14 replies to this topic

[jamesheath]

Hi,

As you are all surely aware, Just fitted my 2 inch RC40(ish) exhaust sytem, sounds great.

Got all the gaskets and other bits from minisport who recommended an AAV needle, not the AAU on that minispares recommend.

First question how different are these and is AAV OK for an otherwise standard 998?

Second question. Other than a rolling road, what will I need to adjust to stop it running like a dog? It may be a simple mixture setting as it is difficult to get the revs up and even then there is little power. I guess in essence..... Going from a standard setup to an AAV will make it richer or leaner?

Cheers guys

J

PS anyone had any joy or reccomendations re exhaust assembly paste?

Edited by jamesheath, 05 September 2007 - 07:58 PM.

[edjohnson]

you will need to adjust your ignition timing to 5 degrees BTDC, which is a pain seeing as the timing marks on my engine are at four and eight degrees!!

and just go for a drive and adjust the fuel till it runs smoothish

check your spark plugs to make sure your richer than you are lean, but a rolling road is needed really

ed

[minislapper]

2" on a 998? Eek!

[jamesheath]

2" on a 998? Eek!

Ummm. Ok, any FAQ or handy tips on how to adjust the timing? Does haynes cover it? Is it really necessary?

I have not even had the chance to adjust the fuel mixture since fittign the new system and needle... may simply just be running too rich?


Ta

Jamesl

Edited by jamesheath, 06 September 2007 - 07:52 AM.

[Scruffs]

Just set the mixture up at idle for the moment and you should be ok until you can get it to a rolling road. Always err on the side of rich though until you can get it set up properly, and set the ignition timing correctly first. In terms of relative richness I think an AAV is slightly leaner at low loads than an AAC (standard?) and ramps up pretty rich at full load.

Whether you're running richer or leaner at the moment will depend on how far into the dashpot piston you put the needle compared with the one that came out, assuming that all else is the same (which it isn't, so that just complicates things!). see if you can get it on a CO meter.

I don't think you're going to be able to do much by changing ignition timing without a rolling road. I'd just leave timing as standard and run it slightly rich until you can get onto one...

I use black silicone when assembling any exhausts because I've got alot kicking around...works great!

[Big_Adam]

2" on a 998? Eek!

Ummm. Ok,

He mean 2inch is too big for a 998 as well as any mini engine. 1.75 is more what you want.

You'll only loose a bit of power though.

[jamesheath]

Cheers scruffs,

Just the info i needed. Will have a fiddle with the mixture this w/e and fingers crossed she will run like a dream! I will use a colour spark kit.

I only really use the car to bash around the local country lanes when the mood takes. If I manage to get her running pretty nicely is there any real need to get her rolling roaded? just being cheap really. Does it really make that much difference?

Also, I take it from your post it is preferable (ie less fdamage) to run the car slightly rich rather than slightly lean?

Ta

James

[Scruffs]

Cheers scruffs,

Just the info i needed. Will have a fiddle with the mixture this w/e and fingers crossed she will run like a dream! I will use a colour spark kit.

I only really use the car to bash around the local country lanes when the mood takes. If I manage to get her running pretty nicely is there any real need to get her rolling roaded? just being cheap really. Does it really make that much difference?

Also, I take it from your post it is preferable (ie less fdamage) to run the car slightly rich rather than slightly lean?

Ta

James

Running lean isn't all that great as things can get a little hot and...melty...

I wouuldn't say it was advisable to *male chicken* about with an engine and not get it rolling road tuned, but certainly people do it (including me! ) without problems. At best you will just not be getting optimal performance/MPG, at worst you will melt your engine (like me too! )

Set it up on your colour tune and keep a keen ear out for detonation...

Edited by Scruffs, 06 September 2007 - 03:33 PM.

[Monstrous]

I had an AAV needle in my 998 on my red mini, had a slight flatspot at about midrange on the revs

then when i bought a new needle for my blue mini (AAU), i tried the faulty AAU one in the red mini, and problem solved, no flat spot

obviously it differs for each engine slightly, but both my 998's prefer the AAU to the AAV

HTH

[jamesheath]

I had an AAV needle in my 998 on my red mini, had a slight flatspot at about midrange on the revs

When you say a 'slight' flatspot. Was it noticable during hard driving or were you looking out for it?

Ta

James

Will let you know how I get on at the w/e

[Monstrous]

I had an AAV needle in my 998 on my red mini, had a slight flatspot at about midrange on the revs

When you say a 'slight' flatspot. Was it noticable during hard driving or were you looking out for it?

Ta

James

Will let you know how I get on at the w/e

it was fairly noticeable

basically accelerating hard in 2nd or 3rd there would be nothing for a bit, then it would all come in one go, sort of thing

with the AAU needle in, it's a smooth curve

[jamesheath]

I had an AAV needle in my 998 on my red mini, had a slight flatspot at about midrange on the revs

When you say a 'slight' flatspot. Was it noticable during hard driving or were you looking out for it?

Ta

James

Will let you know how I get on at the w/e

it was fairly noticeable

basically accelerating hard in 2nd or 3rd there would be nothing for a bit, then it would all come in one go, sort of thing

with the AAU needle in, it's a smooth curve

Cool, thanks. Will look out for that flat spot. Will prob try the AAU if its that bad.

J

[jamesheath]

Cool, thanks. Will look out for that flat spot. Will prob try the AAU if its that bad.

J
[/quote]



Thought I would give you an update.


After solving a few (minor) exhaust leaks I decided to alter the mixture on the HS4 carb. Basically after several tries the best running engine was when I returned the mixture setting to standard and increased the idle speed. ie the best I could find was at standard mixture settings from the factory! Does this sound right with the new AAV needle and monster exhaust with new inlet manifold?

I have to say it seems a little sluggish....no flat spots that I can tell it just seems to take longer to rise through the revs. Is that to be expected or a symptom of incorrect tunning?


Take it to adjust the mixture on an HS4 I simply have to alter the bottom nut on the fuel inlet part (Underneath the carb). Do I need to fiddle with the locking nut above the spring also? The adjustment nut seemed too loose really.

Hope that makes sense.

Ta

J

[ROD]

I had an AAV needle in my 998 on my red mini, had a slight flatspot at about midrange on the revs

then when i bought a new needle for my blue mini (AAU), i tried the faulty AAU one in the red mini, and problem solved, no flat spot

obviously it differs for each engine slightly, but both my 998's prefer the AAU to the AAV

HTH

My 998 the same it runs better with the AAU

[jamesheath]

I had an AAV needle in my 998 on my red mini, had a slight flatspot at about midrange on the revs

then when i bought a new needle for my blue mini (AAU), i tried the faulty AAU one in the red mini, and problem solved, no flat spot

obviously it differs for each engine slightly, but both my 998's prefer the AAU to the AAV

HTH

My 998 the same it runs better with the AAU

Sorted the mixture out ans she runs like a freakin rocket. Sweet noise too. No flat spots, no reluctance, just sh#$ and shovel!

So in summary. The AAV works great with my mini which has a standard HS4 998 setup with a stonking 2inch exhaust and alloy manifold.

Just thought I'd let you know.

J