RG150 short on power

[Sharft 6]

I recently bought an RG150 because I had already test ridden someone else's and I thought the extra power would keep me entertained for a while.

Unfortunatly though, mine is really sturggling to get to 100km/h.

Petrol
It came with very little fuel in the tank. It now has fresh (4day old) fuel.

Oil
It had an oil leek and very little oil in it when I got it. The oil leek is fixed now and the tank is full of fresh (about 3 weeks old) oil.

Battery
It came with a flat battery so I have replaced it with a brand new one.

Spark plug
I replaced the spark plug with a new one that happens to be colder. I think it prefers the old hotter one.

Power vavles
I have spent hours on the power valves because from what I've read, I thought this was by far the most likely problem.
The right power valve is somewhat 'flogged out' in the middle but I can guarantee the valves are fully actuating under the power of the pulley system. I did a test with the valves left as is vs stuck open. It accelerated a little faster when the valves are left as is. When the valves were stuck open, there was no kick of power in the high end. Instead, it ran out of puff at exactly the same way as it did before.
If I leave the bike in neutral and rev it up, I will see the pulley turning and notice the rpm increase when this happens. When it's under load, I don't think it has enough power to reach the power band. It's quite hard to see the pulley directly from the side while riding the bike, but from what I can see, the pulley doesn't move while riding.

Warming
It's quite hard to warm up but I got it to 1/8 on the temp guage for testing.

Carbretor
I opened it up to find the cleanest carbretor I've seen yet. And I've seen 3.

Cylinder
I did a dry compression test and it's blowing about 100-105psi. I have no idea what the compression should be though.
I'm about to open up the cylinder and clean off the carbon deposits.

Exhaust
I'm about to decoke the exhaust.
Either the expansion chamber is a strange shape or it has dents in strange places. Will take some pictures later and post them if necessary.

In case you're wondering why I haven't posted any RPM figures, it's because the rev counter doesn't work. I don't think I'll need it after the bike is fixed anyway.

I'd really like to have the bike ready for the trackday next weekend so if any of you have suggestions, please send them my way.

[Sharft 6]

Ok so I finished cleaning out the carb, exhaust, piston, and head then put it all back together again.

None of the above really required much cleaning so I had my doubts. (which were confirmed with no performance change later)

Then I filmed the power valve pulley while riding and noticed something that might be useful. Every time the valves open, there is a drastic power loss instead of a gain.

http://youtu.be/7mWgjDSl9U8

Any ideas what could be causing that?

[Ocean1]

I'd say it's hugely out of adjustment, but I don't know much about such things.

Good work so far, though, you'll get it in the end.

[Sharft 6]

I tested them while adjusted correctly to the marker but when I had the valve cover open, I noticed there was room to open them more. So I over adjusted them which seemed to make things slightly worse if anything.

Will try under adjusting them tomorrow and see what happens.

[Asher]

You would be best checking the adjustment by taking the chamber off and feeling the power valves by hand and using the grey wire test.
Compression sounds decent.

[Sharft 6]

by grey wire do you mean connect the yellow and white wire to the negative terminal on the battery?

Also, you say feel by hand. What should I be feeling for? The valves fully open with a tiny bit of play?

Cause I've already done that.

[iranana]

I don't know much about RGs but did you check your jetting while you had the carburettor open? Cause if it's still sputtering even with the valves open all the time, seems like it could be a carburettion issue. Someone might have messed with the jetting and muddled it up at some point... perhaps it's worth checking? Check the needle jet to make sure it's not worn and running rich too.

[Sharft 6]

I tried under adjusting the valves about 2mm but I didn't really notice much of a difference. I didn't want to adjust them any further because I'm not sure what part stops them from touching the piston.

The pilot jet is 20 and the main jet is 185. The air screw is 5/8 of a turn out.

The needle still looks symetrical so I think it's fine.

The RG150 is definatly the easiest of my bikes to start and one of them is eletric start, so that's saying something!

I think it runs ok too, until the power valves kick in.

