1978 GS750E Main Jet

[Guest]

I went to start my bike and get it ready for the upcoming riding season and...... surprising started right up! Great, but then it was idling rough and when given gas it bogged down. I took about the carbs to clean the jets and bowl. Sure enough, it needed to be done. Unfortunately I broke the main jet on carb 4. I just bout my bike at the end of Aug 14, so I am still learning. I didn't know the jets were separate from the jet housing and probably should have used a socket instead of a flat head

I broke the jet from the housing, but he housing is fine and free of the jet thread. Here is a picture of the broken piece. It is number a 102.
IMAG0149 (1).jpg


I can only find sets of 102.5 on eBay. Will this .5 increase matter? Here is a set I am thinking about purchasing.

http://www.ebay.com/itm/102-5-Mikuni-KN100-604-Large-Round-Main-Jet-KN100-604-1025-/321698707348?pt=Motorcycles_Parts_Accessories&hash=item4ae6bcb794&vxp=mtr

If the size difference is a problem, where can I find a 102?


Thank you,

[CrazyCloud]

102.5 is the stock size, Z1 enterprises is a good source for jets.

[allojohn]

Or JetsRus

[chuck hahn]

Hold back the needle jet with an 8MM wrench and use the flat tip to remove / install main jets. Dont just screw them in and not hold the 8MM area..to do so is also torqing the threads on the needle jets and the carb body itself. If you strip something its a bad day at the office.

[CUEagle17]

Thanks for the advice everyone. I order 102.5 main jets and they should be in by Friday. I will make sure I install properly!!!

[chuck hahn]

They came with two stock sizes as I remember things. My old one had 97.5 mains and then the other size was 102.5 ( depending on what EPA jetting was put in the particular bike ).

[one_civic]

Don't mean to hijack thread but I have a 78 Gs750 and am installing a yoshimura 4-1 with a stock airbox this year,

I cleaned the carbs and the mains where 102.5, I pulled the plugs last year with stock airbox and stock (baffle less) exhaust and my plugs where very rich. Should I keep the 102.5 mains and do a proper plug chop for the yosh 4-1 or go back to the stock 100 mains?

[chuck hahn]

keep the 102.5s and put in new plugs...THEN see what they look like with the 4 into 1 before throwing money around would be my approach.

[one_civic]

perfect, thanks chuck

[chuck hahn]

My reasoning is that you tend to have to up the jets when going to a 4 into 1...so keep these and try the plugs first...they may be good enough.