Topic: Starting Engine with Loose Fitting Headers

[emitch]

I have a '74 cb750 that i'm trying to start. It's pretty much a barebones engine and frame at this point. I've hard wired everything(sans the wiring harness), and ghetto rigged a gas tank. I cleaned up the carbs, and got em mounted. The engine turns by hand, and I cleaned up the points, changed the oil and the spark plugs. It's pretty much ready to get started, except I don't have an air filter or proper mounting pieces or gaskets for the exhaust.

I can fit the exhaust headers and muffler I have into the exhaust ports, but there's obvious leaks as there's no gasket or flanges. Can I start the engine with the exhaust like this? Also, I don't have an air filter. Will this be bad for starting the engine? Is there anything I need to watch out for, or keep in mind?

Eventually I plan on getting a new exhaust, and air filter, but at this point i'd rather not spend the money on those pieces until I know the engine will start and idle. So at this point, that's my only goal.

Any input is appreciated. Thanks in advance!

[KingCustomCycles.com]

"Is there anything I need to watch out for, or keep in mind?" yes, a fire and possble hearing loss.  I have run them sans exhaust and air filter, bare carbs, but they run really poorly in that condition.  Better if you have raised the needle or richened the jets to compensate for all that air in and out.  Running like that will tell you if you have any major leaks, tranny trouble, or clutch issues.  I ride my rollers with temp. gas cans, no exhaust, no filters, no seat, no fenders, and a garden tractor battery bungeed to the frame, rear brake only.  It ain't pretty but it tells me what I need to know before I invest time and money into a hardtail conversion and frame build.   

[emitch]

Thanks for the reply Kingscustom. So if I do start it up, I should enrich the mixture to compensate - how much would you think I have to enrich?

Would it just be beneficial for me to just go ahead and invest now on the exhaust and air filter pieces? Even though I have no idea in the end of the condition of this motor? Or should I just go ahead and try and start it the way I have it?

[KingCustomCycles.com]

Start it, see what you got, then buy the goodies.  If I end up finding the motor has issues I have a spare or two to swap but I want to know what I have before I install it in my freshly painted frame. 

[ekpent]

[quote author=KingCustomCycle  I ride my rollers with temp. gas cans, no exhaust, no filters, no seat, no fenders, and a garden tractor battery bungeed to the frame, rear brake only.  It ain't pretty but it tells me what I need to know before I invest time and money into a hardtail conversion and frame build.   

  You have got to post up a pic of that please-it would be a classic. Has a Cop ever seen that. Been through Brookston a lot  when I was trucking and doing Indiana and Lafayette,you probably own him or fix his bike HAHA   

[KingCustomCycles.com]

I have considered riding one like that around Lafayette just to show how little it takes to actually go down the road.  Hand signals for safety, of course. :-)

[emitch]

Okay so I'm confused a bit on this, but do u turn the air screws in or out on the early keihin(73) carbs to enrich the mix?

[ekpent]

In all honestly if you do not plan on riding it yet but are just looking to start it up and make sure it runs,fires on all 4,etc. I don't think you need to waste a lot of time over thinking it all. No real damage will be done if it is run for a short period of time with some of the issues you describe. Save the hard work for final assembly and tuning.