1994 ZR700 Dead Cylinder

Snappydon · Oct 4, 2009

I was recently given a 1994 ZR700 in pretty nice condition. Sled has sat for around 3 years. I went thru the fuel system...Got rid of the old gas, thoroughly cleaned and went thru the carbs, new plugs, checked all the fuel lines and connections but cannot get the right cylinder to light off. I've got good spark to both sides and compression on both sides is 155 to 160. Looking in the exhaust and intake ports both pistons look good from top to bottom with no obvious sign of scarring. Thought maybe I might have a reed problem both there doesn't appear to be any reeds.
The left side will run by itself but the right won't do anything. Even installed another exact same carb and still no ignition. Have switched plugs from side to side, carbs also. Float bowl fills with fuel but does not seem to be getting to the cylinder. Coolant system is good and there is no coolant eveidence in the cylinder.
I can normally solve most problems with these older sleds but this one is stumping me.
Could I have a bad crank seal that is sucking air?
Thanks for any help.

clutch · Oct 4, 2009

Could be a bad crank seal leaking air like you said, or it might be a reed problem. The old 650 and 700 engines were a piston port with a cylinder mounted reed. The reeds are on the bottom of the cylinder, you have to remove the cyl. to get at them. If you give it a shot of fuel thru the plug hole will it start and run on that cyl.?

m8magicandmystery · Oct 4, 2009

will she fire on that side spraying some starting fluid in that side ..??

Snappydon · Oct 4, 2009

No...spraying starting fluid in the carb it will not run. BUT...putting a little fuel in the spark plug hole it will! Damn near took off and went thru my garage door! Sooo...what does that tell me? Reeds?

Funoutfitters.com · Oct 5, 2009

Sounds like you have sticky reeds if you can put fuel down the cylinder and it runs. I did have one similar to this and it was the crank seal behind the stator. The sled would run when fuel was poured down the cylinder but not as well as it should.

Let me know if there is anything else I can help you with
Jeff
Gold CatMaster Mechanic
www.FunOutfitters.com
Free Technical Support Line: (866) 531-0123

Snappydon · Oct 5, 2009

Problem solved! Pulled the cylinder and found a hole about the size of a dime in the front lower part of the crankcase. Anyone need any ZR 700 parts? Thanks, for all your input!

m8magicandmystery · Oct 5, 2009

Snappydon said:
Problem solved! Pulled the cylinder and found a hole about the size of a dime in the front lower part of the crankcase. Anyone need any ZR 700 parts? Thanks, for all your input!

jb weld

Snappydon · Oct 6, 2009

Funny you should suggest that...I found what looks to be a lone piston pin bearing laying in the bottom of the case. I figure it got dropped when the last owner put a big bore kit in. He has now told me that when they started it after installing the new kit that it made a "funny" sound so they shut it off and shoved it out back in the shed. Everything else looks really good, pistons and cylinders are like new and the upper and lower bearings are nice and tight. The hole would be very easy to patch and I know that JB weld works quite well on cracked marine blocks. There isn't much pressure or vacuum in the lower case is there? So JB weld might just work?

m8magicandmystery · Oct 6, 2009

yep..maybee use some fine mesh just a bit bigger then the hole with it...you know..like chicken wire and concrete..

Blaine · Oct 7, 2009

Keep us posted on your jb weld project..or maybe see a welder and see what he says. Sounds like you have a lot of mechanical aptitude. Sounds like for just a few $ you'll have a fun sled to ride. It also sounds like you're quickly finding out they are like all toys...a money pit.

Snappydon · Oct 7, 2009

I took the engine out of the chassis last night and actually found 2 other small breaks in the case. After thoroughly cleaning and scuffing up the area around the problem areas I used a small piece of stainless steel screen that I had floating around in my toolbox as a backing. I knew that my hippie days from the 70's would someday benefit me somehow:face-icon-small-hap. Mixed up the ole JB and smeared it on!
Took a look at it this morning before heading to work... appears to have covered the spots very well. Won't be able to reassemble the motor till this weekend but so far I'm optimistic. I'll update as things progress.

extremsledder · Oct 7, 2009

after you have let your jb weld cure well and sanded it smoth inside the case take and put a light layer of sealall over the jb weld because over time the gas and oil will break down the jb weld but not sealall, this is what we did on a 800 with a hole in the case and it worked well the sled is still running after about 4 years now

Snappydon · Oct 20, 2009

OK...Put everything back together, started it up and it idled like a purring kitten! Seems to be operating just like it is supposed to. I'm going to be keeping an eye on that plug pretty close but so far running it thru the rpm range and getting it warm and letting it cool down and restarting it over and over the plug is a nice light tan/brown just like the other! Starts on the 1st pull and idles perfectly. Thanks for the advice all! This is a great forum.

m8magicandmystery · Oct 20, 2009

don;t thank us...buy us something

Idcatman1 · Oct 21, 2009

700 crankcase

I have a good crankcase if your patch doesn't hold. Make me a reasonable offer.

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1994 ZR700 Dead Cylinder

Snappydon

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clutch

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m8magicandmystery

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Snappydon

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Funoutfitters.com

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Snappydon

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m8magicandmystery

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Snappydon

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m8magicandmystery

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Blaine

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Snappydon

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extremsledder

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Snappydon

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m8magicandmystery

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Idcatman1

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