Author Topic: sym gts 125 wont reach top speed anymore  (Read 476 times)

lisamono

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sym gts 125 wont reach top speed anymore
« on: August 05, 2017, 01:07:54 PM »
Hi folks

As title says i have a 2006 SYM gts 125 voyager and it just seems like it has no power anymore. It'll reach 30mph and doesn't want to go any faster.

I've tried a new carb but no difference, I've tried 10 gram rollers but still no difference, I've recently fitted a new clutch and belt . I've fitted a Ramair air filter direct to carb and a Turbokit exhaust. The brakes are not sticking and if it's on the centre stand she will red line on throttle but bogs down when under load.
She will go faster down hill.  ::)

I've replaced the coil a few months back, a new spark plug, fuel filter but so sick of putting money into this and to no avail... It's been ages since she ran like she used to.  :'(

Can anyone give me any pointers to what the problem may be?

Thanks in advance and will try to answer any questions.
Lisa.

redridinghood

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Re: sym gts 125 wont reach top speed anymore
« Reply #1 on: August 05, 2017, 03:30:32 PM »
Engine compression test? 🤐

SYMmike

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Re: sym gts 125 wont reach top speed anymore
« Reply #2 on: August 05, 2017, 04:44:47 PM »
I'm not familiar with that scoot, but look into any vacuum lines for any kind of cracks or leaks or clogs. Check the air intake/filter completely for clogs or leaks. Check for power loss, run the scooter in the dark with the electrical system in view, then try to run it with a load. If you see any sparking, that is your power loss. I take it you replaced the wires when you replaced the spark plug?!
If everything checks out good there then a compression check would be your last resort......
2008 dark grey RV250, 27,000 miles

lisamono

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Re: sym gts 125 wont reach top speed anymore
« Reply #3 on: August 06, 2017, 02:58:31 AM »
Hi and thanks for your replies.

Forgot to say that this is a second engine as had a severe oil leak last year which led to a seizure so have replaced it . This was also happening to the first engine . There are no blockages in the air intake as have fitted a pod style air filter by Ramair directly to the carb. Mainly because the mounts on the plastic air box snapped  :(

I have an MOT a week on Tuesday so will try ask if a compression test can be done but i doubt it's this.

I've a tendency to steer towards no current to the auto choke and thus it not switching off. I may be totally barking up the wrong tree though. :-\

I'm beginning to wish I'd bought something other than an SYM as have sunk so much money into it.

@SYMmike When you say "i take it you replaced the wires when plug was replaced" Do you mean the coil wires, HT lead or?

Any other suggestion would be much appreciated.
Lisa.
« Last Edit: August 06, 2017, 03:01:00 AM by lisamono »

SYMmike

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Re: sym gts 125 wont reach top speed anymore
« Reply #4 on: August 08, 2017, 05:19:37 PM »
@SYMmike When you say "i take it you replaced the wires when plug was replaced" Do you mean the coil wires, HT lead or?

Any other suggestion would be much appreciated.
Lisa.
The wires to the spark plug & coil wires. Are they original? I'm beginning to think you have a power loss somewhere when you start getting a load on your system. It could be a cracked wire or a faulty electrical component.
2008 dark grey RV250, 27,000 miles

lisamono

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Re: sym gts 125 wont reach top speed anymore
« Reply #5 on: August 11, 2017, 12:06:40 PM »
Thanks for your reply @SYMmike

I don't think I have as have had time to think and adjust things...

First I thought as I've fitted a Ramair pod filter ; that surely I'm getting more air into the carb, so adjusted the air/fuel screw a tiny bit to the right (screw in) to reduce the air and it seems to be a bit better and will reach 40 mph.

Secondly I tried not to bang on the throttle to WOT and just gradually open the throttle when riding and she seems to catch up and climb to 60 mph . So I'm guessing when I open up to WOT ; she is not getting enough fuel or too much air and bogging somewhat. I could be wrong and maybe it's the opposite way round .i.e. too much fuel ...I'm just confusing myself now but things are improving.

I'll turn the air/fuel screw a tiny bit more this weekend and see what she does and report back.

Thanks
Lisa.   

BeebBobE

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Re: sym gts 125 wont reach top speed anymore
« Reply #6 on: August 18, 2017, 05:33:40 AM »
consider taking a small engine repair course at a local tech school near you! I think the education would help you tremendously! You could also drop by a local mechanic and get them to sit down with you and explain carbs or grab a manual on engines and carbs!  Gladly I had the opportunity to grow up in the muscle car era and took Auto Mechanics in high school shop classes! I went on from there to tearing engines and carbs apart and putting them back together. If a person rides all the time they need to know about the vehicle and how it works! That's my suggestion for the day!
Ride like a Klingon....

l0new0lf

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Re: sym gts 125 wont reach top speed anymore
« Reply #7 on: August 23, 2017, 08:20:49 PM »
Typically when you modify anything from stock, and removing the stock air filter to a pod type definitely qualify, you are bound to run into issues which unless you're intimately familiar with your engine it's going to take a lot of trial and error unless you get really really lucky.  I also switched to a pod style air filter on all three of my scoots and they all required hours of work not to mention a lot of homework.  All of mine needed larger main jets along with a slide needle adjustment.  And just because it runs well at low speed doesn't mean it's going to run well beyond that.  If the compression test comes back 100+ psi I'd try to score anther stock air filter and see if it is the carb that needs tweaking. 
2010 SYM Symply 125cc - 120 main, unifilter, 13" rear rim, gates Kevlar belt, NGK iridium spark plug/cap, NCY golden variator w 12g sliders
2012 SYM FIDDLE II 125cc - 115 main, unifilter, upgraded front & rear to 12" rims, gates Kevlar belt, NGK iridium spark plug/cap, NCY golden variator 11/12g sli

lisamono

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Re: sym gts 125 wont reach top speed anymore
« Reply #8 on: August 28, 2017, 11:55:30 AM »
Hi and thanks for your replies.

She passed the MOT and was advised to replace the stock air filter so I have but still no luck with top speed. Carb being returned to stock settings too.
Unfortunately I have no local courses as I live in the Highlands of Scotland and I have full time work , so wouldn't have the time anyway.

Any other suggestions please? I think I'm going to have to bite the bullet and take her to the nearest stealership and get ripped off as I'm a woman!! Either that or a gallon of petrol and a match :)

Everything is back to stock now.

Cheers
Lisa

CarefulRider

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Re: sym gts 125 wont reach top speed anymore
« Reply #9 on: September 21, 2017, 12:49:44 PM »
Hello there:

An additional item to check, and adjust if needed, is the valve clearance. If the engine has been used for many miles since the valves were last adjusted; it's good, at all times, to have the valve clearances within specifications. I encourage you to do so, now that you have returned all parts to the original stock. Hope this helps.
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