underside affecting the mixture, and can lead to engine siezure (thank rubber chicken for this info...). Mine's an 88 just passed 60,000km - runs like a swiss watch except for the cut-outs

[AlanH]

My Dommie used to be worse cutting out when the clearances were set tight or the plug was past its best. Setting clearances on the loose side of spec improved matters.

Interesting fact, on my 1986 XBR500, Honda changed the valve clearance specs (increasing clearance) as a fix for cutting out when stopping - and it fixed it.

[catteeclan]

Interesting fact, on my 1986 XBR500, Honda changed the valve clearance specs (increasing clearance) as a fix for cutting out when stopping - and it fixed it.

That's a good one, haven't heard that before but it makes sense.
Did you get a smoother tickover too?

[Rubberchicken]

As was mentioned above: If you do a carb rebuild, have a good hard look at the rubber bit that bolts onto the head:


You also might want to replace the needle tube, they wear out ovally, not good for fuel efficiency:


Putting a platinum or iridium spark plug in will make things a bit better as well... Mine starts easier, and fuel economy got better but I don't know if that's the plug or the needle tube as I did both at the same time.

The idle cutoff thing mostly seems to happen when rolling towards a stop, throttle closed. I've also replaced my slow jet with the next size up, and fiddled with the pilot mixture until it idled best, and I have to say I haven't had as many cutouts as I used to.

(Used to be I could put the bike sideways on a rainy day, by having it stall in second all the time and trying to bumpstart on the wet oily mess you usually find in front of traffic lights. Mind you it'll scare the tourists if you pull up sideways like that. )

With the engine cold all bets are off, but last summer when properly warmed up I've had it idling at the low side of the honda spec around the 1100 rpm mark, without too much trouble, while I used to turn it up to 1500 to keep it running.

[Confucious]

OK AlanH - that's something I could try.... I took my first steps into manhood by adjusting the valves last year...Seeing as the Dommie is still in one servicable piece I reckon I did ok....apart from the cut-out/off. I'll try what you mentioned and see if it works ! As for now, she's laid up til April, by which time the snow may have disappeared.

PS. Bought a virago 750 and now have a flat side on my nuts, where the twins were pushed gainst the tank....

[Windmill John]

Great bunch of responses guys
I'm going to tolerate the cutting out until summer and put up with it for the winter; no garage.
Love the bike though; that's the problem with always wanting something.