DRZ400 SM - Surging issues? - UPDATE

[Richtea]

I have only had my DRZ for about a week and havent done loads of miles but one thing I have noticed that when I try to hold the bike at a steady speed (eg 30mph) the bike feels like it is constantly surging or lurching backwards and forwards.

I know that the characteristics of a single cylinder are different, and to expect a bit of surging compared to my old GS500, but is this normal?

I've read some stuff about opening up the airbox etc but I want to keep the bike standard as I'm on the 33bhp restriction at the moment and so dont need any performance mods.

Thanks
Rich.
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2005 Honda Varadero 125xl > 2005 GS500F > 2007 DRZ400 SM > 600 Bandit & Yamaha YP250

[Suntan Sid]

Try doing a search here:-

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

It's one of their favourite topics.
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"Everybody needs money, that's why they call it money!"

[Richtea]

Thanks Sid.

I did do a quick search on there before I posted but their posts relate more to modified jetting/air box versions.
I don't really want to start changing jets etc as a) it's not something I would want to do myself and b) I want to keep it stock.

I can't imagine that the bike was like this from new and so I was just looking for some tips about what to check, rather than rejetting.

Hope this makes sense.
Rich
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2005 Honda Varadero 125xl > 2005 GS500F > 2007 DRZ400 SM > 600 Bandit & Yamaha YP250

[Fizzer Thou]

It sounds like a throttle position sensor (TPS) problem.

If you have a multimeter check the resistance from fully closed to fully open.On a bike that I tested recently it was 0-5k ohms.

If you bought the bike from a shop tell them that you are experiencing problems with it and what are they going to do about it.
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Just talk bikes.What else is there?

Always have a 'Plan B'

[P.]

[hmmmnz]

before i did any thing else, do the basics,

remove, strip and clean the carb, blow through the jets,

replace the spark plug,

check the wiring, make sure all the earths are in good condition, and that none of the wiring has rubbed through against the frame.

if its still not right start looking further afield
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the humans are dead
I kick arse for the lord
Wiring Diagrams BIDNIP it bitches

[Budgetboy]

Balance the Carbs
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www.Mailorderrepairs.co.uk We service your Carburetor's, Calipers & Suspension for less Also Bike repairs undertaken.

[P.]

[reckless_b]

just had a very similar issue on an xbr500 honda single, at lower speeds surging and popping back through the exhaust, checking the carb settings (didn't bother with balancing ) the pilot screw was set to book settings but I opened it up finally by a full turn and was rewarded by a much smoother running bike without the surging. You'd think a single would be so much simpler with only one of every thing but they can still try you.
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40 years on the road on and sometimes off bikes with a very recent OFF

[Budgetboy]

[Richtea]

Yeah, with my very limited knowledge I think it is to do with the fuelling.
I think I'll start by cleaning carbs/jets but never done it before

Any beginner tips/no no's to stop me ruining the bike?

I'd like to have a go myself 'cos I'm sure a dealer will be silly money.
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2005 Honda Varadero 125xl > 2005 GS500F > 2007 DRZ400 SM > 600 Bandit & Yamaha YP250

[Richtea]

So had a mate round who knows a bit more about bikes. After taking a look/listen said that it sounded a bit like a misfire.

Anyway pulled the spark plug an it was a bit carbonated but nothing major. So stuck in a new Iridium spark plug, and put some Profi Fuel Max through the tank/carbs to give it a flush.

End result? The lurching has almost completely disappeared

So thanks to everyone for all their comments but looks like it just needed a good clean.

Rich
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2005 Honda Varadero 125xl > 2005 GS500F > 2007 DRZ400 SM > 600 Bandit & Yamaha YP250