Engine rebuild/mods, suggestions please
 

Well i've finally decided to rebuild my spare 1999 SV 650 engine. The reason for the rebuild is that the plum who had it before me bent the gear selector shaft, and split the engine case.

I have the new shaft, and cases, but while i'm pulling the blasted thing apart, thought i'd make a few mods.

I'm after achieving 75 bhp from it when its done, but am more interested in improving the usable power.

The pistons look like they could do with replacing, and the bores may need re-doing, mainly cos its been sat in the garden for 3 yrs and they got a bit of rust on them.

The engine has only done 14,000 miles so the bottom end is fine.

Basicaly i could do with suggestions on how to improve it without spending vast amounts of money, also where is the cheapest place to get any bearings, seals, gaskets and other parts.

Cheers

Well, teh 700cc rebuild isn't as expensive as you'd think- contact Wiseco direct, IIRC the pistons are about £170 and boing the barrels out shouldn't cost too much, I was quoted £30 when I was thinking about it. I decided against in the end, but if you think it wants new pistons and the barrels honed or bored, then it's probably cheaper than doing it with OEM bits.

I've got a couple of sets of barrels here though, one might match your case colour if your interested.

And it makes fairly little sense to put it all back together with standard cams IMO. £130 gets you a set of K3> intakes to put in the intake side, and you can use your old intakes as the exhaust cams. Or, you could use the intakes out of both of your engines for a free, but lower, boost, and then just transfer them into whichever one you're using. Or, you could buy my spare '00 intakes for £50 ;)

cheers for that mate, i may well go for the 700cc kit, i guess its gonna depend on if there is anything else that needs doing when i start building it up. Just due to the cost. Can i assume that the rest of the standard internals are suitable for going upto 700cc with no mods needed.

I remember us having this discusion before, i knew i should have saved what you'd said, but it all got lost when the site went down some time ago. TBH i think i'll go for the K3 cams + mine, the idea is to get this engine ready as a stand alone item without touching my current one. Also if i'm gonna swap the cams i may aswell put in the ones that make the bigest difference.

that reminds me, I've got a pair of 700cc barrels and pistons in the shed somewhere, have to dig them out.

only been stored for a couple of years :shock: , but they were well greased up, so hopefully still in good nick.

Next weekend, I'm removing some of the performance bits from my SV so will be outing them all.

BMC RS filter, matched rejetted carbs (can't remember whatsize though), M4 pipework with changeable Titanium can & cut down M4 carbon.

(shameless plug I know :roll: )

Cheers Mark.

There's no definate answer on the 700cc kit unfortunately... You're definately more likely to snap the crank, you have a fair bit more moving mass and a good bit more power, so it's a lot more stress. But some people have run them for ages without issues. Then, some people put them in, take them to a trackday, blow it up. I decided against it as a personal thing because of the possible risk- it might be low, it might not even exist at all, but it was enough for me not to risk in on my sole mode of transport. So I'll probably do Busa pistons and increase the compression instead.

But a spare engine? Different story- if it pops you can just swap them back. If I rebuild one of my spares I'll do it 700cc I'm sure. And since you think the bores might need work, well, that's another thing in its favour, since it'll probably be the cheap option.

It does mean you're going to blitz that 75bhp though ;) Lots more midrange from the 700cc kits too.

700cc kit does give massive midrange, pistons slap a bit at low speed though. You probably need the stronger cylinder studs though. Go for the cam swap for sure, best VFM and no extra dyno time needed.

The busa pistons are no lighter than the 700cc pistons.

My reckoning is that the injected SV can snap cranks regardless of what tuning work you do. Hence why fitting a 700cc kit cant be blamed for some of the failures that have happened...the engine possibly would have gone anyway.

If you go for the 700cc kit then get a slipper clutch put in as this will help to relieve stress from the engine on downshifts.

I have no piston slap on mine and the stronger studs werent needed either.

I really doubt that's the case. THe 700cc ones are a fair bit heavier than standard SV ones, are you saying that standard busa pistons are heavier than SV? Goes against what any of the US tuners will tell you, or Holeshot.

When we did the 700cc kit on my SV the wiseco pistons weighed approx 15grammes more than the SV ones. The busa ones were only marginally lighter than the wiseco putting them between the SV and wiseco's. We had the wiseco pistons cut down slightly so they were very similar to the std SV pistons. The tuner and I chatted about this for a while as i was going to go with the busa piston route. He said it wont make the difference between a crank failiure or not. The failures are mainly due to problems already exisiting within the crank on some bikes and if it has that problem then it will go anyway.

He also said the busa upgrade wont make much unless your raising compression also.

TBH your best off speaking direct to the people that tune the bikes, I trust our tuner as he has built some awesomely quick bikes in the past and reliable ones at that. You never know my bike might blow...but thats racing!. Lets hope not eh!.

Id go for the 700cc kit, raised compression by removing a layer of gasket and the cam swap. If you can afford to then also balancing the crank is a good idea.

Pay the money and get it done properly, its not worth scrapping the pistons for the sake of a cheap rebore, Usually about £75>£100