What does a GT380 handle like?

[sportston]

I've got my GT380, always wanted one, but it needs a bit of restoration work before I can ride it. I am curious, what do they handle like in standard form? While I am restoring it, are there any essential mods that are worth doing to improve the handling?

[sportston]

Anyone? I'm told they all handle relatively poorly. Does everyone just put up with that or has anyone on here tried to modify the frame or suspension to improve things?

[pearljam724]

I've never ridden a 380. But, I'd be willing to bet it handles nearly the same as a 550. The 550 handles leaps and bounds better than the 750 from my point of view. But, in all honesty all of the 70's era motorcycles are very poor handlers comparing them to any motorcycle past that era. There are a couple little things you can do such as fitting a descent set of tires, lighter exhaust, aftermarket fork springs and aftermarket rear shocks in order to achieve proper sag. The most important thing would be setting the sag according to your exact weight in the front and rear. You would first need to learn how to properly measure sag before you can venture into buying parts or adjusting ones you have to accommodate those changes. Any motorcycle needs to have 3 1/4 inch of sag at the front and 1.5 inch on the rear with the rider sitting on the bike to handle best to it's ability. Speaking from stock trim, manufacturers at this time still had quite a bit to learn in regards to building a better handling motorcycle. The main focus at this time was longevity and quality. That equals heavy parts. Plus, it wasn't till later. That more lighter materials were available. Since then, manufactures have learned that better handling is achieved through less mass. Especially, rotating mass. Crankshaft, wheels, sprockets and chain drive. These old bikes are what they are. Poor handling, poor braking and heavy as heck. However, very fun to own and ride. And quite obviously built well. Just my .02

[GT750Battleship]

The standard rear shocks on all the triples are now getting old, & as such need rebuilding,very few shops do this,as they were never designed to be refurbished.The handling was never brilliant from "new" ! The options are to buy a quality aftermarket shock,like Hagon,Ikon or other well know brands,some of these "look" like the originals...so you don't loose the original style & look of a '70's shock absorber.The front suspension can be sorted by new springs & spacers,different grade fork oil etc.
Cheers,
GT750Battleship.

[RING_DING]

Steering head bearings and swing arm bushings are likely worn out too.

[sportston]

Any motorcycle needs to have 3 1/4 inch of sag at the front and 1.5 inch on the rear with the rider sitting on the bike to handle best to it's ability.

Ah now that is information gold! I wasn't aware of that and I'm sure it will come in handy. Thanks for your advice. As recommended I will alomost certainly be replacing the swingarm bushes and checking the headraces is also part of my plan. I am part way through stripping the bike and the first major thing to do is to hammerite the frame in smooth black. I have already made a start on repairing the accident damaged clocks and cleaning up one or two parts. Brake caliper is now cleaned and ready for me to finish painting when I get some more paint. I've also managed to get a set of left switchgear from another Suzuki that will fit nicely for 99pence off ebay. Now I need to find a petrol tap that doesn't leak. I'd happily recon the one I have, but have had no luck finding replacement diaphragms, so I may use one off a GS1000 instead. Progress is slow and hampered by a tight budget, but I will get there in the end.

[tz375]

PJ was making a general comment about the need to set sag. I think something got lost in translation from metric to old school.

The rule of thumb we work to is that sag should be roughly 1/4 - 1/3 of available suspension travel and with long travel suspension it's less. On the average seventies bike that will be about 30-35mm front end sag and 25-30 at the rear.

On a street bike you can get away with plusher suspension than say a race bike but the key is to match the front and rear ends in terms of how the bike rides. First set sag and then have a buddy support the bike as it sits on its wheels to stop it from laying down for a snooze. Push down hard at the rear of the tank (above the center of gravity). Both ends should drop and rise together.

If one end is much slower to drop or rise than the other end, something needs to change in spring rates or damping.

[jabcb]

A few reviews of the GT-series bikes are here: http://www.oldjapanesebikes.com/mraxl_G ... views.html
Reviews of the late 70s GS-series bikes talk about how much improved the handling is over the GT-series bikes.

I don't ride my vintage bikes very hard.
But I had a new GT380 back in the 70s. Didn't have to push the bike too hard to get a noticeable need for a shock upgrade.

A good article on upgrading the forks is here: http://www.ozebook.com/compendium/suzi/mags/forks.htm

Had a serious sag problem with the forks on my T350.
Replaced the springs & used spacers to get the correct sag. Also used heavier fork oil.
Was definitely a worthwhile improvement.

