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Author Topic: Help from anyone with a DR650 and Scorch or free-flow pipe?  (Read 834 times)

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Offline Munro39

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Help from anyone with a DR650 and Scorch or free-flow pipe?
« on: December 11, 2013, 09:16:12 am »
Hi guys,

Recently bought a DR650 second hand with a Scorch pipe on the back. Getting terrible fuel consumption and I've spent a lot of money trying to get it sorted. Still no luck. Did compression tests, valve clearances, carb was reset etc. etc. Still got the same (12-13km/l) fuel consumption, still got black spark plugs, and still unhappy at the moment!

My question is, how should the carb be set with such an exhaust? I know that it still has the stock jets, needle etc. Does anyone with a scorch or free-flow how their carb was set up to accomodate a new exhaust? Could that be causing me to burn more fuel?
 

Offline LouisXander

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Re: Help from anyone with a DR650 and Scorch or free-flow pipe?
« Reply #1 on: December 11, 2013, 09:20:24 am »
Het jy hom gevat v n Dyno? Ek is seker hulle sal hom kan set?
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Offline fredda

Re: Help from anyone with a DR650 and Scorch or free-flow pipe?
« Reply #2 on: December 11, 2013, 09:33:54 am »
What about the air filter? Is it still stock or perhaps dirty?

Maybe with the aftermarket exhaust the flow through the engine is easier with the less back compression, but the stock/dirty air filter can only allow so much air through and then the bike "sucks" more fuel than air.

Also, check the choke? Maybe the choke is stuck?

I don't own a DR yet, so the probable causes are just some guess work from my side.

Good luck!  :thumleft:
Current bike: 2011 BMW R1200R
 

Offline boland

Re: Help from anyone with a DR650 and Scorch or free-flow pipe?
« Reply #3 on: December 11, 2013, 09:41:39 am »
I bought my bike with a Scorch on and got around 18 km/h. After a service at Boland bikes where valve clearance etc was checked I now get around 20 km/l. So there's definately something wrong and you can get good fuel consumption with the Scorch! My carb is stock standard.

Good luck, hope you get it sorted quickly
 

Offline lecap

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Re: Help from anyone with a DR650 and Scorch or free-flow pipe?
« Reply #4 on: December 13, 2013, 08:45:52 am »
That was the DR650Se I did the carb on I believe?

I can only find one possible reason for this bike misbehaving: Some hero reamed out the carb's main jet to "tune" it to run with the "racing" exhaust.
Cheapskate version of fitting a larger jet.
A larger jet would be easy to identify by its markings.
A reamed out jet would be easy to spot IF the hero would have filed off the OEM markings.

A reamed out jet on which the OEM markings were not removed would be... erm ... ???

If I remember correcltly the engine produced symptoms of running rich under full load. This points towards a oversized main jet.

Buy and fit an OEM main jet and see what happens.
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Re: Help from anyone with a DR650 and Scorch or free-flow pipe?
« Reply #5 on: December 13, 2013, 09:02:56 am »
LeCap you are most probably correct about someone fiddling with the jetting.   :thumleft:

If you put an aftermarket exhaust on a thumper (with a carburettor), do yourself (and your bike) a favour and
contact Julian (Wrench on the forum) and book a jetting and dyno session for your bike.

Would put you back R1000 - R1500, but it would be worth every little cent.
Once that is in place, your bike will run at optimal performance en as good as it
can be.  


You can thank me later  ;)  :thumleft:
« Last Edit: December 13, 2013, 09:04:53 am by Operator »
 

Offline Munro39

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Re: Help from anyone with a DR650 and Scorch or free-flow pipe?
« Reply #6 on: January 06, 2014, 01:42:40 pm »
A
« Last Edit: January 06, 2014, 01:44:43 pm by Munro39 »
 

Offline Munro39

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Re: Help from anyone with a DR650 and Scorch or free-flow pipe?
« Reply #7 on: January 06, 2014, 01:43:41 pm »
Just been to Suzuki South and checked the jets. Aside from a little bit of discolouration, its all good down there....

Dave from the workshop suggested that it may be that the vacuum is malfunctioning and sucking fuel through the vacuum pipe. Is this possible and test-able? Baffled for solutions now. Carb checked, jets checked, plugs checked, compression checked, valve clearance checked.
 

Offline lecap

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Re: Help from anyone with a DR650 and Scorch or free-flow pipe?
« Reply #8 on: January 07, 2014, 09:00:41 am »
What does "checked the jets" mean? Did you actually measure the inner diameter of the main jet? Did you replace the main jet with a known good (=new) one?

