Mysterious Engine Problem – '92 Bandit 400N

[Wudy]

Part No of the new pistons is 12100-32C00-040.

A search in Google shows that as being a Part # for the stock pistons (os:0.4) (although my parts listing shows the Part's # as being:
12111-32C04-0F0 - Piston
12111-32C04-040 - Piston (os:0.4)
12111-32C04-100 - Piston (os:1.0)

EDIT: That's the Part no's for my '93 400P though, I guess the '91 400N may have different part no's to what I have.

[Chris H]

Sorry to join the party so late but Uk time difference and all, im thinking pilot screw o'rings, if they are bad you will get the same symtoms. Bad starting and nothing under 300rpm.

[Wudy]

Bad starting and nothing under 3000rpm.

[gsxr400 racer]

would be interesting to know if Canada has these .40 over size pistons available they are not in the US nor  I believe the UK

[Chris H]

Hi Jay,
I will check with a couple of UK suppliers for you.

[mosquito]

<Edited>

FWIW, I've checked a couple of online vendors recently and this is what they seem to indicate for availability (i.e., will it go into the shopping cart?):

                    BikeBandit  Clawson
------------------------------------   
12100-32c00-040     Yes         Yes
12100-32c00-100     No*         Yes

*marked as discontinued / unavailable

http://www.bikebandit.com/suzuki-motorcycle-gsf400m-bandit-1991/o/m6135
http://www.clawsonmotorsports.com/fiche_select.asp

[mosquito]

BTW, did you ever get this sussed, OP? 

I've developed a similar problem with 2 & 3 not firing consistently (and not idling) under about 3k rpm.  I'll be installing new needle jet o-rings tomorrow and if that doesn't do it, I'll start looking at electrical issues.