suitability of the SV650 engine for my project

Hello everybody, I'm Sam: an industrial design student with dreams of becoming a motorcycle designer.

For my thesis project I'm going all the way (I hope), I want to fabricate a fully functional motorcycle based on my own design, kind of like a rolling portfolio. I'm thinking of something with very supermoto roots (nimble, durable, quick, extremely light, and above all: hooligan-friendly), but with the real world practicality of a bigger and more reliable engine.

Being the starving student that I am, I'm forced to choose components from within the realm of feasibility. From what I can tell the SV650 engine looks like a good candidate for my powerplant: light, slim, reliable, 70hp, and most importantly: cheapish.

I want to know if this engine would be a good choice for the application.

My main concerns are:

1. is the power delivery too high strung? I need something torquey, an engine that makes the front end seem light (note that I will be using a final drive that puts top speed around 100mph, this should make the bike a little more peppy). If not are there modifications available to alleviate this (ie. a stroker kit)?
2. is this engine able to handle the copious amount of abuse I'm going to throw at it? Although I am a strict disciple of maintenance, I am going to treat this bike like a supermoto: it will be wheelied/dropped/jumped and generally thrown about. If this engine has a history of frailty it's not going to work out: I need bulletproof. I've read somewhere that the SV1000 engine will start to spit out chunks of itself if the bike it belongs to spends too much time on only the back wheel, has anyone heard of this before? Is this a known problem with the SV650 engine?

Thanks for your help.
- Sam

[empty]

Originally Posted by esskay

My main concerns are:

1. is the power delivery too high strung? I need something torquey, an engine that makes the front end seem light (note that I will be using a final drive that puts top speed around 100mph, this should make the bike a little more peppy). If not are there modifications available to alleviate this (ie. a stroker kit)?

The SV engine is quite capable of lifting the front wheel of its intended motorcycle, which is probably heavier than what you have in mind. Reducing the final drive will help this, assuming you are going to build a frame you will be able move the engine position and geometry of the front and rear to help this as well. It's a four stroke engine, they are fundamentally different to 2 stroke engines, if you want a stroker, buy one of those instead, although choice these days is going to be a bit limited. Only thing I can think of that might be an issue is the length of the engine, being a v-twin it is quite long, so if you are planning on a long rear swing arm (as with most supermotos) you are quite possibly going to end up with a long bike, too, as the front wheel position is going to be limited by the front cylinder. Maybe something like the TDM/TRX parallel twin might be more appropriate, although that might be a bit heavy. The ER-6 engine might be OK too, if you can find one.

Originally Posted by esskay

1. is this engine able to handle the copious amount of abuse I'm going to throw at it? Although I am a strict disciple of maintenance, I am going to treat this bike like a supermoto: it will be wheelied/dropped/jumped and generally thrown about. If this engine has a history of frailty it's not going to work out: I need bulletproof. I've read somewhere that the SV1000 engine will start to spit out chunks of itself if the bike it belongs to spends too much time on only the back wheel, has anyone heard of this before? Is this a known problem with the SV650 engine?

Thanks for your help.
- Sam

The SV engine is OK, but all motorcycle engines do not like being on the back wheel for long periods of time, it causes all the oil to be moved towards the rear of the engine, starving some components. OTOH, people have, with reasonable maintenance, got over 100k miles out of the SV engine, however with serious abuse, this can drop dramatically.

An interesting project, let us know how it goes. I'm sure that if you decide to go with an SV engine, there will be an awful lot of knowledge you can gain from here and loads of people who will be more than willing to give advice!

MT

[northwind]

The SV reaaaally doesn't like long wheelies. It's not so much a reduction of lifespan, as a risk of catastrophic short term failure, the design is such that the oil pickup can be left out of the oilpan with obvious results. Its not epidemic, but it's enough that it doesn't make a great stunt engine. People always talk about rebuilding it to avoid that, and it'd be possible, but the absence of a seprate pan makes it difficult and probably not economic. The newer ones are said to be better, but I've not had one of those open so I really couldn't say.

Sorry, bit negative