My motorcycle pops a lot after I rev it a bit. And it wan...

Hello, Welcome to Just Answer My name is \*\*\*\*\* \*\*\*\*\* I've been an automotive engineer since 1996 and together we're going to solve this issue. I understand that having your trusted vehicle let you down can be frustrating as it rarely occurs at a convenient time, however I will do my best to either help you make the repairs yourself or at least understand the issue so you know what is involved. so for an engine to pop and crackle on the over-run this usually means there's a lack of spark advance as well as fuel coming in if the bike is the fuel injection model then I'd say to check the condition of the ignition system 1st and if thats OK then check the fuel pressure at the injector rail with the engine running 1st thing to try is to remove the fuel filler cap and then flick the ignition on whilst listening for the brief ‘buzz’ of the pump If the connections to the pump are corroded or damaged, then the pump could stop at any time or could not be running at full speed. Check that its relay switches in and out and the relay contacts are clean and bright – replace the relay if in any doubt and do the same for the fuse, Ideally measure the pressure at the injector rail (should usually be around 3Bar / 45psi +) and if this is low check the pump as described and consider changing the fuel filter as if this partially blocked this too will reduce pressure.

Sounds like i meed need some special tools to do this. What should i get?It carbureted

OK in that case I'd say to clean the carbs out, especially checking the condition of the air correction jets all you need for that is a can of carb cleaner and a set of new gaskets also use a timing light to check the ignition timing

Well the carbs were just rebuilt so they should be good, yes, or am i wrong? Ill check the timing. Might it be a air/fuel ratio issue? How could i tell for sure?

OK if the carbs are 100% clean and with no clogged jets then another thing to check for is any vacuum leaks after the carbs, as this will draw air in on the over-run The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane or brake cleaner around each joint in turn. If the engine rev's up you've found your leak. Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident. Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements. Air leaks are very temperature dependent as gaps can open up as things expand with temperature so depending on how the leak occurs ( on a hose joint with a clamp expansion will help seal and on a vacuum hose expansion will make a leak worse) so leaks can be better or worse as the engine warms up ideally to check the AFR you would use a lambda / Oxygen sensor in the exhaust , if you were to put the bike on a rolling road then they usually have a probe that can go up the exhaust and so measure this for you under load and on the over-run