There is no need to test for fuel coming down the vacuum pipe because it's simply impossible as long as no one has done some dodgy modifications.
The automatic tap uses a mechanically connected double diaphragm with a void in between and a pressure relief bore in the void. If the diaphragm on the fuel side tears the fuel will drain out of the pressure relief bore. If the vacuum side diaphragm tears air will enter the vacuum chamber from the pressure relief bore and the vacuum will  tap will no open any more. If both diaphragms tear the tap will not open the fuel feed to the carb and leak fuel at the same time.

A bike with fuel leaking down the vacuum pipe will very likely not start nicely nor will it idle properly.

To test the tap turn to "ON" and disconnect the fuel feed. The fuel feed must be closed. Same for  "RES". Fuel must flow in both positions as soon as you apply vacuum. On "PRI" fuel will always flow regardless if vacuum is applied or not.
"If you think it's expensive to hire a professional to do the job, wait until you hire an amateur." (Red Adair)
 

Offline Munro39

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Re: Help from anyone with a DR650 and Scorch or free-flow pipe?
« Reply #9 on: January 07, 2014, 10:36:40 am »
Checked visually as well as using a reaming kit to confirm that both old and new are the same size.

I rode yesterday on my reserve with the vacuum pipe disconnected hoping fuel would stop and the bowl would empty, so I assumed that's not working properly, but also confirmed that there's no fuel through the vacuum pipe. What it does mean though is that the bike is essentially in pri all the time. Would this matter? I can't quite see how it would because it now simply acts like a gravity flow. Or is the carb going to be sucking far more fuel than it needs because of the  free flow?
 

Offline lecap

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Re: Help from anyone with a DR650 and Scorch or free-flow pipe?
« Reply #10 on: January 08, 2014, 12:00:52 am »
No problem if the tap does not close. Easily fixed though.
"If you think it's expensive to hire a professional to do the job, wait until you hire an amateur." (Red Adair)
 

Offline AlbieK

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Re: Help from anyone with a DR650 and Scorch or free-flow pipe?
« Reply #11 on: February 02, 2014, 06:26:44 pm »
Bumping this thread up because this bike needs to get ridden!

Am I correct in saying that the general consensus would be that it is most likely faulty jets or a carb issue?

What are the options? New Carb? Appointment with Julian on his Dyno?
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Offline lecap

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Re: Help from anyone with a DR650 and Scorch or free-flow pipe?
« Reply #12 on: February 03, 2014, 10:05:43 am »
There is nothing mechanically wrong with the carb.

The symptoms (starts fine and runs fine on partial throttle, poor performance on full throttle) point towards:

Float level more or less correct.
Cold start circuit fine.
Slow circuit fine.
CV diaphragm & slide work.

The only parts left which might cause problems are sitting in the main circuit: Pilot air jet, venturi (Needle jet) / emulsion tube, main jet.

I'd start with buying an OEM main jet and checking the diameter of the pilot air jet.
If that does not help replace the needle jet too.

If still no joy you will have to dyno to see what's actually going on.
Or find out from the previous owner what sort of "tuning" was performed ::)
« Last Edit: February 03, 2014, 10:06:33 am by lecap »
"If you think it's expensive to hire a professional to do the job, wait until you hire an amateur." (Red Adair)
 

Offline AlbieK

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Re: Help from anyone with a DR650 and Scorch or free-flow pipe?
« Reply #13 on: February 07, 2014, 01:29:15 am »
Spoke to Neil a couple days ago, he says he fiddled with something and replaced something else, cant remember the details now but apparently the bike is running perfect now and rearing to go! Thanks for all the advice guys  :ricky: 
"The mind is like a parachute. It only works when it's open".

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Offline Munro39

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Re: Help from anyone with a DR650 and Scorch or free-flow pipe?
« Reply #14 on: February 08, 2014, 12:00:44 pm »
Hey guys - As Albie says the bike is now fixed and running great after a dreadful experience:

I took the bike in to be serviced and was told the slider needle needed to be replaced because it was worn - this is a part which costs R155! I have spent thousands trying to find the problem and I was now being told it was a R155 part. So (LeCap correct me if I'm wrong) the worn needle must have caused the engine to think the throttle was always more open than it was and therefore draw more fuel?

Anyways I paid for this service, rode a few km's and saw the bike was now getting only TEN km/l. much worse than before. And it fired up nice and easy and then died when it warmed up. Called back in a rage and I was about to take it back when I decided to check out the needle myself. Took it out and saw it was on the 3rd clip - fine - but that the plastic spacer that sits against the clip was about 2cm below that - they hadn't even bothered to push that all the way back onto the needle, so now this brand new needle was sitting way higher than it was meant to. Pushed that back up and had to completely reset the mixture screw (it was WAY out).

Went for a nice ride to Hout Bay and after 19,3km, I had used 1,08 litres. Great.

Thanks for all your help on the matter and if you encounter the same problem, don't forget the sneaky needle. The difference is almost unrecognizable because of the taper.