KZ1100 Mikuni CV Carbs

Hi all.

As some of you may remember, I was having trouble with my poor running KZ1100. The problem in the end turned out to be failed spark plugs.

But. There is a new problem..

I'm not sure what the model number for the carbs are, just that they're Mikuni CV items and are a pain in the backside. Taking the top cap off the far left carb, there was water inside (condensation?), but none in the air box or float bowl. A little more investigating, I took the cap off the 2nd left carb and it was dry.. and then the far right, which was also dry. Any ideas? The last time the bike was used it was put on the centre stand, so that rules out rain etc collecting due to it being on the side stand.

The bike is still running poor and lower rev range throttle response is hit and miss. Sometimes it's fine, other times I have to give it a 'blip' to get things going. I dont know much about these carbs.. Just that new diaphragms are horrendously expensive. (£33UK for 1)

An online manual or tips on how to set them up would be brilliant.

When you say in the upper chamber, are you talking, on top of the diaphragm where the spring is or below the diaphragm. If it is on top, pull the slide out and check for tares in the diaphragm. That would be a big problem and explain the poor running. If it is below the diaphragm, than that can happen because that area is exposed to the outside threw a vent hole. It sounds to me that these carbs should be taken off and rebuilt.

Thanks for your promt reply. Yes, on top where the spring is. The others were all ok. I didnt notice any obvious tears, but i'll have another look when i get home later on today.

Are rebuild kits available for these? Also, would changing one diaphragm be ok, or would i have to change all four?

Changing just one is fine. change only if it is torn. Check if it was put in correctly, if it was not pinched. The only way water could get to the top is threw the vacuum hole at the lower portion of the slide, or if the top cover has a hole in it or if the edge of the diaphragm was pinched between the cover and the body. I would rule out the lower vacuum port. So this leaves two options if the diaphragm is intact.

Had a poke around when I got home from work yesterday. Took the cap off to inspect the diaphragm properly and couldn't see any tears or holes. After that i decided to squirt some carb cleaner through the inlet's via the air box. When I started the bike, water was spraying in as were exhaust gasses. Right, so now i knew what the problem was. The emissions system! Took all the pipe work out and pluged the vac pipes up, bridged the two caps on the cam cover and gave it a go. WOW! What a differnce. Came to work on it this morning and it's like a totally differnt bike. Lower rev range is 100% better than it takes less effort to get to the top end. :woohoo:

Thanks for your help on this. I'm used to working on old Triumphs, so this emissions rubbish is new to me. Being in England, we dont get tested for it, so can afford to ditch it all.

Not sure about the Mikuni's, but I know on the Bing CV carbs that the BMW's run they don't recommend using a spray carb cleaner as it can deteriorate the diaphram.

Glad to hear it's running better! I was over in the motherland in the beginning of April. Saw a lot of bikes, but sadly no KZ's...