[e36m3]

Hi, I'm fairly new to riding, and I recently bought a '92 GSX-R750. It runs really rough, and the guy who sold it to me told me that it just needed the carbs to be sync'ed. Well, I took the bike a local shop, and they told me that one of the rod bearings is probably bad, after listening to it with a stethescope.

So what I thought would be a cheap and simple fix turned out to be a very expensive and complicated one! Can someone give me advice on what to do? Should I fix the engine, replace the engine, or replace the bike?

My dad and brother have an auto repair shop (shameless plug: http://www.southbayautocarecenter.com ), so I can probably ask their mechanics to do the labor. I'd just go buy the parts from a Suzuki dealer. Experienced auto mechanics should be able to handle tearing apart a bike motor, right? How different could it be from a car's?

If I were to replace the engine, does anyone know where I could buy a used one? How much do those go for?

Or am I better off just selling the damn bike and getting another one? I paid $1800 for it, thinking it just needed the carbs sync'ed. Now knowing that it needs some major engine work, how much do you guys think it's worth?


thanks,
Shane

 

[Phease]

Surely your dad/brother would be able to tell you if it's the carbs or the piston rod bearings.
Did they synch the carbs firstly then it was still running rough or did they just look at it, tut a couple of times then tell you "it going to cost you, but........."

I would have thought if the rod bearings were shagged then the engine would be running more then a little rough.

Either way bike engines in my limited opinion are way easier to fix than car engines, and for a professional mechanic it should be run of the mill anyway, when it comes to pistons it is fairly the same as in a car but they're easier to get to in the bike once the engine is dropped out of the frame.

Or you can get replacement engines easy enough at brekers yards or on e-bay (watch they're not robbed with the latter option).

Good luck

 

[e36m3]

Thanks, Phease.

The engine doesn't sound like it's obvious there's a bad rod bearing; it sounds quite good actually when you rev it up. It just runs a little rough, especially at low rpms. It makes it hard to take off from a stop because it stalls really easily. They didn't sync the carbs first; they just listened to the motor with a stethescope and told me they think it's a rod bearing.

Anyway, I'll see what my dad's mechanics say after they look at it. If I were to get a new engine, does anyone know where I can find one, other than ebay? (I don't see any on ebay right now.) And what's a brekers yard? Is that what we call a junk yard in US?


thanks,
Shane

 

[doblerj14]

did you make sure that the carbs are comlpely clean and that the jets are the right ones for the filter/can you have on the bike. Personaly i would clean the carbs re sync them and try that before i did a whole tare down

 

[e36m3]

Thanks, doblerj14. I'm getting another opinion now, and I'll let you guys know how it goes.

Oh, another thing I might mention is that the previous owner said that he installed carbs from a GSX-R1100 and that it runs rough because the carbs need to be sync'ed.

 

[Phease]

If the engine sounds good when revved and rough when idling at low revs it sounds more like the carbs, syncing them shouldn't be too hard if you have the correct equpiment to do it with, and you should be able to get hold of that at your dad's garage. you may have to check about the compatibility of the 1100 carbs with the 750 engine though, i'm not sure if you need different needle settings etc... someone else will be able to help with that though.

Sorry yeah a breakers yard is the same as a junk yard, where old/crashed bikes are dissassembled then sold on for parts.

 

[87gsxrnut]

Experienced auto mechanics should be able to handle tearing apart a bike motor, right?

Maybe. Maybe not. It is a different animal, and there are a LOT of differences and things to look for when building one of these motors. I wouldn't take it to them.

I used to live out on your area. Take the bike to one of these places:

Werkstatt in SF

Fastline in Fremont http://www.fastlinecycles.com/

G-Force in Santa Clara
G-Force Performance Center
3473-B El Camino Real
Santa Clara, CA 95051
408-244-8090

They should be able to give you a better idea about your bearings. FYI: If that is a '92 US model, then it is the long stroke motor, the same that was used in the '86-'87 GSX-Rs. '90-'92 motors are also the same.

Don't bother with a junkyard in CA. Too expensive. I tried that a couple of years ago. I hunted around the internet and came up with an '85 motor from Canada, shipped to my house for $700. Best $700 I ever spent. We also found a motor from Conneticuit for $300 shipped (plus spare carbs and other stuff) and another motor off eBay for $300. So, you will have to look around, but the deals on those motors are still out there. They are not as desireable as the 1100s by a long shot.

It is CHEAPER, faster and easier to find a used motor than trying to rebuild that one.

CARBS: I show your bike using 38mm CVs. Which year 1100 were the carbs from? You can swap them back and forth.

To synch the carbs, you need either a vacuum or mercury device that is designed especially for motorcycle carburetors. I highly doubt that any auto service shop has one.

- Nut

 

[87gsxrnut]

Also, most motorcycle "shops" and "technicians" SUCK. I wouldn't trust ANY of them. Those I recommended to you have built thousands of race motors for the AFM and AMA racers in the No-Cal area.

- Nut

 

[semnole13]

Depending on if the bike sat awhile, it could clogged carbs.