YFM250 Moto 4 - Breathing new life.....help?

[pokolbinguy 4]

Hi All,

Following on from the brief interlude in the "introducing myself" thread....

 

In a nutshell, I acquired a YFM250 Moto 4 (1991) for cheap recently with the previous owner citing "no spark, needs a new magneto coil and I don't have time to fix it"... anyway I am dubious that the magneto/generator is the issue and thinking more along the line of ignition coil as after a clean up of the magneto I was able to get a rather decent voltage reading off the magneto with pull start and resistence readings seem to check out that the magneto is all ok (all 3 x phases = 1.2 ohms and no run to ground)

None the less I ordered a new Ignition coil and Magneto/generator coil and am waiting for them to arrive.

 

In the mean time I cleaned up the current Magneto, popped in a new battery and sparkplug, checked out all the wiring harness, all seemed good except I came across the "neutral switch" wire was broken.

 

After wiring up a new neutral switch wire, the neutral light now comes on  (small win) and the starter relay (attached to rectifier) now clicks. If I hit the starter switch on handle bar the starter motor spins and if I  pull the cord starter I get a spark on pull....YAY!! I'll try and attach a video below if possible.

 

So onto the starter motor. Starter solenoid seems to work A-ok, even if it looks crappy and starter motor spins as it should when I hit the start switch....but here is my issue.

 

When the starter motor runs it turns Cog #1 and Cog #2 (see photo below)....but the chain in the back of the starter which I assume is the timing chain, does not move and there is no apparent movement of the piston in the cylinder.

 

If I turn it by hand (per photo) or with the pull starter however the chain moves and the engine turns. However cog #2 rotates but not fluidly with the "Crank" (part I turn by hand) for the lack of a better word to use if that makes sense?

 

 

Is there a grub screw or similar on Cog #2 that fixes it to the center shaft to make it all turn when the starter motor is run? Could there be a part missing? Previous owner had the starter apart so could be possible?

 

The outer/front part seems to be on a key-way so not sure how to remove this easily to check how Cog #2 is attached.

 

What am I missing here?

 

 

 

 

 

Edited January 9 by pokolbinguy

[pokolbinguy 4]

Spark

 

Video if interested.

Edited January 9 by pokolbinguy

[wanrep 54]

You need a starter clutch.  It bolts to the back of the flywheel.  It's a one way clutch that locks up cog 2 when cranking.  You'll need a flywheel puller if you don't have one already.  Be sure to loctite the screws that hold the starter clutch to the flywheel.

Edited January 9 by wanrep

[pokolbinguy 4]

Looking at these links;

 

https://www.partzilla.com/catalog/yamaha/atv/1991/moto-4-yfm250b/generator

 

https://www.partzilla.com/catalog/yamaha/atv/1991/moto-4-yfm250b/starter-clutch

 

I assume the 'starter clutch' sits behind the generator rotor assembly?

 

Surely the original clutch is still in position and just needs freeing up?

 

 

[wanrep 54]

Yes, the starter clutch bolts to the back of the rotor/flywheel.  It has 3 rollers in it that grab the big gear when turned in one direction but freewheels in the other direction.  Usually the rollers and/or springs go bad, allowing it to slip instead of grabbing that big gear.

[pokolbinguy 4]

1 hour ago, wanrep said:

Usually the rollers and/or springs go bad, allowing it to slip instead of grabbing that big gear.

 

 

Thanks for the point in the right direction. Sounds like I need to the rotor/flywheel off. Any tips?

Surely the rollers / springs can be cleaned up instead of replacing the whole clutch?

[pokolbinguy 4]

Rightio so I got the fly wheel off behind the generator and removed the starter clutch......

 

Ummmm....See photo.

 

Where at the internals of the clutch? Springs etc?

 

Seems someone must have had issues with the clutch in the past so has removed the workings of it. Damn...Now I have to replace them / it.

 

In the mean time, is anyone able to explain in layman's terms how this clutch works? there doesn't seem to be anything to physically engage the cog (aka Cog #2 in previous post) when the starter motor runs?

 

How does the magic happen?

 

Cheers, Pok

[wanrep 54]

Someone would have to remove them.  Not like they can fall out.  Here's a pic of what it should look like.  When the sleeve part of that gear is in the clutch, it'll spin free in one direction but lock up in the other direction.

[pokolbinguy 4]

So I had a partial win after a dig around in the 'bucket of parts' (mainly bolts etc) that came with the Quad.

 

I found most of the parts for the starter clutch, well I think so anyway, (photo below)....but missing one part (Grrrr!!!) - 1 x 'CAP, STARTER CLUTCH SPRING' (part 1J7-15583-01-00). Hopefully I can get my hand on this. Partzilla shows it as available so hopefully available in Australia as I am sure it will be cheaper than replacing the whole clutch assembly if I can get away from it.

