KymcoForum.com
Scooters - 125 to 300 => Grandvista 250 => Topic started by: scuba1065 on August 11, 2013, 02:04:40 AM
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I went to go ride last week and realized my rear tire was worn through to the threads. So, I went to the local motorcycle shop but was told, "they don't work on scooters."
It gave me another opportunity to play with the scooter. In doing so, I learned a few things that I thought I would pass on.
I replaced my tires with Michelin Pure SC's from Amazon.com I spent $115.00 to purchase them and took them out of town to have them mounted/balanced to the wheels. ($50.00)
To remove the wheels was extremely easy. Took about 1 hour to remove them and another hour to put them back on. (would take less time if I didn't read each step of the way to make sure I was doing it correctly.) They ride and look great. It fixed a bounce I was getting at deceleration with the old front tire.
While I had it apart, I set the valve clearance. I had a tick and realized that it was set at 0.03inch instead of 0.03 mm. After reading other forums I decided to go with a thiner gap and gapped my valves to 0.03mm. This fixed the ticking and it runs better. Thank you for those that posted videos on you tube on how to do this. It is really very easy, also described well in the users shop manual, also downloaded from a forum posting. Easy to find, A great tool.
I also replaced the belt and rollers. I went with motorscooterparts.com and was very happy with their service. The parts arrived quickly and as promised. I ordered the 1 O15-2286 - 894-23-28 Kevlar Belt - Gates Powerlink 50.99 and 1 U72-1787 - 23x18 Dr. Pulley Sliding Roller Weights 44.49. Very easy to install.
My scooter is well maintained as far as oil, I used to have it serviced by a scooter mechanic that is no longer in business. It has 9500 miles on it.
Also changed the oil, I elected to use 10W40. only 1 liter needed. Also very easy.
Running it today for a 100 mile trip: I have a GPS measured top speed of 80 (speedometer reads 87), up from 75. The acceleration is better, and it runs very smoothly. It's nice when everything works the first time.
Happy scooting. :)
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Hi Scuba, a few questions:
What actual weight did you install for the Dr. Pulley sliders? Same as the roller weight?
You used 0.03 mm for intake and exhaust valves? How do you come up with that? That's too tight! Factory specs is 0.1mm, you are 3 times tighter... You can burn a valve up-hill or wide open throttle, or if the clearence wears any tighter. You need to fix that ASAP!
The 80 mph is that a one time max speed, or can you reach that flat out every time?
What is your gas mileage?
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I put the same weight sliders, I read about putting in 18 to 22 but decided 20 gm was a good starting point. I'm really just looking for reliability.
My valves were set at the 0.1mm setting recommended and it was too loose. I realized that I could have been interpreted as giving bad advice here - just my experience. It runs better than ever at this setting and the settings came from reading the forums here and other places. I just spent another 80 miles on it this morning and at pretty close to WOT and 80 degrees, the engine ran cool and very well. I do appreciate the advice and will keep an eye/ear open for signs of trouble. I will fix my entry if I can. Good catch.
the 80 is down hill with no wind. However the flat out max speed is around 75 and stays that way up most hills. There is not as much speed loss that I was seeing with a belt that had 9500 miles and the rollers.
I will say that the belt I removed was still in spec and looked very good. When I removed the casing, my drive area was clean except for a slight amount of rubber dust, nothing like the guy that had his belt shredded. (another recent forum entry)
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I am sorry, but 0.03 mm valve clearance is just too tight, no matter what. You will not notice ANY problem until it is too late. KYMCO posts its clearance on all 250 cc engines at 0.1mm, and whoever wants to reinvent the wheel with 0.03 not good... (maybe for racing, then it is a totally different story!) Valve clearances get not always wider, they can get tighter, and then you will not know when you have 0.02 or 0.01? Too late; burnt valve(s), bad idle, loss of compression... don't do it. Minimum 0.07mm would be my recommendation. A valve rattle starts usually over 0.12mm and more.
You changed at the same time your roller weights to slider weights; this is responsible for your now higher top speed. The sliders drop the rpm: e.g. at 75 mph you ran 8000 rpm with roller weights, or with slider weights at 75 mph you turn now around 7000 rpm . Your engine doesn't really make any much different power, but you used/adjusted with the Dr. Pulley's your transmission to make most out of that engine power.
I did extensive transmission setting testing with all kind of roller and slider weights. I ended up with 18g Dr. Pulley slider weights as the best benchmark performance (means factual and measured). My Grand Vista runs now GPS verified 77-78 mph flat out, and up to 83 mph down hill; original KYMCO valve clearance specs. ;D
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Gotta agree. You will not notice a difference with too tight valves other than tapping noise going away. Valves tapping a little is a happy sound.....silent valves are bad news.
