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Messages - Thoppa

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General Discussion / Can prayer overcome mechanical problems?
« on: April 03, 2021, 07:35:44 PM »
Happy Easter everyone! I have a miracle to report.

I reconnected everything, refilled the coolant, etc etc. and started her up. But no, she turned over but wouldn't start. So then I start praying extra hard.... and she started on some throttle with a puff of smoke, but she wouldn't idle and was shaking and vibrating a lot. A scary amount to be honest. I couldn't close the throttle or she would die. I ran her for a little bit with the throttle open enough to keep her running, and looked to see if anything else was wrong, but didn't see any issues. So I figured I messed up and that was that.

I started to think about whether it was worth it to begin the repair again, this time with a new cylinder, etc. I disconnected the coolant bleed hose to the thermostat to bleed air bubbles from the coolant, although I don't know why. I guessed she was a dead un.

Figuring I had nothing to lose, while praying for a miracle, I started her up again and tried to set the throttle adjusting screw so she would run on a small throttle without me needing to hold it open. I was adjusting this for a while and finally ended up turning it closed... and she was idling and not too roughly.

What happened? I have no idea. So I'm claiming an Easter miracle - thank God my scooter still works!

General Discussion / Re: Changing cylinders - anyone done it?
« on: April 02, 2021, 09:12:59 PM »
I followed the manual and the only part that caught me out was draining coolant. I drained it from the drain plug but then when other hoses got disconnected, more came out from the drain plug and elsewhere every time a hose was removed. Even knowing this beforehand wouldn't have made sure I collected all the coolant because it comes out of everywhere else, not just the drain plug. Apart from that, quite easy. I decided to use a couple of scissor jacks and a trolley jack to support the engine  and then lift the frame and front end up and forward to take it away from the engine unit. I have fitted the new rings by following the manual and copying what was installed, and how, and that was straightforward. So now I'm at the stage of scraping off old gasket before the slow process of cleaning and rebuilding.
Draining the coolant using an old orange juice bottle

Piston cleaned up with a knife.

new rings - the piston measurements are all within spec so it just needed a de-coke. It shows that oil has passed the oil ring as expected, but perhaps more than expected because it has burnt on as a crust, and the same is less true of the second ring. The cylinder head also has a lot of this kind of crust. I'm surprised I didn't notice any white smoke out of the exhaust. It made me wonder if something else besides rings might be the issue, or if the problem had not go that bad yet.

The residual gasket between the cyilnder and engine block is a pain to remove - soaked in solvent and scraped.

The cylinder bore looks very smooth and polished - there's some honing lines criss-crossing the bore and no signs of damage or unusual wear of any kind. I couldn't measure distortion but the bore measures within spec so it should be fine, assuming my vernier calipers and measurement method are up to the job - the tolerances are very small.

And the gasket has all gone after an hour of work on it...

De-coked the head

I took a break for a long lunch and then started again in the afternoon. I got the head etc reassembled and the engine back in the frame by the end of the day. Tomorrow I try to reconnect everything...

General Discussion / Re: Changing cylinders - anyone done it?
« on: April 02, 2021, 04:22:45 AM »
Thanks - a bit of a mechanical adventure :-)

I got the body work and some bits off in the late afternoon. Under the skin, she was very dirty - huge amounts of dirt on the frame etc - I brushed some off before this photo. I am still wondering about the best way to get the engine out of the frame without damaging anything.

General Discussion / Re: Changing cylinders - anyone done it?
« on: April 01, 2021, 11:19:56 PM »
The parts arrived already!

I bought the gasket for the 278 as well as the 263 to compare and they are 100% identical except for the bore on the 278 is 1mm wider all the way round - so 2mm in diameter more. If I ever need to, it's certainly possible to fit the 263 head onto either the 249 or 278 cylinder/piston. For the 249, it would all bolt on and there'd be a little more squish. The 278 would require some machine shop work to fit but it's doable.
278 vs 263 head gaskets

All parts needed for piston ring replacement

Piston ring set for 263

Citycom 300 / Re: maximum engine mileage
« on: March 31, 2021, 11:07:36 PM »
This is the 263cc engine in a Joymax 300 (RV270?) that is currently for sale on Facebook for US$2,150. Crazy! I bought my Citycom for US$3,000 with 4,000kms, this has 94,000kms![0]

General Discussion / Re: Changing cylinders - anyone done it?
« on: March 30, 2021, 04:33:57 AM »
I've also reached out to family in Taiwan to see if they can get the 263cc parts but since these models are export, it's unlikely.

My sister-in-law is a bloody legend - she has no clue about scooters but still she called around and eventually found a SYM dealer in Taipei who had them in stock. They became concerned that she was planning to do the repairs herself but she reassured them it was for an "experienced" mechanic. Actually, I've only ever once changed piston rings and it was on a real easy two stroke about 30 years ago! Anyway, she bought them today and is sending them on immediately - I doubt I'll get them in time to do the work over the Easter holiday but it isn't an emergency repair, yet. So I think I'll be fine to delay the repair until June when I have the time.

