GR650 Head or valvetrain onto GS500 motor

[Guest]

Hello guyz,

I have bougth a GS500 with a bad valve.

Pulled the head today.



I also have a low mileage GR650 moto that I have been trying to sell for a while and nobody wants it.

The head looks similar and the parts fiche looks very close.

http://www.sbmotor.com/OEMpartfinder.htm#/Suzuki_Motor_of_America,_Inc/GS500F_(2007)/CAMSHAFT_-_VALVE/022980001/56022980011

http://www.sbmotor.com/OEMpartfinder.htm#/Suzuki_Motor_of_America,_Inc/GR650_(1983)/CAM_SHAFT-VALVE/09510001/09510011

Any chance I can rob a valve from my GR650 motor and bring it to the machine shop so he can use it to rebuilt my GS500 head?

Any chance the whole head fits on there? It looks the same but the exhaust ports look different.

[Big Rich]

Why not stuff the GR motor in the GS500 frame? Buddha has done it on the Twins forum with new motor mounts (and custom exhaust of course).

And a front sprocket from a TU250X will fit the GR output shaft, keeping the 520 chain.

[jfman]

Why not stuff the GR motor in the GS500 frame? Buddha has done it on the Twins forum with new motor mounts (and custom exhaust of course).

And a front sprocket from a TU250X will fit the GR output shaft, keeping the 520 chain.

honestly I just want to get this bike back on the road with as little money and work as possible.

valves costs like 75$ Cad and if I have a matching valve in my gr650 motor and am more than happy to cannibalize it.

[Big Rich]

I just hate to see a GR motor torn apart for a single valve. That engine is worth more in a complete / semi usable condition.

I looked on ebay an found GS500 valves for $35-$40 (US $ of course) and would think the cost of machining a GR valve to fit a GS500 head would probably be greater than that. Hell, if I had the time to do it, I have a GS500 engine in my garage that I could donate the valves from.

[jfman]

I just hate to see a GR motor torn apart for a single valve. That engine is worth more in a complete / semi usable condition.

I looked on ebay an found GS500 valves for $35-$40 (US $ of course) and would think the cost of machining a GR valve to fit a GS500 head would probably be greater than that. Hell, if I had the time to do it, I have a GS500 engine in my garage that I could donate the valves from.

Been trying to sell the gr650 motor for over a year. I almost threw it in the metal bin last time a recycle passed by.

[Rensdw]

Been trying to sell the gr650 motor for over a year. I almost threw it in the metal bin last time a recycle passed by.

Don't, I would be more then happy to buy the cylinder head.

Try to find a cheap second hand head, will be the most easy route IMHO.
Or just find a valve, grind it in, adjust the valve lash and go! (do you really need a new valve?)

[bwringer]

The exhaust valves are different part numbers, so odds are very low that the GR650 exhaust valve would fit the GS500.
12912-15500 (GR650)
12912-01D00 (GS500)

Suzuki LOVES to re-use parts on as many models as they can for as long as they possibly can. The GR650 valves are unique in some way.

I'm pretty sure the cylinder head wouldn't work either, but it's hard to find measurements that would prove this. The head gaskets are different part numbers.

There are skrillions of GS500 engines out there with munched crankshafts -- it shouldn't be hard at all to find a cylinder head or at least a valve on fleaBay or on the GStwins forum.

[jfman]

The exhaust valves are different part numbers, so odds are very low that the GR650 exhaust valve would fit the GS500.
12912-15500 (GR650)
12912-01D00 (GS500)

Suzuki LOVES to re-use parts on as many models as they can for as long as they possibly can. The GR650 valves are unique in some way.

I'm pretty sure the cylinder head wouldn't work either, but it's hard to find measurements that would prove this. The head gaskets are different part numbers.

There are skrillions of GS500 engines out there with munched crankshafts -- it shouldn't be hard at all to find a cylinder head or at least a valve on fleaBay or on the GStwins forum.

Well I am going to bite the bullet and buy a new valve and seal from Suzuki.

I dont know if I should replace the guide as well.

[Rensdw]

Well I am going to bite the bullet and buy a new valve and seal from Suzuki.

I dont know if I should replace the guide as well.

Guide should be fine, unless you're planning on doing a full overhaul.

I think the GR650 valves are bigger, I have both the GS500 head and GR650 head laying on my workbench, I can compare tomorrow if I think about it.

[jfman]

I think the GR650 valves are bigger, I have both the GS500 head and GR650 head laying on my workbench, I can compare tomorrow if I think about it.

That would be very helpful!

[John Park]

There are skrillions of GS500 engines out there with munched crankshafts -- it shouldn't be hard at all to find a cylinder head or at least a valve on fleaBay or on the GStwins forum.

Is this a weak spot with GS500s [the 450s seem pretty durable in the crank/rods afaik] or is it just what finally brings the motor to rest? The ones I've seen pics of had the left rod gone, which is the one furthest from the oil pump, but you'd think the size of the gallery would overcome favouritism. Or is it just lack of lube maintenance?

[Big Rich]

John, I've been a member of the GSTwins forum for quite a few years now (despite never owning a GS500). I can't even describe how many threads I've read over there about running the engine down with inadequate oil levels, and then "burning up the bottom end".

I wouldn't say it is a weak point in the engine, more likely there are multiple factors leading to its demise.

[Rensdw]

That would be very helpful!

I forgot...sorry, I'll try again tomorrow :P

[jfman]

I forgot...sorry, I'll try again tomorrow :P

No problem. I cant touch my bike until saturday anyway.

[Rensdw]

No problem. I cant touch my bike until saturday anyway.

I now picture Gandalf the grey guarding your bike: You shall not touch!!!