rb968
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| posted on 20/8/11 at 04:26 PM |
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Emissions pre-IVA retest
Can I just run this by the collective knowledge on here.
Took the Indy to a local friendly bike and car MOT tester and used their gas analyser to see where I was with emissions after failing on them at
IVA.
Engine is B4 ZX9R and the carbs are running 155 main jets and 35 pilot jets (this is how I got the engine) and have been balanced using a air flow
synchronometer.
Initial idle test when hot showed ok HC (just) and CO level but lambda was 1.8
Fast idle at 2500rpm was better with falling HC and CO levels and lambda down to 1.4
We tweaked the mixture screws and the very best we could achieve was a fast idle with very low HC (47ppm) and Co at 0.08% with a lambda at 1.2 however
this meant the idle was now HC 400+ higher CO and a lambda of 2.1
So having previously resealed the exhaust, new gaskets and a half a tube of high temp silicon it still to me seems I have air getting into the exhaust
post combustion causing the mega lean lambda.
Could it be the pilot jets ? Are 35s correct, too big? Should it even run and tick over nicely if it really was lambda 2.1?
I am going to strip down the exhaust again tomorrow and try again to seal the collector as that looks the most likely but wanted a sanity check.
Oh currently we are at 1 1/2 turns on the idle mixture screws.
Help I really want to get the thing back to Carlisle for its retest and this is the last stumbling block.
Thanks,
Rich
Edit: Found this which is quite informative and a useful guide Linky
[Edited on 20/8/11 by rb968]
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rusty nuts
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| posted on 20/8/11 at 07:30 PM |
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Not sure about IVA but for MOT hydrocarbons and lambda aren't checked at normal idle only the CO which should be be 0.3% IIRC. Would have
thought IVA would be the same??
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rb968
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| posted on 20/8/11 at 10:20 PM |
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True enough, but I can't get the lambda low enough at fast idle at the moment and am worried I am altering the mixture and might lean it too
much and cause myself other problems at idle. Hopefully getting the exhaust better sealed or a better exhaust will solve it but wanted to check the
jets I have are in the right ball park.
Rich
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rusty nuts
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| posted on 21/8/11 at 08:20 AM |
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Sorry , got it wrong , hydrocarbons are checked at idle . Just had another look at your figures and notice you now have 0.08% CO which is very weak,
If you richen it up slightly the Lambda should come down and probably the HC as the engine should be running more efficiently . Also check for inlet
air leaks , spray any suspect areas with WD40 with engine idling , any leaks found will cause idle speed to increase
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