RG125F 1994 (is that a bucket?) issues

[marlow]

Have new running problems again now. Today I installed a slightly smaller pilot, there's 3 different sizes across all RG125F models, 27.5, 25 and 17.5. Mine was 27.5 and seeming rich down low so I got a 25. Doesn't seem to have done much but I haven't had chance to set it up air screw/idle speed wise while at running temp. I've been too busy trying to figure out why I was getting splutters all over the place and power was shite. I guess 6 miles into a new piston you shouldn't get optimal performance, but anyways, figuring it may now be too rich I dropped the 240 MJ down to a 230 (at same time as pilot change) and a 9k splutter cleared nicely off. However the initial terrible running at high revs problem which was solved with a new plug...is back with a vengeance Thinking perhaps another dud plug I've swapped for 2 other brand ones, this time no difference. When I had this problem before it wouldn't occur too much in 1st and 2nd, but it did in longer gears. Well now it's the direct opposite!! wtf? I nail it in first and it nose dives at 11ish with a mad splutter refusing to rev anymore, but in 2nd and 3rd it pulls to higher with no problem.

Thinking that maybe 230 MJ is still too rich and causing this madness, I did an attempt at a plug run about 30 miles into the break in. I'm not experienced with plug chops so I'm wondering if I nailed it long enough to get the colour change from mid range point? Basically I nailed it through 2nd and 3rd (where it didn't splutter at all) so probably for around 6-8 seconds I dunno, before killing the switch at around 11,500rpm, and then there was a touch of dethrottle before I pulled clutch in. Well this is how it looks


Well that doesn't look rich enough to be causing this random 10-11k spazzing again. sigh never ends

[F5 Dave]

OK move with caution. First things first. Jets on a slide carb, unlike a cv should be considered on a throttle position perspective. Not revs. Write that down on a piece of paper and bring it out before making any changes as this will trip you up again and again.
I must apologize as I am too lazy to read back the thread (or correct the freaking autocorrect that insists i want to spell using z)

but in no particular order;
Assume foam filter? Clean actually std foam not replacement with unsuitable foam and not drowning in engine oil. (Not that I've ever done this). . .
Plug cap measures <6k or swapped as a trial.
Ign coil but less likely. . . Unless it is a combined cdi/coil like the RG50s which were prone to failing gradually.
Muffler not collapsed or clogged in oil.

Most roadbikes should be fine on std jets. Then you adjust. Fix the problem and it seizes. Course you have the restricted bike settings in uk vs unrestricted.

Be aware that as you bomb along close the throttle and go down the gears from a decent speed, the engine is surviving fed by the pilot jet at high revs for quite some time.

[marlow]

Thanks for the info.

Filter is all standard, foam, used to be oily but has dried out a bit now. Ideally would in the long term like it set up without the lid as that gets the biggest induction roar possible, but not sure if that's practical.

Not sure what plug cap <6k means but I haven't done any electrical testing as yet. How's best to go about that?

Yh the reason I'm having to change from standard jetting is cuz of the brand new Nikkon pipe it has. But as stated earlier, I've had to lean right off on the needle side hence also getting a smaller pilot. When initially starting the new engine with all standard carb settings, it refused to tickover with air screw fully out and idle screw fully in. Only leaning the needle to the max got it to tickover. But it seems at the higher revving range a richer than standard main is needed. I've still not had anyone confirm that yes it's very possible an exhaust change can cuz a richening at one end of the scale and a leaning at the other.

[TZ350]

Not sure what plug cap <6k means but I haven't done any electrical testing as yet. How's best to go about that?

<6k is short hand for "less than 6,000 Ohms resistance."

The the reason I'm having to change from standard jetting is cuz of the brand new Nikkon pipe it has. But as stated earlier, I've had to lean right off on the needle side hence also getting a smaller pilot. When initially starting the new engine with all standard carb settings, it refused to tickover with air screw fully out and idle screw fully in. Only leaning the needle to the max got it to tickover. But it seems at the higher revving range a richer than standard main is needed. I've still not had anyone confirm that yes it's very possible an exhaust change can cuz a richening at one end of the scale and a leaning at the other.

No surprises that the new pipe requires different jetting. It sucks in a different way so needs a different fuel curve.

It has been my experience with the dyno, that if you lean the needle significantly you may very well have to richen the main and vica versa.



All the jets in a carb overlap some what. So leaning one may certainly mean having to richen another.

[TZ350]

Well that doesn't look rich enough to be causing this random 10-11k spazzing again. sigh never ends

Maybe not so rich that its wetting the plug and putting the fire out, but it could be lean. Maybe not so lean that its detonating but lean enough that the motor struggles to make power.

The brown is just burnt on stain from the oil your using and fuel additives.

Links to pages that have a post or two about the proper way to read plugs for mixture strength. You will have to skim down the page to find the relevant post.

https://www.kiwibiker.co.nz/forums/s...post1130773139

https://www.kiwibiker.co.nz/forums/s...post1130454090

https://www.kiwibiker.co.nz/forums/s...post1130461646

https://www.kiwibiker.co.nz/forums/s...post1130463201

https://www.kiwibiker.co.nz/forums/s...post1130464308

[F5 Dave]

Yeah I was typing that on a phone. Try washing the filter in petrol, drying thoroughly and go for a testride. Then recoil it with air filter oil, don't go crazy. Engine oil may block it up enough to be a problem. I once replaced a dirty looking filter with some foam I found and oiled it. Ran dreadful. 17yr old me felt really foolish when the mechanic found it.

