'80 750 4cyl Backfiring issues...Newbie

Hello all, im new to the forum, have been reading it for about 2 weeks now, so much great information really shining a light on things i need to know and look for one this new toy.

Ok so im woring on a 1980 KZ 750 E-1 4cyl LTD, found this by cross-ref the engine vin. for starters it was sitting for over 6 years in some guys lawn, i started with the normal descaling the tanks and just a bit of cleaning the carbs, well i had got it running, but it is missing, will not rev over 3-4000 Rpm from what im guessing (tach is shot) is back firing out of the right bank exaust system but has 1 redeeming quality, only has 22,000 on the clock and 0 smoke out of the pipes, so i know its a good motor to actually spend some time on, what im looking for is what you guys (and gals) usually go through as a check list of sorts to check on a long time sitting bike, or any bike with these symptoms, also it still back fires, slow revving and all when warm, it does act a bit diffrent but mostly the same gremlins, im very new to really tearing into a motorcycle, always been a muscle car guy actually so i have alot of the basic gas in, gas burn, exaust out know how, but the timing, valves are really what im pointing to at the moment, and i am completly lost on adjustment, im going to be looking into the ignition also i have no clue if its points or electronic or god knows what else, ill have more info on that later, thanks for any help and again i do love this forum!

Order a new valve cover gasket as the old one will tear when you remove it to check the valve clearances. You might be able to get it from the Kawasaki dealer if not try at www.z1enterprises.com He might be able to get it or point you in the right direction to find one.

The carbs probably need a good cleaning. www.wgcarbs.com is a carb cleaning service who contributes to this forum a lot. He has a very vast list of knowledge regarding motorcycle electrical systems and carbs.

The various rubber ducts/manifolds/tubes that air moves from the air filter to the carbs are going to be dry and cracked and need replacing. This is usually where air leaks come from and cause high rpm problems and poor running.

A good replacement for the stock ignition system is available at Dynatek www.dynaonline.com Consider doing the "Wired George" coil mod on your bike as it will make it an easy starter and more dependable.

Get a factory shop manual for it at www.repairmanual.com
Bringing these older bikes back to life can be an expendature of time and money but the feeling of getting it running well is very rewarding.

A list of websites for older Kawasaki parts:

1. www.oldbikebarn.com
2. www.z1enterpreises.com
3. www.oldkawman.com
4. www.babbitsonline.com
5. www.redlinecycle.com
6. www.dynoman.net
7. vintagecyclepart.com
8. www.kzzone.com
9. www.crconlinecatalog.com
10. www.sudco.com

I have more for control cables,ststors,electrical connectors,suspension parts,drive chain and sprockets,Carbs,etc.........

It's a 1980 KZ750H1 LTD

Download the Manual HERE

"Complete" tune up, including checking the valve clearances.

Change oil and filters, check all bolts for tightness, check (and probably should change) fork oil and brake fluid, inspect tires and chain (might as well plan on new chain and sprockets), check everything for proper operation.

And before you ask, It will not shift into anything but first and neutral if the bikes not moving, Kawasaki calls it a "Positive Neutral Finder"


Plan on cleaning rebuilding the carbs.

Electronic ignition, no points.


Edit, since I see another post was made while I was typing.

I fail to understand why people push Dyna ignitions, they are electrical power hogs and over priced to boot, you can make your own igniter (should yours fail) that's a whole lot cheaper, uses less power, and works as well (if not better) than a Dyna.

Hmm, maybe they don't know that better alternatives are available.



Another edit

A muscle car guy huh, well, when you're ready for more power just do a search for 810 kits

It's a little cheaper to hot rod these motors than the muscle car motors, but a whole lot easier


And another edit

Under the small round cover on the right lower side of the motor is the ignition pickups and the timing advancer. The timing advancer works just like the mechanical distributor advance in a car, make sure it's not stuck.

Thanks a ton for all the links of Parts venders, i had found a couple but that is going to help alot Mfolks, Alos i did pull the carbs and cleaned them top to bottom, i was very suprised everything was in good shape just dirty, even the rubbers inside were 100% pliable and they sealed back up with no leaks after the cleaning, (first time re-assembling 4 carbs at once) but i got it first try so i was happy, the tires and chain are completly shot as this is new mexico and this state hates rubbers, as for checking the advancer on the ignition, thats a good idea i didnt know it had the old what i call "swinging" one so i bet that has frozen up in its long rest, the valves are going to need tuning badly, i think thats part of my back firing prolem also, a slow closing exaust ect. and a note on that 810 kit, im going to hold off on that until i get a bit more adept on the bike lol, dont wanna go trying to tear off on it and it decide to leave me on the ground. Also that "Positive Neutral" was a great help, i was attemting to roll start it once just cause it does need starter clutches and was trying to put it in a higher gear for easier cranking lol.

:laugh: good news, got new plugs all new rubber lines like vacuum and fuel, took apart and cleaned the percock valve, put alot of high octane fuel in it and the thing is running STRONG, 0 smoke out pipes, taching fast as everything now, only problem is the small backfiring issue still but im going to tackle the Valves tomorrow, get all the size of shims i need and get them ordered aswell as find a good shop here local to synch the carbs and then its just chain tires and making sure the brakes are free and well working and im all set, i want to thank everyone in this forum again to give me the tips and courage to tackle some things on this beast, again im a muscle car guy so i had the basics but alot of this was new to me, so thank you all and ill post some new pics once i get her road worthy and painted soon!

Just an observation, these engines were designed to run on regular, low octane fuel. Check you Users Manual under the seat of all the details. :huh:

I understand that using high octane will not damage anything but will not allow it to work to its full potential/power output. It does not fully ignite the fuel in the cylinder and runs rich and pumps unburned fuel into the exhaust system.

Switch to regular at the next fill-up.

Be very sure you use a clean inline filter and install it between your petcock and the cabs input.

Welcome to the site and best of success.

PS
Add your year, model and location to your signature for the best responses and it's considered very friendly too.

thanks didnt know these are for low octane, but i think it needed the higher operating temps to help it clear its guts out a bit, thanks ill besure to keep the cheap stuff in it now

Hi octane will not produce higher temperature in the cylinder... if anything, one would expect the temperature to be lower. :huh:

Remember that the prime purpose of higher octane is to prevent pre-ignition in engines with higher compression ratios. So, when used in a lower compression engine the result of using high octane is cooler combustion temperatures due to incomplete combustion of all the fuel to start with and then the cooling effect of the unburned fuel in the combustion chamber. :dry:

And forget about the high octane being superior, cleaner, better, etc. one of the major oil companies was successfully sued for false/misleading advertising on that point a decade or so ago.

Best of success.