[riffer]

Might be stupid question but you do have it all connected the right way around? As in the power valve is actually opening, and not closing? Not sure if you can do that, but with two cables connected to it, it seems a possibility.

[Sharft 6]

heh, i supose it would be a possibility with longer cables if you crossed them over. But no the vavles are definatly being pulled out when the pulley turns.

maybe I'm not using the word open and close how I should be. I mean open when the valve is being pulled out, creating more space in the exhaust.

[koba]

Make sure the battery is in good condition, you say the rev counter doesn't work - normal for a bad battery which will also stop it running well up top.

[Sharft 6]

Battery is 4 days old. It's also been charged.

[speeding_ant]

Unrelated, but quick tip for getting the RG nice and warm in our NZ climate: block off the front 1/3 of the radiator with aluminium plate or similar. They were made for Thailand climates, made a big difference for my old one a few years back. Never overheated, just got warm like it should.

Can't help with your problem though :innocent: Unless of course you haven't warmed it up properly before giving it a good fang.......

[eelracing]

The pulley in your youtube vid barely looks like it is turning...maybe 1/8th max.

Are you absolutely positive they are fully opening because it doesn't look it

[oyster]

Comp tests unfortunately are all a bit subjective. I have a special screw in version for rg's and i'm normally looking for 140-150psi. I had one recently, running ok but slow. It had 100psi. On inspection major seize damage to piston rings. If your piston looks in tidy order, ie not seize marks etc, it should go ok. A worn out one will be down a few hp, that means 150km'hr, rather than 160. A low comp one also usually revs out ok, but really misses out on the "roll on" drive from 9000 to 1100rpm.
Re power valves, to isolate your problem. Disconnect at the pulley and turn them wide open, wire in this position. Then start and run OK like this, but run pretty flat and rough from bout 3000 to 8000rpm. From 8000 up to red line they go like a bullet, as per normal one. If you do this and can't get it to go at the "top end", you have another problem. Very rare to have an RG with good comp, valves wide open and not go well at the top end.

Never heard of it, except on a KR150, but check free flow of chamber. The baffling/silencing inside may have come loose and run to the back, blocking things. Take off and shake it to test. Loose bits, big prob! Final place to look is crook carb/airbox. Swap out with one that works to trial. If you are in chch i can look at the bike, should get to prob ok if that helps

[Sharft 6]

Thanks for all the input. Covered lots in this thread.

I narrowed it down to three causes for my problem.
1. I'm mostly used to single cylinder 4 strokes.
2. Not having a rev counter compounds cause #1.
3. There seems to be 2 peaks of power and I was fooled by the first one.

What a noise it makes in the high end though! Now I want a 4 cylinder 2 stroke.

[Sharft 6]

Ok so I took it to a trackday today and I thought it was doing ok getting up to 140km/h on the straight.

Then I had a go on another RG150 which felt at least 2x more powerful than mine. it was very torqey below and very powerful up top. It just seemed to pull A LOT harder than mine throughout the entire rev range.

Last time I checked the cylinder wall looked and felt nice and smooth. I can't see anything obvious wrong with the carb. and yes valves are opening. Not so much in the video because I changed up just as they were opening because I was feeling the power drop off. I also did a test holding the valves open with my fingers and it ran the same as holding them open with the actuator.

I think it's time to take it to a mechanic :weep:

[haydes55]

Is the gearing standard?

[Sharft 6]

don't have a small socket and ratchet to take the front sprocket cover off.

Anyway it's in the shop now so we'll see how it goes.

[kennedyrd]

Hi there. If this is who I think it is then I feel obliged to try and help as it was my RG that made you buy one! First my track RG is a stock standard Street Stock legal motor so yours must definitely be sick. I had the same problem on my road RG after giving it to a shop to "degunge" the carb after sitting for 8 years. I wish I never had. That's what laziness gets you as it ran perfectly 8 years before! I looked everywhere and finally found they had left the power jet out completely! You don't mention it in your list of jets so I wondered if you don't have one so did not notice. It is the one at the bottom of the float bowl. I had a similar problem on an old X7 Suzuki I had. Check the foam filter element is the original and try running without it briefly if it looks "home made". Turned out they had made it from closed cell foam! I think you know where to find my work. Happy to help if you want.

