A little rough when taking back off....

[Craiger]

Let me see if I can explain this right. I've done some maintenance over the winter (replaced plugs, plug wires, R/R, adjusted rocker arms, cleaned carbs). The issue last fall wasn't noticed until a little while into a ride my friend and I were on.

Ran great at first, then seemed to lose power when downshifting and taking back off....sometimes shutting down completely when downshifting to first. Limped it home and started planning the maintenance.

I took it out tonight for a test run and it ran extremely smooth. However, when I downshifted into a turn, I recognized the slight stutter in power when getting back into it. Seemed a bit rough for just a short period of time, then wanted to take off when as the RPMs went up.

I come home and start searching for symptoms on the forum only to find something related to the airbox....a suggestion to seal it up as best possible....that it could be a lean issue. I pull the airbox to seal the lid with weatherstripping and find something I hadn't noticed during maintenance (as I wasn't looking for it). Looks like the PO drilled about six 3/8" to 1/2" holes in the airbox. Could this possibly be the issue? Could it actually be this easy?

For reference, it's an '82 1100E and upgrades include a K&N air filter, Vance & Hines 4-into-1 exhaust, and an Accel ignition.

Plug wires were replaced with new Accel wires and sparkplugs are Splitfire. R/R is from a Honda CBR600.

[tkent02]

Holes drilled before or after the filter?
Either way it could be a factor, if the holes are into the area after the filter it is more likely to be the cause.
Can't hurt to tape them closed and see if it helps.

[Craiger]

They're before the filter.

I'll tape them up and see if there's any change. Thanks for the suggestion.

[bonanzadave]

Do ya think the PO did anything to the carb jetting ? If its still a stock setup those holes in the airbox are leaning it out. There should be one inlet air hole in the airbox and I can confirm where tomorrow if you want.

[tkent02]

They're before the filter.

I'll tape them up and see if there's any change. Thanks for the suggestion.

Who jetted it after the pipes went on?
Have you done any plug chopping to see what's really going on in there?

[Craiger]

I don't know who jetted it....or if they even did jet it. I thought of that earlier in my quest for an answer, but started looking into the airbox issue, first.

The air inlet hole....I was thinking it was supposed to be specifically sized for proper air/fuel ratio....which is why I asked about the drilled holes possibly leaning it out.

What's plug chopping? Sorry....still pretty green.

[Craiger]

Article on plug chopping: http://faq.f650.com/FAQs/SparkPlugFAQ.htm#Plug%20Chop

[Craiger]

Thanks for the suggestions of blocking off the drilled holes in the airbox. That resolved the issue. Rode the bike for a couple hours tonight with zero problems. In fact, it ran GREAT!

Now I'm going to remove the tape and seal them off permanently.