Back firing and after firing at the same time.

[StarTech]

Well one customer here has over 4000 hrs on a Kawasaki FX850 engine and it is still running strong. The only thing than a complete carburetor including throttle bushings that has done to the engine is an oil Gerotor replacement. This seems to a common problem the carburetor where the throttle and choke shafts wear in two. The last it took a sch 80 brass pipe to make the bushings.

And doing a compression test on the the FX751 is basically useless due ACR. The engine passes the modified leak down test fine with < 20% loss which surprises me consider the #2 cylinder problems. If the customer keep running it would had gotten to be a cold cylinder problem but currently it is just a hot cylinder problem. I do have the needed parts on order but the distributor has them on back order.

I kinda lucky to have ran into this just a month ago on another Kawasaki FX-T00V with over 3000 hrs on it too except it had already gotten to the cold stage failure. Slightly different resulting damage so he got lucky on the repair bill. Now of his previous repair shop told him last year he need a $4000 plus engine, which I repaired for $300 last summer due high oil usage. That #1 cylinder but this #2 cylinder went down. Same root cause but did some other damages.

With Kawasaki engines I am seeing several with over 3000 hrs still running strong but of course the customer are doing regular oil changes and using good oil.

 

[Tiger Small Engine]

Well one customer here has over 4000 hrs on a Kawasaki FX850 engine and it is still running strong. The only thing than a complete carburetor including throttle bushings that has done to the engine is an oil Gerotor replacement. This seems to a common problem the carburetor where the throttle and choke shafts wear in two. The last it took a sch 80 brass pipe to make the bushings.

And doing a compression test on the the FX751 is basically useless due ACR. The engine passes the modified leak down test fine with < 20% loss which surprises me consider the #2 cylinder problems. If the customer keep running it would had gotten to be a cold cylinder problem but currently it is just a hot cylinder problem. I do have the needed parts on order but the distributor has them on back order.

I kinda lucky to have ran into this just a month ago on another Kawasaki FX-T00V with over 3000 hrs on it too except it had already gotten to the cold stage failure. Slightly different resulting damage so he got lucky on the repair bill. Now of his previous repair shop told him last year he need a $4000 plus engine, which I repaired for $300 last summer due high oil usage. That #1 cylinder but this #2 cylinder went down. Same root cause but did some other damages.

With Kawasaki engines I am seeing several with over 3000 hrs still running strong but of course the customer are doing regular oil changes and using good oil.

Yes, Kawasaki engines can run 3000 plus hours if well maintained. The leak down test of less than 20% is good. Compression test with compression release is just another test, not definitive, but a piece of the puzzle to figure out issues. Have you checked for intake leaks on gaskets?

 

[StarTech]

Not necessary as I have already found the #2 cylinder problem base on previous experience with a very similar problem except that one only backfire out the air cleaner because the operator let get that bad.

 

[RevB]

My initial thought was that because they were aftermarket coils but I had already swapped them out using OEM coils. Valves rockers were in spec when checked but it is a valve related problem.

The Kawasaki coil wires are carbon track units and they have had problems with continuity before. Ask me how I know. The plug boot connectors are just crimped around the cable with a small spike penetrating the sheath to contact the carbon coated string. Check these as well. I have replaced mine with these....much more secure connection.

 

[StarTech]

Hmmm. I don't use those type terminals here as the high tension leads are strip back and conductor folded back and the terminals are then crimped in place. Matter of fact I replace high tension leads whenever mice chew them in two.

Using those spike type of terminals are just asking for problems.

 

[RevB]

Hmmm. I don't use those type terminals here as the high tension leads are strip back and conductor folded back and the terminals are then crimped in place. Matter of fact I replace high tension leads whenever mice chew them in two.

Using those spike type of terminals are just asking for problems.

Damn hard to replace carbon track when they are moulded into the coil housing.

There is a screw in the cap that screws about 3/4" up into the cable...nothing gets "peeled back".

 

[Red Good]

Loose valve seat ?

 

[StarTech]

Damn hard to replace carbon track when they are moulded into the coil housing.

There is a screw in the cap that screws about 3/4" up into the cable...nothing gets "peeled back".

Most high tension lead are not molded into the coils. They are either screwed in or push in (depending the pin used) and while epoxy holds them in place afterwards. It does however requires very sharp skinny blade knife to do this.

 

[StarTech]

And well there is enough guessing the problem. It is a valve sticking due to valve carbon fouling caused by a slightly blown head gasket. When hot the valve is sticking monetarily in the valve guide which is also carbon fouled.

Normally the solution to clean or replace the valve and clean the valve guide if not worn or displaced along with new head gasket.