I just started watching the video and I felt compelled to write a comment even after watching only the first minute of this video. Let me assure you that the K&B Sportster series are one of the easiest, docile, smooth running engines ever. Just make sure you use a bit more oil in the fuel (around 23% total oil half castor half synthetic should be perfect ) these engines, because they don't have a sleeve, they need a bit more oil. Other than that .. you will have a smooth running engine that will last forever. Watching now the rest of this video and will comment appropriately if needed. By the way, I love watching your engine videos as I, myself, love to tinker and run all sorts of engines as well. Keep up the good work !!!

I have several sportsters. Ive noticed when they are rich a fuel mist comes out of the carb and collects on the head it appears to come from the head.

I have come across what you describe as leaking .. but I dont recall now .. it's not actually a leak .. trying to remember .. hmmm .. cause if the engine really leaked then it would not start to begin with .. see if mecoa has an answer on that. Also, if you notice on the video the "harder" you run the engine the less "leakage" you would see thus it's something else. By the way, you should run the engine as you did on your second / third run .. fast / rich two cycle mode for a couple of mins at a time .. I know this is an old video, I just happened to discovered it .. but I can't wait to hear any recent updates on that engine. Love watching these engines .. keep it up :)

Thank you for posting. it was timely for me because i just purchased a used .20 Sportster. it has very little compression but the motor otherwise is in good condition. I dunked the head in liquid and turned it over; bubbles came flying out between the head and cylinder, just like the fuel in your video. When i took off the head, it appeared to have a machined ring for a head gasket, but there was none present. MECOA says the early models had a rubber gasket, but later models had nothing. My plan is to add some high temp gasket goop and seal it up again. Maybe it will make a nice starting sport engine.

Almost half way through this video .. and I am surprised to hear about your leaking problem. I have had so far two .20's one .28 and one .45 ( all sportster series ) and they perform flawlessly .. In fact, I just fired up my K&B .45 sportster after being "dormant" for almost 17 years .. ( kzread.info/dash/bejne/mZ-p0rGxm9XPdc4.html ) and the engine started in two to three flips by hand .. I am really surprised you have these problems. By the way .. these engines are of AAC constructions (not cast iron) so I am not 100% sure that a very rich / burpling style of initial running is necessary. Make a note that these type of engines along with their ABC counterpart, running them initially very rich might actually destroy the piston fit. I would say the best way to run these is a rich two cycle mode and make sure you have a bit more oil than usual. They will last you a life time. Watching now the rest of this video.

Just a random question David. Would you have a carb for a k/b sportster 45 ??

Put a PTFE pipe sealing tape between the parts, where the fuel leaks. The manual of the MDS engines recommends to put a PTFE pipe sealing tape between the silencer and the engine exhaust port. It seals well. A part of the tape is visible here: kzread.info/dash/bejne/n3pko66RqZWdZJM.html

I almost get the impression that the head is not leaking but maybe the fuel is spraying out the carb or out the front housing and hitting the head. Did you have good compression? I say this due to the fuel on the head being so pink as it is was not burned at all. If you had a head leak, I would expect more of an oil look, not a raw fuel look. Some of my K&B motors will spray fuel out the carb when rich. I guess the crank timing might be a bit strong for the rpm being run. Just postulating. On the other side of this, this is their budget motor and it was kind of a dog power wise.

@dmrcflyr2

7 жыл бұрын

Well since I was the one running it I think I had the best vantage point to determine this. kzread.info/dash/bejne/lomrxtuuo727YqQ.html kzread.info/dash/bejne/en9hmqWfZtS1nrA.html

@rscarawa

7 жыл бұрын

Looks like you fixed the head leak. It is hard to understand how those scratches got on a machined surface. Since you still have fuel most, it has to be either from the carb or from housing. YOu have a lot of videos on various motors and appreciate that you provide this service. While I have not seen them all, I have watched quite a few of them. One thing that you might have brought up that I have not recently seen is how to tighted headbolts on a motor. This is critical for both a tight seal and to keep from damaging the block. It would be beneficial if you would review that process on occasion in your breakdown videos. Just a suggestion. I did have a motor with head bolts far outside the sleeve where this was critical and doing it wrong could easily do block or thread damage.