KZ750H Restoration

Just went and resistance tested the coils. Just wanted to make sure I didn't mess up when I put the new leads on. both were at 21kOhm from cap to cap. Taking off the cap resistance (2 x 5kOhm) puts them at 11kOhm, well within spec (10-16kOhm).
The primary winding read as low as my cheap multimeter goes (3-4 Ohm if you connect the two leads directly). Need to take them in to school to test properly but won't worry about that until everything else has been looked at.
The coils were replacements from ebay. They should be fine but as I don't have an electrotester I'll just have to kill the lights to check the spark.

Tomorrow I'll do the following:
- Check the header temps to see if all cylinders are firing properly
- Pull the plugs and have a decent look at them
- If the header temps aren't all pretty much the same I'll check the spark
- If the header temps are the same I'll have another go at the idle fuel screws

Other than that I'm not sure what to do. Pull the carbs and recheck the float levels to make sure? Any other suggestions?

Edit: will get hold of a strobe light to check the timing as well.

I agree, it sounds like the engine isn't running on all four cylinders. It also sounds like you may have a lot of cam chain noise. I'd check the tensioner function to be sure it's springing out like it should.

Thanks, Ed. I did think it was a bit noisy. [strike]The tensioner was fine when I put it in - could the spring have weakened over time so there isn't enough tension? Just to be sure: I put the tensioner in without the locking wedge (bit that goes in with a spring inside a cylinder with a 17mm hex head) so it could seat properly. Once I'd torqued the bolts I put the wedge in. Is that right?[/strike]
EDIT: When I put the tensioner in I didn't turn the engine over to get it to the correct position :ohmy: . Will do that tomorrow as well.

Will buy a cheap electrotester tomorrow so I can compare the arcing distance. Won't be able to rely on the specs in the manual but I'll see if there is a weak arc. Will then check to see if I get a good spark everywhere. Have a second set of plugs lying around so may just swap them out.
Anything else I should be checking other than spark and timing?

Problem found (but not solved yet). I pulled the plugs today and it was obvious that only cylinders 2 and 3 had been firing. I checked the spark and there was nothing on the right hand coil. I switched the leads on the coils and switched the plugs around and it remained a problem with the right hand coil.
Will order some new coils today.
On the first run all cylinders were definitely firing. I think I may have cooked the coil letting it run on the stand too long. How long do you guys let the bike idle on the stand before shutting down (outside temps 0-10°C)? I've not got any experience working on air-cooled bikes.
Another thing I noticed is that the second cylinder got quite hot (pretty sure it was yesterday when only two cylinders were running). I'll see if I can polish it up so it's back to silver - then I can see if this is related to the failed coil.
Still need to sort the tensioner, but have the weekend to do it now.

Everyone else beat me to the not running on all cylinders.

For cooling, I have a large commercial fan that I use. Was a trash pic too so that was a bonus.

For reference, here was my 750 at idle after tuning:



You can see my fan at the end of this XJ video:

Thanks, good to have as a reference.
I pulled one of the original coils out of storage (one had a split housing, the other one was still good). Swapped out the timing advancer as the old one was stuck. Not sure what happened as it was definitely OK when I put it in. May have something to do with the aforementioned yarding on the nut...
Cam chain tensioner was pretty stuck as well. When I pulled the cap off I couldn't get the push rod stop out. Pulled the tensioner off and made sure everything was OK. Seemed fine. What I wondered about was the push rod stop only stuck out about 5mm - the manual says it should be about 10mm so there is more than the normal amount of slack in the chain. I'm thinking I should have measured the cam chain length... oops.

After sorting all this out I started it up again. Much better, but after a few minutes it sounded like I could hear the cam chain again. Thinking I might need a manual tensioner to take up enough slack and then plan on splitting the cases again next winter and checking/replacing the chain and guides. Thoughts?

Checked the new timing advancer with a strobe and it's working fine. Anyway. It's idling OK, and until I can get some big fans I'll leave it as is and get the rest of the work done. Will see how it behaves on the road before I make any changes. I have a feeling when the oil temp gets to about 40°C that the head and cylinders are so hot it starts misbehaving. With no air flow around the engine by the time the clutch cover heats up it's pretty warm up front. I also question the accuracy of the oil temp gauge, although on the ride back home last year it seemed to work fine (around 70°C in BC at the start of May).

Thanks jayrodoh, scirocco and nessism for your help/input!

Ordered some dyna mini 3 ohm coils today. Went with the mini coils primarily for the cable routing - they route towards the back like the stock ones, not out the side like the standard dyna coils. Decided to go with a trusted brand instead of a set of the cheaper coils (which may have been fine for years but I only wanted to buy one replacement set of coils and I'm already on number two). OEM were an option but would have set me back about $400-450.
Will get some mounting brackets for the new coils laser cut. Priced them up and if I get 5 or more they'll only cost about $6 each. Will get 6 of them as it will only be $10 more than getting 2. Decided against making them as I just don't have the tools. Will weld a couple of nuts to the back, give them a coat of paint and they should be as good as stock.
If anyone in Europe needs a set of coil brackets with a 90mm spacing for the coil bolts let me know.

Great project! Like your organize/structured way of working.

Bike looks better then new

Your first restor. you say, but you have a deep technical understanding!

Keep up, I will watch you

Thanks gordone!

While I'm waiting for the new coils I decided to try and get some painting done. Got the instrument housings primed and finished the centre stand and clutch lever bracket. Will get the instrument housing finished up this week so I can put them back together on the weekend. After that I'll have another go at the switch blocks.

Got a nice bit of kit in the mail today. Should sort out the rattling chain. It's from ETL ( www.camchaintensioner.co.uk/ )

By calum: Ordered some dyna mini 3 ohm coils today. ...

Are the mini coils suitable for street use? I don't know anything about them.

I installed the green Dyna 3.0 ohm coils, but the gray 2.2 ohm are supposed to be a better match for the stock electronic ignition.
To fit them I made some bracket extenders from aluminum angle bar from the hardware store.
I got the green ones in case I needed to switch to the Dyna S ignition system.

.... prototype. finished brackets are similar.

@martin_csr thought about the standard 3 Ohms or 2.2's. Only really went with the mini's as the price was the same and the cable routing is the same as stock, meaning I can reuse my cables and caps. According to dyna the mini coils are street or strip - pretty sure they're just the 3 Ohm coils in a smaller package, but I may be wrong as I couldn't find too much information. The guy I got them from said they're both good (he has them both on his bikes) and only mentioned the size as the main difference



Tried my hand at the methods here: kzrider.com/forum/4-electrical/612300-ha...bar-controls?start=0
Worked pretty well. Not perfect, but I'll clean up around the on/off text when the paint has properly dried and then shoot a coat of 2k satin clear acrylic over the top. Ended up using oil paints so shouldn't be a problem with the acrylic - please correct me if I'm wrong. Still need to do the top left housing - it needs to be repainted after the first attempt with acrylic spray paint for the lettering - oops.
Anyway, thanks to Mikaw, asphalt900 and Kidkawie for the tips/thread!