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DRZ400 S low on power

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quacker_boy
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PostPosted: 22:59 - 05 Oct 2017    Post subject: DRZ400 S low on power Reply with quote

*Tips cap*

Evening boys and girls, been a while.

Won't bore you all with a life update and just cut to the chase.

The old man has got an '03 DRZ400S which he is planning on riding from Alaska to Argentina in 2018 (Hopefully I'll be joining for some of it) and has asked me to do a couple of jobs for him.

One of the things he mentioned was that the bike was low on power. Took it for a "hoon" around the local B roads and he wasn't kidding. My '08 CRF450R was the last 'similar' bike I rode....which you could wheelie with a tug on the bars and a handful in 3rd gear. I knew the DRZ wasn't going to be that arm rip-ingly fast but Jesus, it was almost comparable with a 125 for want of a better description.

Since I was last on BCF I worked as a bike mech in a garage for 4 years so my skillset has improved considerably and I'm not afraid of tearing it apart to get to the bottom of it but before I do, I wanted to see if anyone had come across anything similar and what the solution was...a quick Google seems to throw up threads on other forums which died with no answer, or completely ridiculous solutions (one guy held the throttle open for 3 minutes, 4 times, whilst the bike was turned off, failing to see how that would achieve anything?).

Had a quick look at the plug colour and it looks like the air/fuel ratio isn't a million miles out, so I'm less inclined to think it's a fuelling problem, when idling the throttle response is reasonably quick but under load you try and wind it on for an overtake and it starts to rev, just extremely slowly....the only way I can think of describing it is it's almost like the crank flyweights are too heavy and I actually weigh 20 stone rather than 11 Laughing

God knows I'm going to miss working in an actual workshop with my full toolbox and a bike lift, hence why I don't want to take it apart unless I absolutely have to Rolling Eyes
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jaffa90
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PostPosted: 23:41 - 05 Oct 2017    Post subject: Reply with quote

Maybe the carb slide is not going high enough!
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V2
Nearly there...



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PostPosted: 03:03 - 06 Oct 2017    Post subject: Reply with quote

Throttle cable stretched from too much hooning?
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mattsprattuk
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PostPosted: 03:55 - 06 Oct 2017    Post subject: Reply with quote

S's have the gay carb.
Get the E one.

I don't rate DRZ's from the ones I've seen out here. They burn oil and have an unjustified rep.

Compression test it.
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Blue_SV650S wrote: it was a sh1te wheelie, but it proves that he can get it up in 3rd and can do angles. In summery, mattsprattuk is a gobby little sh1tebag, dopehead tw4t, but sadly for all of us, he probably isn't THAT full of sh1te!! Mr. Green
Kickstart wrote: Hi I tend to agree with Matt. All the best Keith
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G
The Voice of Reason



Joined: 02 Feb 2002
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PostPosted: 07:23 - 06 Oct 2017    Post subject: Re: DRZ400 S low on power Reply with quote

First off - 50hp engine lighter competition bike vs 33hp heavier road bike.

Any dirt bike I try and clean the carb out regularly - so I'd start there and the airfilter.
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quacker_boy
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PostPosted: 09:54 - 06 Oct 2017    Post subject: Reply with quote

mattsprattuk wrote:
S's have the gay carb.
Get the E one.

I don't rate DRZ's from the ones I've seen out here. They burn oil and have an unjustified rep.

Compression test it.


Hah. Fuck me, really has been a while. How are you mate? Still in the South West?

By gay carb do you mean one of the stupid ones with a spring and diaphragm? Is the one on the E an FCR carb?

Dad's one is fairly clean and has something like 3000 miles on it so I imagine she's got plenty of life in her yet.

Hunting down an adapter for the compression tester but it doesn't feel like a slight loss in power like low compression...

G wrote:
First off - 50hp engine lighter competition bike vs 33hp heavier road bike.

Any dirt bike I try and clean the carb out regularly - so I'd start there and the airfilter.


G, I know the two aren't comparable, but this honestly feels like it just lacks the minerals. If I was to stand on the pegs in second and really throw my weight back and pin it, it still wouldn't bring the front end up.

V2, Jaffa...good suggestions and probably linked, I'll check it out Thumbs Up
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G
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PostPosted: 10:09 - 06 Oct 2017    Post subject: Reply with quote

I'm not sure I'd expect it to in the situation you describe, to be honest - not sure my CCM would have and that had the better carb (FCR, same as the E) along with less weight and a higher centre of gravity.

The DRZ may be higher geared and only has five gears.
Though it always felt like the first four DRZ gears were quite close ratio, followed by a more overdrivey fifth.
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Suntan Sid
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PostPosted: 12:25 - 06 Oct 2017    Post subject: Reply with quote

Sorry, can't specifically help you, however when I had my DRZ400E I found this place very helpful:-

https://thumpertalk.com/forums/forum/17-dr-z-400/

My E did not have the FCR carb, it was an early model!
I seem to recall there being specific problems with the accelerator pump on the carb.
I also seem to remember there being problems with valve clearances tightening up on a regular basis.

Has the bike had the air box mod done?

Can't be any more helpful than that, never really had any running issues with mine.
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quacker_boy
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PostPosted: 18:17 - 06 Oct 2017    Post subject: Reply with quote

G, seriously? A thumper enduro bike like the DRZ would surely be capable of wheelies. Ok I admit how well a bike pulls a wheelie isn't exactly a scientific way of measuring it's power output, but honestly man, it feels pathetic!

