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Flatness.

SUZUKI 1982 gs1000Q: Morning guys. I own a 1982 Suzuki GS1000, unfortunately it’s the one with the shaft drive and I’m still looking for the chain drive version if anyone has one?

Anyway, the bike gets serviced by myself seeing as it’s not hard to do, and it’s ran perfectly until the last few weeks. The problem is when I try to pull away from the lights. The bike has become very ‘flat’ and takes ages to get the revs up and running.

I’ve taken the carbs off and cleaned them, which is a right ‘pain’ due to the old and stiff air box and the rubber parts around them. I’ve also changed the plugs and the fuel tap seems to be working correctly. So obviously the question is – do you have any idea what it could be because its more irritating than the UK’s Brexit farce, which I’m sure Bill Hunter will agree with?

Timothy Collins

A: Well, you’ll be pleased to know that ‘we’ know exactly what the problem is with your GS1000, and it is carb related. Also, you’ll be very pleased to know that you wont have to take the air box off again to fix it.

Simply remove the petrol tank and take off the four tops seen on top of the carbs, exposing the rubber diaphragms. One, or all of them, will be cracked or perished because of the age of your bike. These will cause the internal slides to lift incorrectly causing the mentioned flat spot when accelerating. These can be ordered from your Suzuki dealer, or they can backorder them for you. Just slip them it, when acquired, and the bike will once again feel like it did in the eighties?


Weaver.

Z1R KAWASAKIQ: Well hello and thanks for the best site in SA. I also understand that you guys are quite good with classic bikes, hence this mail.

I’ve just bought an old 1978 Kawasaki Z1R, which I’ve restored to near perfect condition, including brand new Bridgestone tyres, with the correct sizes from the Kawasaki manual.

The bike runs sweet but once I get above 150/160kmh the bike weaves quite badly. I’ve tried everything from tyre pressures to lowering, and raising, the front end by ‘slipping’ the forks through the front triple-clamps – but the problem remains.

So, do you informative guys have any answer to this, or, what I could I try next?

Lenny Collins

A: We presume that wheel bearings, head bearings, swing-arm bearings, chain alignment and the like are all correct seeing as you’ve fully restored the bike. The new Bridgestone tyres are the correct size so that’s not the problem, but we know what is.

During the late 70s not much attention was paid to aerodynamics on road-based motorcycles, especially the Z1R with its huge ‘bikini’ fairing. Believe it or not this is the problem. Do yourself a favour and take it off, exposing all your clocks and stuff, and go for a ride. Problem cured Lenny….

It’s just something you’ll have to live with because Bill used to own one and discovered the same problem, and cure…

Barrel lift?

Q: I’ve just acquired an old Suzuki RM250 two-stroke, which is an air-cooled model. I only paid a 4k for the thing and I’m not even sure what I’m going to do with it, and I think it’s from the late eighties.

Besides that I’m sure it’ll be fun to ride and I’ll probably hurt myself. But the reason I’m writing is that a guy told me to fit three to four base gaskets under the barrel to improve performance. So, quite simply, is this true because it’s easy to do on these old engines, and will it affect reliability? Just wondering….

Jarod

A: This has been done for years on many two-stroke engines, and all it does is to raise the transfer ports and exhaust port by a few millimeters, depending on how ‘high’ you lift the barrel.

What this tends to do is increase top end power, sometimes? But the trade off is it makes the engine more ‘peaky’ at the top end and therefore you’ll get a loss of bottom end power. It will also lower the compression ratio and squish band, which isn’t a good thing either.

So it all depends on the type of riding. Personally I’d leave it alone because Suzuki knows what they’re doing better than the ‘guy’ in the pub. Shouldn’t affect reliability though, if you fancy fiddling around.

Stiff boots!

yamaha vmaxQ: I own a Yamaha V-Max from the eighties and it was running a bit rough to say the least. So I decided to check things out and replace the spark plugs, air filter and give it a general clean. I have worked on the bike before so I have good idea on how things work and fit.

But when I took off the air box I noticed two of the rubbers that connect the air box to the carbs’ are stiff and well out of shape causing air leaks. I asked my Yamaha dealer to order new ones but they’re not sure if they can get anymore, and it will take forever if they can.

I’ve heard of different ways of ‘repairing’ them and wondered if you guys knew of anything about this issue, I understand they’re old parts and all of that?

Martin Klimm

A: We’ve seen this problem many times with old bikes because these items always become brittle and perish with old age. But there is one thing you can try.

Take the rubbers and soak them in thinners until they swell up to about ten times their normal size. It’s a bit scary to see but don’t be worried. Then take them out and leave them overnight and you’ll be surprised in the morning that they’re back to their normal size and soft and supple once more.

It’s certainly worth a try especially seeing as they’re hard to find, have a go you have nothing to lose seeing as they’re in such a state?

If any of you have the same ‘rubber’ problem on any sort of motorbike give it a try as well, no guarantee though folks.

 

 

 

 

 

 

 

 

 

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