They are a fantastic little bike and I enjoy it every bit as much as my more exotic GP bikes. Other mates who have raced GP 125's and 250's actually describe it as a mini GP bike and I have to agree!

[oyster]

yep I'd go along with kennedyrd. In that this bike has been fiddled with!
I've seen a few that have had airbox mods that completely screw them. Also common for people to forget to put the little black hose on the carb, the one from the power jet servo. I've even seen it connected to the carb vent instead! The bike runs, but pretty badly. Yes, a thorough check re std settings.

[Sharft 6]

I was thinking on the way home that I should have asked to borrow your carb, especially because you had to take it out for cleaning anyway.

I have tried running without the air filter in and I think it only made a little more noise if anything.

The missing power jet sounds possible though. It never occurred to me that a carb could have 3 jets. I called the mechanic to make sure he checks the power jet but it sounds like you already figured out who I sent it to!

I was wondering what the extra tube attached to the carb was for. It doesn't look out of place where it's attached though, at least not to me.

Fingers crossed for a missing jet or something. It must be getting close to a solution by now.

[Katman]

Don't know if anyone has suggested it but have you checked the reed valves?

[Sharft 6]

The mechanic didn't find any problems with it.

good suggestion but the reed valves have been checked and are ok.

I took it over to kennedyrd who says it does feel a bit flat. We tested the compression of both bikes (which was pretty much identical), disconnected the power solenoid, and swapped exhausts but it's too risky to test in town.

It didn't appear to make much of a difference when I got around to testing it. Next I played around with the carb needle height and fuel mixture. It felt as though I was having some success and some failure. But without a rev counter and no speedometer, my measurements were becoming very subjective.

There is a resistor in a circuit board that connects to the positive end of the rev counter. The resistor looks burnt and it's surroundings are scorched so hopefully that's all that needs replacing to get the rev counter working. Then I'll finally have a better picture of what's going on.

[Ocean1]

The mechanic didn't find any problems with it.

good suggestion but the reed valves have been checked and are ok.

I took it over to kennedyrd who says it does feel a bit flat. We tested the compression of both bikes (which was pretty much identical), disconnected the power solenoid, and swapped exhausts but it's too risky to test in town.

It didn't appear to make much of a difference when I got around to testing it. Next I played around with the carb needle height and fuel mixture. It felt as though I was having some success and some failure. But without a rev counter and no speedometer, my measurements were becoming very subjective.

There is a resistor in a circuit board that connects to the positive end of the rev counter. The resistor looks burnt and it's surroundings are scorched so hopefully that's all that needs replacing to get the rev counter working. Then I'll finally have a better picture of what's going on.

Great work so far dude, I love to see stickability.

[Sharft 6]

I just managed to make out the rating for the old resistor by holding it on the right angle in the sun. If anyone elses's is too burnt to see, it's a 33 ohm 2w resistor.

Anyway I have replaced it and now the rev counter appears to be working agian. Time for carb tuning :)

[Sharft 6]

Nope. Stock carb settings work best.

The bike was crashed on the right hand side. Maybe the bike was left on it's side with wide open throttle until the fuel ran out. That would best explain how the resistor burnt out.

Found out yesterday that the power begins at 8,500 and it doesn't rev past 12,000. I think I'll just ride it how it is. Still plenty to learn even though it accelerates slower than and has the same top speed as the cbf.

[Akzle]

RG150 short on power:
its missing a v

[speeding_ant]

Depends, the RG150 had much more power than the RGV150. Add another 100cc and another cylinder, then you're talking..

