'Amazing Reving CRM' MK11 (I've got one now :-( )

[drillam]

I now know that the AR carb won't work.


To see if the revs would increase by finding the air leak I sprayed some Easy-Start all around the carb, reed block and inlet stub, no difference. I removed the air filter and spayed it directly down the carb but killed it the first time. Second time I sprayed a bit less and the revs calmed down a bit. I'm assuming that what happened here is that the mixture was enriched temporarily by the ether in the spray, so for a short while getting rid of the weak mixture. Dunno if it helps though, still haven't found the scource of the leak, if there is one. Pinning all my hopes on an increase in pilot jet size now.

[fallenmikethebike]

I now know that the AR carb won't work.


To see if the revs would increase by finding the air leak I sprayed some Easy-Start all around the carb, reed block and inlet stub, no difference. I removed the air filter and spayed it directly down the carb but killed it the first time. Second time I sprayed a bit less and the revs calmed down a bit. I'm assuming that what happened here is that the mixture was enriched temporarily by the ether in the spray, so for a short while getting rid of the weak mixture. Dunno if it helps though, still haven't found the scource of the leak, if there is one. Pinning all my hopes on an increase in pilot jet size now.

While the carbs out , check for any indent on the tick over cut away part of the slide, it's the bit that hits the end of the tick over screw, this can sometimes hold the slide body open a fraction, also check for wear on the slide body itself, is it a snug fit in the barrel of the carb, and sealing adequately.

[drillam]

Cheers Mike, all clear there. Throttle slide seems nice and snug in the body.
So while waitng the arrival of bigger pilots I stripped the carb and poked every orifice through with a piece of copper wire then blew through with 100psi. All clear but it made no difference.
Let it warm up then blipped the throttle and let it run at that for a while. There's no tacho so difficult to say what it revs at when they don't die down but it's nowhere near screaming, just a very high tickover.
Cut it and here's the plug

http://i14.photobucket.com/albums/a340/ ... 1702-1.jpg

Took it for a run and going up hill on 1/2 to 3/4 throttle in third, cut it coasted in and here's the plug

http://i14.photobucket.com/albums/a340/ ... C01740.jpg

whatdya reckon?

BTW
The wee bugger goes liike stink out on the road, no fuss, no drama. I'm almost tempted to ignore the tickover revs, if it wasn't for the expense of the possible consequences.

[knackeredMk1]

This might be sillly but try slackening off the adjuster at the throttle by 1 turn.

[drillam]

Just tried it Knackered, no luck

[fallenmikethebike]

Well, to my eyes, that certainly looks leaner on the tick-over, and, slightly, rich, on the 1/2--3/4 throttle opening.
We need the pilot jet.
Mike

[knackeredMk1]

Was just niggling and easy to do .

[drillam]

[quote="knackeredMk1"]Was just niggling and easy to do :cry: .[/quote]

Yep, might as well eliminate all posibbilities.

[drillam]

Well I finally today got around to trying the next size up in pilot jet, No 48,,
Guess what ????


No difference.

So in went pilot jet No 50.
While I was waiting for the engine to warm up again I thought I'd turn the tickover speed down a wee bit and bingo, problem dissapeared. Not what you're thinking, it's not as simple as having the throttle stop screw wound in too much, here's what happens:- when the throttle stop is wound back to a fairly low tickover speed the revs die down nicely when blipped, but turn it up just a touch, and I mean much less thean 1/8th of a turn (literaly a few degrees) and the revs increase very slightly as you'd expect but when you blip the throttle the revs stay on the high side, just as before. I can still force them back down to a nice low tickover by slipping the clutch, in gear, brake on. Into neutral clutch out and it stays stable, as it always had during this process.
So I went back to the standard pilot jet, size 45 and same thing happens.

So what do you think's happening here? Any clue as to why a few degrees on the throttle stop should induce a problem but back off a few degrees and it's cured? Just like an on off/switch - "Problem/No Problem"
Answers on a postcard please !!!!!

Anyway, fuggit, I'm off green lanning up by Alton/Basingstoke this evening so I'll let you know if it survives, or not.
Millard

[knackeredMk1]

It's one of 2 things -

1). The idle screw has made an indentation in the side of the throttle slide and is just catching.

2). The throttle cable is just sticking a bit and is slowing at the point of full extension. It may well 'snap' back when you twist the throttle open and let go but that is not what happens in reality most of the time.

[fallenmikethebike]

Well it's a result of sorts, i wonder if the tick over screw is distorted, ie the end of it oscillates, as opposed to just turning, this could give the effect your experiencing.
Have a good ride tonight. The seasonal TRO on Standfast lane at Hawkley Hurst is lifted at the moment.
Mike

[knackeredMk1]

That's a third option .

Well at least it is sorted.

[drillam]

[quote="knackeredMk1"]Well at least it is sorted. :D[/quote]

yeah, and what a relief, at last.
I'll take the carb apart again today, my money's on a wobbly throttle stop screw. I'll mount it in the lathe chuck and see what happens. At least I know what I'm trying to fix now.

Went out green lanning with a couple of guys from the GS forum last night up Basingstoke way and it went well, no dramas, so very encouraged.

Thank for all your suggestions folks, they've been very much appreciated
Millard