TOPIC:

I took My 82 KZ750 LTD off the road last month do to a fuel leak at the carbs . Other than that she ran good . I took the carbs of and found the leak and rebuilt them . It did have some noise under the valve cover and I thought it might need the valves adjusted so I took the cover off while I was waiting for the carb parts and noticed that the cam chain was really loose . I ordered the cam chain tensioner . I got it in today and put everything together . I did not check the valve timing . Right off it started and seemed to Idle good . I took it for a short ride and it started to back fire and had no power . I did find that the carb clamps needed tighten down more . Now she back fires throw the exhaust and the carb . I ran the battery died so I stopped for the night and put the charger on her . Any thoughts ? I am wondering about the cams might be out of time ? What do you think ?

Mike

When you remove the valve cover, you are removing the upper chain guide. This gives the appearance of a very loose chain. In your service manual there is a service limit for chain stretch, so much length measured at so many link pins. I can't remember the exact #'s.
It is possible for it to be out of time, have you checked compression. if out of time the compression will be lower than normal, or possibly you may have bent valves. this can happen pretty easy if the cam timing is off much. Popping the valve cover to verify cam timing, after a compression test is easy enough. If compression is down, it would be a good idea to do a leak down test, if you have the set up, or just put compressed air to the cylinder with it at TDC firing position. Of course even with the piston in the correct position, you may find the valves are not. That.s why pulling the cover to inspect is a good idea.

I did a little CSI work today . I took a look at the way I had the inline fuel filter and I had a kink in the fuel line that was restricting the fuel . I tried to fix the problem but found out that the filter was just to big to fit bike . So I removed the filter . I will be looking for a smaller one but for now I will be using the one in the tank only . I did remove the carbs and took a look at the work I did to see if I might have done some thing wrong . I found that I had a bad float valve . The rubber tip was bad . Those where just replaced but evidently it was sent out deformed . I ran to the shop and picked one up and I will tell you that those little things make them guys a mint . I paid $15.50 for one . The bike came stock with a foam air filter and with it backfiring throw the carbs it is shot . I will be making a replacement for now until I get a new one . I did not get to put the duct work and air box back on yet . I am leaving it for tomorrow . Yesterday when I started it it would back fire then start and idle well but did not have any power and backfire when you road it . Today I tied to start it with out the duct work on and it started right up with no back fire at all . She did start to rev up but I think it is to lack of intake . I will find out when I put her back together . Tomorrow will be another day and hopefully I fixed the problems .

Mike

When I had my 750, after a couple of years it started backfiring alot. I thought my problem was the anti-smog system (not sure if yours is still on). I pulled anti-smog hosing off the cam cover and used a hose to tie the two cam cover nipples together. Also plugged the vacuum vents on carb #1 and #4. That seemed to clear up my issues.

Gives you another thing to look at anyways.

Good luck

I might look into it . I went out and put the ducts on and stride to start it and it was hard starting . It started to backfire also . The backfire only is there when you start it when it starts it run fine . I took it for a ride and it rode nice . When I got home I shut it down and it was real hard to start and was backfiring . This is a head ace .

Mike

Well well well I do not know what I was smoking when I checked valve clearance but it must have been good . I thought I would get back to basics and stop over thinking . I removed the valve cover and check the timing and it is spot on . Oh I did find out it was backfiring throw the carbs before I took the cover off . I took out my old feeler gauges . They are so old that numbers are worn off . I took out the smallest one and check #3 intake . It looked like that there was no clearance with it and there is none . I think that is where I am getting the backfire throw the carbs and number 4 and 2 exhaust has none also That would explain the backfire out of the exhaust . This old KZ has a lot of where and tar but I can fix it .I just need to stop over thinking stuff and get back to the basics . I will remove the valve shims in a couple of days and find out what size I need to order . This thing should run well after I get her done . It has a lot of new parts in it . I am hoping after I do all of this I get a lot of good miles out of her . I think what had happened is I added some Sea foam to the fuel thinking that would clean the carbs out and it removed the carbon also and that was sealing up the valves . It shore works well . Maybe to well .

Mike

my 82 750 H3 backfires out the carbs every now and then. Did you find the problem with yours. I have a service manual for it if you need any questions on the specs.

ShellBack I have a manual for it and I have been chasing it down for the last couple of days and I think I may have found it with the #3 intake valve being open it would let the combustion get by . I also found 2 exhaust valves that was open and that would explain the exhaust backfire . I just need to get the cams off and remove the buckets to get to the shims and then I will get go 2 sizes thinner and that should do the trick .


Mike

just to give you a heads up my 83 had the same thing and burnt up the intake valves had to get new ones i only had 26000 on my kz when it happen do a leak down test when you have the cams out and see if there holding save you some trouble if there bad