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Now with Pictures
I finished the oil modifications on my '85 VF700S about a month ago. It started out as a minor tune-up, but it developed into a major job. Don't let me scare anyone away from doing the job themselves. I made it more difficult due to my inherent perfectionist personality and the fact that I hate to do a job twice. I appreciate all the help from other members on the list that kept me on the straight and narrow. If I had it my way I would have ended up rebuilding the entire engine. Incidently about five years ago I attempted to install a new exhaust system on my Datsun 280. Three years later and thousands of dollars spent I had a 'show' car. Not only did it have a new exhaust system... it was stainless steel.
Before beginning I reviewed the collective knowledge contained in Robyn's KotV4 web page. Top notch page if you ask me. I decided to use the main oil galley method and steel brake line. I wanted a permanent installation that looked like a factory mod. My expenses were greater than others, mostly due to the additional tools required.
I removed the usual parts, exhaust, clutch housing, radiator and tank. I cut off the original oil line and saved the banjo fittings. Installed a 10 x 1.5mm bolt and washer to seal the old transmission galley. I removed the main galley cap and drilled a pilot hole up through the flat casting next to the oil pan. Using a flat 1" grinding stone and drill I removed a small raised shoulder on the flat surface. I did this because I will be using the original fitting, bolt and washers and need a flat surface to seal. I continued with the galley and drilled and tapped for the original banjo bolt. This was the easiest part. Partial view of the banjo fitting and line from underneath.
Next I drilled out the original fittings to accept the 5/16" brake line. I left a small inner shoulder so that the line would not extend fully into the fitting. Using a tube bender and cutter I tried to route the new lines in between the intake and coolant pipes. Its difficult because of the lack of visibility.
After that second day, I pulled the carbs out of frustration. Big difference when you can actually see what your doing. View from the top with carbs removed I routed the pipe for the rear cylinder down and to the right between the two banks. The other pipe, for the front cylinder head, I made another slight 'S' curve and joined the two by flaring the ends and attaching a compression tee.
Looking at the righthand side of the engine, the feed pipe was routed forward, up and around the starter, between the engine mount and crankcase, and finally at an angle up to the tee. I trimmed the excess length of the lines and temporarily intalled the banjo fittings and bolts. Having marked the lines and fittings I sweated and soldered the joints. With all the fittings installed and the pipes attached to the tee, its solid. I was thinking that I may have to anchor the pipes to the crankcase.
With the rightside clutch cover removed, I replaced the shift lever spring that Robyn mentioned on his webpage. I also dismantled the carbs, and cleaned them while they were out. No major problems found except for the typical split and frayed vacuum lines.
Closer inspection of the the radiator revealed some corrosion and build-up. Using a mild acid cleaner used for commercial heat exchangers I filled up the radiator and let it set for several hours. Drained, flushed and repeated once more. The radiator was a good as new. I had it pressure tested just for grinds. Rodding out the radiator would have costed $70. Anyone trying the same thing, be careful, precautions should be taken when working with acid. Don't try this on the bike either, the acid will eat the aluminum engine.
Well I got everything back together. The first time I cranked it up, it smoked, sputterd, knocked horribly and leaked oil in several places. I was not not a happy mechanic that late evening. I thought for sure I screwed it up. I've always been a little timid about motorcycle maintenance. Give me a GM V8 and I'm happy. The smoking problem was oil residue on the exhaust, the sputtering and knocking was caused by all the tinkering I did with the carbs.
A good balance job took care of the problem. It was so far out of whack that each cylinder wanted to run at different speeds. One of the oil leaks was a loose fitting. The other was leaking at the main oil galley fitting. Apparently I did not get a good square surface on the flat casting. I remedied that by using a 'dowty' seal. Its just like the original crush washers except it has a rubber seal on the inner diameter. Its made by Earl's Performance Products. For FYI, the Honda crush washers I ordered for the other fittings worked fine.
With the carbs tweeked and the leaks fixed, the V4 is purring once again.
I made several oil pressure checks. The manual specifies 53-75 psi at 176F at 5k rpm. Its centered right on 65 psi, but drops off gradually as temp goes up.
At 200F the pressure drops down to about 45 psi. I was told it is normal due to the characteristics of the oil. At idle the pressure was 20 psi when cold and drops to about 6psi. Just to satisfy my concern I borrowed a fellow members Sabre(Mike Berger) and checked the oil pressure. It was a little higher than mine but it did follow the same pressure drop-off. About 53 psi at 5k rpm, and about 8psi at idle. I'm appeased for the moment. I enlarged the original banjo bolt holes, but it dropped the idle pressure to less than 3 psi. I went back to the stock bolt.
I'm going to have the oil analyzed to see if there is any abnormal wear.
With the oil mod and some well needed work complete, and I think my Sabre will last another ten years as long as the cam wear stays in remission.
Earl's Performance Products
Dowty Seal 3/8" p/n 178106 set of two $2.65
Honda
Oil bolt washer p/n 90545-300-000 $1.99
(this one fit the recess in the cylinder heads)
Brian L. Sydness '79 280ZX, '85 VF700 Sabre
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