Need new engine By motley (Read 1,083 times)

[motley]

Well I have a 2008 Vip based model 50cc scooter. The scooter engine it self had a hard long life, Managed to get to 38,000 miles on the thing and two days ago when I started it, it almost sounded like warshers pinging around on the inside of the engine, I already knew right then I was going to be breaking down, made it to the grocery store by time I made it back out to the scooter it sounded like the iner parts of the engine just shattered on starting.

Out of ego, I started it one more time, terrible idle, instant cut off and it almost sounded like a chain started smacking around on the inside when it shut off, I went to start it again xD and there was no air coming from the exhaust port, rpm gauge never moved..

The engine it self in al honesty had a very long life span for being a Chinese scooter. There are no mechanics near me what so ever, there is a vespa shop 50 miles from me and they stated "We do not work on Chinese". I have no way of getting it anywhere and for the sake of my pocket I think it would be cheaper just to order a complete engine?


I should be getting my license soon. So even replacing the engine would help me make it a better bike for a re sell. maybe even a resell for the same amount I payed for the engine lol..Might be better off buying a new speedometer and gear puck while I am at it while the miles those two devices have on them. 

Can anyone help me lol? 
I found this on parts for scooters, not bad.. Really curious if there is something better, or more user friendly to install..
www.partsforscooters.com/Engine_longcase_4-stroke_qmb139?sc=34&category=133360 Maybe even bith a bigger bore or something?


* I do not have a stock muffler.. Mines load, it could cause damage on a new break in?

From a long time ago.. 

Any help is highly appreciated, don't want to get fired for having an unreliable ride

[solymar]

Sounds like the damage to your engine is pretty significant and could have been caused by a few things. From the way you make it sound, replacing the engine probably is your best bet. Motorcycle/scooter shops charge anywhere from $70-$80 per hour labor(at least they do by me). Add in a few new parts and you’d most likely match or go beyond the cost of a new engine. If you have a friend that can do the repairs, say for some beer money, then it might be worthwhile to try to fix it....but it all depends on what damages have been done & you won’t know that until you tear the engine apart.

My personal opinion) - If you’re going to fix it to sell it, probably would be better just to get that stock engine and be done. You probably could sell the bike then for the cost of the new engine, but that also depends the condition of the bike in general. If you’re going to keep the bike, then you can consider getting a bbk/larger cc engine, but only you would know if it’s worth it to you. You may/may not recoup the cost of a bbk if you try to sell it.

Good luck & let us know what you do.

Solymar

[lostforawhile]

it depends on whats wrong, if it could be fixed by a BBC then you might be in luck, a 50cc chinese engine is really not that much, you really need to to pull the head and jug and see if the rod and bearings are ok

[motley]

That's something I am not trying to get into what so ever . I know some things with engines..

But I think it's time this engine gets marked as dead. It was manufactured in 2008, and now has 38,000 miles on it, these engines are only supposed to live for 10,000 miles, I received and extra two out of it.

I think it would make a good engine to learn from. Maybe resell.

I looked near the exhaust port and everything is covered in oil, the block, everything.

But I really do appreciate your advice, the only thing I am worried about on a new break in is the after market exhaust. I don't want to glaze the chamber or whatever on a bran new block. I have ran all of my scooters hard over the years because of living on super long country road. 20 mile trips just to get out of the country. So the break in has to be proper. And the exhaust has to be questioned, I'm sure I will be losing compression as it's not stock, as well the new engine will be a 50 cc where as mine is not so the exhaust might become overkill. So there will be a huge issue possibly in general
?

[lostforawhile]

as long as you aren't running it with nothing attached to the head, it will be fine, what's more important during break in, is that you don't run it all out for long periods of time, the rings need to wear to the bore, valves seat properly etc, don't run synthetic oil during break in, you need some friction, run conventional 15-40 for about the first 1000 miles, change it at 500 miles, then change again to synthetic at about 1000 miles

[motley]

I went ahead and ordered the engine. I'm trying to find out what else I should consider on ordering.

Doesn't say anything about the varistor being there, would be nice if there is a stock ready to go one on it with fresh variator spacers/slides on it. I have a fairly brand ned stock clutch on mine so if that's not on this scooter that's no big deal. I see I need a carb, just replaced mine six months ago so that's a plus. My main worries is the variator.

Something about my gear puck, speedo cable, or actual speedomotor is off. 50 mph on the gauge is actually 30 mph >.<. I did not see my gauge on parts for sccoter, if this is a gauge issue it would be nice to replace it due to miles that are on it with putting a new engine on.

About synthetic oil, I put synthetic oil in mine a year ago, first time it ever had it, it liked it at first. but in 2010 I had a guy tell me "If you run synthetic in it, you will cause the bands to fly apart, to much worse". Dunno what he was talking about. But I think my problem with this scooter is related to that. So I think I want to stay away from synthetic.

Most engine re builders of all types of engines use Castro Gtx, I thing I will run 10w 30 in the engine once she's broken in.

My first scooter I drove 15 - 20 mph for 100 miles. 20 - 35 for 250 miles. 30 to 40 for 500 miles. And at that point I just started driving it like it was an average scooter. Over time I opened the throttle and hit 60 on a stock scooter, seller said it and I should not go that fast on a stock engine, not sure if it were related to the break in lol..

Would it be safe to mainly run it once she fires for about 7 minutes, turn it off, check the oil levels, re start it, let it run for 20 minutes, check the oil levels. let the engine cool down, and run it again for another 20 minutes or so before I even consider on turning the throttle?

[truered]

Hi iv just had a topend rebuild which went fine i have a lexmoto tornado 125 but i got up today and it starts but it cuts out when i pull throttle any help

[lostforawhile]

Dec 26, 2017 6:25:50 GMT -6 motley said:

I went ahead and ordered the engine. I'm trying to find out what else I should consider on ordering.

