RG150 bogging down

**anthraxnz** · 7th March 2014, 18:56

Hi guys,

I have an 98 RG150 (2 stroke), at the moment it seems to be bogging down between 500 - 3000ish RPM. I checked the plug and it seems alright so i might try replacing it this weekend to see if the problem goes away.

Symptoms:
taking off the bike tends to bog down quite a bit to the point it almost stalls unless i rev it up to over 3k and slip the clutch. when i have it in the driveway, if i try to snap the throttle open and closed you can tell there is something going on there that's not normal. I don't know much about 2 stroke as i have a 4 stroke...

The bike had a digital dash in it when we got it and the person who installed it didn't wrap the wires so they chaffed through, one of these wires was for power to the speedo and the other was for reading the RPM off the coil.

I'm thinking that the grounding of the ignition wires caused some damage to the ignition coil otherwise I'm thinking the CDI is on it's way out.

This bike has an aftermarket Arrow exhaust on it and from what i have read, exhaust is super important to 2 strokes, that being the expansion chamber but im not sure about the muffler.

I had a similar issue with my 09 CBR125R where it would cut out and bog down when being rev'd so I'm thinking its the coil.

Can anyone put me on the right path?

Cheers!

**FJRider** · 7th March 2014, 19:03

Originally Posted by anthraxnz

Hi guys,

I have an 98 RG150 (2 stroke), at the moment it seems to be bogging down between 500 - 3000ish RPM. I checked the plug and it seems alright so i might try replacing it this weekend to see if the problem goes away.

Cheers!

It's a 2-stroke. Under 3000 rpm nothing happens. Nothing unusual there ..

Trust me

keep the rev's up ... and you'll be fine.

**Asher** · 7th March 2014, 20:51

What he said.
You want to be riding it at much higher rpms than 3000, in fact its probably causing it to foul up.
2 strokes prefer to be revved, dont be scared to take it to the red line.

**anthraxnz** · 7th March 2014, 21:45

really?

It seems on taking off to just bog down making it harder to get going...

**speights_bud** · 8th March 2014, 01:20

I assume that the bike isn't new (to you) and that this is a 'new issue' that hasn't been present when previously riding?

RG150's need a good battery to run the powervalve servo in them, lots of people have tried taking them out when setting up to race them.

As you said about the electrics, test what voltage the battery has and see how that goes, it will at least tell you if the battery is getting charged by the engine.

Also a good close up photo of the spark plug might help.

I wouldn't be terribly concerned about the 'muffler' part of the ex system being changed.

**avgas** · 8th March 2014, 08:39

About 9,000 rpm is where you want to be on an RG150. Anything less than that and you have about 5hp at the rear wheel.

**anthraxnz** · 8th March 2014, 09:02

Originally Posted by speights_bud

I assume that the bike isn't new (to you) and that this is a 'new issue' that hasn't been present when previously riding?

RG150's need a good battery to run the powervalve servo in them, lots of people have tried taking them out when setting up to race them.

As you said about the electrics, test what voltage the battery has and see how that goes, it will at least tell you if the battery is getting charged by the engine.

Also a good close up photo of the spark plug might help.

I wouldn't be terribly concerned about the 'muffler' part of the ex system being changed.

thanks for the useful advice! I replaced the spark plug and added 5 liters of 98 which seems to have fixed the problem. The bike isn't mine, my mate (who has no licence so can't ride it) bought it a couple of weeks ago and i've been fixing various bits and pieces on it so it may have just had old fuel with crap in it. We'll put some of that fuel cleaner\carb cleaner stuff through it and see how she goes after that.

Thanks to everyone else about how to ride a 2 stroke

i think i'll stick with 4 strokes personally. wouldn't mind a NSR250 for weekend thrashes though!

**speights_bud** · 8th March 2014, 09:13

Originally Posted by anthraxnz

thanks for the useful advice! I replaced the spark plug and added 5 liters of 98 which seems to have fixed the problem. The bike isn't mine, my mate (who has no licence so can't ride it) bought it a couple of weeks ago and i've been fixing various bits and pieces on it so it may have just had old fuel with crap in it. We'll put some of that fuel cleaner\carb cleaner stuff through it and see how she goes after that.

Thanks to everyone else about how to ride a 2 stroke

i think i'll stick with 4 strokes personally. wouldn't mind a NSR250 for weekend thrashes though!

Choice, got a pic of the old plug?

**oyster** · 8th March 2014, 15:31

I guess I'll offend a few people here that really want to help. but most of what is said so far is rubbish. A good RG does not foul plugs, no matter what you do. A good rg will pull like a train from 3000rpm. You can ride them all day below the power valve opening point (around 8000rpm) and the performance is plenty for touring around and commuting. This does not hurt them at all. I rode one through the Rainbow road to blenheim, a full day. The next day bout 10 hrs in the saddle, the sounds and the Molesworth. never once above 7000rpm. bike went (and still is ) perfect. Not on topic, but the comment about remove the servo indicates the bike, if racing, is a cheater. Avoid!
Check fuel delivery (good flow) and all jets in the carb. Especially the pilot, prone to partial blocking and giving your exact symptoms. Exhaust. Use only the std exhaust. years ago I prepped a lot of rg's for racing. A few I bought from the North Island had their chambers and mufflers modified, so were no good for racing. My road bike ended up with one of these. Hopeless. I tried a muffler of RGv 250. Nothing other than the mount bracket seemed different. The bike had flat spots and misfire so bad it was barely rideable. Std muffler, perfect. Also check airbox is std and complete. I've seen mods to airboxes (cheating again in racing) that have made them run like absolute dogs. Summary: get it standard, in good nick and maintained. Engine will be tractable, no fuss, run sweet for a long time. Hope this helps. Sorry to disagree with you other guys.