Not many engines require valves adjusted these days - but I drove and serviced my aircooled VWs for 4 decades - you do not want tight valves!
Adjust them in a cold engine (sitting overnight) and to factory specs - not 1/3 of factory specs! You will have a silently ticking wallet buster if not set with the proper gap.
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I'm just thinking, 0.003" (inch) would be "OK", 0.03mm is too tight. You are not mixing up units and decimals here, right?
BTW: measured on my newer Grand Vista and the valve clearance is tightening up after 4000 miles on the odometer, especially on the exhaust side, where is even more crucial. I re-adjusted. So, if that is the general rule, then you have, as Stig said, with 0.03mm "a ticking valet"..! ;)
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... mounted/balanced to the wheels. ($50.00)
I also replaced the belt and rollers. I went with motorscooterparts.com and was very happy with their service. The parts arrived quickly and as promised. I ordered the 1 O15-2286 - 894-23-28 Kevlar Belt - Gates Powerlink 50.99 and 1 U72-1787 - 23x18 Dr. Pulley Sliding Roller Weights 44.49. Very easy to install....
Wow you spent $50 on a Kevlar belt! I only spent $85 on stock belt from my local dealer - ouch for me. Wow, you spent $50 to have the tires mounted on the rims! While I only spent $95 at my local dealer (just for the mount and spin) as I brought just the wheels and tires in. The dealer said they charge by the hour to mount and spin so the price is not fixed! Ok, I'm done with my local dealer. I will order the sliders from motorscooterparts.com. Great info and updates.
Do you have the link for the valve adjustment video?
For oil I get the 1 gallon of Delco 15w40 (4 qt) jug at wal mart for ~ $12.
Thanks for that informative post - hope it gives other scooter owners the courage to save $$ and do some or all maintenance.
Paul
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I will say that the belt I removed was still in spec and looked very good. When I removed the casing, my drive area was clean except for a slight amount of rubber dust, nothing like the guy that had his belt shredded. (another recent forum entry)
I have 10,100 miles and I changed the original oem belt tonight with a new stock oem belt. I had the same results - almost no dust, all components looked good. Clutch looked great too. My sliders have ver slight flat spots and I will replace them shortly. When I turned the belt inside out and bent it back there were no cracks or dry rot. The only thing I saw is that the belt left marks where it slapped against the bottom of the metal cover between the two pulleys.
This will be my first valve adjustment since buying the scoot 2 years ago with 2,600 miles I know I'm overdue.
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I ended up with 18g Dr. Pulley slider weights as the best benchmark performance (means factual and measured). My Grand Vista runs now GPS verified 77-78 mph flat out, and up to 83 mph down hill; original KYMCO valve clearance specs. ;D
Can you recommend weights. I'm interested in reducing my highway rpms. I run 65 to 70+ mph. I don't care if it reduces the acceleration. Btw, I average 55 mpg - that's with the tallest givi windshield and largest givi trunk / top case (I had to make an adapter out of wood). Stock windshield I got 58 to 60. I find high speed on the highway hurts the most but that is live in San Diego.
-Paul
2005 GV 250 w/ 10K mi.
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Paul, after all my testing the Dr. Pulley Slider Weights at 18 grams are the best compromise, and it will drop the rpm to 7000 rpm at 70-75 mph. If you have standard roller weights you will see an improvement. You can go to 20 g Dr. Pulley weights for a bit less rpm "in the middle" but you will loose acceleration. Your gas mileage depends on that big windshield that is a barn door to push, and yes, I loose also mph and mpg when I have it on it in winter.
Eric
Can you recommend weights. I'm interested in reducing my highway rpms. I run 65 to 70+ mph. I don't care if it reduces the acceleration. Btw, I average 55 mpg - that's with the tallest givi windshield and largest givi trunk / top case (I had to make an adapter out of wood). Stock windshield I got 58 to 60. I find high speed on the highway hurts the most but that is live in San Diego.
-Paul
2005 GV 250 w/ 10K mi.
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I'm confused. I would like to be able to order parts like belts etc. so I tried the link motorscooterparts.com and it looked like that name is now available to buy. Their were some "related links" listed below the message "Click here to buy motorscooterparts.com for your website name". Below it were some links entitled "Related links". Are one of those the one where parts can be ordered for Kymco scooters? Thanks in advance!
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Yeah, that's just a stupid self proclaimed site (they want to sell that domain name to others).
