Basket Cases

[David Lahey]

More on the RL250 motor rebuild
Another strange thing with RL motors is that the vacant chambers between the crankcase/gearbox and the outside of the motor are designed to be open to atmosphere, presumably so they can breathe and self-drain. This makes them attractive hidey-holes for wasps to make nests and lay their eggs. This photo is of the compartment between the crankcase and the front motor mount

[Greg Harding]

Hi Everyone,

Nice repair work Greg and good to see another tank resurrection in progress. There has been quite a bit of tank repair dialog on the OZVMX forums recently too including some quite bizarre techniques for dent removal discussed, including freezing water in the tank. Apart from the craziness aspect, the ice method would never work at our place because the freezer is always chokka-block full
That rubbery-looking stuff that was in the bottom of the RL tank looks like the same stuff that had come loose inside Darcy's TY80 tank and took ages to get it all out using a hooked piece of wire. Why it was in there I don't know because the tank didn't leak after I took the rubber stuff out.

David, Just sharing my thoughts on the rubber stuff inside the tank, that is I think it is the residue of evaporated fuel mix. It certainly would have taken a long time to remove from a TY 80 tank as I had to use a blade to separate it from the inside of the tank and then wire buff. Imagine the bike parked on the stand, that makes the lowest part where the tap is and the second lowest part in the opposite well, exactly where the rubber stuff was, but deeper on the tap side. Along with the varnish smell similar to when fuel goes into a honey like consistency, perhaps someone knows of a mix to dissolve the rubber stuff? Most of my RL fuel taps came out without a strainer, I now know we're they Are!

.....Well now that I have 500 posts, I am wondering what I can build ......

500 posts would be a couple of kilometers of fence.

Mark, I like how you think, maybe a corral at the end for rounding up old Trials Bikes?

When I first checked the RL250 motor out, I noticed it had a badly failed magneto side main bearing. The RL motor is very similar to the Suzuki TS250 trailbike and TM250 MX bike motors of the same era, but while they have those amazing Suzuki CCI oil injection system, the RL250 does not and runs on premix. The CCI system supplies oil to the magneto side main bearing (and the big end bearing), and to the induction tract. Most other two stroke oil injection systems only go to the inlet tract. This had me wondering if the cause of the failed RL main bearing was possibly due to shortcomings in how Suzuki had adapted the RL250 motor to running on premix. As part of this I looked at what Yamaha and Kawasaki did in their trials motors to lubricate that bearing. In the photos you will see the ventilation holes in the three different motors. The idea of these holes is to provide a path for fuel mist to travel through the hole and through the bearing, with the intention of keeping it a bit cooler and more lubricated than otherwise. Some other bike motors of the 1970s (Bultaco for one) don't have those ventilation holes, and tend to suffer from main bearing failures much sooner than the motors with the bearing ventilation.

David, the RL transfer ports are unique to RL as TS ones look like KT and TY ones (full size). Do you think it would be an advantage to open up the ventilation hole to allow more fuel/oil to flow through magneto side main Bearing? Also could you do a comparison of main bearing sizes in the 3 motors as ones look Bigger? The motor you have came out of the Blue Dungar, I fired it up when I bought it and was quite rattly. Next I removed the magneto cover to feel the main Bearings and there was a bit of play but not what I thought to warrant the noise, so I rotated the motor to top dead centre thinking I might be able to feel the free play in big end and little end bearings. Then I reached over to rotate gently through a cycle with my right hand on the kickstart and left on the magneto and it scared the crap out of me when it Started!

1439550282426.jpg (245.91 KiB) Viewed 4856 times

[David Lahey]

Greg there was a very interesting contributor to motor noise in the Blue Dungar motor and there will be photos of it appearing soon (and not big end nor little end)
Yes good idea to show off the RL bearing sizes - one of them is particularly hippopotamic. I hope I have kept some old ones from KT and TY motor rebuilds

[David Lahey]

OK I couldn't find any old main bearings from KT250 or TY250 motors, but did find a Bultaco 250 crankshaft with the main bearing still on it for comparison with the RL250 (GOLIATH)

[David Lahey]

I reckon a fair bit of the engine noise that Greg Harding heard when the Blue Dungar accidentally started was the primary drive gear loose on the end of the crankshaft.
When I pulled the clutch cover off, I found that the nut for the primary drive gear was loose. The tab washer that stops this nut unscrewing was in place, and the tab against the flat of the nut was completely unmarked. This means that either the nut was not tightened fully at the Suzuki factory, or someone in the past had worked on the bike and installed a new tab washer when they reinstalled the nut (not tightened fully).
Either way, the gear which would originally have been a light push fit on the crankshaft, was now a rattle fit, the drive key was very sad and the keyway in the crankshaft was quite battered. Both the gear ID and crankshaft OD have lost metal.
Tricub has repaired this same damage on some RM Suzuki MX bike motors, but motor parts for RL250 Suzukis can be easily and economically sourced. The other crankshaft in the photos will be used in this RL motor after Tricub fits a new conrod.

[paulo]

took the RL for a spin up the range behind where I live. Mr Lahey will probably recognise the landscape from his youth. Anyway, seemed like a good place for a glamour shot

[brent j]

Another RL to add to the mix

Brent here from Darwin. I recently picked up an RL250 in several boxes.
I've pieced it together to see what I've got and what's missing and so far it's lacking an airbox and guards. I've got a complete airbox on the way from the states and while I may try and track down some original guards I think I'll use the fibreglass repros I've seen.

The frame is stuffed in the usual place on the left hand side. I'd like to find a good frame but I will replace the left side frame tube and brace it so this one will be a rider.

I haven't touched the motor yet as I have my TS90MX motor to finish first but it turns over freely. It's been sitting for a while but quite a few little things point to this being a low hour bike.

Piccies below





Paulo, beautiful bike, it's an inspiration for me and beautiful area. Glass House Mountains? I hope to move there in a few years

Cheers

Brent

[paulo]

Looks like a good starting point Brent, the hardest part for me to find was the magneto cover that has the clutch mechanism. It's a fairly lightweight piece and prone to failure from the heavy clutch. I took a few springs out of my clutch basket and made up a one piece pushrod to improve/ lighten the load. I also welded a couple of case savers onto the frame.

That pic is of Samford Valley looking towards Mt Glorious. The Glasshouse area is nice too. Lots of riding areas out there.

[David Lahey]

took the RL for a spin up the range behind where I live. Mr Lahey will probably recognise the landscape from his youth. Anyway, seemed like a good place for a glamour shot

What a fantastic photo. Great to see

[paulo]

Thanks mate, the only decent bike photo I've taken. Somehow its on facebook now