RM125 big bore.

[motomaniac]

Thanks all, lots of info there. Will keep you posted on the progress. Do you mean Husky 390 engine Brent?
Cheers,
K

Yer husky Mick .
I wouldnt go too big on the overbore ,those things are the best 125 motor of the time and are quick enough in standard trim to win any pre 78 race.I'd do the C specs , 2mm bigger Mik , pipe,reeds, shave head and maybe an A piston.

[oldyzman]

Lozza, I would just run caltex 98 at somewhere near std RMP and RM125B ignition, Just really chasing better low and mid range. I was considering trying for 1.2mm squish and 10cc volume, the exhaust port is std.
Brett

[bigk]

The 390 engine was spare until last week Brent, when I decided to build one in a '77 chassis for pre '78 next season. That '80 model 390 I had last season was unreal and still my favorite so far.
Cheers,
K

[motomaniac]

Did that 80 model actually race yet?

[oldyzman]

Hey K,
I think nifty put a PE175motor in an RM125A

[bigk]

I raced it a few times last season Brent, Barabool, Ravenswood & Mirboo North. The guy I sold it to never rode it and just traded it back on a 2010 Husaberg 390. I have sold it to a local vmx'er and you see it in action at Barabool next week. A PE 175 engine is too easy Brett.
Cheers,
K

[Ted]

Hello Suzuki guru's,
I have decided to build a big bore RM125B for a colleague to race pre '78 all powers just for the exercise, but mainly to use up some of the spares I have. We have everything pretty much soughted and while I don't particularly want to divulge exactly what we're doing, I wouldn't mind some leads towards RM specific porting specs. Any leads much appreciated.
Cheers,
K

How did this go? What were the results?

[oldfart]

Teddles, you getting nervous....          Pst -  reliability is the key word   

[Ted]

Nervous.....pfffft. I'm good to go right now

Was just interested if and what was done.

[shelpi]

I agree C specs carb and pipe, the main thing to do is suspension, my RM125B is pretty much a stock motor and yet it will hole shot and punches above its weight, the only way we can go faster is get the power to ground and hit and land off jumps harder   oh and get the gearing right, the only time I ran out of engine was when we rocked up, track changed huge long straight and we needed about a 8 speed box, and bugger that time I didnt take a larger front sprocket

[Davey Crocket]

Bring it up to Conondale next August and well see how it performs, if your lucky you might take home the 1K first prize....you will need to find another 10 horsepower though.

[Ted]

I agree C specs carb and pipe, the main thing to do is suspension, my RM125B is pretty much a stock motor and yet it will hole shot and punches above its weight, the only way we can go faster is get the power to ground and hit and land off jumps harder   oh and get the gearing right, the only time I ran out of engine was when we rocked up, track changed huge long straight and we needed about a 8 speed box, and bugger that time I didnt take a larger front sprocket

What suspension changes did you find worked for your bike?

Cheers

[oldfart]

Yep squeeze as much horse power out of it that you can  and put a young gun on it to boot ...more than likely it will be parked up after race one ;
meanwhile  my stock as a rock shitter will still be circulating after round 3  

[Davey Crocket]

We'll see.....lol.....

[shelpi]

I agree C specs carb and pipe, the main thing to do is suspension, my RM125B is pretty much a stock motor and yet it will hole shot and punches above its weight, the only way we can go faster is get the power to ground and hit and land off jumps harder   oh and get the gearing right, the only time I ran out of engine was when we rocked up, track changed huge long straight and we needed about a 8 speed box, and bugger that time I didnt take a larger front sprocket

What suspension changes did you find worked for your bike?

Cheers

forks,  spring rate, oil wieght, oil volume (oil level) to suit your body wieght and track (see the guru's plenty of new stuff to stick in them) for me I dont use any air pressure 0 and let it out after a race
rear shocks, spring rate, compresion, rebound on your prefered brand (just make sure they are of the best on offer)set to suit your body weight and twig a little to suit the track
tyres, select the best ones that suit you, I prefer something that starts letting go in a controled manner rather than plenty of grip right up to the end and then let go, so tyre pressure is important
gearing, to get it rolling along without bogging down or screaming its head off, take a few front sprockets
I know it sounds like a lot of mucking around but you will find its not so bad especialy if your riding the same tracks and keep notes, if your not getting pounded and hanging onto a twitchy machine thats bottoming out or smacking you in the arse or wanting to slide out , then you can concentrate on ringing its neck