[FruitLooPs]

My RG150 was pretty flat feeling compared to one with lower km's when I tried them both on track, still had a ball with it though anyhow :niceone:

I know that if you had custom powervalves it might struggle in the midrange, but it should pull the same up top. My bikes cylinder was old enough that the powervalve ports had worn to the point it needed a custom set turned on a lathe to get a snug fit and not rattle the stems to breaking point in short order - they were one piece though instead of three, so they didn't transition through the revs as seamlessly. Fine down low, tapers off in the middle roll when the valves would be transitioning to open, wait for the lag as it goes through and it picks up and hauls again - much more fun than a 4stroke in that capacity.

Unlikely you've got them, Oyster made mine and that was cos the bike had nearly 50,000 on the clock - you've taken them out, cleaned and they're 100% yeah, slide as they should?

[Sharft 6]

my power valves are 3 piece and slide nicely as long as I don't do those two lower screws up too much. I even cut up a washer and added it in so that I could do up the two lower screws securly without pinching the valves.

TBH the power band isn't particularly amazing anyway. It will allow me to sit up and still pick up speed where as in the mid range I need to move to a tucked position or change down a gear, otherwise I won't get past about 80 or 90KM/h. Infact even with the power band and tucking in, there is an even higher gear that the bike doesn't have enough power to drive.

[Sharft 6]

Many many thanks to billy from racefairings.co.nz for telling me to check the power valves are not upside down. Only took 4 months to figure that out :-)

Now they're up the right way, the bike has a mountain of power!

[speeding_ant]

Many many thanks to billy from racefairings.co.nz for telling me to check the power valves are not upside down. Only took 4 months to figure that out :-)

Now they're up the right way, the bike has a mountain of power!

Classic :laugh:

[matrox02]

I recently bought an RG150 because I had already test ridden someone else's and I thought the extra power would keep me entertained for a while.

Unfortunatly though, mine is really sturggling to get to 100km/h.

Petrol
It came with very little fuel in the tank. It now has fresh (4day old) fuel.

Oil
It had an oil leek and very little oil in it when I got it. The oil leek is fixed now and the tank is full of fresh (about 3 weeks old) oil.

Battery
It came with a flat battery so I have replaced it with a brand new one.

Spark plug
I replaced the spark plug with a new one that happens to be colder. I think it prefers the old hotter one.

Power vavles
I have spent hours on the power valves because from what I've read, I thought this was by far the most likely problem.
The right power valve is somewhat 'flogged out' in the middle but I can guarantee the valves are fully actuating under the power of the pulley system. I did a test with the valves left as is vs stuck open. It accelerated a little faster when the valves are left as is. When the valves were stuck open, there was no kick of power in the high end. Instead, it ran out of puff at exactly the same way as it did before.
If I leave the bike in neutral and rev it up, I will see the pulley turning and notice the rpm increase when this happens. When it's under load, I don't think it has enough power to reach the power band. It's quite hard to see the pulley directly from the side while riding the bike, but from what I can see, the pulley doesn't move while riding.

Warming
It's quite hard to warm up but I got it to 1/8 on the temp guage for testing.

Carbretor
I opened it up to find the cleanest carbretor I've seen yet. And I've seen 3.

Cylinder
I did a dry compression test and it's blowing about 100-105psi. I have no idea what the compression should be though.
I'm about to open up the cylinder and clean off the carbon deposits.

Exhaust
I'm about to decoke the exhaust.
Either the expansion chamber is a strange shape or it has dents in strange places. Will take some pictures later and post them if necessary.

In case you're wondering why I haven't posted any RPM figures, it's because the rev counter doesn't work. I don't think I'll need it after the bike is fixed anyway.

I'd really like to have the bike ready for the trackday next weekend so if any of you have suggestions, please send them my way.


wow only 100 PSi? that could be the cause, My '90 rm250 sits around 160 psi and there arnt many other bikes that like any less than 120 psi on the poor side

[Sharft 6]

Don't worry it's pulling very hard now. Getting to around 160Km/h at manfield and still gaining speed so I'm not complaining.

it's around 105psi on my compression tester and about 90psi on another. I think the person who said compression tests are pretty subjective is right.