**speights_bud** · 9th March 2014, 20:36

Originally Posted by oyster

I guess I'll offend a few people here that really want to help. but most of what is said so far is rubbish. A good RG does not foul plugs, no matter what you do. A good rg will pull like a train from 3000rpm. You can ride them all day below the power valve opening point (around 8000rpm) and the performance is plenty for touring around and commuting. This does not hurt them at all. I rode one through the Rainbow road to blenheim, a full day. The next day bout 10 hrs in the saddle, the sounds and the Molesworth. never once above 7000rpm. bike went (and still is ) perfect. Not on topic, but the comment about remove the servo indicates the bike, if racing, is a cheater. Avoid!
Check fuel delivery (good flow) and all jets in the carb. Especially the pilot, prone to partial blocking and giving your exact symptoms. Exhaust. Use only the std exhaust. years ago I prepped a lot of rg's for racing. A few I bought from the North Island had their chambers and mufflers modified, so were no good for racing. My road bike ended up with one of these. Hopeless. I tried a muffler of RGv 250. Nothing other than the mount bracket seemed different. The bike had flat spots and misfire so bad it was barely rideable. Std muffler, perfect. Also check airbox is std and complete. I've seen mods to airboxes (cheating again in racing) that have made them run like absolute dogs. Summary: get it standard, in good nick and maintained. Engine will be tractable, no fuss, run sweet for a long time. Hope this helps. Sorry to disagree with you other guys.

No offence taken here.

Perhaps I should have written more clearly (I just re-read my earlier post) what I was referring to was removing the battery (or worse a completely buggered battery) not removing the actual servo's. Because the Servo's and dash (tacho mostly) will not function properly without a good battery.

As you say a 'GOOD' RG should be capable of riding in the lower rev conditions all day. After all they were not designed as a race bike.
However if we were to see the plug and see its oily as buggery or something similar then that will indicate an oiling issue perhaps adjustment of the oiler etc etc. How the plug looks is one of the main indicators of whats going on inside and is a good way to help decide where to next.

If the Spark plug is rooted (physically damaged) then they will often run like shit down low and sort themselves out with a little bit of revs' as the engine produces more juice to fire through them. I ran 6 different plugs for my RG when I was racing, each session we changed to a new one. between meetings I cleaned them and kept one as a control. during one practice session the bike didnt feel right. all the coloration on the plug looked fine, but changing to a new plug fixed it on the spot. Plug #2 got binned and replaced after that. Probably overkill for a lot of people but we were in it for the season points. Otherwise we could have spent all day chasing a rouge plug....

Agree with the airbox mods, they tend to run like crap when someone has fiddled with them. Haven't tried changing to an aftermarket muffler on the RG's though, other 2T's I've worked with (Mostly NSR250's) have responded well to aftermarket cans, but tuning the carbs etc to the new expansion chambers and cans was required as expected.

As above strip and clean the carb thoroughly if it keeps giving you grief. The only race I didn't finish one winter series was due to a blocked jet

**anthraxnz** · 11th March 2014, 11:46

Originally Posted by speights_bud

Choice, got a pic of the old plug?

Finally got around to taking a photo.

**avgas** · 11th March 2014, 13:56

That plug isn't too bad actually. Looks like a bit or unburnt mix is all. No crusty stuff, no white/grey stuff. I really think you should still give it some more beans. You will be surprised what burns out.

Also oyster said about the exhaust - take it with a grain of salt if the exhaust looks standard.......so often I have opened one up to see its been changed or gutted. But I doubt the problem is that.

Put some 98 in the tank, some hi-vis oil (the Motul 8000 or whatever is great as a cleanout oil) in the res and really warm it up one day. If it should start running better, and ironically the exhaust will smoke a bit less than usual.

Out of interest how many k's has it done. They don't live long so you might be due and oil pump soon. Trust me when I say you are better off replacing the pump. Big end vaporized pretty good.

And no oyster I don't feel offended. But you're wrong. Riding an RG below 9K it has respectable power............just as a hooker can earn a respectable coin at the supermaket checkout. But its not really their true calling.
You buy an RG to boot it. If not, you're not doing it justice. Plenty of other bikes out there to ride slowly, usually at a cheaper price.

**speights_bud** · 11th March 2014, 14:20

Originally Posted by anthraxnz

Finally got around to taking a photo.

Choice, as said above it doesn't look too bad, Also as a side note, it pays to run oil designed for injection and not "pre-mix only". There is quite a difference in their consistency and other properties. Just something to be aware of

**anthraxnz** · 11th March 2014, 20:31

thanks you guys. some really helpful stuff coming through

The bikes done something like 25k so it's not so young anymore. We believe it has been rebuilt at some point as the box came with a bunch of spare parts which included a used piston and a quote with a list of parts. Who actually knows if any of those made it into the bike lol...

The oil pump was something i would have never thought about checking up on. I'm guessing that's the oil pump which takes the 2 stroke oil from the tank on the side and delivers it to be mixed with the fuel? I'm comparing all 2 strokes to how my weed eaters design at the moment so bare with me...

I have noticed that the power valve servo unit is bolted only at 1 of its 2 points which seems strange, when i re-attached it the bike started and for a second then died and refused to start until i removed the second bolt again... any ideas on this one?