RG150 vs RM125

[samwalkley]

Hey does anyone know if a RM125 reed block fits into a RG150?

Apparently the RG engine is real similar to the RM (just bored out i guess...) and i'm keen to upgrade my reeds...

[Sketchy_Racer]

Nah they're not at all similar in terms of motors. the only real thing they have in common is that they're powervalved two strokes.

Why do you want to upgrade your reeds?

[samwalkley]

wow, I didn't know the engines were completely different. I got told years ago that the RG was based off the RM... guess I look like an idiot...

Well so far I've D-bored the carby and opened up the airbox to allow more flow - had major issues with that until I re-jetted it, but now it's fine. Can't remember what the final jet size was but I think I roughly quadrupled the jet size. Anything below that and it was starving for fuel in the power-band...

So am keen to upgrade the reeds to newer technology in a bid to improve throttle response and overall flow. I've had the expansion chamber cut open and all the baffles cut out, and bolted on an arrow exhaust to help the flow exit, now I'm trying to improve the flow in. Oh, had the ports cleaned up and opened a little too.

Do you reckon it's a wasted effort trying to find a bolt on replacement reed block? I know Boyesen do two-stage reed petals for the RG but am interested to know if I can get a Rad valve and modify the manifold on it, or if there's a V-force that fits off the shelf...

Any ideas?

[Sketchy_Racer]

Oh ok, No I thought that you had just decided that you wanted new reed valves for the sake of it, with no other mods, but that list is fairly decent.

I can't say I know what reed valves would fit, And i highly doubt you'll be able to make another reed cage fit without some decent modification, but in the saying that, i'd still have a look around.

Oh biggest mod with the RG which makes a huge difference to the power they make, have you got the power valves timed correctly?

[samwalkley]

Yeah I thought that might be the case - I can see I'm gonna have to modify a Rad valve to make one fit. It could be a big waste of money if it doesn't work... but then it again it'll be a lot of fun trying...

As for the power valves all i've done is set them up in accordance with the manual, which was basically adjusting the cables. Is there something else I should be doing to set them up properly? I know they get dirty, and they are due for a clean out...

My biggest concern with the bike is that I used to have another one years ago (it got written off...) and it seemed to rev a lot higher then the one I've got now. This one doesn't rev much over 11500 in the higher gears and my old one revved right into redline in every gear. That's the main reason I've been trying to improve the flow - i figured it mustn't be getting enough fuel at high revs (i.e. main jet was too small) so I started at the carby and everything has kinda snowballed from there... a lot of fun tho...

Any idea why it might not have power right up to the red line? Are my expectations just a little too much for the small engine?

[Sketchy_Racer]

Normally lack of top end revs on a two stroke are caused by being to rich. A rich motor will seem to go ok but not rev out, where as a lean motor will rev to the moon but not really make a great deal of power.

As for the power valves, you want to take your chamber off and using the test wire (the loose one around your batter) earth that and it will open the valves. When they're open they should be dead flush with the profile of the port. if not, adjust the cables untill they are.

Keep it up with the modding, they're fun as bikes!

[samwalkley]

Thanks sketchy,

I'll have a think about the bike being too rich and look over the jetting again - maybe I just need to start to tweak the carb a bit now.

Didn't even think about doing what you said about the powervalves, but it makes so much sense. Thanks heaps for that. I need to replace piston etc soon so will prob have a look then when I've got it apart

Thanks heaps for all your help, really appreciated

[F5 Dave]

As far as the RM goes do you realise that they have been making them for 30 years? and being a competition bike every year is different. As far as the reeds go, until the bike is considerable modified (like different design pipe &/or higher rev range) the stock reeds are likely best if in good nick.
Early RGV carb will fit on easily. But if the bike isn't jetted properly it will be poos if too rich, or seize if too lean.

Those powervalves need regular service of they seize or drop in to piston. Take out & clean/inspect before too late. Do a search here & there should be heaps of info. If you need a good tuner in PN then Pete Sales at Total will be the man, but he does charge what he is worth so don't waste his time if penniless.