Under Powered

Hey all,

I recently bought my first ever bike restoration project - a 1976 KZ750 Twin - and have done some basic work to customise it a little into a scrambler.
Since I bought it I have put new air filters (RAM), and oil change and new oil filter and some styling edits.

I bought it cheap off a dealer who was about as spivy and untrustworthy as they come, and he refused to give me a 3 month warranty, but did drop the price, so I took the risk.

I am now finding the bike is under powered - and when pulling away from standstill seems to drop power even if I open up the throttle.

I am piss poor at the moment so loathe to take it to a garage - can anyone suggest what might be wrong so I can have a go at fixing myself?

My guesses would be:
1. Carbs
2. spark plugs
3. Head gasket - loss of compression?
4. Fuel filter - though I doubt this is it as it revs ok in neutral - but still not quite right

Would seriously appreciate any help if anyone knows what this might be!

Thanks KZ RIDERS!

My guess is that you have not found the elusive magic jetting combination for CV carbs and pods (so few ever have!) Put the air box and stock filter back on and see how it runs. Ed

You certainly want to check the torque on the cylinder head nuts/bolts, they're probably loose, but the gasket itself is probably fine. The first thing you need to do is adjust the valves. If they're too tight (likely) it will run poorly and no amount of playing with carbs and airboxes will fix it--and you may burn a valve.

After the valves have been adjusted, then do a compression test. If the compression is good, then consider yourself lucky because you shouldn't have to do anything else to the motor for a while.

I also recommend ditching the pod filters, but you should also open up the carbs and while you're cleaning them, make sure that the PO didn't mess with the jetting and, if they did, set it back to stock.

That's what you should have done BEFORE using the pods.
Steve

OK so pods are a massive error, I know now. Being a tosser I of course threw the box away thinking I would no longer require it,and I have no storage space.

DOH!

I have no idea how to adjust carbs or valves, so I will need to Youtube to learn...

Thanks!

First clean the carbs and note the needle position and main jet size, check your fuel level with a clear U tube. Try running it without any filters, or reinstate the airbox if you have it. Then try using the choke and see if it is better, maybe lift or lower the needles in the carbs ... You want to narrow it down to what makes it run better or worse to work out where your problem is. Do one thing at a time.

I just started her up for 405 seconds and after the right exhaust was hot and left was cold!
Does that shed some new light? am i only on 1 cyclinder?!

I'm new to this as you can likely tell!
thanks

You say when you bought it you only changed oil, filter, & put pods on it
did you check & replace the spark plugs?
did you check to see if you're getting spark to the cylinder that's running cold ?
Pete

hi pete, no i did not!
How do you check for the spark?

Love this forum so much help!

Cheers all!

H-Bomb wrote: hi pete, no i did not!
How do you check for the spark?

Love this forum so much help!

Cheers all!

might turn into a love hate relationship if you don't try to help yourself too....#1. Get a service manual and owners manual and do a little homework. It's much easier for participants to help you if you are also working out basics yourself.
And piss poor is no excuse for not even asking help on finding a service manual ! Lol

I see this happen time and time again. Modification before sorting out the important things. Congratulations you have a scrambler on your hands. Please don't take that personally, but this is a motorcycle, with some age that will require basic maintenance and a basic mechanical understanding in order to run properly. If you want to modify the engine then I hope you are a qualified engineer, because the design and engineering team at Kawasaki did a fine job back in the day when other motorcycle companies were dealing with oil leaks and poor sales. If pod filters make your scrambler look a certain way, the next thing you need to do is.. well you beat me too it - watch YouTube videos.

You my have a fouled spark plug, bad coil, bad points and condensers (if you have them), weak voltage going to the coils from the battery. Have you checked your timing and points? Could also be a stuck timing advancer, but that would not equate to having one cylinder out. Compression test, clean carburetor... all this information is included in the Kawasaki Factory Service Manual, it will be the best $20-60 you will spend on your scrambler and save you much more as time goes on.

"Revs ok in neutral"... I would start with points and timing

Here is a Service Manual for sale on Ebay , just make sure your particular bike year and model is listed on the back cover of the book before you buy it.

...just my 79 cents

+1 !

Step 1 should be to get the bike performing properly before modifying anything. These bikes ran quite well when new and still do when properly maintained. Do a full tune up; change ALL fluids; etc. That way you establish a baseline from which you can measure the benefits or detriments of any changes you make. If a change makes things better (somewhat unlikely) great; if the change makes things worse remove the change or keep working at it until that change gives satisfactory results. Do one change at a time so you're not dealing with too many variables at once.

Unfortunately, in this case undoing at least some of the changes may be difficult if parts have been thrown out. I guess that can be chalked up in the lessons learned category, so it may not happen on the next project. Ed