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SGX 50 - Poor Mpg

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mr_s81
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Joined: 24 Apr 2008
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PostPosted: 14:31 - 20 Oct 2009    Post subject: SGX 50 - Poor Mpg Reply with quote

I recently bought a Honda SGX 50 moped to get me in and out of work over the winter months. Given that my commute is less than 3 miles each way, I didn't see the point in getting a bigger bike. I also bought it off a work mate at a good price.

Anyway the bike is registered 2001 but hasn't been used a lot over the last few years. It's in good nick and there's only 2500 miles on the clock. The only noticable thing that was wrong with it when I bought it was a rusted exhaust. It was mainly only surface rust, but my preference was to buy a derestricted exhaust for safety as much as anything on the open road - so I bought one of these https://www.hondascooterspares.co.uk/spares/partImage.asp?GPN=GS13260.

During this time I also put a polini speed variator kit on and a honda oversized pulley. All things that were supposed to 'help' with the derestriction process. Didn't bother getting the cdi derestricted or anything like that as I was happy enough that the wee bike did up to 50mph (indicated).

My problem after doing all this is the detrimental impact it's had on fuel consumption. I haven't upjetted the carb (72 jet on there at the mo) as I've been checking the plug and it looks fine. The bike is also running well. There had been a problem with it cutting out when cold when the throttle was closed after a burst of acceleration. To date at least I've got this one sorted by gapping the spark plug properly.

At the minute I'm getting about 40-50mpg. (I get more on my ER6n!) From brimful to the fuel light coming on is about 35 - 40 miles. Hardly impressive given that the thing was bought as an economical way to get to and from work! I've been looking to try and find mpg stats on what I should have been expecting. I was hoping for 80 at least and I came across https://hubpages.com/hub/MPG-Guide-The-Fuel-Economy-Of-250-Top-Selling-Scooters. Now I know my mpg is going to suffer now the restricted exhaust has been fitted, but I didn't think it would have been affected to this extent of 136 to 45mpg??

I should also say that the air / fuel mix screw has to be turned away out for the bike to run at it's best. At one to two turns anticlockwise it appears to bog down and be much too rich. Would the main jet affect this or is it more likely to be the pilot jet.

Anyway, apologies for the essay and noob-like questions. Would be good to get to the bottom of this to establish whether there is something wrong or if 40-50mpg is normal as the wee bike can be quite fun to ride about town Embarassed

Cheers in anticipation!

Ian
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Brolly Dolly



Joined: 12 Oct 2009
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PostPosted: 15:43 - 20 Oct 2009    Post subject: Reply with quote

I had a SGX too, never got anywhere near to 100mpg+ everywhere says it would. I can only suggest getting a newer bike, even my local mech was at a loss for why the mpg was so poor.
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Pussy Magnet
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Joined: 20 Oct 2009
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PostPosted: 16:53 - 20 Oct 2009    Post subject: Reply with quote

could decrease the amount of fuel going in , should be a small screw on the carb .
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mr_s81
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PostPosted: 21:27 - 20 Oct 2009    Post subject: Reply with quote

vanflyheight13 wrote:
even my local mech was at a loss for why the mpg was so poor.


At a total loss myself. Sad Problem is I never rode the thing particularly far in its restricted form to see if there was anything difference in mpgafter changing exhaust etc. Was yours restricted or derestricted?
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mr_s81
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PostPosted: 21:30 - 20 Oct 2009    Post subject: Reply with quote

bikerdudematt wrote:
could decrease the amount of fuel going in , should be a small screw on the carb .


To the best of my knowledge (and I could be wrong), but the air screw on the carb only covers the idle circuit ie closed to quarter throttle. Given that I'm usually at 3/4 to full throttle, I'm not sure that would have any effect?? Confused
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Noxious89123
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Joined: 10 Jun 2007
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PostPosted: 22:00 - 20 Oct 2009    Post subject: Reply with quote

You'd be better off with a 4 stroke 125. Most are good for 100mpg easily.
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mr_s81
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PostPosted: 22:07 - 20 Oct 2009    Post subject: Reply with quote

Noxious89123 wrote:
You'd be better off with a 4 stroke 125. Most are good for 100mpg easily.


Tell me about it Rolling Eyes My original idea was to either get a C90 or CG125, but they all seem to fetch silly money about here (NI). This came up at good money and it's not bad looking (for a moped/scooter).
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Brolly Dolly



Joined: 12 Oct 2009
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PostPosted: 10:14 - 21 Oct 2009    Post subject: Reply with quote

mr_s81 wrote:
vanflyheight13 wrote:
even my local mech was at a loss for why the mpg was so poor.


At a total loss myself. Sad Problem is I never rode the thing particularly far in its restricted form to see if there was anything difference in mpgafter changing exhaust etc. Was yours restricted or derestricted?


I think mine was restricted, never did anymore than 35mph downhill with a running start and a decent tailwind.
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