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Post by arrow on Apr 25, 2012 6:56:08 GMT 1
There are a few reasons this can happen; 1, There are no shims presently fitted to the pump. 2, The shims are in the wrong place (on top of the big washer) instead of underneath it. 3, Since the last time the gap was checked the outside parts of the pump (mainly the screw in the top casting) have worn by more than 0.15mm effectivly closing the gap. This takes a long time to happen, but I've seen it loads of times due to lack of simple maintanence. When you set the gap double the spec. to 0.3mm and the motor will love it. If you find it is over oiling go smaller in increments of 0.05 using 600 wet/dry to thin the shim(s) down, although with the modern oils this should not be necessary.  |
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Post by woodentopp on Apr 25, 2012 9:00:49 GMT 1
I rebuilt mine, the easiest way to measure the gap is to remove the pump and turn the worm wheel by hand that way you have control that the cam is at the right place. Otherwise as Arrow says above.
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Post by stanlc7189 on Apr 25, 2012 18:35:46 GMT 1
Thanks guys. The shims are in the right place but I will add more to get the gap. What I don't quite understand is why the adjustment plate doesn't move in and out at idle unless I push the pulley against the pump body. Is this normal?
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Post by nikfubar on Apr 25, 2012 19:05:27 GMT 1
Thanks guys. The shims are in the right place but I will add more to get the gap. What I don't quite understand is why the adjustment plate doesn't move in and out at idle unless I push the pulley against the pump body. Is this normal? At idle it only moves in & out the 0.15mm if shimmed properly so basically at idle your pump is doing nothing if it's not moving. Here's a tip someone suggested if your having trouble getting the correct size shims, use an old feeler guage of the correct size, drill a 5mm hole through it & trim to the size of a washer. rdlccrazy.proboards.com/index.cgi?board=info&action=display&thread=12280 |
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Post by flames on Apr 25, 2012 19:09:14 GMT 1
no,it should move on its own dude.would an airlock possibly cause it? could be wrong here,but if say when you shut the bike off,the oil drains back or causes an airlock somehow,maybe the plunger wont operate till the oil gets thro? and perhaps when you push the plunger it expels the air and starts pumping? arrow would be the man to ask.......he is the oil pump god.
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Post by arrow on Apr 25, 2012 19:15:25 GMT 1
Thanks guys. The shims are in the right place but I will add more to get the gap. What I don't quite understand is why the adjustment plate doesn't move in and out at idle unless I push the pulley against the pump body. Is this normal? Stanlc7189, read my first post again, reason no. 3. The outside parts (pulley and screw) have worn by more than 0.15mm closing the gap. Wear will make the pulley come forwards and it will touch the big washer all the time unless the throttle is opened, and then the pulley moves down. |
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Post by stanlc7189 on Apr 25, 2012 23:22:44 GMT 1
Cheers. I'll re-shim it setting the clearance to 0.3mm ish and see if that makes a difference. Like I say, the washer does move in and out when the pulley is pushed against the pump body, so I don't think there's an air lock. What you say, Arrow, makes sense to me now. I don't want to ride the bike again until this is sorted. Last summer I blew the crank and it could be that it was oil starvation partly to blame at high rpm.
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Post by arrow on Apr 26, 2012 6:29:40 GMT 1
Oil starvation may well have done it. At full throttle setting the max output from the pump cannot be changed, unless you spin it faster, this is the differance between the 250 and 350 pumps, pump on the 350 spins quicker for any given revs of the motor. The problem is that if you shut the throttle at high engine speed if there is zero gap (it can also be less than zero) the motor recieves no oil. With the correct gap the motor will recieve the correct amount of oil, ie small stroke high turning speed. The gap also has influence over most of the rev range (but not full bore) A negative gap is really bad news. This is where you see no gap add say a 0.3mm shim and the gap measures 0.2mm, it was originally negative by 0.1mm. I have also seen this. Let us know how you get on.  |
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Post by stanlc7189 on Apr 27, 2012 0:59:13 GMT 1
Cheers Arrow, will do. It's a job for Sat am, unless I go to Stafford first (but it won't be on the LC!)
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Post by stanlc7189 on Apr 27, 2012 22:22:25 GMT 1
Just re-shimmed the oil pump. I added a 0.65mm shim to give a clearance of 0.3mm. That implies that the previous clearance was -0.35mm. NOT IDEAL!!! Any wonder that the engine blew up last year!
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Post by arrow on Apr 27, 2012 23:54:54 GMT 1
So is it all ok now, do you have a stroke at tick over ? If so, thats it sorted. |
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Post by stanlc7189 on Apr 28, 2012 0:31:16 GMT 1
Yeh Arrow, decent stroke now. Thanks for all your advice, much appreciated.
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Post by donypvs on May 6, 2012 9:39:59 GMT 1
Hi guys
Just bought a 1984 YPVS and it had the same problem NO shims. Took 0.8 mm to get the clearance right. Motor runs ok but I'm paranoid that damage is in there. Intend to use until a problem shows rather than strip and look. Who know how that will work out.
Don
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Post by arrow on May 6, 2012 14:16:35 GMT 1
Welcome in. At least its getting the right amount of oil now, you might just be lucky.
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Post by captaincaveman on May 6, 2012 19:40:11 GMT 1
whats all this talk about shim then  are they inside the pump? im just about to put my pump back in place don't remember seeing any shims when i took it off  |
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Post by arrow on May 6, 2012 20:22:57 GMT 1
Here; [a href="  "] [/a] |
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Post by captaincaveman on May 6, 2012 20:34:05 GMT 1
are i see well not touched that part of it yet so i,l leave that well along for the time being.
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Post by arrow on May 6, 2012 20:36:55 GMT 1
are i see well not touched that part of it yet so i,l leave that well along for the time being. Just make sure you have some movement of the plunger at tick over with the oil pump cover removed. No movement = bad news/blowup's. The shims control the oiling of the motor through most of the rev range. This is a must check item for these bikes. |
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Post by captaincaveman on May 6, 2012 22:23:50 GMT 1
When it comes it it you can guarantee i,l be asking lots more questions about this little part.
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Post by donypvs on May 7, 2012 7:59:45 GMT 1
Welcome in. At least its getting the right amount of oil now, you might just be lucky. Yeah hope so. I have another LC2 and it had the pump set at 3 times the factory setting and different jets and pilots side for side plus the wrong bowl om the choke carb. This one was a runner that had been fully rebuilt. When you buy a new stroker you have to go through everything I have found. The bike with no shims had heavily corroded float valves - also a runner even if most of the petrol came out the overflows . Hey that's what makes it interesting. Don |
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Post by arrow on May 8, 2012 0:09:18 GMT 1
Welcome in. At least its getting the right amount of oil now, you might just be lucky. Yeah hope so. I have another LC2 and it had the pump set at 3 times the factory setting and different jets and pilots side for side plus the wrong bowl om the choke carb. This one was a runner that had been fully rebuilt. When you buy a new stroker you have to go through everything I have found. The bike with no shims had heavily corroded float valves - also a runner even if most of the petrol came out the overflows . Hey that's what makes it interesting. Don This refers to the shim setup only. The maximum output of the pump cannot be changed of course. The pump is under the influence of the big washer and therefore the shims for most of the rev range. Shimming the pump heavily does have its advantages especially with todays very clean burning oils. |
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Post by fatty on May 8, 2012 22:43:50 GMT 1
Arrow
I could do with your help i have posted in lc chat will you have a look and give me your oppinion on my oil pump please
Ta Ash
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are they inside the pump? im just about to put my pump back in place don't remember seeing any shims when i took it off 
