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Post by darboots on Oct 7, 2019 8:46:49 GMT 1
Morning All.
I'm getting towards the end of my engine rebuild, but am having problems fitting the RHS Powervalve assembly.
The left (servo cable side) PV has gone in fine, and rotates 360 degrees without any issue.
The right (non servo cable side) PV will not rotate more than approx 270 degrees without binding up - without the end cap. When the end cap is fitted, it binds up badly and will hardly move. If I slacken the PV joining bolt, the valve will rotate more easily, but still binds up.
I've been trying to polish the valve where it sticks with Emery cloth, but don't seem to be getting anywhere with that. It seems to improve things slighty, and then nips up again.
Is it likely that the valve itself is fooked / twisted / bent? Or the cylinder itself?
I am using new/replacement (eBay) bearings as the engine didn't come with the originals when bought.
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Post by steeley on Oct 7, 2019 12:51:20 GMT 1
Hi , had this sort of dick dance with a mates tzr 250 . In the end i had the cylinders on the bench and kept fitting the valves and turning them . If they were tight it was took back out and worked on then tried again. It took a while both sides but got it sorted in the finish.
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Post by midlifecrisisrd on Oct 7, 2019 15:50:58 GMT 1
Are the pv's new?
If so gen or pattern
I have a set that are not true so bind like you say
Steve
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Post by tacky1 on Oct 7, 2019 19:10:38 GMT 1
I would check the bolt in the center to make sure it’s not bent.
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Post by jessy03 on Oct 7, 2019 21:35:06 GMT 1
They only need to rotate about 10 degrees, put the pulley on and check, line it up with hole in the holder/cylinder turn it 10-15mm clockwise.
Jess
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Post by darboots on Oct 8, 2019 7:37:17 GMT 1
Thanks for all the replies lads...
Are the pv's new? If so gen or pattern I have a set that are not true so bind like you say Steve They're not new. I'm fairly sure they're genuine, but not 100%. They came with the engine when I bought that in boxes - the engine fitted to the bike was a 350LC motor, so I bought this one to rebuild and replace that one. I would check the bolt in the center to make sure it’s not bent. I wondered that myself.
I've tried swapping the two bolts between the valves (LH <--> RH), and it's made no difference to either valve. The pulley side still rotates 360 degrees, and the non-pulley side still binds in the same place/orientation.
Interestingly, each bolt has a flat surface ground between the head and threaded part - anyone know what the purpose of this is? Are they meant to be like that?
They only need to rotate about 10 degrees, put the pulley on and check, line it up with hole in the holder/cylinder turn it 10-15mm clockwise. Jess I just worry about stretching the cables, or breaking the pulley when they cycle during self test.
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Post by midlifecrisisrd on Oct 8, 2019 8:58:09 GMT 1
I'd guess those bolts have been fitted to a tuned set
Tuners tend to cur the power valves back to stop the rear obstructing the port when fully open
Quite common to go right through to the mount bolts.
That should not affect the valves as the centre face and pins hold it in line
You may have a mismatched valve or a repro one
I found that the valves are made as pairs as if you try and fit halts from different valves some won't line up
Also years ago I bought new pv's from TSS and as they had no billet ones they sent cast ones which had the exact problem yours has
Rh valve binds when the fit the end cap. I trimmed the valve with a flap wheel
Steve
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Post by darboots on Oct 8, 2019 11:19:30 GMT 1
The valves appear to have been polished when compared to pictures of 'new' valves - the exhaust tract part is smooth, unlike what I see of new valves.
I wouldn't be surprised if I've got a mis-matched valve!
Fowlers have new valves listed for both sides at ~£117 ea., however MB-Design have a pair of billet valves cheaper (£189) than Gen Yam.
Where would you trim the valve with a flap wheel? At the cap end?
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Post by midlifecrisisrd on Oct 8, 2019 13:53:22 GMT 1
The valves appear to have been polished when compared to pictures of 'new' valves - the exhaust tract part is smooth, unlike what I see of new valves. I wouldn't be surprised if I've got a mis-matched valve! Fowlers have new valves listed for both sides at ~£117 ea., however MB-Design have a pair of billet valves cheaper (£189) than Gen Yam. Where would you trim the valve with a flap wheel? At the cap end? At the point that rubs on the tunnel Steve |
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Post by roach3 on Oct 8, 2019 15:34:01 GMT 1
I’ve just got a gen set from norbo cheaper than the billet ones
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