New member, old bike

[andys2]

After a break of 15+ years, I've got another LC! This time it's a hybrid of LC and AC



I understand the bike might be known on here? So if anyone can tell me anything about it, please do.

This is what I know

1976 RD250C frame and bottom end
RD400 wheels, brakes and forks
350LC swing arm and monoshock(?)
RD250 bottom end with 350LC barrels with Terry Beckett tune, TZ350 clutch cover & waterpump, RD400 carbs & K&N filters
Lomas pipes

At the moment it has one or two issues, some minor some could be more serious! The clutch slips, but I've fitted new plates and 3x TZ springs. It has a monumental flat spot between 6500 and 8000rpm, hoping to lessen this by fitting spacer tubes on the filters.

The lat one could involve more work! The bottom end is RD250, which is solidly mounted to the frame and the vibrations when it hits the powerband are horrific! You can got through 2 gears before your hands go numb and you can no longer hold on! Afterdoing some research I've found that RD400 crankcases of the same year are rubber mounted like the LC. I'm hoping it's a 'simple' case of getting some RD400 crankcases and re-building the engine into them. Anybody confirm that this can be done??

Future upgrade plans are to beef up the font end and do something with the clocks, possibly fitting something like this

www.ebay.co.uk/itm/261452491221?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

Only ridden it a few miles but I was grinning from ear to ear when it hit the powerband, even if the clutch was slipping!

[copper99]

That looks a really interesting bike mate, sorry, no prior knowledge of it but im sure others will know of it.

I hope the problems are easilly solved for you, keep us posted with its progress.

[steeley]

interesting bike ,could you fit some rubber bushes in the crank cases.i think Armstrongs had the same sort of trouble with a 2/350 they built .I am sure there is an article about it try google.cant see why 400 cases wont work I see your 250 is a points model so you would need 400c cases.have you asked on the aircooled rd forum.

[andys2]

Found this picture the other day and I think this is what I will be aiming for looks wise

[nicki46]

Interesting combination of RD parts resulting in a good looking bike.

[billyboy]

ditch the s and b filters and fit some foam ones ,might help with the flat spot

[andys2]

May 14, 2014 21:51:41 GMT 1 billyboy said:

ditch the s and b filters and fit some foam ones ,might help with the flat spot

Got some Ramairs and tube to make spacers this week, will fit them tomorrow and report back.

[johna]

great looking bike you got there mate good luck with it.

[andys2]

Fitted the new EBC clutch with 3x TZ springs and Ramair filters with 50mm spacers today. The bike is transformed, much better mid-range, still has a flat spot at 6500rpm, but you can ride through it unlike before. The clutch is now not slipping and it's much easier to get neutral, almost impossible before.

The down side is that the vibrations are still as bad and the tune is still way too peaky for my liking so I think I'll be looing for a set of un-tuned or very mildly tuned 350LC barrels.

[phil1966]

Lotta thought gone into the build......looks stunning...

[sparkyrd350]

Looking good, nice work

[iwantalc]

seat dont look too comfortable

[Topman350]

Hi mate great looking bike very hardcore check the carbs are all clean, jets and needles are the right ones all these small adjustments can make a difference it's just getting the mixtures right oh and do a plug chop good luck :-)

[andygasgas]

I ditched my k+n filters fitted ram air foam pods way better minimum flat spots now

[Deleted]

The 400 is a longer stroke than the 250 so that might bugger up the crankcase change idea.

[Paul H]

Nice, a different look to the norm

[eastyorks]

Looks great!

[stevebgt1]

This thread has gone very quiet. Have you still got the bike ? Did you resolve your other issues ?? It looks fantastic !

[adamchance1999]

Looks like a sweeet bike

[andys2]

Not updated this in a while but this is what it looks like now:-





I wanted to get the back end up to make it steer and get as much weight off as possible, changes include:-
Lighter spoked wheels
Fireblade front end
Most fasteners changed for Aluminium or Titanium
Koso dash
New Aluminium subframe with Shorai Li-ion battery
Old engine removed and replaced with full 350LC engine with a Fahron 370cc top end
Aluminium radiator.

Bike is now night and day different to how it was, loads lighter, super nimble and loads easier to ride with the Fahron tune.

[bazzer5115]

I like that.👍