Are you buying otherwise on e-Bay? There you can get all the parts.
Or, type into search engine "Dr. Pulley Slider Weights Kymco 250" (23mm x 18mm and the weight you desire, either 18g, 19g, or 20g) and it should give you several parts suppliers, where you can also get the belt.
BTW: the belt width must be in minimum 23mm (OEM is 24.5mm); Kymco says" "Service belt if less than 22 mm) Some aftermarket belt suppliers are narrower new; I had to send a Gates belt back because it did not match the printed specifications. I ordered a OEM Kymco Belt for my old G/V, and found a "price deal" for the new one on a Malossi belt that's supposed to be top of the line.
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Thanks Windwheeler. I can see from reading this forum that there is a lot to the belt and slider selection. My Grandvista 250 has around 4500 miles on it but it is a 2009 model, so the belt is probably getting old due to age more than mileage.
Rich
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My Bet and Win 250's valve clearances were dead on at 15000 km, but it doesn't take much work to stick a feeler gauge in and check.
Have a look at the belt if you have the tools (wrenches, sockets, mallet, cheap caliper) to do so. My 2008 B&W 250 belt was merely worn down to service limit at 20000 km, but it was in otherwise perfect condition; no rot, no fraying. No point in replacing a good belt.
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I agree, I would not replace a belt at 4500 miles. The wear depends how "hot" the belt gets. Interstate riding is harder on the belt than just around town with lower speed. So, I would "inspect and measure it"; belt width should be above 22 mm, and no big signs of rubber shaved off in the casing. I bet you have none of this. I changed a belt at 11,500 miles because it started to slip, and that was my former 2005 G/V, and I ride a lot of interstate miles always around/above 70 mph GPS...
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Paul, after all my testing the Dr. Pulley Slider Weights at 18 grams are the best compromise, and it will drop the rpm to 7000 rpm at 70-75 mph. ...
Eric
Eric,
Thanks, I decided to try with Dr Pulley 19g sliding weights. I installed them today and road around the block. The rattling noise I would hear while coasting by parked cars around at 15 mph or faster seems to be gone. In a little while I will go on the highway.
Question: when putting the front pulley back on - that is the variator - I saw that the aluminum threads were stripped. I think I might have done this by powering the nut on with my air impact wrench. Does it matter? I could not get the belt out of the way to get started on the splines. Does the holding tool help with that?
Thanks,
Paul
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OUCH! The spline is VERY important, so important that you have to park the scooter immediately until replaced!!! I hope you are not talking about the thread on the crank shaft, right? You are talking about the spline on the face plate pulley, right?
The procedure to get the belt correctly back on requires that you push the other pulley (at the clutch, or "final drive") a bit apart and the belt there a bit down INTO THAT pulley, usually by turning it a bit. that gives you then a bit more length for the front assembly.
Make sure you use before putting all parts/pulleys on the crank shaft a blue = serviceable thread/nut lock like Loctite
In the front you can not use the impact wrench from start; that was your mistake. You have to use a regular socket wrench to ease the face plate pulley onto the shaft and match the spline at the same time! This works with tightening and slow turning at the same time and letting the belt work its way "up" to a larger circumference on the front pulley.
When all is tight, you can use the holding tool and torque to specs, or the Impact wrench shortly until the nut stops moving in relation to the pulley (that you can hold by hand with a strong leather glove).
Sorry, but what you describe, if you ride the scooter you could damage the crank shaft irreparably and that would mean an engine rebuild, new crank, etc. EXPENSIVE! So DO NOT RIDE the scooter until you have the face plate pulley replaced, only about $27 +shipping...
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"I agree, I would not replace a belt at 4500 miles. The wear depends how "hot" the belt gets. Interstate riding is harder on the belt than just around town with lower speed. So, I would "inspect and measure it"; belt width should be above 22 mm, and no big signs of rubber shaved off in the casing. I bet you have none of this. I changed a belt at 11,500 miles because it started to slip, and that was my former 2005 G/V, and I ride a lot of interstate miles always around/above 70 mph GPS..."
Again thanks for the good advice. I inspected my belt and it looks good at this point. The width which I measured at several points is: .94 inches = 23.9 mm. Sorry for the clunky way i did the quote above. I need to figure out how to do it correctly.
Rich
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Paul, after all my testing the Dr. Pulley Slider Weights at 18 grams are the best compromise, and it will drop the rpm to 7000 rpm at 70-75 mph. If you have standard roller weights you will see an improvement. You can go to 20 g Dr. Pulley weights for a bit less rpm "in the middle" but you will loose acceleration. Your gas mileage depends on that big windshield that is a barn door to push, and yes, I loose also mph and mpg when I have it on it in winter.
