1978 GS400 Clymer manual suggestions

[sbrink97007]

there are a couple of suggestions in the back of the 1978 Clymer manual for the GS400.

one was a cylinder bore and larger pistons. i have found the pistons for the overbore from Wiseco. they are a GS750 2mil overbore. the 2 valve GS750 & GS400 apparently share the same piston, so the larger piston will work in the gs400.

second was to upgrade the carbs to the Mikuni Round Slide Carburetor 32mm Bore. the Carb on the gs400 is a 34mm but i will take for granted that the old clymer knows what it is talking about.

here be the question(s)
-has anyone done either or both of these
-the round slide carbs appear to be very different from the carbs on the 78 GS400. does anyone know how you would a) mount them b) run the throttle cables?

thanks for all the information this is a great site

[spots25]

what manual do you have? I have the Clymer for GS400-450 twins, 1977-1987 and it makes no mention of these upgrades... you have piqued my curiosity, could you scan the page?

[sbrink97007]

yup i will do it when i get home tonight. the pages are in the last chapter of the book. i think it is actually called performance modifications.

[Arkaloid]

Old school stuff maybe?

[spots25]

yup i will do it when i get home tonight. the pages are in the last chapter of the book. i think it is actually called performance modifications.

lucky!! I don't have that chapter at all!

[cfcubed]

lucky!! I don't have that chapter at all!

Yes, I happen to have 2 Clymer GS400-450 twin manuals; 1) an old, greasy one - has last upgrades chap. and 2) a new, clean one that does not... Seems newer editions omit it.

[sbrink97007]

yes, mine was old and not so greasy, but now it is getting there and yes, it is Upgrades thanks cfcubed. i will scan and post tonight

[sbrink97007]

so's you see i scanned them big ok, so you could like read them. but now they are too big to be uploaded here. i have posted them on an old free site of mine

they are

http://sbrinkmeyer.tripod.com/gs400/gs400_229.jpg

http://sbrinkmeyer.tripod.com/gs400/gs400_230.jpg

http://sbrinkmeyer.tripod.com/gs400/gs400_231.jpg

[spots25]

very very interesting... i might have to look into that in a few years, although unfortunately, i'm sure most of the parts mentioned (other than the pistons and carbs) are no longer available

[sbrink97007]

i have the part numbers for the Wiseco pistons they are ~100 a piece
the mac 2-1 pipes are $183, the k&n pods are ~80, the carbs are ~100 a piece also. about 800 total hmm not bad for a bike that is worth oh 500 on the open market!

then it is all a matter of time! bwaa haa haa

[spots25]

my question is this: do the same pod filters fit both the stock carbs and the Mikuni rounds? Because i'd like to upgrade to pods now (well, i don't really have a choice) and want to upgrade carbs later

[spots25]

here be the question(s)
-has anyone done either or both of these
-the round slide carbs appear to be very different from the carbs on the 78 GS400. does anyone know how you would a) mount them b) run the throttle cables?

hmmmm... well, I had my first experience with round slide carbs today, and I'm sure the mounting them would be the easy part. Instead of a traditional (as far as I'm used to) throttle system, each carb needs a cable running in the top of the carb. Thats a tough question