Hi all,

Ive got a gs 500 2003 model so its a k model unfaired so no extra oil coolers etc to worry about, what i want to know is can i slot a old gs500e engine into it the mounts etc should be similar but i wonder if the electrics are compatable ? the motor thats in the bike has been removed and has a very broken con rod that said the barrel pistons etc are fine and the caseing's are not holed allthough there is a small chunk taken out of the insode of the case but its in a thick section of metal and im not worried about it.

so my options are fix the existing motor or pick up a whole motor for it now ive never rebuilt the bottom end of a 4 stroke but i have a 2 stroke and ive rebuilt the top end of a 4 stroke before and ive a haynes manuka to assist me should i repair it from what I can see I would have to split the crankcase's to install a new con rod and of course there will be some small amounts of metal in the bottom end but a few very quick filter changes shoud get that taken care of shouldnt it ?  so what would you do is it worth rebuilding the motor or is it better to use a donar motor?

If i use a donar what years motors can i use and will i need to replace anything else to make the new motor work IE carbs? cdi? Clocks ? I heard somewhere that some models run a electronic rev counter soem run one from an electrical pickup ?

Thanks for the help in advance

the newer engines do indeed have an electronic tachometer and also a different ignition system. Not to mention the oil cooler, and the drive sprockets are slightly different. also the carbs are different. I dont know any specific years but I think the 3 circut carbs started in 02 along with the newer ignition system. the oil cooler started on 04 models. any one else with more info

and by-the-way welcome to the forum!

Thanks for the info , Mine doenst have the oil cooler so as long as i stick to before that I shouldnt have that issue there was a what I assume was a tacho cable coming out the front of teh cylinder so maybe mine is a non digital one maybe it was post 04 that tehy went digital tacho? cdi's arent hard to get hold of so woulndt be a problem to get one to go with the other model engine if required the carbs again i could source if i needed to do so but maybe i could get away with the same carbs just set them up to suit the other motor?

the carbs are specific to the type of ignition system, the newer 3 circut carbs have a throttle position sensor that playes with the timing, the old carbs dont. either get the correct year of motor or swap your old parts on to a new motor. (including the cams so your tach will work.)

so your saying a newer models top end would slot onto an older motor?

The 3 circuit carbs started with the 01 model but the 01-02 models didn't have the throttle position sensor which started with the F models.  We never got any 03 model bikes here in the US and all the 04 and later bikes sold here were fully faired F models only.

Don't see any reason the 3 circuit carbs from your 03 won't fit the earlier model engines if you keep the dual cable throttle grip arr't with them.  The 2000 and older models with 2 circuit carbs had a single throttle cable arrangement.  The 01-03 three circuit carb manifolds will bolt up to the older heads, the different carb diameter is taken care of on the other end of the manifolds.

Shouldn't be any serious electrical problems if you have a cable driven tach on the 03 but you might pull the little 3 bolt cover from the right side of the engine over the ignition pickups and confirm there are 2 pickup coils like all the 02 and earlier models have.  The 04 and later electric tach models have a single pickup coil.

great info ill check the carbs for the TPS didnt notice one when removing the engine but i shall double check it, I will also check the pickup and see if is double or single it sounds like I might have the 02 model that was registered in 03 i shall have a look at engine and frame numbers to see if there is any sort of laymans year code on them to tell me  for sure what year it is, Im hopefull its a 02 or earlier as it sounds like I can take my pick of motors to replace it with if thats the case there are a lot of late 90's engines about here for reasonble money when you compare the price of rebuilding the orginal motor...................

Anyone seen the con rod come off because it looks like one of the bolts has come undone before? it looks like it wasnt threadlocked to me and vibrations etc forced it to come undone over time ill grab a picture of the rod and you will see how its come undone later today