Eric
Eric, I installed the Dr. Pulley 19x23mm 19g flat slider weights and the three plastic clips aka guides?. As you stated the rpms are cut and there is a small decrease in the midrange. I noticed I never hit 8000 rpms now which is fine with me. I set a speed record following an suv down a big hill on the highway 87mph indicated and the rpm stayed below 8K. I probably didn't need to replace the guides so I saved my old ones. Thanks for the advice!
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You are welcome! I am sure you will set more speed records, 87 mph indicated is already pretty good. Usually 90-92 mph (true 83-84) is as much as one can get out of the engine, and then it is even with the slider weights turning 8000+ rpm.
So what was the "stripped aluminum threads" you were talking abbout?
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You are talking about the spline on the face plate pulley, right?
Yes, just the soft aluminum pulley splines.
The procedure to get the belt correctly back on requires that you push the other pulley (at the clutch, or "final drive") a bit apart and the belt there a bit down INTO THAT pulley, usually by turning it a bit. that gives you then a bit more length for the front assembly.
Thanks, that solves that mystery.
Make sure you use before putting all parts/pulleys on the crank shaft a blue = serviceable thread/nut lock like Loctite
Will do and I have plenty of it.
Updates:
New speed record: 90mph indicated - again down hill on the highway following an suv. Speed record for me, routine driving / "crusing" for the suv.
I adjusted the valves today and made sure to convert the 0.10mm to 0.004 inches. I rotated the crank three times to TDC. Both valves were very tight. I couldn't get the feeler gauge in until I loosened the lock nut. After I started the motor the valves make a ticking noise where before they were silent.
Also, I noticed the head gasket is leaking some oil but not too bad. The nuts on the cam shafts look like they were removed and reinstalled. I bought this scoot with only 2,600 miles from the second owner (they bought it 3 months earlier than I did with 1,600 miles). They had to have the carb cleaned / rebuilt as it was clogged from sitting with old gas.
I checked the air cleaner - it had the original mfg date of 03/2005 on it. It was pretty dirty so I brushed it off and plan to replace it in the fall.
I removed and checked the spark plug and it looked great. I bought a new NGK DP87EA9 at Autozone for $2.50. The generic 90w gear oil was an amazing $5.99/qt. I changed out the gear oil. I poured the old dark gear oil into a mixing bottle and it was low by about 1.5 oz. It was probably original. I want to take a compression test but I will need to cut the old plug and weld to use it as an adapter as my gauge is too big.
Thanks for the advice, I will post pictures when I get a chance.
Paul
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Paul, if the splines on the aluminum face plate are "compromised" you are playing Russian Roulette driving this scooter. They are absolutely crucial for the power transfer, and if they "ratchet through" due to 20 HP pulling on them not only will you get stranded, could theoretically even crash (block rear wheel) if the belt entangles, but it also can damage the crank-shaft, belt, etc, and then you need to rebuild the engine with a new crank... I saw one Kymco G/V where this happened. I is a quite significant issue you should not ignore, and really not ride the scooter in that condition until fixed. All I can do is "warn" you, the rest is your decision...
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As I said before, OEM Kymco valve clearance is 0.10 mm factory recommended setting, but reducing it to 0.07-0.08 mm is no problem, makes no difference in performance and safety, and yes, it is quieter (less ticking noticeable; but a it ticking is OK!). However, any setting under 0.05 mm is just too tight and also dangerous for the engine in the long-run if they get tighter. Think about climbing a longer hill or longer time wide open throttle on the interstate... Too tight will burn valves.
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As I said before, OEM Kymco valve clearance is 0.10 mm factory recommended setting, but reducing it to 0.07-0.08 mm is no problem, ....
Ok, good news. I went back in there and this time I put feeler gauge blades that were bigger than 0.10mm I was able to fit as large as ~ 0.17mm. So I readjusted things and came up with exactly 0.10mm (0.004") on the intake and (0.12mm for the exhaust). Now things are nice an quite with only a tiny almost in audible slight tick. I decided to go with 0.12mm for the exhaust because I know the exhaust will tighten up over time.
I installed a new NGK DPR7EA9 ($2.50 at Autozone). The old plug looked really good with 10,400 mi on it. I put some anti-seize compound on the threads gapped it to 1.0mm. I going to do the fuel filter next. It is brown. I also tossed in a few oz of fuel injection cleaner.