1980 Main jet

[ajs350]

I have my carbs apart for cleaning and they contain 115 main jets while the manual says they should be 110's. I run a stock exhaust, stock airbox and a K&N filter. Are the 115's OK or do I need to replace with the 110's? Thanks Ross

[oilheadron]

Have your bike dynoed by a pro if that's feasible. That's the very best way to answer your question definitively.

Whoops, missed the part about the carbs being apart. There are about a million variables here (for why somebody might have changed the mains in the first place, wisely or not), but I'd probably go back to stock mains while the carbs are apart and then have the bike dynoed.

[zxbob]

They should be 110s as the book says. On my 80, I took out the 110s and installed 112.5s but I am running a Kerker exhaust and
a K&N filter in the stock air box.

I pulled the plugs a couple weeks ago and could'nt ask for a better looking plug. I think the 115s would be to rich for a stock set up.

Bob

[EMS]

All CBXes are usually set lean from the factory. I wouldn't think the 115 is too rich....

[daves79x]

Actually, I think you'll find the CBX is a wee bit rich on the very top (totally on the main) and lean everywhere else. EPA only checked idle and part-throttle emissions, so that's where the carbs were set for. The K&N drop-in will lean you out a bit and you may want to shim the needles .020 or so and go back to the 110 mains. Your pipe choice does not matter much.

Dave

[oilheadron]

My '79 has stock numbered jets and needles (which don't show any signs of mods, but who knows), but like Dave mentioned it's rich on full throttle. Quite a bit rich in fact. (Usually the Japanese manufacturers made the the A/F close to optimum at full throttle on showroom stock bikes back then, but this bike has a DG 6-1 with a baffle, stock airbox and filter, and I'm wondering if the DG might be choking it down a bit.) The 6-1 systems are apparently not known for the best hp, but I'd love to lean it down a smidge and see what happens on the dyno. BUT, with the stock airbox minus the air filter the bike ran WAAAAYYY lean. Lots of variables going on here (for example, the bike had been run without the baffle for a long time and when we installed a used baffle we had to literally pound it into place to seat it). So in my mind I'm seeing a folded up restricted joint in there. :) It doesn't run that way though, it gets on the cam nicely at about 6k and revs very cleanly all the way to the redline, even though it's admittedly too rich for optimum power.

[SanDogDewey]

I have my carbs apart for cleaning and they contain 115 main jets while the manual says they should be 110's. I run a stock exhaust, stock airbox and a K&N filter. Are the 115's OK or do I need to replace with the 110's? Thanks Ross

My 1980 has 115's but I'm running stock airbox w/K&N and Kerker 6-2's.