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Hi, can anyone help with a problem I have with a 1982 suzuki gsx1100 powered outfit? It suffers from terrible understeer. On most tracks it is ok, on fast corners its ok. but at broadford ( I'm in australia you know) there are two large radius 180 degree right handers that I just cannot get around. I lose 10 to 20 metres to other bike on these two corners alone. The bike is basically a Windle copy built in 1982 and as I said has a big heavy gSX1100 engine mounted right up close to the front wheel. It turns in OK but when I try to get on the throttle it just wants to run wide. I have been riding it for around two years and have tried several things but no luck so far.

My guess is that the bike is getting under steer. Get your passenger to move forward, allowing the rear wheel spin up a bit.

lower the front in the spring so it's not topping out straight away, less rebound damping to stop the front wheel being lifted up as the front goes light, move the chair wheel forward.
Put a decent front tyre on, make sure the passenger has his left foot well away from the back corner of the chair as that will lift the front up terribly, find out whether him putting his weight onto the chair wheel makes it better or worse (varies from outfit to outfit on shorter bikes)
Check it's toe-ing in and not out - you would likely notice that on faster corners as well though where it just gets vague if the thing has been clouted into kerbs a few times.
You can have all the weight on the front but it's not on the front when you open up by the sound of it, or it's being pulled left by something else (the chair wheel)

Try hardening up the front suspension.

Thanks guys, That sounds similar to what I have been thinking. I was given wrong info a while back regarding tyres (plenty of experts here pity none of them know anything). Dags gave me Steve Smith from avons number so I rang him and now I know the correct tyres to put on. I previously had a 6.2" on the front but it probably needs a 7.2" because the GSX1100 engine is a fair bit heavier than a modern 600 engine. Our biggest problem is those mosquito bikes (TZ750s) A few blokes are getting them going very quickly now so we need to find a couple of seconds per lap to beat them. Will keep you informed on the progress, again, Thanks

sidecar 10 wrote:Thanks guys, That sounds similar to what I have been thinking. I was given wrong info a while back regarding tyres (plenty of experts here pity none of them know anything). Dags gave me Steve Smith from avons number so I rang him and now I know the correct tyres to put on. I previously had a 6.2" on the front but it probably needs a 7.2" because the GSX1100 engine is a fair bit heavier than a modern 600 engine. Our biggest problem is those mosquito bikes (TZ750s) A few blokes are getting them going very quickly now so we need to find a couple of seconds per lap to beat them. Will keep you informed on the progress, again, Thanks

Ah, proper sidecars eh?