Start of the RD350LC refurb.

It’s been over 20 years since I last rebuilt or refurbished the 350LC.
She is looking a little sad. The bodywork paint is cracking up and flaking off, the engine is rattling, and it’s unclear whether it’s the clutch, top end or crank. (Although my money is on the top end which has 10k miles on it and has been moderately thrashed).

So here is the outer cosmetic view of the bike.


This is not a 100% original LC. Over time, modifications have been made, parts swapped, and alternative, (cheaper) parts used.

  • The carbs are 28mm flatslide Mikunis, from a Suzuki RG250. They work OK, but I’ll be swapping back to 4L0 or 31K carbs.
  • The swingarm has been braced. I did this. The minimal additions move the high speed weave from 70-80mph to 90-100mph. (It wouldn’t be an LC if it didn’t weave at all!)
  • The pipes are 31K YPVS pipes. These fit with a bit of filing, and allow the engine to breath, (and rev) a bit more than the original pipes. Visually, they are a little fatter, but could be mistaken for original pipes at a distance.
  • The front brake is a single Lockheed caliper. It really doesn’t need any more for road use.
  • As the frame is stamped 4L1, then technically, the top end is a modification… it being 350 barrels, pistons and head.

Work started while rebuilding the 250

While rebuilding the 250, having the running 350 around was useful for swapping bits on and off, testing, (for instance) shock damping with a variety of different options, and many more things.
Consequently, a lot of irritating things were sorted on the 350, before I decided to give it the stripdown/rebuild treatment.
An example, again relating to the different shocks, was the 4 hours spent releasing the completely corroded shock bottom mount, to remove the Hagon shock which it had had for 25 years.

Swapping the functional RG250 carbs for a pair of rebuilt, cleaned 31W carbs was another.

Ultimately, I wanted the engine out, so I put together a “spare” engine I had comprising a bottom end with about 10,000 miles on the crank, (which was removed from the bike previously because it had developed a bit of a rattle), and the top end being a Stan Stephens “stage 2”, which had melted a piston after less then 500 miles.

I cleaned up the alloy smear as best I could but it is still visible.

The skimmed and profiled head which came from Stan was irretrievably pitted with ring fragments, so a standard head was used, resulting in a slightly lass than optimal compression ratio, and a thoroughly poor squish of over 2mm.
I had to ease out the inner diameter of the head gasket with a file to accommodate the 2mm oversize pistons.
The head was sprayed with copper gasket before reusing. It didn’t seal properly, so I stumped up for a new gasket.
Still, it ran, was surprisingly quiet… even the bottom end, but at the age of 62 (My age… not the engine 🙂 ), it felt too peaky for me, with the power coming in at circa 8000 rpm, and a big dead spot between 4000 and 8000.

Having ridden the SS stage 2 again, I rubber stamped my decision to get the Bob Farnham “endurance race tune” top end re-bored. This top end has a lovely pull through the midrange, and lasted over 10,000 miles.

What kind of rebuild/refurb.

I have thought long and hard about what to do with the refurb. There are a number of options, ranging from (a pointless) concourse restore downwards.
It being a 250 4L1 frame, I even considered rebuilding as a 250… for about 5 seconds 🙂
I already have a 250, the engine and frame numbers don’t match, I LIKE the bracing I did on the swing arm… etc.
So it is really just going to be a tart up, with top end rebuild, (on crank with about 3k miles), everything cleaned, new bodywork and all the minor irritants cured/fixed.

Next Steps

Notwithstanding the stuff which has already been done, there is still much to do.
First off will be to cure the excessive lean of the bike when on the side stand, (which culminated in me welding an extra inch into it).
In the picture below, you can also see the snotty welding on the bracket where it has been inexpertly reattached in the past. I suspect this is the problem.

Some more pictures of the bike.