And the cost? Camcover gasket, US$5, head gasket and piston rings, US$20, cylinder/block gasket US$3. I'm not sure what shipping will be I'm sure the total cost is less than the cost of the piston rings alone on Ebay.

You might think the price doesn't matter that much but I'm planning to buy the Z+ 300 so this repair is just for "fun" - to see what state the cylinder/rings are in after so many years, and who knows, maybe get her near to full power again? Wish me luck!

General Discussion / Re: Symply 50cc VIN/chassis number location
« on: March 27, 2021, 06:20:54 PM »

There is a manual you can download and on page 5 it says where you should see the VIN. There might be a more accurate location further on in the manual.

Page 118 shows a plastic frame number cover - typical of SYM design.

General Discussion / Changing cylinders - anyone done it?
« on: March 25, 2021, 06:49:25 PM »
Hi everyone,

Has anyone tried swapping cylinders/pistons from the different SYM engine sizes? How about using different piston rings? I might have to 'cos of a parts availability issue so if anyone has looked into this, or done it themselves, please let me know. As far as I can see, swapping the 249cc and 263cc parts is straightforward, albeit time-consuming, but the 278cc might need major modifications.

So why do I ask? My 12 year old Citycom is just shy of 50,000 miles and is using oil (300ml extra needed between changes), has low compression, 10kg/cm2, and makes a knock noise when the engine is cold. It all points to worn piston rings/cylinder.

At the moment, it's looking like I'm going to have to fit a new piston, cylinder, etc from the 249cc engine, not the current 263cc, because that's all that's available at reasonable prices. It's no more expensive to convert than it is to repair, and the conversion would include a new cylinder too, so it might last longer/seal better than a repair. I don't think the 278cc cylinder will fit the engine block, although I'm in the process of checking for sure.

My problem is that I cannot get new piston rings locally - part no 13010-LEA-000 (the numbers denote a piston ring set, the letters denote the model) - the dealer doesn't stock them and won't order them. I can only get a complete cylinder and top end build and the dealer wants to charge me big bucks for this. Ebay is a similar story with 500% overpriced parts; however, I can buy a piston, cylinder, rings and gaskets for both the 249cc and 278cc engines, and for US$150 for either set - by far the best value. I've also reached out to family in Taiwan to see if they can get the 263cc parts but since these models are export, it's unlikely.

All the 249/263/278 engines have the same stroke but 2mm bigger bores - 71/73/75. The Citycom is 263cc - 73mm bore x 63mm stroke, and the cylinder/engine block gasket is the exact same part as the 249cc engine - both HMA. This means the smaller cylinder and its piston and rings should be fine. The piston will probably be lighter, which will reduce the load on the rod and big end. The issue will be whether the head from the 263 works efficiently with the 249 piston. I'm guessing they used the same design and sleeved the cylinder an extra 2mm for the smaller piston, with only a slightly different head shape. For example, the inlet pipe assembly, the camshaft, the valves... all the exact same parts for both. I've not been able to check exhaust, except for the gasket, which is the same. However, the head gasket is different - LEA for the 263cc and HMA for the 249cc. I will need to disassemble and measure to see which gasket would work best for the smaller diameter piston, assuming everything else mates up, as I think it will. Probably the bigger one, the LEA, is better to create a seal.

The 278cc is 75mm bore, same stroke - it has a different engine block/cylinder gasket part code (RFA not HMA) so the 278 cylinder might not fit the 263/249 engine block. The 278cc engines appear to be all RFA code parts for all gaskets and either L3A (GTS300i) or L9L (Z300) for piston rings/cylinder - 2 codes 'cos the latest 278cc cylinder is ceramic not steel lined.

Parts numbers are here:

The other option is to look into rings from a machine with a 73mm bore (Honda GX240 for example).

Here's some pics of the 2 troublesome parts that are specific to the 263cc engine - the rings and the head gasket. The other parts I need are the same (HMA) as the 249cc engine.

I can get this gasket for US$35 locally - the price in Taiwan is around US$10. The piston rings are on Ebay and they are about 5x the Taiwan price.



Citycom 300 / Re: Citycom 300i starting problem
« on: March 21, 2021, 08:30:27 PM »
Thanks for the follow up. I thought I got a bargain with a nearly new CC for half the new price, but that is definitely the best deal ever!

General Discussion / Re: New-ish SYM scooters?
« on: February 11, 2021, 07:42:47 PM »
rang motogb the uk importer and aked if there was any intention to bring the Z+ or cruisym alpha to the UK, they said no at the moment unless SYM agree an attractive price agreement

That's a shame - but at least it means they know the new models exist so they might be available at some point.

It's the lunar new year here (Year of the Ox) so most shops are shut for a holiday. They'll reopen late next week and then I'll ask the importer here.

General Discussion / Re: New-ish SYM scooters?
« on: February 11, 2021, 07:39:46 PM »
All very technical. I also used to set points in the distributor when we had HT coils as well. I also run a Honda Silver wing 600 and the only time I have had breakdowns it has been electrical problems. All very well when everything is working okay but, a real problem when things go wrong. Machines of today are not meant for home maintainance, "take it to your dealer" is the mantra.

