Replacing spray bar in a SAITO 72
05-02-2007, 08:25 AM
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Replacing spray bar in a SAITO 72
One of my Saito engines, a .72, had a too hard contact with terra firma, resulting in a bent the needle valve and a deformed spraybar.
I am a little bit uncertain about how to go about replacing the spraybar (picture below), which seems to be a press fit.
Presently I do not have access to a press tool so I am considering heating the carb house in the oven in as I usually do with engine crankcases when fitting new bearings. Has anybody tried this method of mounting the spraybar? Any advice is very much appreciated.
/Red B.
I am a little bit uncertain about how to go about replacing the spraybar (picture below), which seems to be a press fit.
Presently I do not have access to a press tool so I am considering heating the carb house in the oven in as I usually do with engine crankcases when fitting new bearings. Has anybody tried this method of mounting the spraybar? Any advice is very much appreciated.
/Red B.
05-02-2007, 08:54 AM
#2
RE: Replacing spray bar in a SAITO 72
You can drive out the old one with a rod or something. Drive it from the outside towards the inside.
Then new one is pressed in from the inside. Some are not very tight. Others are really firm.
There is a little tiny thin o-ring that goes under the nut.
I used a mandrel to press the new spray bar into place so I wouldn't mess it up.
Most Saito's have a slit in the end of the spray bar. If you find this slit, it goes towards the intake manifold as squarely accurate as possible.
I used an arbor press on the half dozen or so I have put in. But there's no reason you cannot use a drill press or vice.
With the thing being so small, there no reason you cannot use a small hammer. You need some sort of sleeve to go over the spray bar and you will need a hole in your board for the threads to stick out into on the outside of the needle valve body as you drive the spraybar home.
Then new one is pressed in from the inside. Some are not very tight. Others are really firm.
There is a little tiny thin o-ring that goes under the nut.
I used a mandrel to press the new spray bar into place so I wouldn't mess it up.
Most Saito's have a slit in the end of the spray bar. If you find this slit, it goes towards the intake manifold as squarely accurate as possible.
I used an arbor press on the half dozen or so I have put in. But there's no reason you cannot use a drill press or vice.
With the thing being so small, there no reason you cannot use a small hammer. You need some sort of sleeve to go over the spray bar and you will need a hole in your board for the threads to stick out into on the outside of the needle valve body as you drive the spraybar home.
05-09-2007, 01:25 PM
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RE: Replacing spray bar in a SAITO 72
Just a short note to let you know that I succeded in replacing the spraybar with almost no tools at all All it took was a wooden dowel, a 1/8" drill and a hair dryer :-).
I made a makeshift "mandrel" from a piece of 5/16" wooden dowel by drilling a 1/8" hole in the end of the dowel. The part of the spraybar that projects into the carb throat was a squeeze fit in this hole. I heated the carb body (after removing all o-rings) using a hair dryer.
When the carburettor body was really hot (my guesstimate is approx. 300F) the spray bar could be installed by firmly pushing it in place with the dowel.
/Red B.
I made a makeshift "mandrel" from a piece of 5/16" wooden dowel by drilling a 1/8" hole in the end of the dowel. The part of the spraybar that projects into the carb throat was a squeeze fit in this hole. I heated the carb body (after removing all o-rings) using a hair dryer.
When the carburettor body was really hot (my guesstimate is approx. 300F) the spray bar could be installed by firmly pushing it in place with the dowel.
/Red B.
