M1tch's SV650 kart project

Hi all,

First of all if this topic isn't in the correct part of the site please can the mods move it, I can't seem to see a 'project' section on the site so as my project is around tuning and tweeking I have started my thread here.

I am going to be building a kart with the SV650 engine in it as some of you have commented on already but I wanted to start a proper thread so that everything is in the same place.

I have decided to do this project as a bit of fun and plan to drag race it down Santapod or indeed try and drift it with the power it will have! THe kart won't actually be allowed on a proper kart track due to the power it will have, some of the top tier 250cc superkarts do use full sized car tracks for some of their races due to the fact that they can probably go round faster than some cars!

I have found that the actual kart and chassis aren't actually expensive when compared to other motorsport components, but its mainly the heavily regulated engines that cost a lot to buy and also race and rebuild with a lot of restrictions and high parts costs, which is why I decided on going for a bike engine.

When I initially started to think about what engines I should go with for the project, the 250cc superkarts use a single or twin cylinder 250cc 2 stroke engine making around 90bhp, the engine is fully rebuilt after each race though making running that sort of engine pointless for me.

I was looking at 2 strokes, I found that I could get a cheap CR250 engine from a dirt bike, they were around the 50bhp mark and were fairly light, the issue being that they were more complicated to tune and would need rebuilding every once in a while and need a top end rebuild etc. Ive rebuilt the top end on my mini bikes, its pretty easy, but the costs can mount up if a ring trashes the cylinder wall and there is always the issue of making sure the premix is ok.

I had a look at some other engines, but as they were mainly inline 4 engines they were a bit too wide to fit properly and safely on the chassis and would usually mean having to extend and reweld the chassis to fit it - something im not going to be doing.

The issue I had was the fact there were no compact big single cylinder engines that were common, they were all multi cylinders, I did have a look at the RS250 engine which is a V2, 2 stroke but those are quite expensive and apparently quite hard to work on.

I then asked about what the most commong V twin engine was and I was told it would probably be a SV650, which got me thinking, the SV650 seems to be only slightly wider than a large single cylinder CR250 engine/other 2 stroke engine, its water cooled and the earlier engines had carbs meant that I wouldn't need to worry about a load of wiring to get it to run.

I have a Volvo estate as my daily driver and an RX7 I take drag racing, here are the key things I am aiming for with the kart:

• Fits in the boot - not messing around with trailers
• Cheap to repair ie pistons,rings
• Engine fits in the OEM kart engine location
• Decent brakes

I have the kart chassis already, its a Zip tornado chassis with hydraulic brakes, including front disk brakes (only the high end karts have those)



The seat will be offset as it is in superkarts and other bike engined karts, here are a few karts with the wider inline 4 bike engines:





Due to the V twin engine being narrower I shouldn't need to move the seat over quite as much - the seat is offset to both fit the engine plus offset the weight of the engine.

Having a large inline 4 engine with a high CoG isn't the best:

http://www.youtube.com/watch?v=ls5dN...eature=related

There has already been an SV650 kart built, however I havn't seen any other photos of it apart from this video:

http://www.youtube.com/watch?v=7JVn13eNDD4

My inspiration comes from the Gixxerkarts:

http://www.youtube.com/watch?v=_nQW0jsqv4Y

And this CBR1000 nitrous drag kart:

http://www.youtube.com/watch?v=G7Q8t7XJ5hY

[DaveW_42]

wow. Can I have a go!?

Im sure it will be at Santapod when its done lol will be a long project!

The engine I am getting is coming out of a working bike, the guy is basically going to sell me EVERYTHING that makes the engine run - he is even going to make sure it runs on the bench before sending it over to me. Its apparently high milage, but the previous owner used it as their commuter bike and serviced it every 3k miles - you don't want your daily drive failing on you.

I plan to use the original engine mounts on the frame as the frame to be attached to the kart - will probably mount the OEM engine mounts onto a moving platform so I can tension the chain, on the bike its tensions via the rear wheel, on the kart its tensioned via the engine, shouldn't be too hard to weld it onto a stable platform on runners with supports

Can the tyres get the power down or are they just totally overwhelmed and spinning at full throttle?

In terms of your chain tension, why not run the chain over a third, free spinning, but adjustable, sprocket. That way your rear drive and your engine can be fixed.

Originally Posted by -Ralph-

Can the tyres get the power down or are they just totally overwhelmed and spinning at full throttle?

In terms of your chain tension, why not run the chain over a third, free spinning, but adjustable, sprocket. That way your rear drive and your engine can be fixed.

.....awesome idea mate! I hadn't thought of that! It would solve soo many issues! Now all I need to do is not solidly weld on a engine cradle onto the kart and adjust by using the sprocket! I could have the sprocket to be adjustable on a screwthread or something to increase or decrease the tension on the chain.

As to the question on the tyres, the 250cc superkarts ar around 90bhp, so they product more power than the SV650, I have checked with some karting people and if I go with some Dunlop tyres they are specifically designed for the higher power karts.

250cc superkarts cornering at 130mph between houses:

http://www.youtube.com/watch?v=g6H2HvsiTjo

If I do lack grip its easy to change the rear hubs, this 1000cc nitrous kart is running drag radials on the rear:

http://www.youtube.com/watch?v=4oMOzlMRURc

Plan is to have a set of cheap tyres for a bit of fun, and then a full set of decent Dunlop tyres - the cheaper tyres aren't rated over 100mph and have no tyre beads, the Dunlops and the higher end tyres do.

Originally Posted by m1tch_1987

.....awesome idea mate! I hadn't thought of that! It would solve soo many issues! Now all I need to do is not solidly weld on a engine cradle onto the kart and adjust by using the sprocket! I could have the sprocket to be adjustable on a screwthread or something to increase or decrease the tension on the chain.

Doesn't even need to be as complicated as a screw thread adjustment mate.

You'd just need a cam puller type adjustment

Don't try to solve problems yourself, somehow, somewhere, an engineer has already solved them for you.

You could get an eccentric sprocket, basically get an eccentric bearing which will have a threaded bolt sticking it out of it off centre.

Get the bearing to fit inside the sprocket ( bore it out maybe) then nobs your uncle, adjustable bearing.


I've built a production machine using a similar method.

Originally Posted by specialone

You could get an eccentric sprocket, basically get an eccentric bearing which will have a threaded bolt sticking it out of it off centre.

Get the bearing to fit inside the sprocket ( bore it out maybe) then nobs your uncle, adjustable bearing.


I've built a production machine using a similar method.

Same principal as the adjustment on a single sided swingarm!

You really need to keep your kart project and get a big bike engine Phil!

Trouble is though col, I need at least two tyres, a new seat, the new engine, exhaust, bigger battery etc etc.

Can't justify the room in my garage or the cost ATM.