classic motorcycle forum

I have a pair of RD350B forks, wheel, calliper and disc sat idle in the garage.

It was parts inherrited from a mate, back in the late1980's, when he emmigrated.

They were part of a project to fit them to a CZ350 drum braked bike. It turned out that the RD forks screwed up the handling and the disc wasn't any improvement over the TLS Drum he was replacing, so they were removed again.

So they've sat in my fork collection ever since then, coated in grease for protection.

Check to see that it sin't leaking air into the engine when hot. Top split engines to have a nasty tendency to leak around the join when old and hot. Usually this manifest itself with burning oil, a favourite GT500 trick after 15,000 miles or so.

Or it could be like an engine I had to rebuild because the previous owner didn't quite understand why silicon sealant is used during rebuilds. Yep, it sucked in air and blew out oil when hot plus was a !"£%^% to start when hot.

The rebuild was done wrong as well because a clutch bearing was in all wrong, causing it to friction weld a gear onto the layshaft.

GT500 engines are nice to rebuild and the Clymer Manual show how to do it in detail.

If you're having hot starting problems, check the oil level and check if the exhaust smells of gear oil.

If so, then check the torque settings of the crank case bolts. If that doesn't solve the problem then the engine will need cracking open and the cases resealed with generous amounts of silcon rubber sealant.

Smearing the silicon sealant during a rebuild is another reason some engines don't seal properly.

However it could just need new rings, so check the compression first. Japanese strokers were never very high on compression when new, so wear and age can drop this further.

Old strokers can be a real pain sometimes when it comes to starting.

However the general rule is that a fast two stroke will always be a bad starter. Good starters are always the slower than average ones.

The coments, in the used bike magazines of the 1980's and 1990's were usually on the lines of the GT380 could only pull 6th level. On owner joked that the bike would do 85 MPH in 5th and 65 MPH in 6th if there was the slightest headwind.

My yonuger brother's GT380M could still manage to put 106 MPH on the clock (about 101 MPH in reality) when prone on the tank. He passed his bike test on the thing with a Sidewinder attached. It was faster without it obviously.

On long bike rally journeys, it was confortable and he even rode with his mate "Heady Skid", so named as he fell off of the back of another friend's GPX 600 and discovered that unlike on TV and in the movies, he needed to do his helmet strap up. Yep, he had gravel rash on the back of his thick head which took months to heal up. However the nickname "Heady Skid" is with him for life.

The split middle exhaust is what slows he bike up. A friend's wife's brother fitted another right hand pipe to his, ala the KHs, and this improved performance.

We junked the centre stand and saved about 3 stone on weight!!

The only serious problem he had wth it was when a piston ring broken and scored the left hand cylinder. It was 1 day before a rally and so I had to arrange for a mate's bike shop to rebore the cylinder that morning, fit the new piston and rebore cylinder, then have my younger brother ride up and down the local bypass, that evening, until he'd put 100 miles on the clock to run it partially in.

At 4 AM, the following morning, we met up with the rest of the gang and set off on a 300 mile run to a rally. We travel fast, hence the running in of the new piston and rings.

On JAWA and CZ speesdo errors....

On my cousin's XS250, 70 MPH on his clock was 62 MPH on a CZ 250 clock riding alongside. That was actually the first time I was aware of the error being negative and not positive.

Every JAWA or CZ I've owned reckons that cars and trucks in the slow lane on motorways are doing 44 MPH when it is obvious that they are doing 47ish MPH (50 MPH on a car speedo allowing for the up to -10% error).

My outfit doing 89 MPH.... the following Kwack GT550 had me at 93 MPH!! I could only stick at this speed for about 3 miles as the drag form the sidecar is extremely heavy on the bars. The bike wants to veer left and I have to use muscle power to keep it straight. This becomes very tiring.

About 60 to 65 MPH cruising is the fastest the thing will go without arm ache for the rider. Speeding on outfits is for masochists only.

Having been called in to fix numerous 2 stroke triples over the years, I reckon that the GT380 was the only practical one of that era. I've ridden and fixed KHs, which were luckily someone else's problem, all of which were horrid.

The last KH I fixed was 3 years ago whilst up at a mate's place in Oxford. Someone he knew had bought animmaculate Y -Reg KH 250 B5 but none of the bike dealers in the area knew how to set points (true)!!

So I was roped in and spent an afternoon servicing the thing.

I was even nice enought to struggle to remove the biscuit tin airbox, dismantle it, remove the engine power intake restrictor pipe in the airbox and reset the carbs again.

It now went better and did more than the stock 88 MPH that the B4 and B5 versions were restricted to. I'd converted it to B3 spec.  

The general rule with KHs is, unless totally insane, steer well clear of the things. They require constant fettling, even during rides, to keep going properly.

