GS400t with 4 valve cyl head

[mikestp]

one hour to pull apart 3 hours to reassemble .....

[mikestp]

Ok to keep this posting up to date. I was able to find a new piston for this bike in Singapore. And the gaskets from Japan. There are very few parts that are interchangeable with the two valve model. the cylinder head bolts are a different spacing, the gaskets are all different, the rings are different, the head gaskets are different as are the base gaskets. in fact, in my opinion, the only thing that might interchange is the spark plugs. So if you are considering repairing a 4 valve, either search the net for the proper parts or swap out the complete engine with a two-valve engine.

[John Park]

The head bolts are only different spacing on the roller crank 400 '77 - 79. I think the 450 base gaskets are the same; everything above that IS different but bolts directly on. Below the beltline they are identical, except for the rear camchain guide, which works anyway.

A two valve 400 is very different, and could be a challenge to get into the newer frame. Hard to imagine why you would want to, unless you already had a nice one looking for a new home. The two valve 450 top end drops right on the four valve. Exhaust fits, carbs fit, but intake boots are different.

Glad to hear you found a piston; I had some well used ones but gave them away along with the rest of the plot this Spring. Considering the cost of gaskets and such, you're better off with a new one anyway.

I disagree; you don't have to swap the whole engine. Used 450 engines worth buying are usually twice the price of just the top end, plus you get to inspect everything and use new gaskets etc. OTOH to plug and play a used engine is quick, if it works out; in many cases you end up undoing the top end of the 'new' used one anyway.

[mikestp]

The head bolts are only different spacing on the roller crank 400 '77 - 79. I think the 450 base gaskets are the same; everything above that IS different but bolts directly on. Below the beltline they are identical, except for the rear camchain guide, which works anyway.



A two valve 400 is very different, and could be a challenge to get into the newer frame. Hard to imagine why you would want to, unless you already had a nice one looking for a new home. The two valve 450 top end drops right on the four valve. Exhaust fits, carbs fit, but intake boots are different.



Glad to hear you found a piston; I had some well used ones but gave them away along with the rest of the plot this Spring. Considering the cost of gaskets and such, you're better off with a new one anyway.

I disagree; you don't have to swap the whole engine. Used 450 engines worth buying are usually twice the price of just the top end, plus you get to inspect everything and use new gaskets etc. OTOH to plug and play a used engine is quick, if it works out; in many cases you end up undoing the top end of the 'new' used one anyway.

Base gaskets are different the head bolt stud spacing is about .100 off from the holes in the base gasket. The head gasket is the same problem. The bore is a different size, The rings, of course, are different I do not know if the crankshaft is different but since the other major parts are NOT interchangeable it would be fruitless to even bother to look. In other words, there are perhaps a few interchangeable parts..... spark plugs, hmmmmm im running out.... No way will any parts from a 2 valve 400 era 1982 fit a 4 valve 1982.

In the USA, there are no 400 4 valve engines since they were never sold in the USA. only Canada and Europe and Japan had em.

The xhaust does indeed fit onto the two valve head. But since you cannot fit a 2 valve head onto the cylinder of a 4 valve engine... why would anyone care.

I think you did not read the entire thread to find out I have a 4 valve GSX400E I needed a piston and after 4 weeks i found one in Singapore. Gaskets were found in Japan. Bike being reassembled now. I just wanted to update the thread in the hopes that anyone else looking for parts for a 1982 GSX400E should not waste any time looking in the USA for such parts. I started the thread with the possible swapping of some parts from the 2 valve engine. But alas no parts interchange. It might be possible to swap out the 4 valve engine for a USA 2 valve engine either a 400 or 450, but I am not sure of the engine mountings.

[Gorminrider]

John, what do you think are specific differences between camchain guides gsx 400 to gs 450? part numbers are very close ...gsx400=128-44250 versus gs450=128-44150.

