I'm still trying to get this Magnum 1.08 broken in, but am having some trouble.
I think I've got the high end set, so now I'm trying to work on the idle.
Last week I put two tanks of fuel through it without much trouble.
So yesterday I start it up, and re-check the high end, and then try to idle. Here is where it gets strange.
As I get the throttle down toward the last couple clicks, it still idles pretty fast, so I take it down as far as it will go, and it speeds up[sm=confused.gif]
So I try reving it a little to get it to quit, and it won't, so I have to pinch the fuel line to get it to die.
I richened the idle, and it wouldn't start, put the idle back where it was, and still wouldn't start. Unfortunately the engine sits too high on the Dragon Lady so it's hard to keep fuel up to the carb when starting. I think this may be the reason I couln't re-start. I hope.
What's going on with the idle??

Couple more questions.
When I start it, I'm using a technique a guy at the field showed me. Prime the carb, and then flip the engine clockwise and let the compression kick it back the other way to turn it over. It has been working, but is this o.k. to do?

When people say "lean it out" shouldn't they really say "lean it in" since to lean it, you turn the valve clockwise, which is tightening it, and turning it in?

Here's what's happening. You are running the top end rich -correctly. The idle is probably a little rich too. Good. When you get to full idle, the tank is too low to draw fuel, and it leans out and speeds up since your setting is a little rich. Not sure with a fix. You really need to raise the tank or lower the carb centerline. You can rotate the engine from upright to sideways and that will lower the carb - or try a pump and leave the rest the same. Make sure also that you can close the throttle barrell completely with the throttle trim too as a safety issue so you don't have to reach towards the engine every time to shut it off.

It is mounted sideways[]
I guess I could mount it inverted.
Shoot, then I'd have to get a new cowl. And change the exhaust. It has a Bisson on it.
Probably not what I want to do.

I agree that it sounds like what ual767 is saying. But if the engine is sideways, and the tank center line is pretty close to being in line with the spraybar, then it's something else.

But the basic problem of the mixture leaning, I think, is right on. So, the question becomes why is the idle leaning as you idle down.

Another possibility is that there is an air leak in the carb or carb mount area. This would allow too much air in, and cause the engine to not draw fuel like it should at idle.

Just to clarify, it sounds like the engine idles a bit fast, but is stable, and transitions to higher throttle settings fine? If that's the case, then I'd probibly just reset your throttle linkage to allow the barrel to close fully, and go with it.

Also, on any engine, but espeically ringed engines (as the 1.08 is), the idle can take a long time to really settle down. If you only have a few tanks though, I wouldn't sweat idle oddities right now.

O.K.
Now that you mention the leak at the carb you reminded me that I do remember hearing a hissing type sound when I prime the carb.(Thumb over inlet, while turning prop)

I'll check that out tonight.

Backwing,

Yes, the 108's do take a couple extra seconds to "idle down", as Montague stated. The one I had about a year ago also had a problem with the head bolts loosening. Give them a check also, and re-torque if necessary. This could also be part of the problem.

They are a little temperamental until you get a couple gallons through it. In fact, my Son-n-Law has mine now and it can still act up now and then!

I wouldn't mess with, or change the way you have the motor mounted...horizontally should be fine.

Best of luck to ya!

Gary

Alright, so how would you check to see if the carb has an air leak?

Well I think you can disregard the previous post[sm=bananahead.gif]

I put my lips over the carb and blew into it. There is air escaping out the carb retainer bolt, but on the opposite side of the nut.
I don't want to ruin the threads or get the retainer slot out of place by trying to thread the bolt in further. Could I just use some type of sealant to seal off the leak?

Thanks for your help.
Jordan

Yep, you can seal it right up. Get some high-temp RTV (room temperature vulcanizing) silicon gasket material from an auto parts store. I use the red stuff, (because that's what I bought when I was there first), though I hear the black stuff is better. Anyway, I use the red stuff to seal up carb mounts that leak and such. I've also used it to seal around fuel tank stoppers as well.