#1 cylinder not getting hot

hi all new to site i have a 1981 650 csr with 9000 org. mi. sat in heated garage for 14 yrs. changed oil cleaned carbs. new batt new air filter cleaned plugs rebuilt front master cyl. rebuilt front brake. starts and runs good dont know why #1 cyl. does not get hot. maybe carb sync off bad plug any help would be welcome thanx.jim pics soon.

Welcome aboard! OK, we need a little more info to help you. What spark plugs are you using? When you pull the #1 plug is it wet or dry? If it's dry you may not be getting any fuel to that cylinder (would suspect plugged up carb). If it's wet it may be a spark problem (maybe bad plug, cap, or wire). One thing to try is swapping #1 plug with any other to ensure the plug isn't at fault. Ed

Disconnect then reconnect the spark plug wires at all points from the coils to the plugs. The wires unscrew from the coils - unscrew the ribbed compression boot then the wires. The coil has a twisted/pointed terminal that the wire screws onto. The connections become poor from oxidation over time. If there's the white crusty stuff, you could nip off the ends of the wires a tad - not too much though - you don't want them to end up too short.

I solved an intermittent firing problem on #1 & #2 by doing the above... same bike - 81 KZ650-CSR. Some contact cleaner spray might help to clean the connections & some dielectric grease wouldn't hurt. I went ahead & did all four spark plug wires & the igniter leads on the other end of the coils. Good luck.

thanx for the info jmkzhi will try cleaning connections this weekend jim.

plug looks dry. swapping plugs no change, will check cap and wire this weekend. will look at carbs also. thanx 650ed


jim

I would go ahead & check the compression. It's kinda handy to do it when the carbs off the bike, since you won't have to fiddle with the throttle grip.

I would also do the Service Fuel Level check to make sure the fuel level in the carbs is correct. It should be 3mm +/- 1mm below the bottom of the carb body. Check by attaching clear tubing (w measuring device) to the bowl overflow nipple. I use a medical syringe w mm marks scored into it using a utility knife.

Simple.

#1 cylinder is not getting fuel. Check to see if fuel is getting into the float bowl. If it is then it's a plugged pilot jet or pilot circuit, very common on a bike thats been sitting so long.

My guess is that the float needle is stuck closed and not allowing fuel in to the float bowl.

81kzjim wrote:

hi all new to site i have a 1981 650 csr with 9000 org. mi. sat in heated garage for 14 yrs. changed oil cleaned carbs. new batt new air filter cleaned plugs rebuilt front master cyl. rebuilt front brake. starts and runs good dont know why #1 cyl. does not get hot. maybe carb sync off bad plug any help would be welcome thanx.jim pics soon.

Hello, James, and WELCOME to KZR!

Could swap outside plug wires to see whether non-combustion moves from #1 to #4 cylinder.

If #1 begins combusting and #4 stops combusting, it indicates a wiring issue between coil and plug.

If #1 continues non-combusting and #4 keeps combusting, it indicates a carb-related or compression issue with #1. Given the low mileage and extended storage, it's likely a carb issue, but would first assure acceptable compression and valve clearances being within specs on #1 cylinder before further addressing #1 carb.

Good Fortune!

If needed, here's one way to clean the pilot circuit.

Good Fortune!

[Click on image to enlarge view.]

Once again, lets jump to conclusions and look at the hard stuff first...
Verify spark at #1 using a known good plug.
Check carb synch.
Does the bike run good at mid range rpms, does the #1 cylinder get warm then? Drive it down the block and back and check.
The float level using the tube method is 2.5mm- 4mm, I dislike this method personally and think it is only useful to see if the floats are functioning under load.
Check the plug cap to see if the resistance is too high.
Verify the valve clearance is correct, only a little off isnt gonna be it either.
BTW, it is a good idea to always replace the plugs at tune-up. NGK stock type plugs typically cost about $2-3 each at the local auto parts store. Cost more in time to clean them, than to replace:lol:
as likely as not, the first thing that came to mind is synch, you just rebuilt them, were they bench synched?

TerryK wrote:

Simple.

#1 cylinder is not getting fuel. Check to see if fuel is getting into the float bowl. If it is then it's a plugged pilot jet or pilot circuit, very common on a bike thats been sitting so long.

My guess is that the float needle is stuck closed and not allowing fuel in to the float bowl.

+ 1
if the plug is dry, he is not getting fuel. he did say the plug looked dry.
pipe can't get warm if there is no combustion.

thanks for all the ideas, will get busy this weekend, will post progress soon.





jim