I'm looking at one here from a gsx400 that needs replacing. ... the one from my spare engine torn down is a lot better to look at but is showing tiny cracks in the plastic..... I'm not too happy to go through the trouble if the replacement is no better while a new one for a 450 seems easier to get...(59.00 US!)

[John Park]

Base gaskets are different the head bolt stud spacing is about .100 off from the holes in the base gasket. The head gasket is the same problem. The bore is a different size, The rings, of course, are different I do not know if the crankshaft is different but since the other major parts are NOT interchangeable it would be fruitless to even bother to look. In other words, there are perhaps a few interchangeable parts..... spark plugs, hmmmmm im running out.... No way will any parts from a 2 valve 400 era 1982 fit a 4 valve 1982.

In the USA, there are no 400 4 valve engines since they were never sold in the USA. only Canada and Europe and Japan had em.

The xhaust does indeed fit onto the two valve head. But since you cannot fit a 2 valve head onto the cylinder of a 4 valve engine... why would anyone care.

I think you did not read the entire thread to find out I have a 4 valve GSX400E I needed a piston and after 4 weeks i found one in Singapore. Gaskets were found in Japan. Bike being reassembled now. I just wanted to update the thread in the hopes that anyone else looking for parts for a 1982 GSX400E should not waste any time looking in the USA for such parts. I started the thread with the possible swapping of some parts from the 2 valve engine. But alas no parts interchange. It might be possible to swap out the 4 valve engine for a USA 2 valve engine either a 400 or 450, but I am not sure of the engine mountings.

Yes, I did read the entire thread. I'm less concerned about whatever you believe than what others might be led to believe. The 450 topend bolts directly to the GSX400 bottom end. The factory made the variation an easy one. I've been riding this swap for several years and maybe 20,00 miles now. Yes, like you, I have a 1982 GSX400 and swapped a 450 cylinder, pistons and head on the original 400 block.

Someone who used the WHOLE 450 topend would definitely care whether the exhaust would fit. The stud spacing measurement you tout seems dubious unless you had a 450 block around to compare measurements with; going by the gasket holes isn't any confirmation. I am sure of the engine mountings being the same.

And the spark plugs are a completely different size; as if it matters. The cranks are the same; in fact I think they stayed the same on the GS500 thru 2009. You could put a GS500 barrel/pistons and a GS450 head on your GSX.

450 topends are available used quite economically on Ebay and are a lot easier to ship than a whole engine - plus you get to see the insides as you buy them and can fit new gaskets, rings, lap valves , etc, so when you are finished you have a bottom end you are familiar with, already installed. It's just a complete topend rebuild with different parts. The way you're doing it works but the one thing you can't fix is the 4 valve parts availability which is currently on life support.

I'm all for doing what you did. It's just not the only way.

[John Park]

John, what do you think are specific differences between camchain guides gsx 400 to gs 450? part numbers are very close ...gsx400=128-44250 versus gs450=128-44150.

I'm looking at one here from a gsx400 that needs replacing. ... the one from my spare engine torn down is a lot better to look at but is showing tiny cracks in the plastic..... I'm not too happy to go through the trouble if the replacement is no better while a new one for a 450 seems easier to get...(59.00 US!)

The 450 one is longer, unfortunately. The 400 cams are further apart but sit a little lower so the cam chain is the same length. Thus the part line to crank distance is shorter. This also moves the rear guide further aft than the 450 so you have to make a spacer for the cam chain tensioner when you do the swap.

Have you tried Suzuki Canada?

I've seen that microcracking thing on guides I've taken out of engines and it didn't seem to have been a problem. The face of the guide is under compression so the cracks are being forced closed. I guess it could eventually start to break up....does cmsnl have any? Should be cheap to ship.

I have one inside a low miler engine that I haven't taken apart yet. It's destined for the 450 conversion so I could pull the guide out and see how it looks if you're stuck. In fact, you can have the whole topend when[ever!] I'm done.

