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2000 Yamaha Big Bear 400 No Spark Mikuni Carburetor Install (Continuation of No Spark)

Go to solution Solved by Gwbarm,

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Thanks Mech, the oil did still seem like it had viscosity but not as thick as when I put it in. The noise does go away immediately when I increase throttle just a little bit, no really reving it up just increasing engine speed slightly. I did blow out the oil cooler with an air pump didn't get crazy with it ,so im sure I didnt get all of it out.

Judging for how much rust I got out of the stator cover I figured I had the same in the clutch cover and that I would have to pull it to work on stuck clutch plates, even ordered a gasket for it I was so sure, but it moved ,so far I haven't pulled the clutch side, so I will see how it goes.

As always thanks for your help.

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Working on front brakes today, master cylinder reservoir screws had disintegrated as usual got the cover off plastic cover found the rubber seal was filled with water got it out no fluid in reservoir added fluid piston stuck , I am not even wasting my time I ordered o new one. So im going to try and flush out the lines more than likely the bleeders are coroded to the caliper, haven't got there yet . More fun!

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Bleeders were in good shape opened them up and nothing came out.

Found this in my stash, its for a 1 inch bar not 3/4, oh well, that's what gaffers tape is for. I did hook up the line before I tried it.



It pumps really well according to the puddle underneath the left caliper



I first thought it was a disintegrated hose, but it appears to be at the connection to the caliper, I will dig further when I get the wheel off.

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I got the front brakes fixed, I was so convinced it was the caliper seals, that I ordered a set of new calipers, got all of the mud chiseled away so I could free up the bleeder valves and one was stuck in the open position, assuming previous owner never finished the job, decided brakes were just a luxury anyway. That is where my fluid was coming from. So before i put on the new calipers I decided to give these a try. Got my new master cylinder installed filled with fluid, started looking for my brake bleeder, hadn't used it in a while, must have been a longer while than I thought, because the pump seals had gone bad. I hate having to stop and go to the store, kind of puts a kink in your routine, and takes a little while to get back on track. So I devised a bleeder, I know, why didn't you just pump and open and pump and open, that's too easy, I have to make things complicated, so I devised a brake bleeder and it worked very well. I generally use this to suck oil out of places that I don't want it or add oil to tight places, like differentials.



Got the old fluid out of the lines, nothing but water was in the rubber seal, reservoir was dry, i cycled fluid several times through the line to make sure I got all the crud out, closed the valves and had a nice firm lever. Not factory issue, but it works.






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I just wanted to share this bit of information, about a year ago I bought a Milwaukee cordless cutoff tool, they had been out for a while and I always looked at it and just kind of ignored it, wasn't sure how it would work and what I really needed it for.

Since I have had it its one of my favorite tools. I use it for everything. I used it fabricating my Granite countertop, it won't cut sheets of granite, but it perfect for doing little touch up areas, small cutouts etc. that you can't get to with a grinder. I have used it for cutting aluminum shed roofing it does a perfect job on that, no jagged edges like you get from tin snips. It's perfect light easy to handle and powerful.

I work on a lot of vintage bikes and its perfect for cutting 40 year old rusted bolts, small, light, get in tight places etc.


Im sure a lot of you guys already use one , I just wanted to share my experience with it.


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Good work.  A bit of sheet aluminum might be better that gaffa tape to shim the handlebar.

And for future reference Gw..  Brake calipers almost never leak from the piston seals. The pistons don't slide on the seals in operation. The seals jamb on the piston under pressure and flex to allow the piston to move the tiny distance they need to press the pad on, then it's their un-flexing that pulls the piston back a tiny amount. Even with rusty pistons they don't seem to leak more than enough to catch a bit of dust.

And what sorts of old bikes do you work on ? I have lot's of manuals, paper and pdf, for old british stuff. Matchless, ajs, bsa triumph, norton.. Worked on all of them and some of the smaller british and euro stuff.

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Thanks for the tip on the caliper never had one leak there like you said, but I have had them get stuck where you could not move them.

Right about the tape it works, but I don't think its a long term solution, I will try the aluminum sheet. 

I have mostly Vintage Japanese bikes. All of the honda 305s from the 60s, two  Kawasakis from the 60s, Samurai 250 and Roadrunner 120, 2 stroke, both Yamaha Big Bears from the 60s, 250 and 305, 2 stroke. I do have a triumph Trident 1973, my favorite year, Suzuki RE5 Rotary from 1976. Oh and 2 Black Bombers 450.

I have been collecting for quite a few years and my plan was to restore all these when I retire, I got a few done, but I forgot to calculate into the equation, was the energy level decline as you get older. 

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Went out today to check the differential fluid, the front bolt came out, not without  a fight, a normal ratchet wouldn't do it, had to get my 24 inch out, the rear one is an Allen or appears to have started out its life as an Allen, it is stripped, appears it might have been worked on with an SAE too small not metric. Im afraid im going to have to chisel it off. Front was 17mm bolt, this appears to have been a 5mm, I got a 6 in there but it wouldn't get it. Im going to try smoother things tomorrow,



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Who.. very cool collection Gw..  The 305s were a classic..  and the rotary. ..  Good work preserving them even if you never do get to restoring them.

That allen key will be 6mm.  4,6,8,10 are what the japs use.  At least it's got the big flange head to tap around huh.. 

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