[pearljam724]

PJ was making a general comment about the need to set sag. I think something got lost in translation from metric to old school.

The rule of thumb we work to is that sag should be roughly 1/4 - 1/3 of available suspension travel and with long travel suspension it's less. On the average seventies bike that will be about 30-35mm front end sag and 25-30 at the rear.

On a street bike you can get away with plusher suspension than say a race bike but the key is to match the front and rear ends in terms of how the bike rides. First set sag and then have a buddy support the bike as it sits on its wheels to stop it from laying down for a snooze. Push down hard at the rear of the tank (above the center of gravity). Both ends should drop and rise together.

If one end is much slower to drop or rise than the other end, something needs to change in spring rates or damping.

Some of you older guys would know a better sag rate to these stock components than I would. However, the fact remains. If the sag is not set correct to what works best for these particular stock models. The best aftermarket springs or rear shocks that money can buy will mean absolutely nothing it the sag is not set correct for that particular riders weight using those new parts. Some people assume that a more expensive, better built or newer shock automatically improves handling. It the sag is not correct with those new pieces. You would be better off keeping the old stock parts. Correct sag on any model is very important. And yes, that sag rate does vary from some models to the next. Often it takes a lot of testing under different riding conditions to find what works best for some models. Problem with these stock components. There is next to no adjustability. Depending on your weight, how and where you ride. Your stock springs and rear shocks may or may not be suitable. Regardless, these bikes will never in anyone's wildest dreams. Be a good handling motorcycle. The crank alone on a 750 weighs 150 pds. That's a ton of rotating mass that effects handling to a huge degree. Not to mention the other handling down falls that can't simply be totally fixed. Unless, the bike is reformed. But, I like them for those down falls. Some people also have different definitions of what a good handling motorcycle is.

[JoostGT]

Especially on the larger 750cc bikes of the 70s, the front fork is almost always too sloppy, stiffer springs and thicker oil will help, but it's the combination of worn bushes and (very) thin fork stanchions that ruin it.

I fitted a '90 GSXR upside down front fork in my GT750 and noticed an incredibly increase in handling, the feel through the front end is like a sportsbike and the stock rear end just wallows around.

After this I also fitted the rear swingarm from the same 90s GSXR and used needle bearings instead of bushes, again an improvement, but not as much as the front fork.

If I were you, I'd try to find a thicker, classic looking fork, maybe a GS1000 or GL1000? Then check suspension geometry, does the rake and steering head angle make any sense? Try dropping the front or lifting the rear to gain some adjustment.

If you want to keep it stock, fitting a fork brace, new wheel bearing, new headstock bearings and rear swingarm bearings/bushes will probably be your best bet.

[Alan H]

Personally I'd ride it and enjoy it as it is but with 'new' aftermarket rear shocks and the same amount as standard, Duckhams 20w50 in the forks. Treat it with a bit of respect and you'll be OK. Just remember to leave a bit more room between you and corner in front before you try to brake and get round it. It will never be a Fireblade or Gixxer.
All the triples are low and ground easily.
I scraped mine - both sides, on the way home from the dealer with my 550J the day I bought it back in 1972.
Crooks Suzuki told me about the Duckhams trick, also to throw away the centre stand and fit a 19" rear rim.
With racing tyres it was as good as you could get back then and I used to spank it severely at every opportunity.
Can't wait to get the 'new to me' 550K on the road in the next few weeks and play again, a bit more gently this time than when I was 21.

[sportston]

Can't wait to get the 'new to me' 550K on the road in the next few weeks and play again, a bit more gently this time than when I was 21.

Haha...Pussy!
I am planning on increasing ground clearance on mine too. I've ditched the centre stand. I'm going to chop and weld a set of folding footpegs onto mine. Last thing I want to do is to watch my pride and joy skid down the road, but I'm damned if I want to give up riding like a loony.

[Alan H]

Pussy off! I intend riding for many years and the traffic is a lot worse that when I started.
I said 'a bit more gently'. Emphasis on 'bit', that's as much respect for the bike as me.

[sportston]

Pussy off! I intend riding for many years and the traffic is a lot worse that when I started.
I said 'a bit more gently'. Emphasis on 'bit', that's as much respect for the bike as me.

Ah well thats alright then. Maybe you aren't a pussy afterall. I know what you mean about the traffic being worse. I've been riding now for over 21 years and even in that short space of time the amount of cars to get in the way has increased a lot I'm sure.