Hi Jon I am 60 years old been messing with bikes since I was 14,I have a F9 Bighorn that I bought used and was told that all it needed was crankshaft seals it still ran strong and started easily but smoked like a B52 bomber,so I replaced the seals which was pretty easy and everything went great I put it together and it started on the third kick but now it smokes like two B52s and leaves a big trail of transmission oil on the ground,it appears to be injesting trans fluid at an alarming rate when running,I think there was more wrong with engine than owner told me what do you think any ideas?
Did you replace both crankshaft seals? If you did then it sounds to me like the large o-ring seal on the rotary valve cover is leaking. Try replacing that first. Also replace the right hand seal if you didn't before.
I have a 73 F-11 250 It has 2900 original miles it starts right up and runs great for about 6miles and then starts to "soft seize" it gets real hot and and spits and sputters and dies out. I drained all the fluids when i first got the bike(two stroke and trany) I have verified the oil pump is working, by loosening banjo bolts briefly and watching it pump oil. I was also told to let it idle for about 5 min at 2000rpm and hold oil pump wide open to prime ( it smoked alot). I am at a loss!!! any help greatly appreciated!!
Have you checked or replaced the crankshaft seals? This seems like a lean condition and assuming you have the carburetor set to the factory settings, crank seals might be the problem.
No I have not checked crank seals but i am not loosing any transmission oil. I rebuilt carb with new float bowl and jets could that be it if not right settings? Also I just put a no name brand 2 stroke pre-mix oil in injector reservoir, could this be culprit?
When I drained the crank i got about a half quart 2 stroke oil, is there away to prime that or refill? How much should be in the crank?
In reguards to the crank seals I am mostly referring to the left (ignition side) seal. That is the most common side on any 2 stroke to fail or leak, thus causing a lean condition from a vacuum leak.
I am not sure what you mean by "I drained the crank I got about half a quart of 2 stroke oil" Being a 2 stroke there should be no oil in the crankcase when the bike is stationary. Also on the F11 there is no way to drain the crankcase without removing the cylinder.
I am a little concerned about you using a premix oil in the injector system as typically premix oils don't flow well enough for use in the system. Check the bottle to verify it can be used in the injector system. If it doesn't say then that may be the problem is lack of proper lubrication to the piston, rings, rod, crank bearings.
When I got the bike I pulled to different plugs from the bottom side of the engine one was center of engine closer to shifter side and had a spring and cap in the plug, this one drained out about 1/4-/1/3 quart 2 stroke oil. The other plug solid and more towards the rear clutch side of engine drained clutch side engine oil.
Also I will try new injector oil, any recommendations?
Ok, I see the plug with the spring is not a crankcase drain. That spring holds tension for the shift pawl de-tent for the shift drum in the transmission. I don't like to recommend any specific brand, just use any 2 stroke oil that specifically states it will work in injection systems.
I am trying to replace the rotary valve on a 1970 350 Bighorn. Any hints on removing the primary and oil pump pinion gears.
After that it should be easy to remove the rotary valve cover.
You need a special socket to get the pinon gear, which also doubles as the nut, off. I had no luck with a wrench. I had to use the special socket and my impact. You will probably have to make your own socket out of an impact socket using a dremel tool to grind the flats away. To my knowledge the F5/F9 is the only bike that is setup this way. All others have a separate nut, then the oil pump gear and then the primary gear. FYI the rotary valve itself is fine, it is steel and doesn't really wear out and it only goes on one way. The only reason to do the job is to replace the big o-ring and crank seal.
Are you open to an apprenticeship?? lol You're wealth of knowledge is amazing and reminds me of the days spent with "the old man". The grandpa figure that was had "been there done that" and was always the wisest guy in the shop. That man could fix anything. Good job on the series, very enlightening and confidence building. Keep em' coming for our sake! God bless.
I need to find a wiring diagram for a baja 200 5 speed dirt bike . Could you help me? Thanks
I am currently working a 1971 Kawasaki F7 (175cc), it arrived to me in boxes woth the engine case completely split down to the crank.
I have rebuilt the motor using all new seals and gaskets, also a new piston kit and cylinder hone.
I also had the electronic igntion rebuilt by Ricks motorsports and have an excellent spark.
I triple checked the timing marks on the back plate against the mark on the crankcase.
The carburteor has been rebuilt and gone through several time, float heights set correctly and rechecked.
There is great compression and spark. The plug gets very wet whenever I attempt to start the bike.
I have checked and re-checked the rotary disc timing, I have aligned the mark on the disc itself with the pin on the crank several times.
I also checked the rotary timing with a dial guage to ensure it was opening and closing at the specified degrees in releation to TDC.
I also as a precaution blanked off the carb drain in the crankcase.
I pressure tested the lower end of the motor since the rebuild several times, there is a very small amount to zero leakage..nothing more than 1-2 psi over 10 minutes. I would not think this would prevent start up, (I am inclined to think it would lead to a more erratic/lean condition).
Any help or advice you can give would be most helpful..everything in theory is in place for the bike to start up and run fine.
I am at a loss to what else could be amiss.
P.S: I also have an issue with the clutch, I cannot get it to disengage fully so that I can bump start the bike either. Think that could be weak springs?
Hi Mr Junk Man
I hope you're doing well. I recently gained my motorcycle training certificate in Canada, but I've been in love with motorcycles for almost 10 years. I've never had enough money to buy a brand new motorcycle and the ones that I do like are still pretty expensive to buy as pre-owned. I like your videos, they're very informative and I am now thinking of buying an old motorcycle and restoring it. I have my eye on a 1982 Yamaha Maxima (or is it Maxim) 650 cc, with 33000 km on it. I saw photos of it on KIJIJI and the exhaust pipes are very rusty and the tank looks a bit rusty. The seller is asking $600. They corresponded and said that it has been sitting in storage for a few years and still runs but needs a new battery and that they are selling it as it is. They also said that it has never been in an accident. But I wonder if there's more to the bike's history than they are telling me. But based on your videos it looks like most bikes can be restored. As a new rider I'm not deterred by the initial look of the bike because of what I've seen you do with restoration, but I just wanted to know if you think I should take a chance on this bike. I trust your judgment sir. I will place a link in this comment in case you want to check it out for your self
The bike is located in toronto, ontario.
I plan to look at the bike on Saturday morning May 13th 2017. Any advice would be greatly appreciated.
Yeah, any bike can be restored. It is just if you have the money and the time as well as the know how to do it right. $600 doesn't sound too bad really, but plan on another $1000 probably to get it in really nice shape.
Thanks for the response sir. I will take a look at it. If I buy it I will update you on my progress. I may even start a youtube channel. Thanks for the encouragement and advice.
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