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Post by 50cckeeway on Oct 16, 2008 0:41:26 GMT -5
First time scooter owner. Bought a slightly used 2-stroke 49cc Qianjiang (QJmoto) Venus. Now also sold as the Keeway Venus. Had 180miles at time of purchase, I put another 3,000+ before the odometer broke.
Want to do my own maintenance but haven't been able to find a manual or much info specific to my make/model.
I'm a completely inexperienced owner so please excuse/correct any incorrect terminology.
Questions:
I've been using 2 stroke outboard engine oil and have had no probs but is this best?
What type of oil goes in crankcase and how much?
Doesn't idle well, and dies while warming up a lot. Adjust idle or might there be another prob?
If needed, how do I adjust idle?
Maxes out at 40mph. Easiest way to push that to 50 without buying aftermarket parts?
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Post by troj4nm4n on Oct 16, 2008 6:29:46 GMT -5
2 strokes are the same brand to brand ... same idea anyway ... try using 2 stroke oil for bikes .. mobile has some pretty good synthetic .. no oil in crankcase if its a 2 stroke ... in the tranny use a good synthetic gear oil ... try adding some sea-foam or some heet to the gas , check all hoses and change the plug , gas filter , and check the air filter .. after all that it should run better .... no way to max it out without parts unless its still restricted ... if you need more info ask ... some1 will answer ya
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Post by scosgt on Oct 16, 2008 8:44:58 GMT -5
With over 3K miles you better inspect that CVT belt, it is time for a change.
Rough idle when starting hot is common. Mine smooths out after riding a minute or two.
There is an idle adjustment screw, but again, with that many miles, you should possibly get it into a shop.
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Post by rallyrrr on Oct 16, 2008 13:25:59 GMT -5
If you're up to it, removing the cyl. and raising (grinding/filing) and widening the ex. port would be about the only way to get this amount of speed increase. You would sacrifice some of your bottom end power though. Other than nitrous (and that wouldn't be for long and wouldn't be cheap) I don't know how to get this much speed w/o pipe & carb upgrades. We're up for suggestions from others though aren't we 50cckeeyway.
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Post by 90GTVert on Oct 16, 2008 13:41:11 GMT -5
Other than port work like rallyrrr suggested, some of the other ways I can think of off the top of my head to get more speed without aftermarket parts would be :
-Make sure your engine is in proper tune.
-Check squish / mill the cylinder head or cylinder down (it won't be free though, unless you have access to a machine shop).
-Lighten the stock clutch to help make up for some low end power loss if you decide to port like rallyrrr said.
-Remove unnecessary parts to reduce weight.
-Make sure your brakes aren't dragging.
-Mod the variator for more roller travel.
-I've heard of people filling rollers to make them heavier and drilling them to make them lighter. I'd rather just buy the rollers though.
-Modify your stock muffler to lose weight and/or restriction.
-Modify the stock airbox for more airflow (may require re-jetting the carb though).
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Post by 50cckeeway on Oct 19, 2008 9:00:00 GMT -5
Thanks for all the input, everybody.
Will try adding Heet and checking hoses and plug first as it sounds easiest. Will check out the CVT belt too.
I haven't removed any restrictors. I hear many scooters have a small washer that can be removed to increase top speed. Also I think the stock exhaust system is restricted but I don't know if the problem is the pipe or not. I removed the exhaust to check it out and the opening is much narrower in the bike, it looks like the opening is about half filled in.
This is a lot of help. If anyone can think of anything else I should know it'll all be appreciated because I'm definitely starting from scratch here. Had to look up what a CVT belt is, if that gives you any indication.
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Post by scosgt on Oct 19, 2008 18:59:15 GMT -5
If it hits 40, it is NOT restricted. There is nothing much you can do without changing parts to get more speed. Mine is also a QJ, probably the same motor. 1300 miles now. I use Spectro 2T semi-synthetic blend, supposed to be good oil.
I tried an Iridium plug, it possibly gave me a slight power increase, but it was horrible until the engine warmed up, and it ran rich. went back to a standard NGK BPR7 and it runs much better. Idle can be a bit rough, when starting hot it needs some throttle to start. Has always been that way. Never stalls, except when first started if you don't give a little throttle, will get the choke looked at when I get a chance.
