New pipes that don't fit ports
by Bob Wemmer - RT custom Cycles
(Omaha NE USA)
From Bob Wemmer
I have a customers bike he brought in with a set of new shorty 2 into 1 header style pipes. He tried to get them bolted in to the exhaust ports and slide the flanges over the studs, but the pipes were 1/4 inch short from lining up. The flanges would not slide on the studs and with both of us trying to hold and pull the front pipe into place it would not go.
Answer: Heres what I did. New pipes when welded together will contract during the welding process or if taken out of the jig too soon before they have cooled down.
Sometimes the application for various types of choppers will vary slightly and not fit exactly.
What to do. Put a block of wood on the floor and rested the back cylinder pipe on the block. You will need a second person to help hold the pipes and blocks. Put another block of wood (2X4's short pieces) on top the the pipe and place the front base of a small 1 & 1/2 ton floor jack on top of the second block. Use about a 1 foot 2x4 stood on end on top of the jack raising plate and place it on the bottom of the upper pipe end. Jack up the floor jack to expand the pipes. If the pipes are 1/4 inch too short jack them apart 1/2 inch because they will contract back about a 1/4 inch. I measured the pipe ends before doing this procedure and knew I needed to expand them 1/4 inch. They measured 16 & 3/4 inches. It took two tries and finally ended up with 17 inches. We put them back into place and they fit perfect. The flanges slide into place with no trouble and they bolted up with no effort.
