Agility 125 low power & burning oil

[Emil]

Hi there,

My 2009 Agility 125 with about 28k km started burning oil maybe 2k km ago and recently also started loosing power.
I have replaced the belt and roller weights, inspected clutch etc. and everything looks good.
Discovered only a few weeks ago that the exhaust is smoking a bit.
The engine seems to be running a bit rough and acceleration up to about 40/45 mph is quiet lousy. After that it doesn't feel much different from before, but there are very few stretches where I can go that fast anyway.

Can someone give me an idea where and how I should start testing?
My knowledge and equipment is limited. The most advanced stuff I did so far is putting in an NCY variator transmission set and changing the brakes - so please be patient. But I am willing to learn. Mostly of course because I don't want to spend a lot of money

Thanks and happy new year,
Emil

[beermak]

If its burning oil and smoking... those arent good signs.
Try a heavier oil wt. For example if you are doing 10w40 go for a 20w50.. that might help its worth the try.
But in the end your looking at an engine rebuild certainly.

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[Emil]

Engine rebuild... yes, I had that feeling. How should I start this? I guess 1st testing compression to make 100% sure that's where the issue lies?
And when compression is low, what would I look into? New piston, piston rings, cylinder head, ... everything?
Assuming that the scooter won't last for that much longer anyway, would it be worth to get a big bore kit such as this one? http://www.racingplanetusa.com/cylinder-naraku-160cc-585mm-forged-piston-kymco-p-21469-1.html?backcPathco=25&cPath=2_1184#.VorLmFJH7Sg
What would be easiest while not costing a ton of money? Bringing the scooter into a shop is probably not worth it.

[Emil]

No ideas anyone? 

I'll try to clarify my intents:

• Cylinder seems to be gone, but I would like to make 100% sure this is true before taking actions. How to find out?
• If cylinder needs a rebuilt, I am weighing up between saving money (new scooter) and spending valuable time on it (diy repair). Giving it to a repair shop seems too expensive for a scooter that age. Does anyone have an idea how much work I need to put into this?
• Is it worth to do a little cc upgrade? The idea would be to increase performance just a little, without requiring carb, intake, exhaust,... upgrades. Can I easily upgrade to 150cc? Is it even worth it?

Any input is welcome.

Thanks,
Emil

[mrbios]

At $166 I think the kit seems dirt cheap.  Also, in the condition your scoot is it would be hard to sell.  I've never installed one of these kits so you might want to do some research to help ensure the new motor comes out ok.  Nice jump in power and I even saw they offer a kit for my GV250 to 300cc but at almost $400 it isn't cheap but I might consider it. 

[CROSSBOLT]

The first thing in a situation as this is do a compression test. I predict the pressure will be very low. Then squirt some engine oil into the spark plug hole and do the test again. The valves will be leaking if the reading is the same. The piston/rings will be the problem if the reading is higher.

Karl

[mrbios]

The first thing in a situation as this is do a compression test. I predict the pressure will be very low. Then squirt some engine oil into the spark plug hole and do the test again. The valves will be leaking if the reading is the same. The piston/rings will be the problem if the reading is higher.

Karl

Good points, it is important to collect this information even if you have already made up your mind to do the big bore engine upgrade.  The goal is a story that is supported by the facts such as:

1. My scoot lost power (usually this happens slowly over time and miles, but it could be suddenly).
2. Started to smoke and I saw a drop in gas mileage [good to check mpg every fill up as this can be an early warning of engine problems]
3. I did a compression test and got 110psi and the manual / other owners said it should be at least 140psi [My manual says 180 to 200psi? but I only measured 140psi and many owners report the same].
4. I put a squirt of oil and either the numbers (valves not sealing) jumped or stayed the same (rings / head gasket).

But if you do a compression test and the numbers are excellent then you may a totally different problem - electrical or fuel that will carry over to the new engine. 

What you don't want: read the begin of the thread by Wolfman1
http://buggynews.com/gy6-150cc-loss-of-compression-after-storage-t15258.html

"I did all of this because I thought I had a fuel or spark problem; but to my dismay, it turns out that I have little to no compression."

This site suggests 140 to 150 psi is "very good":
http://www.jacksscootershop.com/tips.html

[Emil]

Thanks for the input. I will definitely start with compression testing and oil squirting and will post the results here.

-emil

[Emil]

Ok, so I got myself a compression tester and these are my findings:
Recommended pressure is 13kg/cm² ~ 185 psi
Let the scooter run for a few minutes to warm it a bit up.
Got 125 psi both electric and manual start.

Added some oil into the cylinder and got 130psi. Thought the little difference must be coincidence and decided to add a bit more oil.
Then, with about 1ml oil total I got 125psi again.

Conclusion for now is that it's the valves but I might be able to run another test with pumping in compressed air.

Assuming that it is the valves, what do you recommend I do next, just replacing the valve inlets?
Here is a diagram with the engine parts: https://kymcopartsonline.com/catalog/search_diagram_detail.php?s_fk_manufacturers_id=21&s_fk_model_year_id=1&s_fk_scooter_model_id=1&s_parts_diagram_id=6

Also - to get back to the big bore idea- would the valve work with OEM parts be easier than putting in a big bore kit?
I'd love the extra power but have limited time, and reliability is super important to me.

Thanks,
emil

[Emil]

Did adjust the valves today. They where pretty tight - recommended distance= 0.12mm but couldn't fit 0.10mm gauge in between.
Tested again, but with same result (130psi, cold engine). Well, maybe better than before because tested with cold engine, but still ways off the required 185psi.

Then I started the engine without seat etc. and heard a bit of clicking that seemed to be coming from the valves. Is this normal? I never started the motor without cover.

Anyway, next step will be new valve stems and seals. Too bad, was silently hoping the valve clearance adjustment would do the job.

Will keep you posted...

-e

[mrbios]

Then I started the engine without seat etc. and heard a bit of clicking that seemed to be coming from the valves. Is this normal? ...

Valve adjustments rarely would have much effect on compression.  Especially if they are on the tight side adjusting them could reduce compression (slightly).

Valves should not make a ticking noise.  Mine did after I adjusted them at 10,400 miles (first time being adjusted) because I mixed up metric and SAE (inches).  The instructions say 0.10mm for both intake and exhaust but my set is in inches (SAE). 

0.10mm =  0.004 inches

Your Agility 125cc looks like it is 0.12mm which would be: 0.0047 rounding to:  0.005"


The next day I readjusted them using the tiny tiny tiny 0.004" blade and was extra careful and retested AFTER tightening the lock nut.  No more ticking and no problems.  Last July I adjusted my valves again at 17,218 miles using the correct 0.004" blade and had no ticking noise. Currently, I'm just over 19K miles and the motor runs great and thats with lots of WOT on the highway to keep up with traffic that is always going too fast.

[blue]

check all your seals.makevsure nom leaks there...........

[Emil]

@mrbios: The metric values are printed on my feeler gauge. Only problem: there is 0.10mm and then next 0.13mm, so I decided to measure with 0.13mm, but very tight.

@blue: How do I know if the valves leak? There was oil under the cylinder head cover, but not to the point that it dripped on the floor.