Finding Air Leaks + Carb clean??

[Ricko19]

First up, can anyone tell a newbie a safe and reliable way to find/see air leaks in your fuel/airbox/exhaust connections area? Preferably something non-flammable!

My bike is running a bit rough (1980 GSX750ET 16V) with popping and cackling coming from the exhaust - it has a 4 into 1 aftermarket system which was on it when i bought it a few months ago, with stock airbox and filter. It is doing it at idle, also when moderate revs are held at standstill, and when closing the throttle after acceleration. No sounds from the carbs, just the exhaust. It still revs cleanly to redline and has good power, but doesn't sound great when I am just cruising along - an unhealthy burble.

I put a new airfilter in a few weeks ago and it seems to be a little worse if anything, though the bike was sitting for around 6 weeks during this time. It also has fresh fuel, new OEM petcock and new plugs. Intake carb boots etc all look like they have been replaced by a previous owner and look good. No obvious splits, hardening or cracks in the airbox or rubbers.

I know everyone is going to say strip and clean the carbs - no they haven't been done since i got the bike. I wanted to exlude any airleaks in the system before I go anywhere near the carbs, mainly because:

1. Being a newbie I am not confident at all about pulling them apart and getting them back togther again corrrectly, and

2. With my poor health and serious allergies I can't go within a mile of carb dip/cleaner, solvents, paint, brake cleaner etc. without landing in hospital or worse. So the best I could do would be a little WD40 (which makes me sick enough) and compressed air. Due to extremely limited funds, I also couldn't afford to pay a bike shop to do them for me - so I'm a bit stuck there

I guess If I can't find any obvious air leaks I will have a go at the carbs for a basic clean. Should I be careful around anything in there with the compressed air? ANything in particular to pay attention to? Will I need to separate the carbs?

Any help appreciated If anyone can suggest air leak detection methods first though that would be great.

cheers

[chef1366]

I don't think there are any hypo-allergenic carb cleaners.
I'll save you and rebuild the carbs for you.

[Nessism]

Could be a jetting issue also. I'm a proponent of freshening the carb O-rings as a matter of course but the issue may be due to the header leaning out the mixture.

[Ricko19]

Thank you chef - if only we lived in the same country

Thanks Nessism - looks like I will be pulling them apart at some stage during the search, so will check and replace the orings if need be. Have never had any leaks (touch wood) but i know what you're saying

[Darkchyld]

Ricko19, Dishsoap. Take the fueltank off and rigg up a way to supply gas. I've used a quart oil bottle hanging on the handle bars.. Set the idle on the hi side.. 1500-2000 r's.. then with a small paint brush put the soap on.. often you'll see it get sucked in and the sound of the engine will change for a moment when you find any leaks. There are o-rings on the intake boots to the head that are high on the suspect list. And getting the carbs gone through.. kinda a must.. Hope you can find someone nearby to give you a hand with that..

DC

[reddirtrider]

You can check for air leaks around the carb boots by spraying water on them. If you detect any change in the RPM or observe white smoke you hav an air leak.

If the carbs have not been rejetted for the header you're probably running a bit lean anyway. So, to make a long story short, you'll probably need to pull the carbs, replace the boots/o-rings (depending on model), and clean/rejet the carbs.

Where do you live?

[rustybronco]

I know everyone is going to say strip and clean the carbs - no they haven't been done since i got the bike. I wanted to exlude any airleaks in the system before I go anywhere near the carbs, mainly because:

2. With my poor health and serious allergies I can't go within a mile of carb dip/cleaner, solvents, paint, brake cleaner etc. without landing in hospital or worse. So the best I could do would be a little WD40 (which makes me sick enough) and compressed air. Due to extremely limited funds, I also couldn't afford to pay a bike shop to do them for me - so I'm a bit stuck there

cheers

Try boiling them in a solution of water and washing soda (detergent) or water and lemon juice, then cleaning the passages with different size strands of copper wire.

[MacGyver]

Are the clamps maxed/stretched out? That was an issue on my GS550E and as a temporary fix/test I put zip-ties in place of the clamps. Other issues remained, but the sporadic idle was gone, the clamps were obviously not tight enough after that test.

[Ricko19]

Thanks very much for all the help and advice guys - will try out those methods and hopefully find my leak.

Another member of this forum, and member of a local club down in Oz has very generously offered to strip and clean the carbs for me (cheers Zooks) so that is a huge relief to me. Will take the opportunity to go over the boots/gaskets/airbox/clamps with a fine tooth comb and make sure they are sound.

Thanks again for all the help everyone. WIll hopefully have her running sweet in the near future