Suntan Sid, thanks dude...been a while since I've taken one of the diaphragm carbs apart but I didn't think they had an accelerator pump? That was what I first thought but when I had a look at the carb and saw it wasn't an FCR I ruled it out.

Valve clearances is an interesting one, I'll definitely be looking at them anyway Thumbs Up

No airbox mod....or anything mod to the fuel/air system or exhaust system either...I just refuse to believe they feel that slow and sluggish, need to ride another one for a comparison more than anything I think.
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G
The Voice of Reason



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PostPosted: 18:51 - 06 Oct 2017    Post subject: Reply with quote

It's a trail bike not an enduro bike.
Well, the E is more of a trail bike, with the S being a street bike.
Taller gearing could mean 2nd is similar to 3rd on the CRF.
So have a heavier, lower slower bike and it's going to struggle.

See how it does in first. From what I remember my CCM preferred first - thought I only had one sprocket which meant that with the trail wheel on, it may have been extra tall geared.

But I don't know of course if it's just a DRZ being a DRZ or is actualyl sick.

I'd still be cleans the jets whatever.
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Suntan Sid
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PostPosted: 08:36 - 07 Oct 2017    Post subject: Reply with quote

quacker_boy wrote:
I just refuse to believe they feel that slow and sluggish, need to ride another one for a comparison more than anything I think.


It shouldn't feel sluggish, it should feel very torque-y, even on knobblies you should be able to win the traffic light GP every time!
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G
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PostPosted: 08:56 - 07 Oct 2017    Post subject: Reply with quote

Suntan Sid wrote:

It shouldn't feel sluggish, it should feel very torque-y, even on knobblies you should be able to win the traffic light GP every time!

No next to a competition bike I'd say; but he question is exactly how sluggish relatively?
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Suntan Sid
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PostPosted: 11:59 - 07 Oct 2017    Post subject: Reply with quote

Relative sluggishness.

I'll offer a point of reference, my E would pull hard from a near standstill in second gear.
IME if the bike is not doing that then there's a problem.

As I recall, the stator windings can be a bit flaky, although It's unlikely that would be causing the OP's problems, especially if it's starting easily on the button.
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G
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PostPosted: 13:20 - 07 Oct 2017    Post subject: Reply with quote

What was it geared for for the top speed in top gear?

My CCM wasn't too bad in lower gears with SM wheels - same sprocket with a chunk enduro wheels and it was definitely first gear for technical muddy stuff.
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Suntan Sid
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PostPosted: 15:45 - 07 Oct 2017    Post subject: Reply with quote

G wrote:
What was it geared for for the top speed in top gear?

My CCM wasn't too bad in lower gears with SM wheels - same sprocket with a chunk enduro wheels and it was definitely first gear for technical muddy stuff.


I was running 14/47, so not geared for top speed, with these sprockets you would maybe hit 70mph in top!
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G
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PostPosted: 16:02 - 07 Oct 2017    Post subject: Reply with quote

With the Enduro wheels mine was more like 90-100mph theoretical top speed..

So your second was probably more like my first!
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Suntan Sid
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PostPosted: 16:51 - 07 Oct 2017    Post subject: Reply with quote

So OP, what sprockets does the bike have on it?
Has it been geared up and gutted for road use?
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quacker_boy
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PostPosted: 21:57 - 07 Oct 2017    Post subject: Reply with quote

Thanks for the replies Suntan and G.

Not sure on gearing...but let's say for argument's sake it's on stock ratios. I tried to wind it on along a straight section of asphalt and it struggled to get to 55 mph.

Riding up anything more than 5/6 degree (potentially an exaggeration, but your average hill on a country B road) hill means you actually have to drop it through the box as the revs start to fall to pretty quickly.

Maybe I should have left out the bit in the OP about comparing it a CRF then but hopefully that clarifies exactly how 'sluggish' it is Laughing

I've read about the stator as well Suntan, going to be replaced before the big adventure but I doubt it's capable of causing THAT much of an issue.
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Suntan Sid
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PostPosted: 22:28 - 07 Oct 2017    Post subject: Reply with quote

quacker_boy wrote:
Thanks for the replies Suntan and G.

Not sure on gearing...but let's say for argument's sake it's on stock ratios. I tried to wind it on along a straight section of asphalt and it struggled to get to 55 mph.

Riding up anything more than 5/6 degree (potentially an exaggeration, but your average hill on a country B road) hill means you actually have to drop it through the box as the revs start to fall to pretty quickly.

Maybe I should have left out the bit in the OP about comparing it a CRF then but hopefully that clarifies exactly how 'sluggish' it is Laughing

I've read about the stator as well Suntan, going to be replaced before the big adventure but I doubt it's capable of causing THAT much of an issue.


Well that doesn't sound right.
When it was on the standard gearing it had no problem pulling up steep gravel track hills.
I changed from the standard gearing, (can't remember what that was), down to 14/47. I down geared it only to get up nasty boulder strewn, narrow, steep, tracks in second gear rather than risking looping it in first!

If it starts easy enough, I'd be looking at the carb.
If it's difficult to start, as well as being down on power, I'd be looking at the valve clearances, valve timing, (is it on the original automatic cam chain tensioner or has it been swapped for a manual one), as well as checking the air filter, air box for leaks, the exhaust for leaks, cooling system, etc. etc.
Mine was an E, so I don't know if the S has a side stand cut out switch, might be worth checking that.
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