just bought sv650, surging and backfiring (yoshi fitted)???
 

Hi I just bought a 2000 Suzuki SV650 today. Looks great and everything appears to be in good shape other than a few cosmetic/minor things the previous owners messed with.

My only concern is that the bike surges to some degree and what annoys me a little less is that it backfires when you close the throttle when it's in gear. I am wondering if this is because of the Yoshi can that's fitted and whether getting it to a dyno and having them sort out the fueling with make this less of a problem.

Is the backfiring common on v-twins...esp with aftermarket exhausts? I've noticed most harleys back fire when the throttle is closed. As for the surging...it's not too bad, but it seems to become more apparent when you are above 3000 rpms and trying to hold a steady speed...not sure how bad this is as I haven't driven it more than a few hundred years and only in first and second.

As for mods, this bike already has as stated before a yoshi end can (full exhaust?), frame sliders, body-colored rear hugger, polished lip on rims...carbon fiber accents, clear turn signals...and I think that's about it...

I still am getting used to the amount of engine braking this bike has over my old 87 zx1000r...my buddy locked up the rear a little downshifting it today...he also did like 5 wheelies on the ride home...this bike seems pretty badass

http://b.im.craigslist.org/0g/pE/410...iP8RVjH4sQ.jpg

Popping on overrun on the carbed models usualyl means there's a bad seal somewhere on the exhaust, check it for blowing when it's running would be the first step... As for surging, lots of things that can cause that I'm afraid, no simple answers.

Does it surge right up through the rev range?Many bikes have a flat spot lower down the range which can give some rough running,specially as you have the can on it.

Odds are it's not properly set up for the can/zorst, get it on a dyno. Popping on overrun is usually a leaky exhaust header, but on some Yank models they have a system to add extra air (PAIR?) which causes trouble with aftermarket exhausts. Harleys don't backfire, it's just pressure waves in the exhaust, you must notice a fair bit of noise from yours under engine braking? My sister thought the same thing about Harleys, just noisy old nails. Surging sounds like lean midrange, especially if it seems to go faster as you're shutting the throttle.

sorry to state the obvious but have you ridden a twin before? the first twin i rode was a yamaha trx850 and i took it back to the shop complaining of surging but it was me :oops: because i was used to il4 machines that rev smooth and you said you had a zx1000r :roll: the sv at low revs can feel like its surging with the pulses of the engine does it feel the same at 6 or 7000 rpm?


i'll get my coat :roll:

You may be correct, I thought my buddy was right about the surging, but he also has only driven i4 sportbikes and a few harleys years ago. I'm obviously not used to bikes that much as you can probably tell, so the problem is probably two-fold lol.

I also visited svrider forums and found out about the pair system last night...most likely I will plug it to see if that rids me of the backfires. I actually don't mind them and it's only one or two when I let off.

As for reving it to 6-7k...Haven't tried that yet I don't think...I've only made it up to about 20-30mph in second...not sure what that is in terms of revs...but most likely I haven't seen much over 5000 rpms...I'm trying to take it slow with this bike as I am slightly gun shy after my 'fun' with the zx1000r...quite a lot of bike to start with to say the least...

Although this bike feels much more responsive, twitchier and overall more wheelie-able. My old zx could be launched really hard and it would just move...I'd imagine it would roast the rear before hoisting the front...if it can even hoist the front with it's almost 600 pound wet weight.

I love the SV650 though...seems really controllable and the power is there whenever you need it...pretty predictable steering and much more user friendly than anything I've sat on so far.

give it some rev's! it'll smooth out and for the back fireing (popping) thats the best bit! :D

I rode it for an hour last night since it's finally legal for the roads and it backfires a lot. If I going anywhere under 35, above 3000 rpms and trying to hold the throttle steady all I hear is a few bangs every couple seconds.

The fact that the previous owner had moded some stuff had me curious, so I checked the air filter when I got done with my ride. It's a K&N...so now my question is that the surging and excessive backfiring is probably due to a lean condition and purchasing a stock suzuki air filter should fix all of this on its own right? The end can rarely changes the air flow much from what I understand due to the restrictive stock piping...so I should be able to get away with that being left on...I'd prefer not to dyno and jet the bike right now.

Anyway, noticed the previous owner also upgraded the front brake lines to goodridge stainless and piano wired the throttle.

One last question, do these bikes typically come with some of the exhaust bolts and other bolts wired so they don't loosen? Or did the previous owner do this? I'm beginning to wonder if this bike was maybe a track bike, but there is only a little evidence to back this up...I just don't understand why you'd drill the edges of the bolts and wire them together so they don't back out unless you're really caining the bike regularly...

Unless it's the PAIR system, popping like that sounds like it might even be a bit rich, either stuck chokes or someone has been rejetting and got it wrong. The can will make a difference to the fuelling, the pipework itself doesn't cause the restriction. Get in on a dyno, one run should set you back around $50 (with exhaust gas analysis), then you can decide what to do about it. There's no other way to set up CV carbs I'm afraid. Keep the K&N, it'll either be better or the same as stock.

Lockwiring is usually for racing, but then people often copy racers so not necessarily the case. They may have done it for a track day, either it was required or they thought it would be.