NGK DCPR8E vs DCPR9E - chasing lower RPM load issue

5255 Views 7 Replies 5 Participants Last post by Hacker-Pschorr, Aug 24, 2018

Hacker-Pschorr

Discussion Starter · Aug 17, 2018

2003
14k miles
K&N Filter, Vance & Hines pipes, Power Tune installed (no idea who tuned it).

Here's the skinny, below 3k RPM my bike is not happy. Now I know this is a high revving motorcycle, I have zero history with air cooled HD's, I'm used to sport bikes and German cars which like to stay in the upper RPM's too.

However, in 2nd gear below 3k it shouln't run like this, especially trying to slowly roll on from 2k. It's not like I'm trying to lug it around at 1,500 in 5th....

Downshifting into 2nd for a slow corner, it's not happy until well past 3k, don't like it.

The plan is to take the bike to my local tuner, have him go through the map. In the meantime, decided to replace the spark plugs and since I'm starting fresh with the bike, figure new ones won't hurt so I know the history of whats in there.

The Question:
Trying to decide if I should stick with the stock range DCPR8E or go one range colder (as I've seen recommended in other threads) DCPR9E.
In most of my cars I run at least a range cooler since at minimum the exhaust is freer flowing, timing is higher....similar to my bike here.

Here is one of the installed plugs, just grabbed the easiest one to pull for now.

On a side note, the breather hose on this head had two loose hose clamps, not sure what to make of that other than a previous mechanic who forgot to tighten them.

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Hacker-Pschorr

Discussion Starter · #2 · Aug 17, 2018

Did some more poking around, seems most using the 9's either have NOS or boost.

I'll stick with the 8's gapped to .035

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biker bob

· #3 · Aug 17, 2018

Sorry to tell you but if your 03 is like mine and all the other's you will never get it to run smooth at a low RPM I call mine a one gear bike in town I have to go at least 30mph before I think about going to second even then it wants to jerk a little only thing may help you is go to a 28 tooth sprocket you will shift quicker my 02 turbo had a 28 tooth and my 03 had the stock 30 tooth I could not get use to the 28 tooth after I have had my 03 for so long so I put a 30 back on the turbo I can see why they put a 28 tooth sprocket on all the bikes after 03 because most bikes are rode more in town and you have a more normal take off than with the 30 tooth.

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hdbikergreg

· #4 · Aug 23, 2018

My 03 kind of chugs in that area as well. It's a big bore and stroke 1350.

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Hacker-Pschorr

Discussion Starter · #5 · Aug 23, 2018

Update

Changed the spark plug and plugged my bikes setup into the V&H website and discovered not one field was the same in my FuelPak.
Now stupid me did not take down the program that was in there....but I entered in the new values and it's significantly better.

I fully understand that below or right around 3k RPM this engine is not designed to be anywhere near it's optimal area, but mine was really bad. Like wanting to stall / chugging below 3k.

Now I can smoothly roll around between 20-30mph in 2nd gear, which is how I more or less expected it to be.

I'm really tempted to go with the DynoJet computer or a 100% stand alone and have my expert tuner go through the bike. We'll see, only have a few miles on it so far, not sure what my plans are.

One hiccup, twice now the engine has stalled when downshifting as I hit first with the shifter, before letting out the clutch.
Both times the engine was cold....

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thunderdemon

· #6 · Aug 23, 2018

NGK recommends DCPR8E for the 1130 motors and DCPR9E for the 1250 motors..
your plugs looks like your bike is running lean,AFR should be around 14 in low and mid range and 13 to 12.5 in higher RPM range,and than you tune the cylinders separately to get a smooth running motor that can be ridden in low rpm also

try to give her a little more fuel in low rpm range and see what happens..
I think it will run better without the fuel pack imo and look for a better tuner where you can fine tune the VE tables

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rbabos

· #7 · Aug 24, 2018

Hacker-Pschorr said:
Update

Changed the spark plug and plugged my bikes setup into the V&H website and discovered not one field was the same in my FuelPak.
Now stupid me did not take down the program that was in there....but I entered in the new values and it's significantly better.

I fully understand that below or right around 3k RPM this engine is not designed to be anywhere near it's optimal area, but mine was really bad. Like wanting to stall / chugging below 3k.

Now I can smoothly roll around between 20-30mph in 2nd gear, which is how I more or less expected it to be.

I'm really tempted to go with the DynoJet computer or a 100% stand alone and have my expert tuner go through the bike. We'll see, only have a few miles on it so far, not sure what my plans are.

One hiccup, twice now the engine has stalled when downshifting as I hit first with the shifter, before letting out the clutch.
Both times the engine was cold....

Tuned right, that engine will run smooth everywhere, even at 1500 in fifth and slowly accel from there. I remember trying it when I was tuning mine to fill certain ve cells. No I don't do this normally. As for the Dynojet or any of the others, it's not magical and requires EFI knowledge to get the most out of it. Just out of the box and limited skill, most will end up with the don't run smooth below 3-4k crowd. Even some dyno tuners use this excuse when they can't get it right. Revolution is a tough engine to tune well.
Ron

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Hacker-Pschorr

Discussion Starter · #8 · Aug 24, 2018

thunderdemon said:
your plugs looks like your bike is running lean

I have no doubt it's running lean. Without CATS there is zero fuel smell, none, even when starting ice cold.
If there were O2 bungs I'd already have my Innovate LM-1 wired in.

thunderdemon said:
I think it will run better without the fuel pack imo and look for a better tuner where you can fine tune the VE tables

Here's my ultimate dilemma, I have two cars I'm working on converting to stand alone ECU's and programming them over the winter. I wasn't really anticipating having to do such things with this bike.
I just wanna ride the damn thing as much as possible before the snow flies. :goof:
This is one vehicle I really didn't want to modify, outside of a better looking exhaust and creature comforts.

rbabos said:
Tuned right, that engine will run smooth everywhere, even at 1500 in fifth and slowly accel from there. I remember trying it when I was tuning mine to fill certain ve cells. No I don't do this normally. As for the Dynojet or any of the others, it's not magical and requires EFI knowledge to get the most out of it. Just out of the box and limited skill, most will end up with the don't run smooth below 3-4k crowd. Even some dyno tuners use this excuse when they can't get it right. Revolution is a tough engine to tune well.
Ron

I'm very lucky. I have a world class tuner right in my back yard. In the past couple of years he's branched out into UTV racing and is modifying / fabricating / tuning those.

But again, when I started getting serious about finding a V-Rod, I never anticipated having to do such work before I was happy with it.

I've put a few more miles on it this week and I'm much happier with it compared to how I bought it.

So now I'm studying the ThunderMax computer, I see Motec has a motorcycle ECU... My tuner is certified with Motec and AEM.

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NGK DCPR8E vs DCPR9E - chasing lower RPM load issue

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