Given the choice between a GT380 and a KH400, I'd pick the GT380 ever time. They're just so nice to cruise around on.

Catenaccio, you can buy a sorted GT380 for under £500 at the moment. A GT380 will cruise at 70 MPH for hours on end, as my younger brother used to be able to match the cruising pace set by my 1977 JAWA 350 back in the 1980's.

We once rode from the M25 junctionof the M3 to the M27 non-stop at between 75 and 85 MPH coming home from one Essex bike rally in 1989. I was riding one of the 6 only 1980 rare unrestricted faired CZ350 Custom Sport Mk.III. bikes, which was the only stock CZ sold in the UK that could go faster than 100 MPH. Only six were built and I own one of them!! It is soooooo different than the stock CZ350 to ride.

You should look around for a sorted nice GT380 and you will find that it will fill your requirements just right.

The point of the original posting has been missed here, anyway.

On the advice of friends who've owned and suffered these and myself also, usually having to try and mend them, avoid any of the following.:-

Voskhod 175.... No body has ever seen one running!! I know a friend who has one and it has never run in 15 years despite his and mine efforts. He see it as a challenge.

HONDA CB250N Superdream.... this was the slowest 250cc learner bike in the late 1970's and early 1980's.

Every magazine slagged them off. Bike magazine speed tested one and stated that it was 3 MPH slower than the CZ 250 and MZ 250,at 83 MPH, making it the slowest 250 on UK roads.

Chinese 125s will out accelerate it!!

It is so unbelievely heavy for a 250.

"They don't accelerate actually, they sort of gain momentum", is what a friend reckoned about it when he rode one.

Basically they're overweight slugs and have put many youngsters off motorcyling for life in their heyday.

Bike refered to them as the "Side Street Sleeper", everyone else called them "Wet Dreams"

Exhaust note is like a sick BMW.

Just don't even consider buying one.

Yamaha XS 250/400.... carb diaphrams, similar performance to a Superdream, mechanical auto advance rusts and seizes up. However they do sound good when they run.

Any Kawasaki with KH in front of it, unlessyou enjoy constant maintainance and fettling. These are for serious fanatics only. They were just as bad when new!!

A GT 380 makes a reasonable choice of classic bike.

It sounds good, spares support is good, easy to work on.

It isn't that fast, even when new they do only 101 MPH.

OK they handle poorly but aren't the worst 3 cylnder bike with handling hastles.

The engines are pretty easy to rebuild and the only bug with them is the wiring rotting with Verdegris, a problem with all old Suzukis.

They go and sound good.

They were generally stronger buit than the finnicky and fragile Yamaha and Kawasaki 2 strokes.

The Japs did manage to make the occasional reliable 2 stroke bike and the GT380 is one of them.

The people that usually give them away are older riders who aren't able to ride anymore or they've married and are not allowed to.

Some times they've inherretted the bike from a dead relative and don't ride motorcycles themselves.

The usual thing is a simple MOT failure and the owner just hasn't the skills to fix it up.

The fact that they will continue to run even with a ring gap of 4mm. (One I fixed this year for someone) and still make 65 MPH eventually.

My Type 632 outfit towing a Velorex 700 has a top speed of 89 MPH, though riding outfits at this speed is akin to flying a twin engined bomber on one engine.

It is more happy to cruise at 70 MPH on motorways and I set up the engine to do this.

The original JAWA 350 Type 634 had a small airbox and filter from the 1960's Californian model. This put out 22 BHP. Later ones churned out 28 BHP and had a better designed airbox system. These were the high torque models, as the earlier versions we'ren't up to the sidecar tug job.

I've had an early version, back in the early 1980's, and it made only 75 MPH top whack. However fitting a later carb and a K&N filter added another 20 or so MPH to this.

Like with all old bikes, they come in various conditions and states. However they should not go slow or be sluggish unless something is seriously wrong. If yours wouldn't out accellerate a 125 then it was seriously sick. In fine fettle a JAWA 350 will match speed with an aircooled RD 250 easily. Mine was better than my 22,000 mile Suzuki X7 on acceleration back then.

The workshop manual vary between models, as do technical specs. There were 7 different variants built over the years.

My only complaint with all the 1970's models I used was the abismal stock brakes. I forked out and replaced all the shoes with Ferrodo AM4 items. In the dry the brkae were as bad as 1970's Suzuki GT brakes in the wet!!

Yours sound like some of the bikes I've aquired that have clocked up a fair few miles and need a rebore. I've had both excelent, good and cronic plus a few terminal cases, but they all managed to run somehow, usually n defiance of the laws of motorcycle physics.

The best case was a 1973 CZ 250 a friend had turn up at his breaker's yard, which had last been on the road in 1975, according to the tax disc.

