tony.mon wrote: ↑Fri Apr 12, 2024 11:49 amYes, I did, Chris. My storm was quite a bit lighter then, and so was I!
Very impressive stats I thought, do you realise Tony that was in 2008
Chris.
The RD400 drag bike
Re: The RD400 drag bike
Very impressive stats I thought, do you realise Tony that was in 2008
Chris.
Re: The RD400 drag bike
Rebuild is started.
Phase 1 :
A) get the crank rebuilt with new rods, all new brgs, labyrinth seal, trued up then welded
B) get the barrels bored out to 2nd oversize,
C) cut windows in the back of the pistons to suit the boost port.
I would then collect these parts, rebuild the bottom end , put it in the frame, chain on, carbs on, ignition on etc and take the whole bike back for phase 2.
Phase 2:
A) reprofile the combustion chamber in the heads to suit the new piston curve
B) set the squish
C) cut up the expansion pipes and lengthen them by making them cross over, making all the shapes so they fit the frame and avoid the foot controls
D) get it started and time up the ignition and get some heat cycles on the engine.
Harry the engine tuner goes off to Thailand (for 3 months) in 4 weeks time, so I had the chase him to get my engine phase 1 work done, as I will only have 5 days available before he goes away to get phase 2 done.
He said he would have the bits done for me to collect Saturday, but the crankshaft fought him for 3 days as it is getting old and sloppy from being taken apart too often in the past. Getting it to run true took him till Friday night so when i arrived we still had to do the barrels and pistons.
While the boring was going on, we checked the crank on the bottom cases and noticed that the new main bearing had much bigger locating pegs and they were in a slightly different position too. So we had to cut new locations into the cases to suit, then wash it all again for assembly.
With the crank now in, I put the gear clusters back in, added gasket compound to the mating faces and bolted them together.
Once the bores were cut to the new size we dry fitted them with the piston (no rings) and new .5mm base gaskets to check the deck height and port timings on each side to see if they are matched.
Harry wasn’t happy with one exhaust port higher than the other and some variations in the transfers, so he scribed a line where he wanted them to be and got his porting tools out to cut them to the new height and shape.
Then he started the honeing process to get the piston clearance up to 0.0025” and a good surface finish for the rings to bed to.
This should have been easy but the large ports keep catching the edge of the stones and breaking them off the tool holder, so about 2 hr later we have the clearance right on both barrels!!!!!!!!!
It has taken us 9hrs to get to this point and we still haven’t cut the piston windows in! so that just puts a bit more work onto the phase 2 visit.
Some photos
This was the crank waiting for assy with its new rods
Then once assembled checking the runout
The boring bit…… literally
Engine together to check the deck height (how much the piston is above or below the top of the barrel)
Adjusted the transfer ports
And I noticed some std rd400 barrels so it was interesting to see the difference
And as he makes most of his money in scooters now, here is one of the street tuned Lambretta motors with special barrels and his billet head
Phase 1 :
A) get the crank rebuilt with new rods, all new brgs, labyrinth seal, trued up then welded
B) get the barrels bored out to 2nd oversize,
C) cut windows in the back of the pistons to suit the boost port.
I would then collect these parts, rebuild the bottom end , put it in the frame, chain on, carbs on, ignition on etc and take the whole bike back for phase 2.
Phase 2:
A) reprofile the combustion chamber in the heads to suit the new piston curve
B) set the squish
C) cut up the expansion pipes and lengthen them by making them cross over, making all the shapes so they fit the frame and avoid the foot controls
D) get it started and time up the ignition and get some heat cycles on the engine.
Harry the engine tuner goes off to Thailand (for 3 months) in 4 weeks time, so I had the chase him to get my engine phase 1 work done, as I will only have 5 days available before he goes away to get phase 2 done.
He said he would have the bits done for me to collect Saturday, but the crankshaft fought him for 3 days as it is getting old and sloppy from being taken apart too often in the past. Getting it to run true took him till Friday night so when i arrived we still had to do the barrels and pistons.
While the boring was going on, we checked the crank on the bottom cases and noticed that the new main bearing had much bigger locating pegs and they were in a slightly different position too. So we had to cut new locations into the cases to suit, then wash it all again for assembly.
With the crank now in, I put the gear clusters back in, added gasket compound to the mating faces and bolted them together.
Once the bores were cut to the new size we dry fitted them with the piston (no rings) and new .5mm base gaskets to check the deck height and port timings on each side to see if they are matched.
Harry wasn’t happy with one exhaust port higher than the other and some variations in the transfers, so he scribed a line where he wanted them to be and got his porting tools out to cut them to the new height and shape.
Then he started the honeing process to get the piston clearance up to 0.0025” and a good surface finish for the rings to bed to.
This should have been easy but the large ports keep catching the edge of the stones and breaking them off the tool holder, so about 2 hr later we have the clearance right on both barrels!!!!!!!!!
It has taken us 9hrs to get to this point and we still haven’t cut the piston windows in! so that just puts a bit more work onto the phase 2 visit.
Some photos
This was the crank waiting for assy with its new rods
- Crank bits ready
- Crank true
- The boring
- Deck height check
- Deck height check
- Fixing the porting
- Std RD 1
- Std RD2
And as he makes most of his money in scooters now, here is one of the street tuned Lambretta motors with special barrels and his billet head
- Lambretta 225 special
AMcQ