 

What I didn't come across, and not sure if I need them or not are the unknown parts that are shown on the exploded parts diagram (see below as "What is this?) - When I have looked at photos of the Starter clutch on line, replacement parts etc there doesn't seem to be any other parts?

 

Also, am I correct that the dowel pins are out of scale in the exploded view? I assume they are the the parts I have marked in my photo below and not another part that I require???

 

Cheers, Pok

 

Link to Partzilla with parts diagram as per below - https://www.partzilla.com/catalog/yamaha/atv/1991/moto-4-yfm250b/starter-clutch

 

 

[wanrep 54]

I think the mystery part in the diagram is still inside the clutch.  If it came out easily, there'd be a part # for it.  The dowel pin, in the diagram, is the big roller that you have.  They didn't draw it to scale.  Looks like all you need is one of those spring caps.

[pokolbinguy 4]

8 hours ago, wanrep said:

  Looks like all you need is one of those spring caps.

Nice ! if I can get them I may as well replace the springs while I am at it. I figure they are really the only parts that can fail?

[pokolbinguy 4]

So I got a new Starter cap today (part #9 on diagram), but still waiting on the new springs (part 8), I have the original three springs but figured they were the weak link in the chain so worth replacing....BUT they are coming from Japan and I won't have them until next week at least and I was hoping I might be able to get the old girl running sooner than that, so I thought I would put the starter clutch back together using the old springs. 

For the sake of it some photos attached to show the Starter clutch fitted back to the fly wheel to show it all ready to roll.

However, when I attempt to install the fly wheel  / starter clutch on the bike one of the little dowels keeps falling out.  VERY frustrating.

Am I right to think the springs need replacing and they are "lazy" ? Therefore they don't apply enough pressure on the dowel pin within the clutch plate to hold it into position as the flywheel/clutch is installed? Or am I just not doing it right...is there a trick?

Any suggestions?

 

Cheers, Pok

 

 

 

Edited January 22 by pokolbinguy
grammar

[wanrep 54]

If the springs are too weak to hold the rollers in, it's good you ordered new ones.  They are probably too weak for the clutch to work properly even if you got everything together.  I'd wait until you get the new springs.

When you're ready to install it, put the gear into the starter clutch first.  Then slide it on the crank as a unit.  Before you slide it all the way on, you'll have to fit that small gear (cog #1 in your picture) into place. 

[pokolbinguy 4]

Alright so I have finally had all the parts delivered that I was waiting to come in.

For interest sake, new parts include battery, starter clutch springs, case bolts, ignition coil (didn't end up needing it) , regulator/generator (didn't end up needing it either), spark plug, oil filter, air filter, engine oil.  I think thats all of it...not all yet installed.

 

First port of call was to put the starter clutch back together with the new springs (x 3) and a new gasket for the starter assembly cover. Assembled, connected all the wires and hit the starter button....still have spark...nice start, that means the starter clutch is doing it's job now.

Put the spark plug into the head, hit the switch....sounds like she wants to run.

Pulled the carby apart, cleaned it out, found a bit of crap it in. Fuel flow now all good. Put back together. Hit the button, still wants to run but just not getting there...a bit of "start ya bastard" (aka aero start).....and ...well see video.

***See post below for video***

 

......watching video....seeing awesomeness....Yeee Haa !!

So now that I have had that side of things sorted it looks like I am heading in the right direction....so now to check the drive side of things....damn, for the life of me I can't get the oil drain plug off. All that is happening is rounding the head off the bolt/cover.  So removed the oil filter cover to find the lovely contents within....seems this bike has, as suspected, been very wet at some stage in its previous life, possibly a flood.

Off with the oil filter cover, and out with the oil filter....

 

 

Mmmm yum. Took the other cover off the side of engine....not sure what this cover is called;

 

 

 

That junk under the cover screams flood to me !

 

Any hoo, seems things are going the right direction at this stage in regards to getting the engine running but I have one question that I was hoping for some feedback on.

 

If the previous oil had water / other crap in it and I can't get the drain plug off, I was thinking of filling the engine with basic cheap engine oil (read cheapest available - Gulf Western Hi Tech Premium Engine Oil - 20W-50, 5 Litre  e.g https://www.supercheapauto.com.au/p/gulf-western-gulf-western-hi-tech-premium-engine-oil---20w-50-5-litre/105586.html?cgid=SCA010704#prefn1=size&srule=Price+Ascending&prefv1=5+Litre&start=1), possibly without oil filter, run engine for a very short period, to loosen any crap in the engine, drain contents at oil filter housing. Put in new filter, again cheap oil. Run, drain. New oil filter, new good oil (Castrol Activ 4T 15W-50 ...already have 4L of this on hand) ..happy days??

