View Full Version : X7 Performance transformed!!

06-14-2012, 02:31 PM
I have been in touch with team talk on two issues on my (new to me last year) 2005 X7 with 350 MCX engine.
1. Pause on initial acceleration out of the hole
2 Disappointing top end speed (4200 revs and 42 mph)

Not much came back from TT but, as suggested, I did fit new plugs as supplied by Mastercarft UK (NGKs 5ES).

No real change.

Based on advise from a visiting Ski Nautique engineer who fitted DiaCom to check out EMS, I then had some platinum plugs (which he said Mastercraft fit as standard when boat is supplied new) fitted.

They were comparitively expensive 140/$210 but what a difference !!!!

Acceleration pause has gone and engine now revs quickly and cleanly to 5000 rpm.

The engine also runs as smooth as silk !!.

Is it true that MC fit Platinum plugs as standard.

Also if anyone else has fitted cheaper plugs, has it also hit performance.

I just find the difference incredible !!!

For the first time I am really pleased with the X7

06-14-2012, 09:53 PM
Per the owners manual, the mcx 350 has AC delco 41-932 as the correct spark plug which is a platinum plug and should be less than $10 per plug in the US. Parts may be higher and scarce overseas idk, I would try amazon or ebay next time. You can check out http://www.sparkplugs.com/ for a cross reference.

06-15-2012, 08:30 PM
What part # are the platinum plugs that you installed? I have AC 41-932 plugs in mine now.

Just curious, as I'm due for a set in my MCX powered X-star.

06-18-2012, 07:45 AM
The plugs that have been fitted in the UK by an approved Ski Nautique technician at a cost of $26 each or $210 (140) for 8 are AC delco 41-101.

Checking on the AC delco web sit these are "Iridium[/B] plugs" that in the US appear to be about $7 each or $64 for a set of 8.

The supplier said they are good for 600 hours.

The answers to my TT question say Mastercraft recommend AC Delco 41-932 which according to web site are a platinum plug at a price in US of circa $9 eac or $72 for a set.

Can anybody give me advise on the Iridium versus Platinum plugs for the MCX 350.

The 4 times price differential is still being checked out as on a web search of UK suppliers I cannot get either!!!!!!!!!!!!