[Gorminrider]

Roger that, John! thanks... yes now, I recall you saying the tensioner was problematic and you say "taller too?...well, then I guess I won't bother with the 450 guide...I had a look at CMSNL but they aren't available...I'll dig around a bit. Hopefully I won't be taking yours away from you (super Thanks!) ...but really this spare one I have should do for this bike...the one presently in is cracked across just above the thick bit at the tensioner "landing" but I'm even considering leaving it in as it has been functioning ok

...SUCH a b*gger getting these out, I know now! I had to move the crank shaft so the thick bit would come through the tunnel where it's slightly wider... This tensioner guide must have been the first part they put in on assembly!

[John Park]

Roger that, John! thanks... yes now, I recall you saying the tensioner was problematic and you say "taller too?...well, then I guess I won't bother with the 450 guide...I had a look at CMSNL but they aren't available...I'll dig around a bit. Hopefully I won't be taking yours away from you (super Thanks!) ...but really this spare one I have should do for this bike...the one presently in is cracked across just above the thick bit at the tensioner "landing" but I'm even considering leaving it in as it has been functioning ok

...SUCH a b*gger getting these out, I know now! I had to move the crank shaft so the thick bit would come through the tunnel where it's slightly wider... This tensioner guide must have been the first part they put in on assembly!

I didn't realize that you were referring to the rear guide; I'm not going to have one of those available. The 450 guide will be taller and a different shape. I think you might end up with a bit of a corner for the chain to get around. The 400X guide with the 450 top end has been no problem.

Yes, the rear guide does look like it goes in before the crank. Kind of a non optimal design, but then they have been functioning fine for the last 35 - 40 years so not much right to complain.

There's not much load on the back side, BUT...at high revs the chain wanting to be a circle and the guides and sprockets trying to make it otherwise will generate considerable force, and above the tensioner the guide is free floating with the expected stress riser right above the landing.

I hope you have something else to ride while you're doing this invasive surgery.

[Gorminrider]

above the tensioner the guide is free floating with the expected stress riser right above the landing.

demonstrably, in my case..

Oh,yeah! Two others licenced so not missing this magic weather! but I always miss this 400E... I figured that last rain would sock in so I started in on it..(low compression one side...valves bent I figure ...a mishap with me as root cause I believe...but apparently the cam chain guide took a bounce too...yet pistons look absolutely fine)

[mikestp]

Well, I am probably at fault in my descriptions. I have a Canadian GSX400 bike circa 1982. It has 4 valves per cylinder rather than the more popular two valve variant. I have a spare junker engine that is a two-valve also 400 CC. The bores for both are different. The cylinder and the head form the 400 2 valves will NOT work on the 4 valve bottom end. This I know as I have both here. The measurements of the stud spacing are out by .100 The 2 valve base gasket will not fit the four valve bottom end. Both in size and in oil passage to get the oil to the top end. I am sorry to have not given proper descriptions, but I am worried people looking to do as you suggest will get screwed. Also, the crankshafts are different, the 2 valve model has a stroke of 60 mm and a bore of 65, whereas the 4 valve model has a bore of 67 and a stroke of 56.6. I am sure you are referring to swapping parts from the 450 2 valve model with a 400 2 valve model or perhaps you are swapping a 450 top end onto a 2 valve 400 bottom end. This is NOT what I am doing. There are two different models of the GS400 bike only one of the two was sold into the USA. Both were sold into Canada. Also, I think the EU and Japan. perhaps Aus as well. My apologies for your misunderstanding.

[John Park]

Yep, the old roller bearing 400 is a different beast entirely. I now see what you've been getting at; didn't realize that you had one around. Parts for those are getting pretty thin too. They also made a 425 version with a 67 bore.

The 450 top end easily swaps onto a 4 valve 400. While it looks more similar to the old version 400 head - as you say - it won't go, unless you're a master machinist looking for a retirement project.