Thoughts?

Cheers, Pok

 

Video of awesomeness.

Edited March 5 by pokolbinguy

[Frank Angerano 550]

Nice work on the progress.  I would not run the engine without a filter.   The filter will catch any junk that’s in the engine as your running it clean.    So unfortunately it sucks to have to waste a few filters but I would do it at this point based on what you have into the bike already.  

Use a cheap oil at first for a flush, put a fresh filter in.  Run the bike leave the filter in drain the oil. Put fresh oil in run it again and drain once more changing the filter and oil this time and you should be good to go. Maybe put a few hours on the bike and change it one more time.  

As for the oil plug that’s a bummer but there is an alternative to get the oil out.   Take a look at this. It’s a small pump with a tube that gets down in the engine.

They have electric ones as well but this one works good. My buddy uses it on his boat engine and the price is right.

Made in USA -GasTapper () Power Equipment Model w/filter - Gas, Oil, Water, Fluid Changer Pump for Lawnmowers, ATV's, Quads, 4 Wheelers, Power Equipment, Motorcycles, UTV, Generators, Tractors - Search "by Gentap" to see other versions https://www.amazon.com/dp/B00TA5ECJQ/ref=cm_sw_r_cp_api_i_bOLFCb26VZSZC

[pokolbinguy 4]

21 minutes ago, Frank Angerano said:

I would not run the engine without a filter.   The filter will catch any junk that’s in the engine as your running it clean. 

 

Yeh fair point. My gut says don't run it without a filter....my tight arse wallet says do it just to loosen everything up and then dump the oil....but I guess there is little benefit to doing that.

 

21 minutes ago, Frank Angerano said:

 

Made in USA -GasTapper () Power Equipment Model w/filter - Gas, Oil, Water, Fluid Changer Pump for Lawnmowers, ATV's, Quads, 4 Wheelers, Power Equipment, Motorcycles, UTV, Generators, Tractors - Search "by Gentap" to see other versions https://www.amazon.com/dp/B00TA5ECJQ/ref=cm_sw_r_cp_api_i_bOLFCb26VZSZC

 

 

They don't ship to Australia Shall keep any eye out for this sort of gear though. good idea. Otherwise could just use the big syringe type.

 

Edited March 5 by pokolbinguy

[JacobSlabach 92]

I would definitely try to find a way to get that drain plug out.  As for starting, I would check compression, and try to get the specs on the carb adjustment to start there.  Make sure you have fuel, make sure your sp is good.  have fun.🤘

[Frank Angerano 550]

Any boat marina service location should have something like that since it’s really a device for boat engines.  Try a local auto parts place.   You will find one.  It’s not that hard to find.  

 

[JacobSlabach 92]

7 hours ago, Frank Angerano said:

Any boat marina service location should have something like that since it’s really a device for boat engines.  Try a local auto parts place.   You will find one.  It’s not that hard to find.  

 

But that wont get all the crap out of the bottom of the engine will it??

[Frank Angerano 550]

There shouldn’t really be any crap in there it was just water in the oil.  Most of the stuff will get pushed through the filter as the bike is ridden over time and removed by doing oil changes.  Whatever crap was in there should flush through the system and get trapped in the filter I would think.   If the drain plug gets destroyed while trying to remove it then it’s party over ! We all seen that with the plug on that post a few weeks back by one of our members.  So I would think if that’s going to be it and not touching the plug as to not destroy it then go with the pump.  

[JacobSlabach 92]

oh ok.

[pokolbinguy 4]

Update - The old girls seems to want to run quite well.

I need to adjust the H-L-R adjustment as getting into reverse is not working properly and need to replace carburetor gasket...but at the moment  all sounds and seems to function normal in forward gears......well as much as up and down the driveway. Need to get the H-L-R sorted and get his old girl on the farm to see how she reallly runs.

 

So far....winning !!!

 

Edited March 12 by pokolbinguy

[Frank Angerano 550]

Nice work ! Good luck and safe riding ! 

[pokolbinguy 4]

Hi All,

I am hoping someone may be able to help me with how I go about adjusting the H-L-R lever.

Currently I have the shaft (marked below as A) installed but have the catch/locator (for the lack of a better term) that engages "B" off.

Bike is running well, and I assume it is in High range.

When the shaft is connected to the H-L-R lever I can not get it to move from H all the way through to R. I assume due to being out of adjustment however when I move the shaft (A) back and forth when disconnected  from the H-L-R lever it seems to click back and forth into two different positions.

Now this is where I am confused? If there is High,Low and Reverse, should there  be 3 positions, not two?  OR is the lug marked as "B" on the below image involved in engaging Low?

 

Any tips on how to adjust the H-L-R lever would be great as it would be handy to be able to use reverse.

 

Cheers, Pok