It was 1996 and in between this time it had laid on its side with a Privet hedge growing throughand around  it.

It was unloaded from the van and a small audience gathered to watch John work some magic on it.

It was seized solid.

In went the Coke-Cola and I helped him rock it backwards and forwards in 1st gear to free up the piston. Meanwhile bet were being placed as to wether he could make it run.

The engine eventually managed a complete revolution.

Next in went the Duck Oil and the bike was rocked again backwards a forwards and then run around the yard, plugs out in gear.

Then some petrol was poured into the carb, some petrol was poured down the plug holes and the plugs fitted.

Then it was push started and it fired up on one cylinder, closely foloowed by the other cylinder within a minute. JIhn then rode it around the yard showing off.

The crowd of punters was gob smacked and John rode back to state his belief that, quote, "JAWAs and CZs never die, they just hybernate between owners!!"

It kick started afterwards as well.

Another CZ 250 was found at the bottom of an old flooded quarry back in the 1990's, by some divers. It was about 50 feet down, the female owner (one of the divers) told me.

Anyhow, the bike was recovered and it actually still ran OK so they MOTed it and it passed. Despite being underwater for a number of years, the enamel paintwork and chrome had survived as well.

OK now would any other make of bike survive like this??

Definately nothing Japanese.

I find it easier to fix old JAWAs and CZs to fixing the occasional Jap bike that comes my way. Jap bikes are always an up mountain struggle as they seem to have inbuilt self destruct systems built in to bypass and override. Czech bikes are a stroll in the park when compared and just seem to have some immunity to corrosion. I wish that my Suzuki GT 550 B had the same ability.

The fact is that they are made of better materials and quite well engineered with the intention of lasting a very long time and being infinately repairable.

The majority of surviving everyday use two stroke motocycles from the 1970's and 1980's are JAWAs, CZs and MZs. They just outlived the competition.

You need to have a go on a sorted out JAWA and see how they should go.

If it is a Chinese motorcycle, then "Vintage" is anything still running after two years!!

I occasionally spanner for a 75 year old who still rides competively in 500cc Grass Track Racing.

He rides late 1920's and 1930's Rudges, which he's always raced since the 1950's.

So he's a vintage racer on a vintage bike.

You have to admire the design and toughness of a late 1920's Rudge, as it is a high revving (for those days), many modern features used on modern Japanese bikes. (Radial Four Valve Combustion, built up roller bearing cranks, etc.)

Rudge also were the first manufacturer to produce a truw Ton up 250cc road bike, their last bike, in 1938, decades before the Japanese made numerous claims to have done so.

Another modern everyday thing Rudge introduces was after market tuning kits, 'cos you'd obviously be tempted to race the bike once you'd bought one.

His most recent project is an aluminum cylindered Rudge stuck into a JAWA Type 896 Grass Track frame, which he intebds to race in modern bike classes. He figured that this was the way Rudge would have gone if they'd not had their factory destroyed by the Luftwaffe during the war.

Like he says about the Rudge Ulster, "Half the size of a Brough Sueriour but a lot better and faster!!" Having ridden one of his Ulsters many years ago, a bike with all the aftermarket factory goodies fitted, I can quite believe him.

I think vintage should be when the generataion that could buy the bikes new, when they were teenagers, reach retirement age (65) then those bikes should be deemed vintage.

Ridng a motorcycle usually involves someone else's insurance footing the bill for the accident their client caused.

So far, in 27 years of riding, I've yet to a crash that was my fault. I've always had some idiot crash into me. The last one, in 1991 involved a woman doing a U-turn on a roundabout 10 yards from a Traffic Cop car.

I had no problems with the claim there considering the witness I had!! Oh and she was done on 4 counts including not signaling when performing the illegal maneuver!! The cop asked me, whilst I was in the ambulance, if she was signalling as he wanted to do her for 4 things instead of 3!!  

My bike, a 79,000 mile Aprillia 350 A/C 2 stroke suffered a smashed sealed beam headlamp, bent left hand shock absorber unit and a broken pillion footrest/exhaust frame hangar. I had to dismantle the whole bike and find a specialist fram welder to fix it. I still haven't reassembled the bike yet after all the years since then. Maybe I'll think about it tomorrow.

The weedling out thing with insurance companies, only happens if the engine is totally different than the engine that should be in the bike. Insurance claims are on culpability and only actions that made the vehicle illegal to use allow them to weasle out of coughing up.

Being over the drink driving limit and then having someone crash into you automatically prevent you making a claim on someone's insurance!!

Like I said, never caused an accident in 27 years, so far, and enjoying paying peanuts (£86 per annum) to Norwich Union to run four of my bikes on the road each year.