Doesn't say anything about the varistor being there, would be nice if there is a stock ready to go one on it with fresh variator spacers/slides on it. I have a fairly brand ned stock clutch on mine so if that's not on this scooter that's no big deal. I see I need a carb, just replaced mine six months ago so that's a plus. My main worries is the variator.

Something about my gear puck, speedo cable, or actual speedomotor is off. 50 mph on the gauge is actually 30 mph >.<. I did not see my gauge on parts for sccoter, if this is a gauge issue it would be nice to replace it due to miles that are on it with putting a new engine on.

About synthetic oil, I put synthetic oil in mine a year ago, first time it ever had it, it liked it at first. but in 2010 I had a guy tell me "If you run synthetic in it, you will cause the bands to fly apart, to much worse". Dunno what he was talking about. But I think my problem with this scooter is related to that. So I think I want to stay away from synthetic.

Most engine re builders of all types of engines use Castro Gtx, I thing I will run 10w 30 in the engine once she's broken in.

My first scooter I drove 15 - 20 mph for 100 miles. 20 - 35 for 250 miles. 30 to 40 for 500 miles. And at that point I just started driving it like it was an average scooter. Over time I opened the throttle and hit 60 on a stock scooter, seller said it and I should not go that fast on a stock engine, not sure if it were related to the break in lol..

Would it be safe to mainly run it once she fires for about 7 minutes, turn it off, check the oil levels, re start it, let it run for 20 minutes, check the oil levels. let the engine cool down, and run it again for another 20 minutes or so before I even consider on turning the throttle?

what bands is he talking about? there is no wet clutch in a 139 QMB,  they normally take 15W40 which is heavy duty diesel oil, don't run lighter oil in it, these air cooled engines are really tough on oil, run regular dino oil for about a 1000 miles to allow proper break in, avoid constant wide open throttle, then switch to synthetic, there is nothing in the engine that will be hurt by it, all it will do  is protect your engine better.   It needs the dino oil  at first, because it needs some friction to allow proper break in, synthetic is so slippery the engine will never break in, you want this AFTER the first 1000 miles.  Nothing is going to beat synthetic in a high revving high heat air cooled engine like this, it's a little pricey, but it takes less then a quart per change, by the time you do  several changes, you have enough left over to do another.  

[cyborg]

Lost is correct,,,,Dino first break it in then switch to synth,,,when I did the switch to synth my temps dropped 75*+ same motor same day in a hotter part of the day,,,forget the dope with the bands comment,,,he's talking sh(t and doesn't know what end is up,,,and I would heat cycle it like you mentioned

[motley]

Thank you guys for the info

I'm honestly not sure if I will use synthetic oil in my engine due to prices. With conventional oil I actually tend to change my oil to often, with synthetic this would become a little expensive to be changing the oil twice in one month "Living Pay check to Pay check".

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Apparently; parts for scooters said the engine is bone stock.. I really wanted to know the specifications, even over the phone they were not able to tell me.

The engine model is: jn1p39qmb
The only known info I can find on that model is here: en.jnen.cn/products_details3.aspx?id=110&type=15

Here is a cheat sheet:

Commercial Name JN1P39QMB  50CC
Dimension(L×W×H)(mm): 580×410×320
Nominal displacement： 80ml
Displacement： 81.5ml
Bore： 50.0mm
Stroke： 50.0mm
Compression ratio: 10.4:1
Rated power:       3.2kw/7500r/min
Maximum power:   3.6kw/8000r/min
Maximum torque:     4.5N.m/6000r/min
Maximin null-load speed: 1700±100r/min
Maximin fuel comsumption: ≤367g/kW·h


If anyone knows what any of that is, or if there is a proper place to find info on my motor that would be great!!
Thank you everyone for your helpful messages

[lostforawhile]

it takes less then a quart to change the oil on a 139 QMB, add a couple of partial quarts together, and you've got an oil change, with synthetic you could probably extend your oil changes to once a month, using cheaper oil is poor economy in the long run, the most critical thing to an air cooled high RPM engine, is the oil .

[motley]

It's just a preference to be honest. I typically run Castro Gtx. two years ago I started running Mobile 1 in the blown motor xD.

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Of course,  I don't have a better photo of the two at the moment. But the drum brakes on the motor look totally different o.O? The brake shoes are there on the new one, But the old motor makes it look like I need another part lol?

cdn.discordapp.com/attachments/281096255558385666/400987675475181578/JPEG_20180111_072138.jpg

cdn.discordapp.com/attachments/281096255558385666/400988017495506957/JPEG_20180111_072255.jpg

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I can take better photo's if need be when I get off work. This is all I have at the moment :/
I'm assuming it's a 10 year design difference

[motley]

Not sure if that's going to upload.. But this engine is slightly longer than mine, I know I need the plate as it is for the second shock "Yes this is a 50cc with two shocks".

Also the rear wheel would rattle to death unless I had a spacer of some type..
The exhaust also does not meet up. Sits to high actually, but I know a welder down the road from me.

If Anyone can help me with possibly finding maybe something like a spacer that would be awesome, this would be a quick fix to bypassing this. Also not sure if it would be okay to bypass the second spring? I think it's just for sway?

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EDIT: I was able to get the exhaust to fit luckily. I thought there would of been gaskets on a new motor for the exhaust port..

As for that bracket I'm a little lost. I think the only bypass is axle spacers as the wheel is very flat and designed for two shocks. still a little lost on what to do 

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Welp, If I get an answer as to if I do not need the second shock, then I will just do this instead:


So basically the bottom hole meets with the hole at the top, in this case it would work as a spacer, and it would prevent this device from spinning. I would be able to find a correct fix for latter on.