Yeah, that barrier to maintenance and modification bothers me too - I really like to be able to work on a machine - needing to plug it in to a diagnostic computer is the big issue for me. 

Citycom 300 / Re: Citycom 300i starting problem
« on: February 11, 2021, 07:35:12 PM »
Great job - it's not easy fixing multiple electrical problems... it can be very frustrating!

I have had a starter relay die on another machine - I reckon lots of cranking in cold weather was the cause.

How did you identify that you were getting no fuel? I guess you tested the pump? Another thing to check is fuel lines - maybe they got gummed up from the machine sitting for too long?

Let us know if it turns out that was all - starter relay and fuel pump.

General Discussion / Re: New-ish SYM scooters?
« on: February 06, 2021, 08:52:54 PM »
I know the principles behind ABS but, how does Traction control work, Thoppa ?


I'm not too sure how it works exactly - I always assumed an ABS/TCS system measured the rotational speeds of the front and rear to detect if the front or rear is either locking up (ABS) or the rear was spinning too fast (TCS). ABS would then modulate braking pressure by pulsing it and TCS would lower engine torque to reduce any difference between front and rear rotation speeds. Because scooters are usually cable-pull throttles and single-cylinder engines, I assume that engine torque is lowered by retarding the ignition - so ABS can be used to measure wheel speeds for the TCS, and TCS controls slip/spin by retarding ignition.
I even find it hard to write that clearly! I hope it makes sense :-)

Bosch say in their documentation about the 9.1 system ( that their TCS can be added to their ABS, however, they are quite vague and don't give any technical details so I don't know for sure how it works - I assume it's much the same thing on the front and rear - a disc/sensor combo that create a large number of pulses every rotation - plus the TCS has to be integrated into the scooter's ignition (& fuel injection, etc?) systems so it can lower engine torque output - so I guess that is software added into the scooter's ECU but maybe it works some other way to control the engine. Does it need a ride-by-wire throttle or just a throttle position sensor or....? how about a torque sensor or calculation? I dunno. I guess that, as a basic system, it just needs to be able to lower the engine output until the rear wheel is turning at the same speed as the front but I don't know how it does it. Ideally, it would be able to know when the tire is experiencing high torque (gear, throttle, engine speed, wheel speed) and instantly detect a sudden spike suggesting a spinning rear is starting and cut it even before the spike had any real effect.
This is their ABS page :
and motorcycle stability control page:

I'm not the only one who has noticed how vague the manufacturers are about their technology. Here's an article on TCS that suggests different companies do it different-yet-similar ways and that no-one is giving up the recipe of their secret sauce. The article is a little out of date as many bikes now have six-axis inertia measurements so they have cornering abs, tcs, wheelie control, launch control, off-road and hooligan settings... you name it.

I'm old enough to remember setting the points, and then how wonderful electronic ignition was... and I loved it when fuel injection became better than a carb.... but now there's bluetooth-enabled speedos with smartphone apps for I don't know what. I dislike this trend but a bike with a six-axis imu does sound like a good idea - not idiot proof exactly but maybe clumsy proof - something  I'd appreciate :-)

General Discussion / Re: New-ish SYM scooters?
« on: February 06, 2021, 02:04:53 AM »
I saw that SYM had updated the Cruisym, now called an alpha, i think. It seems they have introduced an electronic dash panel and changed the halogen headlights to L.E.D. That was one of my niggles, having the speedo in Km instead of M.P.H. My Cruisym 300 will be three years old in May, so i will not be changing it just yet. I got my info from You Tube.

Yes, a Cruisym alpha - dunno when this was updated - do you know?

The other change appears to be traction control so that will mean a small bump in the price I guess. I would like traction control but I wouldn't buy a new scooter to get it, especially not if mine was only 3 years old - save the money for when they release a significant model upgrade.

My Citycom is 2009 though, and looking fairly tatty. It seems to be doing okay at 73,000kms but top speed is now about 120kmh (GPS) when she was capable of a little over 130kmh before, and fuel economy is 10% less (usually 32kml but now 30kml) so I guess it is wearing out slowly. I told myself I'd run it until it died but I'm hankering after a new machine!

General Discussion / Re: New-ish SYM scooters?
« on: February 06, 2021, 01:57:14 AM »
Seeing the images just fine, but sadly SYM's offerings in the U.S. are pretty slim pickings compared to whatcha get in your neck of the woods.
True of all marques really, & likely for valid reasons.

Aha, thanks for that feedback - it seems the images won't appear in Edge browser but are fine in Firefox.

I'm not sure we'll get the new models here either - there's already a different version of the Z available (in China and Japan it seems) but we only get the older one, and we don't get the HD models or Citycom either. The alternate Z has a radial mounted front brake caliper and a single LED headlight. It's strange as I thought this minor variant thing is more costly for the manufacturer - more parts, more inventory, etc.
Bulb light

LED light

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