Rebuilding GS engine...is it as good as "new"?

[Anonymous]

I'm curious: If done properly, is a rebuilt GS engine (or any engine for that matter) as good as new? I'm thinking there should be no reason why it wouldn't perform like it did in 1980.

Any thoughts?

:-)

Rudi

[argonsagas]

I have not rebuilt a GS as yet, but every other engine I have done came up better than what it was before.

Having said that, it had to be better than what it was before, as I had to rebuild it, so it was not very good.

Actually, I have almost always added something to the engine to make it better than it was new.

If properly done there is no reason a rebuild cannot match the quality of new. In many cases, it will be superior, even if no go-faster parts are added.

Quality parts are essential. After that, it's a matter of how much attention is paid to doing the work well.

[Anonymous]

What parts of an engine can be replaced with superior parts? I know Hap was talking to me about "welding" a certain piece within the engine...making that apparatus stronger. Hap, what was that again? :-)

Rudi

[KGB]

Rudi,
I re-built my GS1000S 2 valve motor years ago.
It was blowing oil, the valve guides had dried out from years of sitting,
and neglect from the previous owner.
I'm the 2/nd owner.

The only parts left in the motor from the factory are the crank,connecting rods and cam.
Once we opened up the motor it took on a life of it's own.
What started out as a simple and cheap valve job.....well read on.
I put in new stainles steel valves from Orient Express Racing in NY.
I bored the cylinders 20 thousands. The pistons from Orient were cheaper than the stock units. Plus the cylinders were out of round, kinda "egg" shaped from piston slap and the rings wearing. The head was "decked" or shaved as was the cylinder block. This does 2 things, insures a tigher fit of the head mating to the cylinder block, and increases compression, slightly.
I had a 3 angle valve job done. This increases flow and the "swirling" into the cylinder. Better burn= more power and efficiency.
I took it easy for the first 500 miles, no full throttle.
Changed the oil, cut open the filter to inspect for metal, found none.
Adjusted the valves again, re-tourqued the head and rode the crap out of it. 5 years and about 25K miles and no problems at all.
Was it worth the $2500 in parts and labor? Absolutely!!

This is not a drag motor, this is my daily ride.

You asked about welding. Some people weld the crank to keep it from twisting. This is done at the journals. It strengthens the conenctions.
Most, not all crankshafts are 2 pieces of metal bounded together, or held together at the journals by cuffs. Welding at the connections/cuffs keeps it stronger.
Some people weld the clutch basket. GS are known to warp or crack the clutch basket. This is what holds the fiber and steel plates together.
Drag racers are known to do both, weld the crank and the clutch basket.

Hope this helped.
Remember...one thing leads to another=$$$$

[Anonymous]

Rudi,
I re-built my GS1000S 2 valve motor years ago.
It was blowing oil, the valve guides had dried out from years of sitting,
and neglect from the previous owner.
I'm the 2/nd owner.

The only parts left in the motor from the factory are the crank,connecting rods and cam.
Once we opened up the motor it took on a life of it's own.
What started out as a simple and cheap valve job.....well read on.
I put in new stainles steel valves from Orient Express Racing in NY.
I bored the cylinders 20 thousands. The pistons from Orient were cheaper than the stock units. Plus the cylinders were out of round, kinda "egg" shaped from piston slap and the rings wearing. The head was "decked" or shaved as was the cylinder block. This does 2 things, insures a tigher fit of the head mating to the cylinder block, and increases compression, slightly.
I had a 3 angle valve job done. This increases flow and the "swirling" into the cylinder. Better burn= more power and efficiency.
I took it easy for the first 500 miles, no full throttle.
Changed the oil, cut open the filter to inspect for metal, found none.
Adjusted the valves again, re-tourqued the head and rode the crap out of it. 5 years and about 25K miles and no problems at all.
Was it worth the $2500 in parts and labor? Absolutely!!

This is not a drag motor, this is my daily ride.

You asked about welding. Some people weld the crank to keep it from twisting. This is done at the journals. It strengthens the conenctions.
Most, not all crankshafts are 2 pieces of metal bounded together, or held together at the journals by cuffs. Welding at the connections/cuffs keeps it stronger.
Some people weld the clutch basket. GS are known to warp or crack the clutch basket. This is what holds the fiber and steel plates together.
Drag racers are known to do both, weld the crank and the clutch basket.

Hope this helped.
Remember...one thing leads to another=$$$$

It sure did help! Thanks for that great posting!

A couple quick questions, though:

1. Is welding the journals really necessary? Is there really that big of a problem of "twisting"?

2. How would one know to have the cylinder boared? What advantage can I gain by doing so?

Thanks!

Rudi

[SqDancerLynn1]

If you are going to have any work done to the crank, have it welded otherwise use it as is. It is advisable if you run the motor hard. The only way to tell if you need to rebore the engine is to have it measured to see if it is within the service limits

[Anonymous]

If you are going to have any work done to the crank, have it welded otherwise use it as is. It is advisable if you run the motor hard. The only way to tell if you need to rebore the engine is to have it measured to see if it is within the service limits

I see...Thanks!

[Mastiff]

Rudi, you might want to look at http://www.dansmc.com/pistons.htm . It is probably more information than you want, but I always prefer to know more than I need, rather than less. Check out the guys main web page, http://www.dansmc.com/ . I use it as my home page. Everytime I go on the PC, this comes up. I read a little bit about motorcycle repair, then go on to whatever I was going to do.

[Anonymous]

Rudi, you might want to look at http://www.dansmc.com/pistons.htm . It is probably more information than you want, but I always prefer to know more than I need, rather than less. Check out the guys main web page, http://www.dansmc.com/ . I use it as my home page. Everytime I go on the PC, this comes up. I read a little bit about motorcycle repair, then go on to whatever I was going to do.

Cool website...Thanks! 8)

[Anonymous]

There's also the issue of balancing the engine components- that is, making sure all the pistons weigh the exact same amount, down to a fraction of a gram. The crankshaft can also be balanced, meaning all the reciprocating parts are the same weight & it spins freely, kind of like balancing a wheel when you mount a new tire. This can be time consuming, but it leaves you with a smoother running, longer lasting enigne, & it may be worth doing if you have the engine disassembled anyway.

[KGB]

There's also the issue of balancing the engine components- that is, making sure all the pistons weigh the exact same amount, down to a fraction of a gram. The crankshaft can also be balanced, meaning all the reciprocating parts are the same weight & it spins freely, kind of like balancing a wheel when you mount a new tire. This can be time consuming, but it leaves you with a smoother running, longer lasting enigne, & it may be worth doing if you have the engine disassembled anyway.

Good point, and I did have mine balanced.

To check your cylinders, use a micrometer. One used to check the "roundness" of a cylinder. There should be NO deviation.
Air cooled 4 cylinder motors have a tendency to put more heat into the 2 center cylinders. They heat up and cool at different rates than the outer cylinders. This is what can cause them to be out of round, or elliptical, "egg" shaped. This causes excessive piston ring wear and cylinder wear. The skirts of the piston may then slap against the cylinder walls.Both the psiton and cylinder will now need work.
The psitons can be expensive, about $45 each. The cylinder work is labor, no parts, hopefully.
Check around. ask around for a good machinist. It's not a tough job, lots of labor and perfection is the key.

[Hoomgar]

If it is done right by competent hands it should be better.

[Anonymous]

Wow! Dan's web site is great. Thanks.