GS750/VW Reverse Trike...Help needed from GS experts!!!

[aaronbev79]

I have quite a bit of experience with small motors, gearing, and big tires/weight.

I own a Suzuki Samurai with a 1300cc engine. It's a 4x4 vehicle with 26" tires stock, and it weighs about 1800lbs stock. After I was done with it I had 33" tires and it weighed somewhere around 3500 lbs with winches, new heavy duty bumpers, and a custom half-cab.

BUT, I kept the stock motor. What made the difference? Gearing. With the stock gearing I was eating up clutches like crazy, but after going to a much lower gear ratio, my motor was moving those big tires like they were 26" again.

I may not have a lot of experience with bike clutches, but I know that if you significantly lower your gearing you will make it MUCH easier on your clutch. Does this make sense?

[fast pom]

PS all the advice you will recive here is done with the best intent please dont think fellow GSers are trying to put you off , but a lot of us have made costly mistakes in the past .

[aaronbev79]

PS all the advice you will recive here is done with the best intent please dont think fellow GSers are trying to put you off , but a lot of us have made costly mistakes in the past .

I know, and I appreciate it. But there have been many guys who have used 750cc motors without a problem.

[salty_monk]

Thanks again, but if you do the math, 63hp with 800 lbs is a better power to weight ratio than 100hp with 1500lbs. The Rayvolution EVO -- the car that I am copying -- weighs just over 800 lbs and has a 750cc motor. Granted, my motor is not as good as a GSXR, but what I don't have in power I will try to make up some-what with gearing. And what I don't have otherwise, I will not worry about since I'm going to spend about $2000 total on this project since I'm building it myself.

How much do you spend on your Lotus cars? I bet I will spend a fraction and have a hell of a time with my cheap 750cc engine.

Ok, but you will want more power Lets now do the Torque figures for your 800lb (if you even get there, you'll be surprised how it adds up!) & we'll see a different story, Torque turns wheels. I'd be surprised if the 750 in the bike will pull much better than a 6 sec 60 time......

I think it's a great project & don't get me wrong you'll have fun whatever, I would just encourage you to "future proof" it in your design to take the bigger engine if possible.

The GSXR motor is a lot different to the one you plan to use...

Those replica's can be built & registered for $3000 or so depending on spec & how much you do yourself. As for those two.. about $4000.

The 750 is no different to any other GS engine. Very long lasting as long as it gets adequate cooling & plenty of oil changes.

[fast pom]

Then go for it my friend keep us informed on how you go like i say the 750 is a great engine all the best

[aaronbev79]

Ok, but you will want more power Lets now do the Torque figures for your 800lb (if you even get there, you'll be surprised how it adds up!) & we'll see a different story, Torque turns wheels. I'd be surprised if the 750 in the bike will pull much better than a 6 sec 60 time......

I think it's a great project & don't get me wrong you'll have fun whatever, I would just encourage you to "future proof" it in your design to take the bigger engine if possible.

The GSXR motor is a lot different to the one you plan to use...

Those replica's can be built & registered for $3000 or so depending on spec & how much you do yourself. As for those two.. about $4000.

The 750 is no different to any other GS engine. Very long lasting as long as it gets adequate cooling & plenty of oil changes.

Just to be clear -- this thread has never asked for help on HP or Torque -- I've asked for help on clutches and gearing. I'm well aware of where I am with power/torque, and I think it's quite obvious to anyone that a 1100cc engine is better than a 750cc engine. If you want to donate an 1100cc engine to my project, I'd gladly make a straight-up trade

Otherwise, I appreciate the kind concern, and I didn't mean to seem annoyed.

[aaronbev79]

Here are some pics of my actual bike, rear swingarm/6" wide wheel from ZX9R, and my seat. Also pictured is the Acewell 3900 custom gauge unit that I will be using to replace the stock GS750 gauges. The Acewell unit uses generic speed, RPM, and heat sensors so I will be able to run things without having to worry about extending the connectors as I would have if I were using the GS750 stock gauge cluster.






As far as gearing, I ran the numbers, and with a low profile tire on the 17" ZX9R wheel, a 46-47 tooth rear sprocket will put me around 95mph on the top end -- greatly reducing the stock gear ratio. Hopefully, this reduction, combined with upgrading the stock clutch, will keep this thing moving down the road. Are there any stock parts from an GS1100 that could be used on the GS750 clutch to improve it...such as the springs?

[fast pom]

Get your self a new set of HD Barrnet springs {not expensive] none of the clutch parts are interchangeable with the 750. Check the centre nut on the clutch hub is tight and that the basket is not groved were the plates sit. Like the acewell unit is the rev counter elec or dose it use the mec drive from the cam Thanks

[aaronbev79]

The Acewell uses an electrical signal for the tach.

[salty_monk]

I suspect the unit uses a magnetic pulse counter or proximity sensor to work out speed. You can mount them on a driveshaft or something similar, as long as you know what pulse ratio etc to put in there (for example 1 pulse for every turn of the rear wheel with a certain wheel circumference).
There's a few of these things out on the market now.... not sure on that one but the cheapest I've seen in the UK is about £70 ($110). Not sure it comes with all the idiot lights like that one though!

Looking forward to following this project...

[fast pom]

Sorry dont mean to hijack your thread but looking for a tacho for my race bike with elec pick up

[scrapper]

ah heck put a 5.0 litre out of a turbo mustang in it. put 4 wheels on it an call it a car.

[aaronbev79]

I suspect the unit uses a magnetic pulse counter or proximity sensor to work out speed. You can mount them on a driveshaft or something similar, as long as you know what pulse ratio etc to put in there (for example 1 pulse for every turn of the rear wheel with a certain wheel circumference).
There's a few of these things out on the market now.... not sure on that one but the cheapest I've seen in the UK is about £70 ($110). Not sure it comes with all the idiot lights like that one though!

Looking forward to following this project...

Yeah -- the Acewell is little over $100, and is really reasonable when you consider how expensive custom gauges are. Not to mention, they are pretty cool looking and relatively complete in terms of everything they can do -- I love the digital display. Also, Acewell brags on their site about how durable their stuff is -- they are supposed to be extremely waterproof and vibration resistant.

[aaronbev79]

Sorry dont mean to hijack your thread but looking for a tacho for my race bike with elec pick up

Just google Acewell and you'll find them -- they are cheap and since they are primarily used for quads and dirtbikes -- they seem like they'd be reliable.

[gearman]

Popular Mechanics had an article on one of these back in the 80's. I don't remember all the details, but it used 4 cyl ujm and a 2 seat subframe fitted with v dub steering grafted to the front. The bodywork was made from shaped foam skinned with fiberglass. As I recall, they said the handling was great. You'll definitely have to keep engine cooling in mind as you design.