decisions decisions...what to do?

[DR]

Mario, my Clymer manual doesn't give rod clearances or other details except a crank width of 56mm (2.205inch)

[rocketfrog]

Doc, I have a pretty average RM100T Roller that you might be able to use, its in Newcastle area.

The Frame has a side cover bracket missing and there has been a dodgy weld repair to the lower engine cradle, the swing arm has a dodgy pivot bolt set-up and the rims are pretty much stuffed.

If this sounds too good to be true, then your welcome to it.

You will need a seat and a few miscellaneous bits to get it complete, I dont know when I will be up your way again, but I will keep you in mind if your keen.

[DR]

Sounds too good to be true alright keen as mustard I am, thank Jason! I have a little RM80 down that way at Mick's (Cooranbong). If nothing eventuates I may have to think about heading down to collect these treasures personally in the new year    

[monaro308]

Thanks Doc...looks like i have some homework to do to find the specs.
I measured the width and spacing between the crank webs before i pressed the pin out just in case.

Jason,i checked my RM100X cases and they are better than i thought.
I'll have to sit down and see how many parts are missing out of that engine and if its missing too many parts to be worth putting back together,i'll let you know about the other stuff.

What engine model year are you building?
I'm not sure how many parts of an 100X crosses over to the earlier RM100ABCNT.
cheers...Mario

[rocketfrog]

Mario, apart from the throttle and stickers the 100 T and X are virtually the same bike. Suzuki decided to fit a PE gear type throttle to the 100 in 81 but I dont suppose there was much point in going to floater or much of any up grade at all since the model was dropped by the following year. The writing must have been on the wall for the 100cc class.

On the weekend I took my young bloke out for a spin on his YZ100 and I think I had as much fun as he did. I cant wait to get the RM100 going, were going to have a vintage shoot out between the YZ100 G and the RM100 T.

If the RM is half the bike the Yamaha is it should be a treat, That lil' YZ hauls like a demon. I like the light switch performance of these little motors, they really howl when your on the pipe.

Our RM came with the STD 100 crank but a 125 barrel and head, surprisingly it ran, but not real well.
So after pulling the engine down, we found that the con rod was awfully floppy and the bearings were shot. I wont go right into it but you could say it was a can of worms. I bought a second bike for parts and I have just about got all the bits together to rebuild to a very tidy standard.

Still looking for forks with decent chrome and rear shockers that still have some life left in them. Stand by for the 1980 100cc shootout results when we have a contenter ready for the mighty YZ Hungey!

[SUZUKI311]

i had a RM100T new back in the day, STD it ws the most sluggish thing i had ever ridden, changed the gearing from 12/62 to 13/59, and a few other mods and made all the difference. Handled much better than my mates YZ100G. Funnily enough there is now one grazing in the shed awaiting some (read-much needed) attention...Old Suzooks seem to be breeding, wonder what will be in there this time next year...

[rocketfrog]

Suzuki311,
              I will make sure to check that gearing combo when I get new chain and sprockets, was yours a 428 or 520 chain? It looks like the 125 should have 520 std and the 100, 428 chain. What other mods did you do? I would think that the cylinder head could use reconfiguring to a centre plug arrangement, ie not canted and the 125 crank and top end would be the best and cheapest mods.

[SUZUKI311]

From memory i had the local dealer tidy up the ports, ran a thinner head gasket which was available from Suzuki as an optional part, advanced the ignition timing slightly, had a modified pipe which had a 20mm section cut out of it near where it goes into the 'tail' part of the expansion chamber, (this mod was the most beneficial, with susbstantial gains when tested back to back  with a std pipe). The std chain was a 428, and i pinched the half worn out set from my mates 125N (which also had 428 chain) to try. i have a DG gold head for one also.

[rocketfrog]

Yes the pipe does appear to have a lengthy expansion chamber and converging cone, I imagine shortening the pipe would increase mid range to top end HP. Do you rate the DG head, it seems to look just like the STD head but with Radial fins? I spoke to Lozza about this and the most efficient design is reckoned to be a central plug, normal to the piston crown.

The best part about the RM100 is the parts interchangeability with the 125, in the T models anyway. When the boy outgrows the 100 We can upgrade to 125 with a few susp changes and the donk, which shouldn't be difficult to source.

[SUZUKI311]

Yup, DG head is more of a wank factor thing, looks good though! You are correct as to difference in power with pipe mods, and yes, if you go through the parts book, most bits (but not everything..) interchanges with the 125T motor. They can be a cheap source of parts for anyone needing 125t engine bits.

[monaro308]

I wonder if this is mod is what you were talking about Suzuki311.
This is the pipe i cut up to use on my RM175 project...and now i realised i cut up the 125T pipe BUGGER!


This is on the bike with the 100 set-up and is definetly a 100 pipe as the inlet/flange is smaller in diameter
than the 125 flange.
I haven't measured the header diameter.I might have to run the 100 flange plate or chase up another 125 T pipe.

[SUZUKI311]

Memory a little foggy, but from what i remember that looks like it! i often wondered if the same mod would work as well on a 125....

[Lozza]

Cut n shut the rear cone would not 'substanitialy' increase output (unless the pipe was way to long to begin with) it would condense the band and make it hit harder coming onto band with the bonus of more over rev.The output would be the same just some HP shifted from 1 point to another.

The 125 pipe on the 100 cylinder would probably work a treat to as can the TS125/100 cylinder.

[SUZUKI311]

Lozza, same part no. for both 100 and 125 pipe and muffler!! parts management at its best.....Technically you are no doubt correct, but "seat of the pants" testing showed a big difference with absolutely no other mods, even treid swapping them back to make sure we werent dreaming!! Go figure!

[VMX247]

I've have come to decide what to do with my RM125T.
I've mentioned that this bike has a 100 crank and top end after the previous owner/s seized the big-end and decided to use the 100 parts to keep it going (must have had a spare 100 engine and used the above parts)
Trying to work out if its worth rebuilding the crank with a new rod kit and putting it back together and selling as a 125.
The bike came with all the original 125 top end and blown crank (crank is fine).
Sell it as it is with all the parts and let someone else rebuild/enjoy the bike....i never ride it.
What do they charge these days for a crank rebuild??
The bike is quite nice,rear shocks (damn hard to find) is in excellent condition and has new oil and regassed,shafts spotless.
Forks,the same only the lower legs look dirty from the crappy varnish.
Seat cover A1,front and rear guards and side covers were painted before i got it,tank isn't painted but very good.
It has a N model swingarm and brand new rear tyre,90% front M12,new sprockets and chain.
The rear axle took me ages to find (nuts on both sides).
The rest of the bike is nice too....runs ,stops,
Not sure what the front plate is off...part no 94911-14100 (maybe a cut down 125X plate)
What do you (Suzuki boys)all reckon???
Fix it up as a 125 again.....more cost to me
Sell it as it is and let someone else fix it?
I could wreck it out and maybe make the same money as it is (dont care about the money)
I'd like to keep the bike,but i don't ride it,it will give me the extra room,etc
HELP!!!!!!!!!!! 

Two years on, is there anyone willing to add to this thread.We have come across a nice rm100n.Which would near make our 'N' family complete.
cheers a