RG150 short on power

[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

[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

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?