[marlow]

Thanks for all the links TZR350 very helpful

Then recoil it with air filter oil, don't go crazy. Engine oil may block it up enough to be a problem. I once replaced a dirty looking filter with some foam I found and oiled it. Ran dreadful. 17yr old me felt really foolish when the mechanic found it.

Do you not put 2-stroke oil on filter foam then?

Well I've not altered anything of late other than tweaking the PV a mm or two one way and another, as it really is quite an imprecise thing on these bikes. Quite confident I've go it down now though.

I'm wondering though if another issue may be causing fueling irregalarities. And that is the amount it smokes. My bike does smoke more than all my mates 125's, quite alot when cold, then ok once warm, then blasts pretty big clouds out when giving a handful even when hot. I think I read the more 2-stroke oil in the mix then the leaner the fuel mix is? But that would make things even more confusing becuz I've had to lean off both needle and pilot as it is. And sa things stand, idle speed still rises at 3 turns out on the air screw indicating even further leaning of the pilot jet is required?

Regardless of that, remember the picture of all the stodge my powervalve breather is kicking out? Well it's still the same. I obviously have the pump set correctly according to the alignment marks, but the method the manual uses to detemrine just how much oil I'm getting is a confusing one I don't understand.



I don't know what a "special tool" is and I don't get how you run the engine so the oil is pumping into somewhere else, surely then the engine isn't getting any oil?
Are there any simpler methods to determine if my oil pump is pumping too much oil through?

[FastFred]

"special device" my bet is they are talking about a small measuring cylinder. At 3-3.6ml (ml=cc) a 10cc disposable plastic syringe would be good enough. The oil pump sucks out of the measuring cylinder and continues to pump into the motor.

[marlow]

Ah right I get it now, I was thinking of it back to front

Maybe not so rich that its wetting the plug and putting the fire out, but it could be lean. Maybe not so lean that its detonating but lean enough that the motor struggles to make power.

Also regarding this, if leaner is going to lose power then why was the bike an aboslute rocket ship with 180 MJ? Plug pictured is with a 230 and power feels almost halved lol. Ok probably overly exagerrated but I'd take a wild stab that as much as 5-6 ponies have buggered off now. Almost feels as though it's around one pony per jet size or something. 5 jet sizes bigger, 5 ponies difference, but obviously won't blow up.

[TZ350]

Also regarding this, if leaner is going to lose power then why was the bike an aboslute rocket ship with 180 MJ? Plug pictured is with a 230 and power feels almost halved lol. Ok probably overly exagerrated but I'd take a wild stab that as much as 5-6 ponies have buggered off now.

It is my experience that those ponies have attention deficit syndrome because some of them are always buggering off, happens to us a lot too. ....

180 MJ works 230 is leaner, it can easily happen because a cheap Chinese 230 might very possibly flow less than a genuine 180 MJ jet.

Anyway different manufacturers can have different ideas about what 230 actually means.

Not saying this is the problem, only it is just another issue in the mix to consider.

When setting up, I always try to use jets from the same manufacturer if I can.

[jasonu]

\ Try washing the filter in petrol,.

Tightarse, buy some proper filter cleaner.

[Drew]

Tightarse, buy some proper filter cleaner.

Why? It's no better than petrol for the task.

[marlow]

Well more hilarity has ensued for the unluckiest biker in history Just got back from the holiday all this 125 bollox had been geared up for...on a recovery truck!

The 2.5hr ride up was great, with nothing but rain forecast for our 3 day duration, it was in fact quite the opposite, thus proving the rumour the weather cannot be predicted at all, it's all just another scam. During the time there we had one little jolly out, a 20 mile round trip or so, and over the course of my thrashing, it seemed power was coming oln stronger by the day, maybe as the piston was running in more? Then what became more and more prevalent was clutch slip, to the point where I couldn't give it any hardly anywhere. If I managed to keep it stable up to 10krpm it would suddenly slip like a lunatic at 11krpm, which funnily enough I was quite happy about cuz it meant an even further power boost was coming in at this point.

Then today on the final day, with the skies clear and promising a really good run home of swapping and switching positions from front to back of our 4 bike convoy, seeing off my buds' power and top speed with consulate ease should I choose to do so, went typically up in smoke as I started the bike this morning. On the ubtton as usual, ticked over for 5 seconds and then just conked. Never to start again. No spark, but coil fine. Got a pocket tester, resistance good on pick up wire, other coil wires, earths etc blah blah, then took off the CDI and tested the prongs on it according to these manual steps


and got zero reading on all bar one or two connections. Also on opening the back of the CDI to reveal all the circuitry, it had a weird smell inside. RAC recovery guy confirmed with his multimeter and also said it smells like something's burned out.

You just couldn't write it. Why does my CDI just randomly blow up at 1,000 revs idle out of the blue?? Guess I should be thankful it was at the holiday park and not the side of the road, especially as total rocovery arrival took 5 hours!!

[marlow]

People saying no CDI readings is normal and every circuit can't blow at same time. kden

Not sure how to go about full on testing. Manual talks about ohms resistance everywhere, all forums talk about AC/DC testing while cranking with so and so plugged/not plugged in. Feel like just buying a stator (£35 on ebay compared to £50 for the CDI). I can get the CDI tested by a friend of a friend who's a student in electronics but my gut tells me it's not CDI (despite it smelling like a strange kinda shit). Whatever it is must've been responsible for my first-gear-only-10krpm-splutter. Mods can stick this thread in the idiot humour section of you like.

[Drew]

A CDI won't burn for no reason. But getting a lot of AC current isn't 'no reason'. So you need to check your stator (it's easy, there should be no continuity to ground from any of the three phases), and have the regulator/rectifier checked.

Then you will still need a CDI to make it run again.