40 MPH is about the limit, make sure to remove all un needed weight, including tools and GAS. yes, it will run faster on 1/2 tank of gas. I always top off when I get home, so I give up a little speed until I do 30 miles or so, then the weight comes off and I get a little faster!
Probably need to change the spark plug, that might help the idle. If you have the same QJ motor as me, the plug is either a BR8HSA or a BPR7HS, the 7 being slightly hotter. Mine came with a TORCH Chinese junk plug from the factory, and runs smoother and with better MPG with the NGK replacement.
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Post by rallyrrr on Oct 19, 2008 21:37:03 GMT -5
One thing that I might add to 90GTVert's post would be to change out your stainless steel reeds to carbon fiber ones. If you get your intake flowing better these will add power at high rpm. They are not too hard to change out either. Locktite the reed retaining screws and nuts so they don't get loose in your crankcase.
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Post by jtl on Oct 21, 2008 13:40:49 GMT -5
I don't know if this is true for all scoots but on mine it was suggested to over inflate the tire by a few pounds and it made a difference. I changed the pipe and roller weights and that make a huge difference in term of acceleration. I'm new to this stuff but I have two scoots and I read alot of info and many people are looking for a 50cc to do more then is physically possible. I can do 45, but that is it. To do more is larger cylinder, bigger carb, ect. On mine people are even purchasing a rebuilt 100cc engine used on BWS which is not sold in the U.S. buy Yamaha, but the frames are the same so it is a direct bolt on. The price is $1500 which is a lot of money to get another 10-15 mph.
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Post by 90GTVert on Oct 21, 2008 13:51:57 GMT -5
Raising tire pressure is an old trick that is effective on pretty much any soot to some small degree. The increased pressure does two good things for top speed. It decreases rolling resistance by making a smaller contact patch and it increases the diameter of the tire. Of course the added tire pressure also makes the ride a little bumpier. Going to excess with pressures can cause even more problems. Long story short, it's good for a minimal increase but don't go crazy with the pressure.
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Post by jtl on Oct 21, 2008 14:05:27 GMT -5
I agree. I think I went from 28 to 33 psi. Those big ole fat tires on the Zuma can handle it. I have been thinking about doing the same thing on my wife's Vino but those little tires scare me. That Vino is a rocket for a 50cc with just the exhaust mod. My friend who also has a Z50 says he wishes he hadn't taken the Vino for a ride. The scoot is so light which is what I think makes the big difference. It would be fun to put a 70 kit on it, then it would really be a "sleeper". As always I appreciate your comments, you have helped a lot of people, including me.
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Post by 50cckeeway on Oct 26, 2008 20:35:48 GMT -5
Probably need to change the spark plug, that might help the idle. If you have the same QJ motor as me, the plug is either a BR8HSA or a BPR7HS, the 7 being slightly hotter. Mine came with a TORCH Chinese junk plug from the factory, and runs smoother and with better MPG with the NGK replacement. Posting some pics to see if we're talking about the same QJ/same plugs. Picked up a new plug at the dealership where I got the scooter and when I got home to install it the one I removed looked completely different. Did they give me the wrong one?   |
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Post by scosgt on Oct 26, 2008 22:04:27 GMT -5
The one on the right is the same but a resistor plug. The nut on top screws off. It if is more than finger tight just use a pliers and twist it right off.
It looks like your scoot is running very rich, but the photo may not be accurate?
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Post by 50cckeeway on Oct 26, 2008 23:28:56 GMT -5
The photo is pretty accurate, maybe a bit blurry. I took it just a couple hours ago. Got your reply and took the nut off and installed it. Thanks for the help.
Since my initial post the scooter has stopped running. Changing the plug and adding Heet has been my first attempt at troubleshooting. Not sure what else to try.
The kick start just went out too. Seems to be falling apart on me all of a sudden.
Suggestions?
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Post by scosgt on Oct 27, 2008 18:55:12 GMT -5
I am not a mechanic, but from what I have read here, check your air box. That plug looks like it runs WAY rich. Did you gap the new plug? Should be .026
Did you add ISO HEET? Two strokes can not use regular HEET, they use ISO HEET. IT does state that right on the bottle.
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