engine modification

[sachinpg]

will it be fine if we take a bigger engine and then reduce its displacement below 610cc using sleeves inside cylinders?? http://fsae.com/groupee_common/emoticons/icon_rolleyes.gif

[sachinpg]

will it be fine if we take a bigger engine and then reduce its displacement below 610cc using sleeves inside cylinders?? http://fsae.com/groupee_common/emoticons/icon_rolleyes.gif

[murpia]

no, it will rain

[Chris B]

without meaning to sound disrespectful, why would you want to do that? why not just get one that's under 610cc and therefore definitely legal in terms of size and thus avoid the potential possibility of rocking up at comp and getting failed in tech inspection, etc for having a non-compliant engine?

btw you're question will be best directed to the rules comittee, they'll be the most legitimate source of advice for this.

[Hector]

You sure can. Why you would want to is beyond me.

[Luniz]

Maybe to be able to run a Triumph 675 Daytona engine... that would be the only reason that would remotely make sense to me...

[Mbirt]

I believe it's successfully been done to the Yamaha XT660/Raptor engine to create a legal "big single" that isn't as on the ragged edge as the 450-class thumpers. A team did it, supercharged it, and wrote an SAE paper about it. I think they were Italian. Teams have also modified the KTM 690 engine for displacement reduction, but I'm not sure if they de-bore or de-stroke it.

[AxelRipper]

Also done with most Briggs engines... the 16-18 hp V-twin class engines sit at ~620 cc

[manifold]

sure you can do it.

[Mbirt]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by AxelRipper:
Also done with most Briggs engines... the 16-18 hp V-twin class engines sit at ~620 cc </div></BLOCKQUOTE>Don't they just decrease the squish volume to reduce displacement according to QWR's formula?

[dazz]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Mbirt:
Don't they just decrease the squish volume to reduce displacement according to QWR's formula? </div></BLOCKQUOTE>

Thanks, this just made me actually laugh out loud and brightened my day!

[Adambomb]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Mbirt:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by AxelRipper:
Also done with most Briggs engines... the 16-18 hp V-twin class engines sit at ~620 cc </div></BLOCKQUOTE>Don't they just decrease the squish volume to reduce displacement according to QWR's formula? </div></BLOCKQUOTE>

ROFLMAO!

As to the OP, sleeving it is one method, although if you only need to change it a little another hot rodder's trick is to offset-grind the crank. This will naturally decrease the diameter of the rod journal, which may or may not add additional headaches. It's one thing to reduce the rod journal radius of an old-school big block V8 originally designed for 5,000 rpm, but I would suspect a modern motorcycle engine would probably be less tolerant.

Either method would probably take a significant amount of work, if nothing else in research to find a parts combo that will get the thing reliable.