Colder plugs? anyone tried?

Did a full service on the SD in October and decided to change the plugs to, fitted some DCPR9EIX,s in place of the standard 8s,

The theory being that an engine tuned to produce more power will run better on a colder plug and also the plug electrode will wear less quickly, a plug that is overheating will burn away the electrode increasing the plug gap leading to bad running and poor performance

Anyway, I did this years ago with my TLs (Changed the standard 8s to 9s) and the bike ran better and picked up 2bhp from 6-9500rpm, back to back runs on a good dyno

So, i popped the SD on a local Dynojet 250 dyno for a quick power run and got a peak of 127.7 bhp, the last dyno run on the same dyno back in May was 126,2bhp, not comparable i know but i have not lost anything and the bike does feel crisper at the top end

Interesting Russ, ive always founds colder plugs abit of a hit/miss affair when tuning motors!

Good to no that they will actually work with the SD - what tuning do you have on your SD?

Looks like il be picking up a pair for the coming year when the motors back together!

Where did you pick yours up from? price?

Stew

Good idea, I used to do that also on tuned car and bike engines in the past. Never crossed my mind to do it on the SD.
The original plugs are most likely also a part of the greater scheme of anti pollution laws as keeping thigs hotter is supposed to decrease pollution.
Going up one grade colder will probably have the effects you mention, great work!
It will also help things a bit cooler in a hot climate or on the race track.

Anybody thats interested this is the cheapest i can find them -

http://www.ebay.co.uk/itm/1x-2316-DCPR9 ... 2eb6a7f352

Presume these are the right plugs?

Russ, are you using the standard 0.8mm gap?

No probs, i hadnt ordered them anyway!

Edited my post also

I wonder if today's new cleaner burning fuel has something to do with how the plugs look after being used. Old style plug-chop is getting harder to read with "clean fuel".

Hot plugs would explain why the bikes don't foul plugs running the Akra map. Just my thoughts...

I have some DCR9EIX's here, not the DCPR. The NGK site says the early SDs use DCR8EIX and later models the KR8DI with a 0.1mm smaller gap at 0.8mm. It also states the DCPR is a copper one and the DCR an iridium but I'm pretty sure they're both iridium.

So what's the difference between the DCPR9 and the DCR9?

I beleive its the 'I' or 'IX' suffix that designate Iridium on NGK. That noted, I think you're correct Hidrio - that the for plug models you note, are all Iridium.

A general remark ... I've had less than positive experiences (on higher compression fuel-injected bikes), interchanging a standard plug for iridium and vice versa, when the opposite type was OEM specified. Your results may vary.

The 07-onwards owners manual states KR8BI but the NGK site states KR8DI. Again I'm not sure which is right as they seem to be 2 different plugs.

All this talk of plugs and I'm sure I had a misfire this morning when blipping hard from idle.

Assuming I can get a pair of DCPR9EIX, will these be fine?

I always get my plugs here as well as any information or cross referencing.

http://sparkplugs.com/sparkplug411.asp

Here are the plugs mentioned above at $7.83 each

http://sparkplugs.com/results_cross.asp ... &x=52&y=13

The NGK KR8DI is an Iridium plug, I dont think NGK make a KR9DI plug, I have Googled KR9DI but no results, you would have to check with NGK themselves,

The NGK spark plug specifications list I have indicates that the KR8DI is a special application plug (The D denotes special application) The I denotes Iridium,
I have been trying to post the NGK specification list on here but China has decided recently to block Photobucket............

I will post it up when I an in Hong Kong next

Try Brisk plugs.