This may seem silly, but I'm asking anyway. I've just moved, and am short of tools and space. I balanced my '00 F4's carbs about a week ago. I have a rough idle, which I expect to be pilot circuit related. For lack of tools and space, I'm struggling to work through a full cleaning of the pilot circuits. About all I can do just now is blow carb cleaner through the jets once I remove the screws, and scrape off a miniscule amount of blackness from the needles.

It's been suggested to me by potential servicers I might hire, that a compression & leakdown test should (or must) be performed before any carb work, so as to eliminate potential valve or piston/cylinder troubles before spending time dealing with the carbs. The bike has close to 17k miles on it, but runs very well and neither uses nor leaks any oil whatsoever over the course of 1,000 miles. I ride it 70 - 75 miles every day, mostly on the freeway, in southern Arizona.

I understand the logic behind wanting to test compression, and have contemplated doing that myself. I haven't done it because there are no issues which suggest to me a potential compression problem.

So my question is: Given the above info, would you agree to let a shop check compression first, or skip that step? My logic is that I'd expect _some_ other indication of trouble if there was low compression somewhere, and specifically I'd expect carb balance to be either messed up or difficult to set on account of I would expect that low compression leads to low vacuum.

What do you think? Thanks.

 

They are not wrong, and i think u agree there is logic to there suggestion. but it is only a suggestion not a must do. 1 reason for poor compression could be lack of valve shim clearance.
if u have already found minor dirt in the jets ,there is reason to believe there could be more in the carb body cavities. i would try running a few tanks of carb cleaner through it , and see if that helps , then resync, before spending money.

 

That the kid I got it from gave me a bike with filthy carbs is true. A fast but decent (except I didn't have the D-shaped wrench for the pilot circuit needle) cleaning I performed during the winter cured the carburetion issues other than the less-than-perfect idle.

I believe the comp. chk will only add ~$50. I only struggle to say yes on account of I can do that somewhat quickly and very easily myself once I get tools back, and because $ is at a premium during this move. Perhaps I should wait until I get tools back, and run through all this myself. That'll save me (and CBRForum ) any more of my whining, and the bike runs fine apart from a rough idle.

Thank you for your reply.

 

I'd say wait for your tools. Sounds like you're doing it more for peace of mind than diagnosing a serious problem. Peace of mind stuff that I can do myself, I do it myself.

Use the $50 for beer and pizza while you work on her till you get setup to do it yourself

 

I would never pay some more money than what I can pay for the tool and do myself.

Now, for your issues, a bike with 17K miles on it I think is very unlikely that your valves are out of adjustment or having any problems at all. No real symptoms. A bike that's 11 years old with only 17K miles on it is very likely to have carburetor problems. A proper cleaning and then synchronization is probably in order.