yamaha 1200r engine failure

[kend301]

Re: yamaha 1200r engine failure

If I did my math right , .66mm clearance , one thousandanth of an inch is .0254 mm so .66 divided by .0254 gives you 25.98 thousandths of an inch .
WOW THAT IS LOOSE !!! I would check all cylinders and sleve the dammaged one (chip sounds big ) and get proper pistons that have about .002 to .003 thousandths of piston to wall clearance. You may need to get .020 over pistons for a kinda of close fit . To do it properly you need to get a machine shop envolved !

 

[Angus R]

Re: yamaha 1200r engine failure

That's the figures i came up with also. Sure does sound loose. All the cylinders are the same as well as all pistons are that same small size. I'm having a machine shop that is familiar with these engines re-do the cylinders and replace the pistons. I'm also having the head trued up, it's not off much but i figure, fix it now so it's right. Can i buy replacement gaskets to use when i clean the carbs or do i have to buy complete re-build kits, they are kinda pricy.

 

[kend301]

Re: yamaha 1200r engine failure

What kind of carbs are they ? I can find them and look at a pic and tell you what you really need to do just a cleaning .

 

[Angus R]

Re: yamaha 1200r engine failure

They are Mikuni BN44"s. Thanks for your help.
Angus

 

[kend301]

Re: yamaha 1200r engine failure

Are they standard bn44's or super bn44's ?
the proper rebuild kits are $38.00 for standard $57.00 for supers . Given all that is included in the kits, you will need it all, it is not a bad price .
See your PM for the site I found these on .
You may also want to PM Jeff W .. see a few posts up , He seems to have a better grip on details like this and may know a better place to get kits than I do and he has posted some fantastic help for alot of people.

 

[Angus R]

Re: yamaha 1200r engine failure

As far as i can tell they are not super bn44's, just regular bn44's, at least that's what the shop manual says. You are right about Jeff, he is very knowledgeable about these things. Thanks for all the help...
Angus

 

[Angus R]

Re: yamaha 1200r engine failure

How can i test the oil pump in this pwc to be sure it is working properly?

 

[kend301]

Re: yamaha 1200r engine failure

Can't help you on this one , My Sport Jet is an older Pre Mix , Never ever read the oil injection part of the shop manual ... Good question for Jeff W !!!

 

[Angus R]

Re: yamaha 1200r engine failure

I'm sure Jeff knows, Jeff??

 

[Jeff Walkowiak]

Re: yamaha 1200r engine failure

with the pump off the engine,you use a reversible drill with a short piece of nylon tubing placed on a drill bit of appropriate diameter and then push the other end of the tubing on to the drive shaft of the oil pump, hook up an oil supply,, usually another piece of tubing with oil in it,, then run the drill in reverse and see if the oil comes out in even spurts from the holes that feed the oil lines,, usually the pumps don't fail,, the lines fall off and kill one cylinder,, island racing in new york has kits to replace the oil lines and clamps.

 

[kend301]

Re: yamaha 1200r engine failure

Jeff never fails to come through for someone needing info !!! I have alot of respect for this man !!

 

[Angus R]

Re: yamaha 1200r engine failure

So do i Ken, Jeff knows his stuff alright, thanks again Jeff. Here's another question. Jeff, awhile back you said i should possibly surface the head on this. How much can i surface assuming i take the same amout out of the "squish ring"?
Thanks,
Angus

 

[Jeff Walkowiak]

Re: yamaha 1200r engine failure

you surface it by hand on a piece of glass with sand paper glued to it.. you do it till it is free of dark spots,, do not use a mill or other machine,, and only clear it of dark spots,, do not do anything to the gaskets etc,, you will be taking a very small amount off doing it by hand. I use 80 grit paper..

 

[Angus R]

Re: yamaha 1200r engine failure

Thanks Jeff, i'll try that.

 

[Angus R]

Re: yamaha 1200r engine failure

Hi all,
While cleaning out the crankcase in this engine i found the washer/shim that was missing on #1 rod/wristpin. I'm now thinking this dim bulb that "rebuilt" the top end dropped it down there and did'nt bother to fish it out. I think it got picked up by the crank and ended up between the piston skirt and cylinder wall and that's what broke the piston skirt. This washer was bent pretty badly on one side as if it may have broke the piston. Anyone have any thoughts on my theory, Jeff? Ken?

 

[kend301]

Re: yamaha 1200r engine failure

Can you post a pic of the washer as it is ? Might help . Anything being beat around a crankcase will find a way to do damage , Looks like you found your point of failure to me !!! Post a pic .. more curious than questioning .
Bob

 

[Angus R]

Re: yamaha 1200r engine failure

Thanks for your input Bob. I can't get this picture to load for some reason, probably me. Anyway, this washer is kinda rolled up and mashed pretty badly on one side. I guess that's the best way to describe it.
Angus