400e rebuild

[moose200]

I am rebuilding a 83 400e , I was wondering if there is a cam that works better then the stock? and any other mods that would help?? gs40-115524 is the engine model
thanks

[Mekanix]

Hey another Canadian model Most people here are 450 fan's with 2 valve per cylinder engines. I'm the 4 valve per cylinder 400 guy

There isn't a cam that works better than the stock one as a direct replacement no matter what year or model. Best bet is to get WEB cams to regrind them to your specifications. I'm going with a 355 grind as suggested by Ray. The rockers give a multiplier of 1.52 x the cam which is 0.180 stock and that gives you a 280" cam lift for both the intake and exhaust. The lobes are asymmetrical and its the same for the larger inline 4's.
On the 450's and 500's the cams are symmetrical as are all the two cylinder engines and installing one of those would be insane because the resultant lift is somewhere near 460 They are meant only for the shim over bucket heads. You cannot use a cam for a 4 cylinder in this engine even if you cut the outer lobes off. IT would fit though but the cam lobes would be 90 degrees off because the 4 cylinder's middle pistons rise together where the twin are 180 apart.

The porting on these isn't that good to start off with, the castings have obvious flaws.

Rapid Ray is the guy to talk to about anything really technical like that.

This engine is quite good the way it is though. It puts out almost 46hp at 9000.
The initial powerband starts at 4000 and goes to 6000 then smooths out until it comes alive at 7000 to redline. It can shift very quickly with minimal clutch and its quite fun to drive.
The ignition advances fully after 4000 and is mechanical in nature. The springs can wear and allow it to happen sooner.

The original charging system sucks!! There are many threads on what to do about that and what new parts fix the problem.

The stock gearing is ok in general but upping the front one tooth helps with highway driveability because normal cruising speed is right in the 5-5500 range and that's where it vibrates the most.


I think i can help but I'm going way way overbore.

This is my build: http://www.thegsresources.com/_forum...d.php?t=172422

Happy reading.


Next your going to get a MEGA welcome from Basscliff our local welcoming comity. Welcoming you to the site and giving you the link to the almighty gs database that is his website.

There you will find manuals that you can download. How-to tutorials and much more along with the top 10 noob mistakes.

Here is the link: http://members.dslextreme.com/users/bikecliff/


This engine is special because it has many parts interchangeable with many of the larger engines with 4 valve per cylinders

Here is a website that you can look up part numbers for your bike and different bikes to compare: http://www.cmsnl.com/suzuki-gsx400-1...617/partslist/


Your pistons, rockers, springs, cam chain tenssioner, valves,...... are all interchangeable with a 16 valve 750. And their big bore kits work in there too.

The base is the same on all twin cylinder 400-500 from 1981 on.
So you can use any of those parts as well. the only difference is the cylinder block, head, and pistons.
They are not interchangeable but you can put them on either one's base and its identical.


The engine is a 56.6mm stroke with 67mm bore. Compression ratio or 10.5:1

They do have a few problems that might be fixed by your 1983 year.

1 cracking between the exhaust valve and spark plug hole.
1980-1982 was a problem and it was fixed in later years. Not sure how but it was. The only difference between the 1980-83 and the 84 up is the valve cover and gasket has the bolt holes in different places.

There are 2 upgrades that are a must!!

1 take the exhaust rockers out that have a slit in them. They are supposed to be plain just like the intake ones. I believe the next year after yours has this fixed already. Its a Suzuki fix because the cam was getting grooved in the middle where there was no contact and it was wearing out the cams. Oil shoots up the middle and misses the rockers for the most part. You could replace the cam and rockers from a junk engine but just use the intake rockers. I can upload pics if you want to see what that's like.

2 the clutch pushrod under the sprocket cover is 2 pieces in later years and is one piece in early years. The one piece rotates with the clutch and wears out the clutch seal. The two piece rod stops this from happening. you will know what you have if you can pull the rod out and its only 6 inches long. if it doesn't come out easily at all then its the old style. IT doesn't hurt anything but there is an upgrade. kind of like a service bulletin.


Adding pods and jets will help and being a Canadian model you have adjustable needles where as the others are hit and miss. The many performance exhausts for the 450's are a direct bolt on for these as far as I know and only require jetting.

Hmm what else :P




Oh yeah, Download the two manuals he has for the twins, they both have different information and the Haynes manual has an upgrade section in the back.

Download the 750 and 1100 manuals as well because they actually tell you everything about how everything works and the theory where as the 400's manual really sucks if you want to know WHY about anything.



A few things you have to do while your introducing yourself.
Add the Year, make, model, name or quote to your signature. Its in the User CP section on the top left of the page and on the side of the next page.

Next post some pictures in this section http://www.thegsresources.com/_forum...d.php?t=166061



Feel free to ask questions, this site is quite active.





You can slot your cam sprockets and play with the powerband a bit by moving the cam centers, It all depends on if you have the valve clearance.

You can bore and fit half a gs750 big bore piston kit.

Cometic can make you a gasket for it.

The sleeve sidewall is around 4.5mm thick so you can bore up to 5mm over or just drop in a 450 or 500 block and go bigger but use your head.

You can have pistons made for that as well by CP or JE or Wiseco.

[pete]

Welcome to the forums! Bit of a GS twin fan myself, but yeah... I got the 450 2 valver

However, Mekanix knows his 4 valvers and will definitely steer you right

[moose200]

Thanks, and I did notice a little wear on the cams from the split rocker...