Tappets too tight.

Top End (cylinders pushrods etc.)
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Woodstock
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Tappets too tight.

#1

Post by Woodstock »

Bought a set of stock replacement Sifton tappets and they will only go into the guides about half way. Anyone ever deal with this before? If they were the wrong size they wouldn't go in at all right? Do I need to hone the guides?
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Re: Tappets too tight.

#2

Post by Cotten »

Woodstock!

First I would micrometer the tappets' diameters along their length to determine if they are tapered.

And then gauge the tappet guide block bores for comparison. More likely that they are tapered, we should hope.

With luck, the tappets are slightly oversize, so that the 'blocks' can be honed to take up wear.
(Early blocks require unique honing mandrels. Mine disappeared....!)

....Cotten
Woodstock
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Re: Tappets too tight.

#3

Post by Woodstock »

Cotten

The tappets are not tapered and every reading I've taken on the guides reads slightly larger than the tappets! I'm doing something wrong here cause from what I'm seeing they should slide right in.These are after market guides that I bought years ago (don't even remember who made them) and they ought to be loose if anything not tight. I was thinking that making a light pass with a hone might be all it takes.
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Re: Tappets too tight.

#4

Post by RUBONE »

Woodstock,
Keep in mind the way the tappet thrusts against the guides along their length. The slight amount of ovality created by that thrust combined with minor wear could be allowing the tappets to only go in part way. Careful honing should help make them round once again and true to the tappet body with the proper amount of running clearance. Good luck and keep us informed about how it goes.
Robbie
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Re: Tappets too tight.

#5

Post by Cotten »

Woodstock!

Before blindly attacking anything with machinework, you might try inking up the tappets with a felt-tip marker, and determine exactly where the interference is.

A carborundum stone may do wonders.

....Cotten
Woodstock
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Re: Tappets too tight.

#6

Post by Woodstock »

Thanks for the input guys. I'll see what is revealed with a felt tip pen and go from there. I'm not in any hurry, this bike has been down a long time, and while money is pretty tight with me I'd like to do as good a job as I can. I'll keep you posted and I'm sure I'll be asking a lot more questions before it's all said and done. Thanks again.
Jim
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Re: Tappets too tight.

#7

Post by 6hds »

Woodstock, seems like you could have got the set I sent back 2 months ago to v-twin. I ordered standards, which would measure .731 and all of them were .7317. They do list a OS tappet they say is .732, so maybe what we got was boxed wrong in Taiwan. If you don't want to send them back, honing the blocks OS is a fix. The best way is done with a mandrel type hone (like a Sunnen) to keep the hole true. A floating stone or berry bush type will just follow the wear pattern established in the bore, and not renew the fit.
Woodstock
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Re: Tappets too tight.

#8

Post by Woodstock »

6hds

These measured out at .731. I'm going to do what Cotten said with the felt pen and see what kind of wear pattern shows and then either find a mandrel hone or replace the guides when I can come up with the bucks. Thanks for the info.

Woodstock
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Re: Tappets too tight.

#9

Post by 1951 adam »

Woodstock, measure the ID of the tappet bores in both axis , top ,center, bottom. That will tell you exactly what's up. Use a mic and a small telescoping gauge for accurate readings.
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Re: Tappets too tight.

#10

Post by Izh Kabob »

Woodstock,
I know this sounds smartass but if you don't find it with mics, I either mixed my intake & exhaust or put them in backwards (rotation) and had same problem. I swear they looked right until someone showed me.

Harry

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Re: Tappets too tight.

#11

Post by 6hds »

return them, get .005 O/S and send them to Veetwin racing. $55 to re-fit them, and on a Sunnen hone. Done right. Fast turn around too. Gary
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