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by Gui.dorey
Sun Dec 30, 2018 6:00 pm
Forum: Four stroke
Topic: Square Four Push Rods
Replies: 31
Views: 1754

Re: Square Four Push Rods

Well, I believe I have found the answer, which confirms the measurements from Bill just above. Among the box of old bits that came with the bike I found two old valves, springs and 3 old guides. The valves and the springs match the new ones exactly, so the collet groove is correct as well as the ste...
by Gui.dorey
Sun Dec 30, 2018 1:16 pm
Forum: Four stroke
Topic: Square Four Push Rods
Replies: 31
Views: 1754

Re: Square Four Push Rods

IMG_1537.JPG So, here's a complete measurement of the whole assembly. All 8 are the same as all parts came new from Drags, the only difference being of course inlet and exhaust valve diameter. Springs, collars, collets, guides and stems are all identical. Comparison dimensions would be lovely if so...
by Gui.dorey
Sat Dec 29, 2018 11:09 pm
Forum: Four stroke
Topic: valve guides
Replies: 8
Views: 880

Re: valve guides

Thanks Bill, There are two different guides for the MkI, but I have the correct ones for my engine. There's a description of the difference on the Draganfly catalogue. You can check online under MkI head on their web pg. The top of my guides isn't concave - it might just be the picture that appears ...
by Gui.dorey
Sat Dec 29, 2018 8:32 pm
Forum: Four stroke
Topic: Square Four Push Rods
Replies: 31
Views: 1754

Re: Square Four Push Rods

And two more.
by Gui.dorey
Sat Dec 29, 2018 8:31 pm
Forum: Four stroke
Topic: Square Four Push Rods
Replies: 31
Views: 1754

Re: Square Four Push Rods

Hi Simon,
The rocker arms are equal lengths. Did think of that as well and had checked them before.

Hi Paul,
As far as I can tell, the parts are correct - collets are 1/4" in length.

Here are some pics. Maybe you chaps can spot something. Measurements are in inches.
by Gui.dorey
Sat Dec 29, 2018 2:25 pm
Forum: Four stroke
Topic: Square Four Push Rods
Replies: 31
Views: 1754

Re: Square Four Push Rods

I've got the valves all running freely in their guides now. There was a small burr on the top edge of the guides which was catching on the valve stems. My fault, when I drifted the new guides in and didn't check them properly after reaming. However, I still think I have a problem. I still couldn't t...
by Gui.dorey
Sat Dec 29, 2018 11:06 am
Forum: Four stroke
Topic: Square Four Push Rods
Replies: 31
Views: 1754

Re: Square Four Push Rods

Nothing worked, so I disassembled the rockers and found that the inlet valves of Nr 2 and 3 were stuck in their guides. So next the head came off again, and those two valves are definitely not moving for some reason, so will have to disassemble them as well. All other valves are moving fine, althoug...
by Gui.dorey
Sat Dec 29, 2018 8:16 am
Forum: Four stroke
Topic: Square Four Push Rods
Replies: 31
Views: 1754

Re: Square Four Push Rods

Hi everyone, Thanks for the replies. I don't think I have the push rods crossed - I checked this thrice before assembling the rods and I do have the circlips on the followers. It seems as if the inlet valves for Nr 2 and Nr 4 are stuck or hitting something. I still haven't assembled the timing chain...
by Gui.dorey
Fri Dec 28, 2018 7:37 pm
Forum: Four stroke
Topic: valve guides
Replies: 8
Views: 880

Re: valve guides

Hi Bill, Did the same not too long ago,but be prepared for a lot of foul language. I put the head in the oven at 150C and was able to drift the old guides out without too much trouble. The new ones were from Drags and they are a tight interference fit. Head back in the oven and the guides in the ice...
by Gui.dorey
Fri Dec 28, 2018 3:43 pm
Forum: Four stroke
Topic: Square Four Push Rods
Replies: 31
Views: 1754

Square Four Push Rods

Hello everyone, My engine rebuild is progressing along and I've assembled the head now. Today I assembled the rockers, but I must have done something wrong because the camshaft only turns a few degrees fwd and backwards and seems to get stuck, as if the valves hit something or reach the end of their...

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